An implantable neurostimulation device

Abstract

The disclosure relates to an implantable neurostimulation device. The implantable neurostimulation device comprises an electrode lead having a free end shaped for blunt dissection of a patient's tissue during implantation of the implantable neurostimulation device. The electrode lead comprises a first portion extending along a first length of the electrode lead and including the free end. The electrode lead comprises a second portion extending along a second length of the electrode lead, the first portion having a higher stiffness than the second portion.

Description

AN IMPLANTABLE NEUROSTIMULATION DEVICEBACKGROUND

[0001] Implantable neurostimulator devices are known for nerve stimulation to treat a variety of conditions, include sleep apnea, urinary dysfunction, chronic pain and migraine.

[0002] Known implantable neurostimulators have a housing and an electrode. A power antenna, microcontroller, and communication antenna are disposed in the housing for receiving power from an external source and receiving / transmitting sensor information relating to the electrode. A delivery system can be used to position the neurostimulator in a patient, in particular proximate to a nerve, by cutting an opening in the patient and passing the delivery system into the opening to position the implantable neurostimulator.SUMMARY OF THE INVENTION

[0003] According to the present invention there is provided an implantable neurostimulation device comprising an electrode lead having a free end shaped for blunt dissection of a patient’s tissue during implantation of the implantable neurostimulation device.

[0004] In examples, the electrode lead comprises a projection which projects outwardly to extend beyond a diameter of the electrode lead, the projection being disposed at or proximate to the free end of the electrode lead.

[0005] Advantageously, the blunt dissection of the patient's tissue, provided by the free end of the electrode lead, may reduce tissue damage during advancement and may reduce the risk of nerve or vasculature damage. As explained below, when the implantable neurostimulation device is received in a needle of a delivery device the free end may protrude beyond a tip of the needle to provide the leading point of the assembly during at least a part of the implantation method. Where present, the projection may protrude beyond the circumference of the needle, which may reduce tissue damage caused by the tip of the needle.

[0006] In examples, the projection may comprise a rearwar dly facing surface for anchoring the free end of the electrode lead in the tissue. In particular, the rearward facing surface may inhibit rearward movement of the electrode lead through the tissue. Advantageously, the projection may therefore act as an anchor or anti-migration feature at the free end of the electrode lead. Advantageously, after implantation of the implantable neurostimulation device with the free end proximate to a target nerve, the projection may help to prevent movement ofthe free end and therefore maintain the implantation position of the electrode lead relative to the target nerve.

[0007] In examples, the rearwardly facing surface may project away from the axis of the electrode lead (e.g. radially). The rearwardly facing surface may engage a tip of the needle and / or act as an anti-migration member.

[0008] In examples, the projection may be wider than a diameter of the electrode lead and comprises a rim. In examples, the electrode lead may be receivable in a needle of a delivery device for implantation of the implantable neurostimulation device such that the free end of the electrode lead protrudes beyond a tip of the needle, and wherein the rim is sized to abut an end of the needle.

[0009] In examples, the implantable neurostimulation device may comprise a cavity for accommodating at least part of the tip of the needle when the electrode lead is received in the needle of the delivery device. In examples, the implantable neurostimulation device may comprise an annular cavity for accommodating the tip of the needle when the electrode lead is received in the needle of the delivery device. The annular cavity may be formed in the rearwardly facing surface of the projection. The projection may extend circumferentially about the electrode lead, fully or partially. When at least a part of the tip of the needle is received in the annular cavity it is covered and provides for blunt dissection by the free end of the electrode lead during implantation, and provides additional stiffness for the free end of the electrode lead.

[0010] The tip of the needle may be defined as a terminal face of the needle (i.e. the surface extending between the inner surface of the needle (which defines the lumen) and the outer surface of the needle). Where the terminal face of the needle is angled (non-perpendicular) with respect to the inner surface of the needle and / or the outer surface of the needle, the tip may be defined as the leading edge of the needle.

[0011] In examples, the projection may be attached to, or co-moulded with, a terminus of the electrode lead.

[0012] In examples, the implantable neurostimulation device may comprise an end cap.

[0013] In examples, the electrode lead comprises a first portion extending along a first length of the electrode lead and including the free end, and a second portion extending along a second length of the electrode lead, the first portion having a higher stiffness than the second portion.

[0014] The implantable neurostimulation device may comprise one or more anti-migration members. The one or more anti-migration members may extend at least partially around the circumference of the electrode lead. In examples, the one or more anti-migration members may be positioned on the first portion of the electrode lead. The one or more anti-migration members may be proximal to or at the free end of the electrode lead.

[0015] In examples, the implantable neurostimulation device may comprise a plurality of antimigration members spaced at intervals around a circumference of the electrode lead. In examples, the implantable neurostimulation device comprises a first set of anti-migration members and a second set of anti-migration members. Each of the first set of anti-migration members and the second set of anti-migration members comprise one or more anti-migration members. The first set of anti-migration members are spaced from the second set of antimigration members along the length of the electrode lead. In particular, the first set of antimigration members are closer to the free end of the electrode lead than the second set of antimigration members. The anti-migration members of the first set of anti-migration members and / or the second set of anti-migration members may be moveable with respect to the electrode lead. They may be deployable from a closed configuration to a deployed configuration. In the deployed configuration the anti-migration members may extend further from the electrode lead than in the closed configuration.

[0016] The anti-migration members of the first set of anti-migration members and / or the second set of anti-migration members may be configured to be received within a profile of the lumen of the needle. In examples, the anti-migration members may be covered by the needle, prior to deployment, when the electrode lead is received within the lumen of the needle. In examples, the anti-migration members may be tines or other protrusions.

[0017] The first set of anti-migration members may be configured to act in an opposite direction to the second set of anti-migration members. For example, the first set of antimigration members may act to resist movement of the electrode lead towards its free end (i.e., against movement of the electrode lead deeper into the tissue). The second set of anti-migration members may act to resist retraction of the electrode lead towards the skin. In examples, in the deployed configuration the anti-migration members of the first set extend further from the electrode lead as the distance from the free end decreases. In contrast, in the deployed configuration the anti-migration members of the second set extend further from the electrode lead as the distance from the free end increases.

[0018] A distal length of the electrode lead (distal from the housing portion) comprising the free end and the first set of anti-migration members may further comprise at least one electrode. The first set of anti-migration members may define a (virtual or physical) boundary between a distal side of the electrode lead which is distal from the housing portion and a proximal side of the electrode lead which is proximal to the housing portion. The free end of the electrode lead forms part of the distal side. The at least one electrode may be positioned: on the distal side; or at a same length along the electrode lead as the first set of anti-migration members; or on the proximal side. In examples, the electrode lead may comprise at least one electrode positioned on the distal side, and at least one electrode positioned on the proximal side e.g., between the first set of anti-migration members and the second set of anti-migration members.

[0019] In use, the electrode lead may be partially deployed to expose the distal length of the electrode lead. Once exposed, the first set of anti-migration members adopt the deployed configuration to anchor the free end of the electrode lead. The at least one electrode which is exposed can be used to test the position of the electrode lead relative to the target site. If the electrode lead needs to be re-positioned, the needle can be pushed forwards to re-sheath at least part of the electrode lead and force the first set of anti-migration members back into the closed configuration within the needle. The electrode lead may then be repositioned as needed before being re-deployed and re-tested as needed. Once the lead is in the appropriate position, the electrode lead can be fully deployed to expose the second set of anti-migration members. This may be achieved by retracting the needle to a greater extent than when only the distal length of the electrode lead is deployed. The second set of anti-migration members may deploy automatically once exposed, adopting a deployed configuration. In this configuration, the second set of anti-migration members inhibit retraction of the electrode lead towards the skin as the needle is retracted thereby ensuring appropriate anatomical positioning of the lead is maintained during needle retraction. According to the present invention there is also provided an implantable neurostimulation device comprising an electrode lead and an end cap provided at a free end of the electrode lead, wherein the end cap is wider than a diameter of the electrode lead.

[0020] The end cap may comprise the projection. The end cap may be shaped for blunt dissection of the patient's tissue during implantation. The end cap may have a penetrating outer surface. The penetrating outer surface may be shaped for blunt dissection, for example thepenetrating outer surface may terminate in an apex. In examples, the apex of the end cap may be pointed, rounded or substantially flat.

[0021] In examples, an outer diameter of the end cap may increase away from the apex to a maximum diameter at or near a rear end of the end cap. In examples, the outer surface of the end cap may taper.

[0022] In examples, the end cap may shield the free end of the electrode lead.

[0023] In examples, the end cap may be at least partially hollow for receiving the terminus of the electrode lead and is attached to, or co-moulded with, a terminus of the electrode lead.

[0024] In examples, the end cap may comprise a body portion. The body portion may cover a terminus of the electrode lead. The body portion may comprise the outer (blunt-penetrating) surface of the end cap. The body portion may be configured to be received within the lumen of the needle. The needle may be configured to receive the end cap therein. The end cap may be wider than a diameter of the electrode lead. The body portion may have the same width or be wider than the diameter of the electrode lead.

[0025] The end cap may include an attachment member for connecting the end cap to the electrode lead. The attachment member may extend from the radially projecting rim. In examples, the attachment member may comprise a socket for receiving a terminal end of the electrode lead. The annular cavity may be defined between the flange and the attachment member and / or the electrode lead.

[0026] In examples, the end cap may comprise a first tapered part and a second tapered part. The first and second tapered parts may be connected to each other, with the smaller end of the first tapered part attached to the larger end of the second tapered part. The first and second tapered parts may be integrally formed or attached to each other. Such an end cap with first and second tapered parts may improve anchoring of the free end of the electrode lead after implantation.

[0027] In examples, the electrode lead of the implantable neurostimulation device may comprise a tubular lead body. The tubular lead body may comprise or consist of a silicone rubber, a silicone elastomer, a polyurethane, a polytetrafluoroethylene (PTFE), or any other flexible biocompatible material. The one or more electrodes may be provided on the tubular body. The tubular body may be manufactured by extrusion or moulding, or a combination of extrusion and moulding. Lead wires may extend through the tubular body, for example connecting to the electrodes. An antenna, for example an antenna wire or helix, may beprovided in the tubular body. The antenna may be a wireless power receiver antenna. The tubular body may be at least partly filled, for example backfilled, with a filling material. The filling material may comprise or consist of silicone rubber or an adhesive, such as an epoxy. The filling material may be added to the interior of the tubular body in liquid form and then cured or polymerised.

[0028] The end cap may comprise a rigid material. For example the end cap may comprise or essentially consist of polyurethane, silicone elastomer, silicone rubber, platinum iridium, or nitinol. In some examples the end cap is attached to the electrode lead, in particular the tubular body, for example by adhesive, suturing, or welding. In other examples the end cap is comoulded with the electrode lead, in particular the tubular body. In other examples the end cap is over-moulded onto the electrode lead, in particular the tubular body.

[0029] In examples, the electrode lead may comprise one or more electrodes positioned at or near the free end. In examples, the electrode lead may comprise a plurality of electrodes grouped at or towards the free end of the electrode lead.

[0030] In examples, the implantable neurostimulation device may comprise a housing portion operably connected to the electrode lead. The housing portion may be connected to the electrode lead at a second end, opposite to the free end. The housing portion may comprise an electronics assembly connected to the one or more electrodes for stimulating a target nerve during use. The electronics assembly may comprise a power supply for powering the electrodes to generate electrical impulses. The electronics assembly may be hermetically sealed within the housing portion. The housing portion may be a cylindrical housing. The housing portion may be tubular. One or both ends of the housing portion may include a housing portion end cap. The housing portion end cap(s) may be flat or rounded. A rounded housing portion end cap may assist in implanting the housing portion as described below.

[0031] In other examples, the electrode lead may comprise a connector at a second end of the electrode lead, opposite to the free end. The connector may be for connecting an implantable pulse generator (IPG) or other electronics that operably couple to the electrode lead, in particular the electrode, for providing nerve stimulation.

[0032] The electrode lead may be connected to the housing portion and extend from the housing portion. In examples, the implantable neurostimulation device may comprise a connector which connects the electrode lead to the housing portion.

[0033] The connector may comprise or consist of an elongate lead connected between the electronics assembly of the housing portion and the electrode lead. When the implantable neurostimulation device is received in a needle of a delivery device the elongate lead may extend from the housing portion out of the side slot of the needle to the electrode lead. The elongate lead may have a similar diameter to the electrode lead. In some examples the connecting lead may have a smaller diameter than the electrode lead. The connector may comprise one or more additional electrodes.

[0034] The electrode lead may be configured to prevent translation of the electrode lead through a slot in the needle of the delivery device. For example, the electrode lead may have a greater diameter than the connector. The electrode lead may include one or more side projections configured to fit within corresponding grooves in the needle for retaining the electrode lead within the needle.

[0035] The one or more side projections may extend along a full length of electrode lead. The one or more side projections may comprise two projections disposed on opposite sides of the electrode lead. Preventing translation of the electrode lead through the slot may prevent inadvertent buckling of the electrode lead when the needle is advanced. The one or more side projections on the electrode lead may be configured to prevent the electrode lead from exiting the slot.

[0036] In examples, the electrode lead may comprise a sleeve which at least partially surrounds a circumference of the electrode lead. The sleeve and / or side projections may increase an effective diameter of the electrode lead. The sleeve and / or side projections may be positioned at a rear end of the electrode lead e.g., proximal to the connector.

[0037] In some examples, the electrode lead may be directly connected to the housing portion. Prior to deployment, a length of the electrode lead may be received within the lumen while a second length may be located outside of the lumen of the needle such that the electrode lead extends from outside of the needle to within the needle through the side slot.

[0038] In examples, the electrode lead may be at least partially flexible. For example, the electrode lead may be flexible. In examples, the electrode lead may have a first portion with a first stiffness, and a second portion with a second stiffness, the second stiffness being different to the first stiffness. The first portion may be at a distal end of the electrode lead (including the free end), and the second portion may be at a more proximal part of the electrode lead.

[0039] The different stiffnesses may be provided by different materials and / or construction of the different portions of the electrode lead. For example, the first portion may include a stiffening member or a material with a higher stiffness, and / or a larger diameter. In examples where the electrode lead comprises a tubular body, the stiffening member or material may be provided within the tubular body. For example, a metallic stiffening member may be provided in the tubular body in the first portion, or a stiffening filling material may be provided in the tubular body in the first portion. In one example, the tubular body may comprise a first filling material in the first portion and a second filling material in the second portion, the first filling material having a higher stiffness than the second filling material. In other examples, the tubular body may comprise a first material in the first portion and a second material in the second portion, the first material having a higher stiffness than the second material. The first portion of the electrode lead (with a higher stiffness) may comprise one or more electrodes, in particular a plurality of electrodes. The first portion of the electrode lead (with a higher stiffness) may comprise the free end. Accordingly, the distal end of the electrode lead (with the free end) may be stiffer than the proximal end of the electrode lead.

[0040] Advantageously, the stiffness of the electrode lead at the distal end (including the free end) may improve advancement of the electrode lead during implantation by blunt dissection. In particular, the stiffness of the electrode lead may support the free end (with optional end cap), allowing the free end to be pushed through the patient's tissue.

[0041] Further advantageously, the (more) flexible proximal end of the electrode lead may allow the proximal end to be implanted at a different orientation to the distal end. For example, as described further below, the proximal end may be implanted along a non-linear path and at least partially at an angle closer to parallel with the skin. This may improve the location of a housing portion or IPG attached to the proximal end, and improve power transfer from an external device.

[0042] In examples, the implantable neurostimulation device comprises the projection or end cap as described above, and does not comprise any further anchoring or anti-migration members. In this way, when implanted the implantable neurostimulation device is anchored at the free end of the electrode lead, which holds the electrode lead in position relative to the target nerve, and the remainder of the electrode lead is able to move a small amount within the tissue. This may beneficially allow the electrode lead to move with the tissue, for example dueto muscle or body movements, while the free end is anchored in place to ensure that the electrodes are positioned relative to the target nerve.

[0043] In examples, the implantable neurostimulation device comprises multiple (two or more) projections which project outwardly to extend beyond a diameter of the electrode lead, the multiple projections being disposed at or proximate to the free end of the electrode lead. The multiple projections may be spaced form one another around a circumference of the electrode lead. Alternately, each of the multiple projections may be aligned at a same circumferential position around the electrode lead. In such examples, the multiple projections may be spaced from one another along a length of the electrode lead. Providing such aligned projections may allow each of the projections to be accommodated within a single slot in the needle prior to deployment (or following re-deployment of the needle).

[0044] According to the present invention there is also provided an implantable neurostimulation device comprising an electrode lead, wherein a free end of the electrode lead comprises a penetrating surface for blunt dissection of a patient’s tissue.

[0045] According to further aspects of the present invention there is provided an implantable neurostimulation device comprising an electrode lead having a free end shaped for blunt dissection of a patient’s tissue during implantation of the implantable neurostimulation device. The electrode lead comprises a first portion extending along a first length of the electrode lead and including the free end, and a second portion extending along a second length of the electrode lead, and wherein the first portion has a higher stiffness than the second portion.

[0046] The different stiffnesses may be provided by different materials and / or construction of the different portions of the electrode lead. For example, the first portion may include a stiffening member or a material with a higher stiffness, and / or a larger diameter. The first portion of the electrode lead (with a higher stiffness) may comprise one or more electrodes, in particular a plurality of electrodes.

[0047] Advantageously, the stiffness of the first portion of the electrode lead at the free end may improve advancement of the electrode lead during implantation by blunt dissection. In particular, the stiffness of the electrode lead may support the free end (with optional end cap), allowing the free end to be pushed through the patient's tissue.

[0048] Further advantageously, the (more) flexible second portion of the electrode lead may allow the proximal end of the electrode lead to be implanted at a different orientation to the first portion. For example, as described further below, the second portion may be implantedalong a non-linear path and at least partially at an angle closer to parallel with the skin. This may improve the location of a housing portion or IPG attached to the second portion, and improve power transfer from an external device.

[0049] According to the present invention there is also provided an implant delivery apparatus comprising the implantable neurostimulation device described above and a delivery device for implanting the implantable neurostimulation device within a patient, wherein the delivery device comprises a needle having a lumen for receiving the electrode lead such that the free end of the electrode lead protrudes beyond a tip of the needle.

[0050] In examples, the projection may extend outside of a profile of the lumen.

[0051] In examples, the needle may comprise a slot extending at least partially along the length of the needle and wherein the projection is received within the slot. In examples, the needle is retractable relative to the electrode lead during implantation. In particular, in examples the needle is retractable between: a first position in which the free end of the electrode lead, including the projection, extends beyond a tip of the needle, and a second position in which the free end of the electrode lead is positioned within the lumen of the needle and the projection sits within the slot of the needle.

[0052] In the first position the implant delivery apparatus may be advanced and the free end of the electrode lead provides blunt dissection of the patient's tissue. In the second position the tip of the needle provides the front-most point and the implant delivery apparatus can be advanced with sharp dissection provided by the needle. In the second position the height of the projection is mitigated by being received within the slot of the needle. Accordingly, in the second position the anchoring or anti-migration effect of the projection is reduced or prevented by the slot of the needle, which reduces the amount of the projection that is exposed to the patient's tissue. This may permit the implant delivery apparatus (including the electrode lead) to be retracted and repositioned.

[0053] The implant delivery apparatus may be changed between blunt dissection and sharp dissection by moving the needle between the first position and the second position. Additionally, after implantation the projection may provide an anchor or anti-migration member holding the free end of the electrode lead in position.

[0054] As described above, in some examples the electrode lead may comprise an end cap comprising the projection, and when the electrode lead is received in the lumen of the needle the end cap may protrude beyond the needle and at least partially cover the tip of the needle. In examples, the end cap may comprise a rim for engaging the tip of the needle, and the tip of the needle may contact the rim of the end cap. In examples, a tip of the needle may be substantially flat.

[0055] In examples, the needle of the implant delivery apparatus is retractable relative to the electrode lead during implantation. In particular, in examples the needle is retractable between: a first position in which the tip of the needle is positioned close to, against, or within the end cap of the electrode lead, and a second position in which the electrode lead extends beyond the tip of the needle and the end cap is spaced from the tip of the needle

[0056] In the first position the implant delivery apparatus may be advanced and the end cap of the electrode lead provides blunt dissection of the patient's tissue. The needle supports the free end of the electrode lead in this position, providing stiffness that enables blunt dissection. In the first position the anchoring or anti-migration effect of the end cap is reduced or prevented by the needle, which reduces the amount of the rearward facing surface that is exposed to the patient's tissue. This may permit the implant delivery apparatus (including the electrode lead) to be retracted and repositioned.

[0057] In the second position the end cap is exposed to the patient's tissue and acts as an anchor or anti-migration member. In this position the implant position of the electrode lead may be tested.

[0058] In examples, the electrode lead may comprise one or more further anti-migration members extending at least partially around the circumference of the electrode lead. In examples, the electrode lead may comprise a plurality of anti-migration members spaced at intervals around a circumference of the electrode lead. In examples, the one or more antimigration members may be fixed with respect to the electrode lead and may be configured to be received within a profile of the lumen of the needle. In examples, the one or more antimigration members may be covered by the needle when the electrode lead is received within the lumen of the needle.

[0059] In examples, the one or more further anti-migration members may be tines or other protrusions. The one or more further anti-migration members may be provided on a proximal part of the electrode lead (proximate to the housing portion or connector), or on the housing portion where present. The one or more anti-migration members may act in an opposite direction to the anchoring effect of the end cap. For example, the end cap may resist retraction of the electrode lead towards the skin, and the one or more further anti-migration members may act against movement of the electrode lead deeper into the tissue.

[0060] In examples, the delivery device may comprise a second needle having a lumen adapted to receive a housing portion of the implantable neurostimulation device. The needle described above may be a first needle. In such an example, the housing portion may comprise an electronics assembly attached to one or more electrodes of the electrode lead for stimulating a target nerve during use.

[0061] The second needle may be larger than the first needle. The second needle may be parallel to the first needle. The second needle may be axially offset relative to the first needle such that the housing portion is not aligned with the electrode lead.

[0062] In examples, the implantable neurostimulation device may comprise a connector which connects the electrode lead to the housing portion and wherein the first needle comprises a slot extending at least partially along the length of the first needle. The connector may extend from the first needle, through the slot and into the second needle. In this example the electrode lead may be configured to prevent translation of the electrode lead through the slot. In examples, the electrode lead may have a greater diameter than the connector and / or the electrode lead may include one or more side projections configured to fit within corresponding grooves in the first needle for retaining the electrode lead within the first needle.

[0063] In examples, the first needle may be retractable to deploy the electrode lead from the first needle. The delivery device may comprise a handle. The first needle may be movable or retractable with respect to the handle. The second needle, where present, may be fixed with respect to the handle.

[0064] According to the present invention there is also provided a method of implanting an implantable neurostimulation device using an implant delivery apparatus such as the implant delivery apparatus described above. The implant delivery apparatus comprises a needle for receiving at least part of the electrode lead therein. In examples, the implantable neurostimulation device may have any combination of features associated with any of theimplantable neurostimulation device described herein. The method comprising inserting a portion of the needle in which the electrode lead is received, into a patient, such that a free end of the electrode lead provides blunt dissection of the patient’s tissue during insertion. In examples, the method may comprise at least partially retracting the needle to expose the free end of the electrode lead.

[0065] In examples, the method may comprise testing the implantable neurostimulation device to determine if it is suitably located in the patient’s tissue.

[0066] In examples, at least partially retracting the needle to expose the free end of the electrode lead may deploy the free end of the electrode lead at an implant location within a patient’s tissue. The implant location may be proximate to a target nerve.

[0067] In examples, at least partially retracting the needle to expose the free end of the electrode lead may expose at least one of the one or more anti-migration members to the patient's tissue.

[0068] In examples, the method may further include re-extending the needle such that the electrode lead is once again received within the needle and subsequently repositioning the electrode lead using the needle.

[0069] In examples, the method may comprise at least partially retracting the needle to expose the free end of the electrode lead to deploy the free end of the electrode lead in a second implant position in the patient’s tissue, wherein the second implant position is different to the implant position. In examples, the second implant position is proximate to a target nerve. Retracting the needle may expose one or more electrodes of the electrode lead. At least partially retracting the needle to expose the free end of the electrode lead may deploy the free end of the electrode lead at a first location within a patient’s tissue.

[0070] In some examples, the method may include a step of extending the needle such that the electrode lead is once again received within the needle and subsequently repositioning the end cap and the free end using the needle. Re-extending the needle may include bringing the needle tip back into contact with the end cap.

[0071] In some examples, the method may involve testing the implant to determine if it is suitably located in a patient’s tissue. For example the location of the needle and / or end cap may be monitored during insertion and / or repositioning, e.g., using an ultrasonic transducer.

[0072] The functioning of the exposed electrodes may be tested to determine whether the electrodes are positioned close enough to the target nerve to stimulate a desired response. For example, an electrical impulse may be sent to the exposed electrode(s) and muscle contraction of the patient monitored. In examples, an electrical impulse may be sent to the exposed electrode(s) and evoked action potentials produced by the target nerve can be monitored.

[0073] In examples, the method may include a further step of retracting the needle to expose a free end of the electrode lead to deploy the electrode lead in a second position in a patient’s tissue, wherein the second position is different to the first position. For example the second position may be closer to a target nerve to be stimulated than the first position.

[0074] The steps of re-deploying the needle and repositioning the electrode lead, retracting the needle, and testing the implant to determine if it is suitably located may be repeated any number of times e.g., until the free end of the electrode lead is located optimally.

[0075] In some examples, at least partially retracting the needle to expose the free end of the electrode lead exposes at least one anti-migration member to the patient's tissue.

[0076] In some examples, the method may further comprise a step of advancing the deployed electrode lead through the patient's tissue by blunt advancement, as described in detail above.

[0077] In some examples, the method may comprise a further step of at least partially retracting the needle to expose the free end of the electrode lead to deploy the free end of the electrode lead in a second position in the patient’s tissue. The second position may be different to the first position.

[0078] The first position and / or the second position may be proximal to a target nerve or a nerve branch of the target nerve.

[0079] According to further aspects of the present invention there is provided a method of implanting an electrode lead of an implantable neurostimulation device. In these methods, no housing portion is attached to the electrode lead during implantation. A housing portion, for example an implantable pulse generator (IPG), may be attached to the electrode lead after implantation of the electrode lead.

[0080] In one example, the method comprises using a delivery device with a first and second needle. The first needle may be smaller (higher gauge) than the second needle. The first needle may be retractable relative to the second needle. The first needle may carry a leading part of the electrode lead and be used to implant the electrode lead as described above. The second needlemay carry a rear part of the electrode lead. After the first needle has positioned the leading part of the electrode lead proximate to the target nerve the first needle may be retracted. The delivery device may then be tilted or rotated, and the second needle used to implant the rear part of the electrode lead at a different angle to the leading part of the electrode lead, for example approximately parallel to the skin. The electrode lead may be bent or kinked during implantation of the rear part of the electrode lead. The electrode lead may include an end cap, as described above, and / or other anti-migration members. The end cap / anti-migration members may prevent movement of the leading part of the electrode lead during implantation of the rear part of the electrode lead.

[0081] In a further example, the electrode lead may be implanted using a delivery device with a single needle. The single needle is first used to carry the leading part of the electrode lead and implant it proximate to the target nerve. The needle can then be removed, leaving the electrode lead implanted. The rear part of the electrode lead can then be placed in the needle, and the needle can be used to implant the rear part at a different angle to the leading part, for example closer to parallel with the skin. The electrode lead may be bent or kinked during implantation of the rear part of the electrode lead. The electrode lead may include an end cap, as described above, and / or other anti-migration members. The end cap / anti-migration members may prevent movement of the leading part of the electrode lead during implantation of the rear part of the electrode lead.

[0082] In a further example, the electrode lead may comprise a loop and the delivery device may comprise a hook for engaging the loop and carrying the electrode lead during implantation. In examples, the electrode lead may comprise a loop at a leading part of the electrode lead, and the delivery device may include a needle with a hook at or towards an end. The hook may engage the loop such that the needle can be used to implant the electrode lead proximate to the target nerve. The hook and loop may disengage when the needle is retracted. In examples, the rear part of the electrode lead may also comprise a loop, and the hook of the needle can be used to implant the rear part of the electrode lead after implanting the leading part. For example, the needle may be used to implant the rear part of the electrode lead at a different angle to the leading part, such as closer to parallel with the skin. The electrode lead may be bent or kinked during implantation of the rear part of the electrode lead. The electrode lead may include an end cap, as described above, and / or other anti-migration members. The end cap / anti-migrationmembers may prevent movement of the leading part of the electrode lead during implantation of the rear part of the electrode lead.

[0083] In other examples, the electrode lead may comprise an expandable antenna. The expandable antenna may be located at or towards the rear part of the electrode lead. The electrode lead, and the expandable antenna, may be held within a lumen of a needle during implantation. In this position the expandable antenna may be held in a collapsed or compressed state. When the needle is retracted the expandable antenna may expand. The expandable antenna may thereby provide anchoring and / or extend in a direction preferable for wireless power and / or communications. In this example, the implantable neurostimulation device may not comprise any further part, such as a housing portion. The electrode lead may include an end cap, as described above, and / or other anti-migration members.

[0084] As described above, the invention provides an implantable neurostimulation device and associated method of implantation of an implantable neurostimulation device. The implantable neurostimulation device includes an electrode lead that is implanted proximate to a target nerve of the patient. In examples, the target nerve may be a deep nerve, a peripheral nerve, a nerve branch, a medial nerve branch, a distal nerve branch, a ganglion, a nerve root, a tissue target point adjacent to a distal nerve, or an organ target point adjacent to a distal nerve.

[0085] Advantageously, the methods of implanting the implantable neurostimulation device may include implanting at least the leading (distal) end of an electrode lead of the implantable neurostimulation device at a first angle and then implanting the rear (proximal) end (or housing portion, if present) at a second angle. In particular, the distal end of the electrode lead may be implanted at an intramuscular injection angle, and the proximal end and / or housing portion may be implanted at a subcutaneous (or shallower) angle. This method allows the implantable neurostimulation device to target deep nerves that might otherwise be difficult to access, while also implanting the proximal end of the electrode lead or housing portion (or subsequently attached IPG) at a shallower tissue depth and in a different orientation. This helps to implant the housing portion / IPG at a beneficial location and in a position and orientation that is beneficial for power transfer from an external device.

[0086] In some examples, as described above, the electrode lead may be implanted by a delivery device using blunt dissection for at least a part of the implantation method. Optionally, the delivery device may be able to change between blunt dissection and sharp dissection by moving a needle of the delivery device relative to the electrode lead. In other examples, theelectrode lead may be fully held within a needle of the delivery device, which includes a sharp needle for sharp dissection.

[0087] Use of blunt dissection, at least when close to a nerve, reduces the chances of nerve, tissue and / or vasculature damage and improves the accuracy of implantation.

[0088] Further advantageously, implanting the proximal end of the implantable neurostimulation device (proximal end of the electrode lead and / or subsequently attached IPG and / or attached housing portion) improves the implant location and improves power transfer from an external device.

[0089] For bilateral indications, two implantable neurostimulation devices may be implanted to target nerves on both sides to achieve bilateral stimulation.

[0090] In examples, the target nerve may be the hypoglossal nerve. More particularly the target nerve may be a branch of the hypoglossal nerve such as the medial branch, or the distal branch of the hypoglossal nerve. The medial branches of the hypoglossal nerve innervate oral cavity muscles such as the genioglossus muscle, and also the geniohyoid, styloglossus and hyoglossus muscles. Some of these muscles cause protrusion of the tongue, and others cause retrusion of the tongue. The most distal branches of the hypoglossal nerve form the genioglossus nerve branch, which innervates the genioglossus muscle. Contraction of the genioglossus muscle causes tongue protrusion.

[0091] To implant the implantable neurostimulator device to target the hypoglossal nerve (in particular a distal branch of the hypoglossal nerve) the implantable neurostimulation device is advanced percutaneously from a submandibular location, proximate to the submandibular symphysis of the patient, towards and into the genioglossus muscle. Two implantable neurostimulator devices may be implanted to target the nerves on both sides - bilateral stimulation.

[0092] In other examples, the target nerve may be a medial branch nerve (MBN) of the posterior ramus of the spinal nerve. Stimulation of the MBN of the posterior ramus of the spinal nerve may be used to treat chronic back pain and instability.

[0093] To implant the implantable neurostimulator device to target the medial branch nerve (MBN) of the posterior ramus of the spinal nerve the implantable neurostimulation device is advanced through the intertransversarius muscle. The implantable neurostimulation device may be advanced at an intramuscular injection angle (approximately 90 degrees to the skin surface), or at a subcutaneous injection angle (approximately 45 degrees to the skin surface).

[0094] In examples, two implantable neurostimulator devices may be implanted to target the medial branch nerve (MBN) of the posterior ramus of the spinal nerve on both sides - bilateral stimulation.

[0095] In other examples, the target nerve may be the vagus nerve. Stimulation of the vagus nerve may be used to treat one or more of: inflammatory bowel disease (IBD, Crohn's disease, and / or ulcerative colitis); rheumatoid arthritis and other inflammation-related conditions; epilepsy, seizures; depression; anxiety; cluster headaches; migraine; heart failure; and poststroke recovery. To target the vagus nerve the implantable neurostimulation device may be advanced through the neck region towards the vagus nerve.

[0096] In other examples, the target nerve may be the phrenic nerve. Stimulation of the phrenic nerve may be used to treat diaphragmatic dysfunction, and / or central sleep apnea.

[0097] In other examples, the target nerve may be the trigeminal nerve. Stimulation of the trigeminal nerve may be used to treat one or more of: trigeminal neuralgia; migraine; cluster headache; and / or epilepsy.

[0098] In other examples, the target nerve may be one or more occipital nerves, in particular the greater occipital nerve. Stimulation of one or more occipital nerves may be used to treat one or more of: occipital neuralgia; chronic migraine; cluster headache.

[0099] In other examples, the target nerve may be a dorsal root ganglion. Stimulation of the dorsal root ganglion may be used to treat complex regional pain syndrome (CRPS) and / or chronic neuropathic pain, and / or herniated disc and failed back surgery.

[0100] In other examples, the target nerve may be one or more of the ulnar, median and radial nerve. Stimulation of the ulnar, median and / or radial nerve may be used to treat upper limb pain, carpal tunnel syndrome, radial tunnel syndrome, and / or complex regional pain syndrome (CRPS).

[0101] In other examples, the target nerve may be the sural nerve. Stimulation of the sural nerve may be used to treat lower limb pain, and / or neuropathic pain in the foot or ankle.

[0102] In other examples, the target nerve may be the lumbar dorsal rami of the spinal nerves. Stimulation of the lumbar dorsal rami may be used to treat lower back pain and / or to provide functional restoration of the multifidus muscle. Two implantable neurostimulation devices may be implanted to target the lumbar dorsal rami nerve roots on both sides, for bilateral stimulation.

[0103] In other examples, the target nerve may be the suprascapular and / or axillary nerves. Stimulation of the suprascapular and / or axillary nerves may be used to treat shoulder injuries, subacromial impingement syndrome, and / or arthritis.

[0104] In other examples, the target nerve may be the saphenous / genicular nerves. Stimulation of the saphenous / genicular nerves may be used to treat chronic knee joint pain.

[0105] In other examples, the target nerve may be the sciatic nerve. Stimulation of the sciatic nerve may be used to treat chronic sciatic pain and / or diabetes.

[0106] In other examples, the target nerve may be the femoral nerve. Stimulation of the femoral nerve may be used to treat postoperative ACL reconstruction pain.

[0107] In other examples, the target nerve may be the intercostal nerve. Stimulation of the intercostal nerve may be used to treat intercostal neuralgia as a result of rib fractures, herpes zoster, and / or chronic abdominal pain.

[0108] In other examples, the target nerve may be the obturator nerve. Stimulation of the obturator nerve may be used to treat chronic pain due to fascial entrapment.

[0109] In other examples, the target nerve may be the brachial plexus nerve network. Stimulation of the brachial plexus may be used to treat postoperative pain after a rotator cuff repair procedure.

[0110] In other examples, the target nerve may be the tibial nerve. Stimulation of the tibial nerve may be used to treat one or more of: urinary, fecal and sexual dysfunction; urinary incontinence (primarily overactive bladder); pelvic pain including prostate, bladder, sexual pain and dysmenorrhea / menstrual pain; and / or irritable bowel syndrome (IBS).

[0111] In other examples, the target nerve may be the sacral nerve and / or sacral root. Stimulation of the sacral nerve and / or sacral root may be used to treat one or more of: urinary, fecal and sexual dysfunction; urinary incontinence (primarily overactive bladder); pelvic pain including prostate, bladder, sexual pain and dysmenorrhea / menstrual pain; and / or irritable bowel syndrome (IBS). To target the sacral nerve the implantable neurostimulation device may be advanced through the sacrum to the sacral nerves

[0112] In other examples, the target nerve may be the pudendal nerve. Stimulation of the pudendal nerve may be used to treat pelvic pain, including prostate, bladder and sexual pain, and / or dysmenorrhea / menstrual pain.

[0113] In other examples, the target nerve may be the sacral S2, S3, S4 nerves, and / or pudendal nerves. Stimulation of the sacral S2, S3, S4 nerves, and / or pudendal nerves may be used to treat pelvic pain, urinary, bowel and sexual dysfunction, and / or urinary (both underactive and overactive bladder).

[0114] In other examples, the target nerve may be the carotid sinus nerve and / or the carotid sinus baroreceptors. Stimulation of the carotid sinus nerve and / or the carotid sinus baroreceptors may be used to treat hypertension, heart failure and angina pectoris. To target the carotid sinus the implantable neurostimulation device may be advanced through the neck region towards the carotid sinus.

[0115] In other examples, the target nerve may be a sphenopalatine ganglion (SPG). Stimulation of an SPG may stimulate the SPG, afferent, efferent, parasympathetic, and sympathetic fibres than input and output the SPG. This may include the SPG, maxillary nerve, DPN, GPN, VN, nasopalatine nerve, superior posterior lateral nasal branches from the SPG, lesser palatine nerve, greater palatine nerve, and / or inferior posterior lateral nasal branch from the greater palatine nerve. Collectively, these may be referred to as an SPG target site. Stimulation of the SPG target site may be used to treat cluster headaches, migraine, trigeminal neuralgia, trigeminal autonomic cephalalgias, craniofacial pain, post-traumatic headache, sinus headache, pain, dry eye(s), nasal congestion, Alzheimer's disease, ischemic stroke, and / or to alter the blood-brain barrier (BBB) permeability to aid in the efficacy of the above indications. The SPG target site may be accessed by a transnasal procedure, a transoral procedure, or a transcutaneous procedure, preferably a transcutaneous procedure. In a transcutaneous approach, a high-frequency linear ultrasound probe may be positioned inferior to the zygomatic arch and angled approximately 45° cephalad to image the pterygopalatine fossa (PPF) between the maxilla anteriorly and the ramus of the mandible and pterygoid process of the sphenoid bone posteriorly. A small needle containing the implantable neurostimulation device is percutaneously injected through the cheek. In some cases the implantable neurostimulation device may be inserted superior to the zygomatic arch and posterior to the posterior orbital rim. The implantable neurostimulation device may be directed approximately 45° caudad, 10° anterior, and advanced 50 mm into the PPF, where the electrodes can be deposited in proximity to the target nerve. In other cases the implantable neurostimulation device may be inserted in variations to the above procedure. Using the implant delivery apparatus described above, on retracting the needle, the electrodes of the implantable neurostimulation device can be deployedat the SPG target site and the proximal portion of the neurostimulator (with lead antenna and / or housing portion) can be deposited at a different orientation, closed to parallel to the skin.

[0116] In other examples, the target nerve may be the sphenopalatine ganglion (SPG) and trigeminal nerve and more specifically branches innervating the (medial and lateral) posterior superior nasal nerves which are branches of the maxillary nerve (CN V2) that arise in the pterygopalatine fossa from pterygopalatine ganglion and pass through the sphenopalatine foramen into the nasal cavity to innervate the nasal septum. Stimulation of this target nerve may be used to treat sinusitis and rhinitis.

[0117] In other examples, the target nerve may be the splenic nerve. Stimulation of the splenic nerve may be used to treat one or more of: rheumatoid arthritis; inflammatory bowel disease (IBD); sepsis; systemic lupus erythematosus; multiple sclerosis; type 2 diabetes and metabolic syndrome; and / or other autoimmune diseases. Stimulating the splenic nerve can reduce pro- inflammatory cytokines (e.g., TNF -alpha), leading to decreased inflammation throughout the body.

[0118] In other examples, the target nerve may be the superior ovary nerve. Stimulation of the superior ovary nerve may be used to treat one or more of: polycystic ovary syndrome (PCOS); chronic pelvic pain; menstrual pain / dysmenorrhea; endometriosis; infertility; and / or ovarian hyperstimulation syndrome.

[0119] In other examples, the target nerve may be the T2 to T4 of the sympathetic ganglia, or the thoracic sympathetic nerve chain. Stimulation of the T2 to T4 of the sympathetic ganglia or the thoracic sympathetic nerve chain may be used to treat one or more of: hyperhidrosis; heart failure; angina pectoris; hypertension; arrhythmias; complex regional pain syndrome (CRPS); and / or Raynaud's phenomenon.

[0120] In specific examples, stimulation of the thoracic sympathetic nerve chain may be used to treat hyperhidrosis. Specifically, the target nerve may be the sympathetic ganglia located along the upper thoracic spine. The levels targeted depend on the condition being treated but are often between the T2 to T4 ganglia. For palmar hyperhidrosis (excessive sweating of the hands), stimulation may be targeted on the T2 and T3 ganglia. For axillary hyperhidrosis (excessive sweating in the underarms), the stimulation may be targeted at the T3 and T4 ganglia. In some cases, facial blushing may be treated by targeting the T2 ganglia.

[0121] In examples, the implantable neurostimulation device may be implanted in a similar procedure to that of the endoscopic thoracic sympathectomy (ETS) to target the thoracicsympathetic nerve chain. Small incisions are made under each armpit, through which 1) the needle of the delivery device with the implantable neurostimulation device is inserted and advanced towards the target nerve, and 2) optionally surgical tool(s) and / or an endoscope are inserted for implantation of the implantable neurostimulation device. When the implantable neurostimulation device is deployed from the delivery device (e.g., by retraction of the needle), the electrodes are deployed at the target nerve and the proximal portion of the implantable neurostimulation device (lead antenna and / or housing portion) can be deposited at a different angle to the electrode lead, for example closer to parallel with the skin.

[0122] In other examples, the target nerve may be the lumbosacral dorsal nerve roots below the conus medullaris of the spinal cord. Stimulation of the lumbosacral dorsal nerve roots may be used to treat pain of the lower extremities, including the most distal portion of the feet. The target nerve roots may be accessed percutaneously via the epidural space below the conus medullaris (spanning the L2-S1 vertebral region), which is the caudal terminus of the spinal cord. Using the implant delivery apparatus described above, the electrode lead of the implantable neurostimulation device can be deployed by introducing the needle within the dorsal epidural space at the L1 / L2 level. Then the electrode lead is advanced retrograde toward the target dorsal nerve root using an imaging device such as x-ray fluoroscopic imaging. Once the proper location of the stimulating electrodes is confirmed, anchoring members are deployed to hold the electrode lead to the muscles. Then, the proximal portion of the electrode lead (with antenna and / or housing / IPG portion) can be deposited at a different orientation, closed to parallel to the skin.

[0123] In examples, two implantable neurostimulator devices may be implanted to target the lumbosacral dorsal nerve roots on both sides - bilateral stimulation.

[0124] According to the present invention there is also provided an implantable neurostimulation device comprising: an electrode lead comprising a free end which includes one or more electrodes for stimulating a target nerve during use; and a housing portion comprising an electronics assembly operably connected to the one or more electrodes.

[0125] The housing portion may be coupled to an end of the electrode lead opposite the free end of the electrode lead. 1

[0126] The electronics assembly may comprise a power supply for powering the electrodes to generate electrical impulses. The electronics assembly may be hermetically sealed within the housing portion.

[0127] The housing portion may be is tubular in shape. One or both ends of the housing portion may be provided with an end cap. The end cap(s) may be rounded. This may improve the ease of insertion.

[0128] The electrode lead may include a narrowed portion (e.g. for extending out of a side slot of a delivery device). The narrowed portion having a smaller diameter than the remainder of the electrode lead.

[0129] The electrode lead may comprise a protrusion for anchoring the free end of the electrode lead within the patient’s tissue. The protrusion may be located at the free end of the electrode lead proximal the electrodes. For example, the protrusion may be located at a terminus of the electrode lead.

[0130] The housing portion may have any combination of the features described herein with regard to housing portions of alternate aspects.

[0131] According to the present invention there is also provided a delivery device for implantation of an implantable neurostimulation device.

[0132] The implantable neurostimulation device may be any of the implantable neurostimulation devices described herein.

[0133] The delivery device may comprise a handle and a needle. The needle may have a lumen configured to receive a length of the electrode lead therein. The needle may include a side slot which extends along the length of the needle. Part of the electrode lead may extend out of the side slot of the needle to the housing portion.

[0134] The side slot may extend around half a circumference of the needle. In some examples, the side slot may extend around more than half of the circumference of the needle or less than half of the circumference of the needle. The electrode lead may have a diameter that is less than or equal to a width of the side slot.

[0135] The delivery device may have any combination of the features described herein with regard to implant delivery devices of alternate aspects.

[0136] According to the present invention there is also provided an implant delivery apparatus comprising the implant delivery device and the implantable neurostimulation device of any aspect.

[0137] Where the electrode lead includes a narrowed portion and the delivery device includes a side slot, the narrowed portion may extend through the side slot of the delivery device. In examples where the delivery device includes a side slot and the electrode lead comprises a protrusion, the protrusion may be aligned within (i.e., received within) the side slot.

[0138] According to the present invention there is also provided a method of implanting an implantable neurostimulation device using the implant delivery apparatus, the method comprising: inserting a portion of the needle in which the free end of the electrode lead is received, into a patient; and at least partially withdrawing the needle to expose the free end of the electrode lead to the patient’s tissue.

[0139] The delivery device may comprise a handle and a needle. The needle may have a lumen configured to receive a length of the electrode lead therein.

[0140] The implantable neurostimulation device may include a housing portion comprising an electronics assembly operably connected to the one or more electrodes.

[0141] The handle may be used to advance the electrode lead through the patient's skin and into the subcutaneous tissue such that the electrodes on the electrode lead are positioned proximate to a nerve branch of a target nerve. At this stage, the housing portion and part of the electrode lead opposite the free end may remain outside of the patient's tissue.

[0142] The needle may be advanced at an intramuscular injection angle (approximately 90 degrees to the skin surface), or at a subcutaneous injection angle (approximately 45 degrees to the skin surface), depending on the location of the target nerve and the surrounding tissue.

[0143] Once the electrode lead has been positioned, the needle may be withdrawn. The needle may be withdrawn by pulling the handle of the delivery device away from the patient’s skin. As the needle is withdrawn, the electrode lead may pass through a tip of the needle out of the lumen of the needle. Where the electrode lead comprises a protrusion, the protrusion may act to anchor the electrode lead within the patient’s tissue preventing the electrode lead from being withdrawn as the needle is withdrawn.

[0144] Once the needle is fully withdrawn out of the patient’s skin, the free end of electrode lead may remain in an implanted position with a portion of the electrode lead opposite the free end and the housing portion extending outside of the patient’s skin.

[0145] The method may include inserting the housing portion under the patient’s skin through an incision. The incision may be made before the needle is inserted, after the needle is inserted and before it is withdrawn, or after the needle is withdrawn. The housing portion may be inserted before the needle is inserted, after the needle is inserted and before it is withdrawn, or after the needle is withdrawn. Once the housing portion is inserted, both the housing portion and the electrode lead may be positioned beneath the patient’s skin.

[0146] The method may include a further optional step of closing the incision. The incision may be closed using sutures and / or dermal adhesive.

[0147] According to the present invention there is also provided a delivery device for implantation of an implantable neurostimulation device.

[0148] The implantable neurostimulation device may be any of the implantable neurostimulation devices described herein.

[0149] The delivery device may comprise a delivery sheath for insertion into the patient's tissue. The delivery device may comprise a handle which remains external to the patient's tissue during insertion. The handle may include a grip which is adapted to be held by an operator.

[0150] The delivery device may have any combination of the features described herein with regard to delivery devices of alternate aspects.

[0151] The delivery device may be configured designed to split into at least two parts.

[0152] The delivery device may be divided into two parts: a first part and a second part. The two parts may be symmetric and each define half of the delivery device. In other examples the split between the two parts may be asymmetric and / or the delivery device may be split into more than two parts (e.g., three or four parts).

[0153] The two parts of the delivery device may be connected together via a connector which allows the delivery device to come apart when a splitting force is applied to separate the two parts.

[0154] The connector may be a frangible connector. The connector may include a line of weakness in the delivery sheath that defines a line of breakage of the delivery device. Forexample, a wall of the delivery sheath may have two opposing continuous or discontinuous lines of weakness along its length (e.g., opposing sides of the wall may comprise thinned portions to define opposing aligned lines of weakness).

[0155] In examples where the delivery sheath includes a side slot, the side slot may be aligned with and / or extend from the frangible connector. A front line of weakness in the front of the delivery sheath may only extends along part of the length of the delivery sheath (e.g., from the handle to the side slot). The side slot may extend between the front line of weakness and a tip of the delivery sheath. In other examples, the side slot may instead extend along the full length of the delivery sheath.

[0156] The side slot may be particularly advantageous in examples where the free end of the electrode lead comprises a protrusion for anchoring the free end in the tissue. In such examples, prior to insertion the protrusion may be received within the side slot.

[0157] The handle may comprise two or more parts connected via the / a connector. For example, the handle may include an extension of the line(s) of weakness of the delivery sheath. The handle may include a continuous or discontinuous line of weakness, such as a thinned portion or a line of perforations, aligned with the length of the sheath. In other examples the handle may comprise two independent parts. These independent parts may be reversibly coupled together e.g., via a clip or another fastener.

[0158] According to the present invention there is also provided a method of implanting an implantable neurostimulation device using the implant delivery apparatus, the method comprising: inserting a portion of the delivery sheath in which the free end of the electrode lead is received, into a patient; and separating the delivery device into at least two parts during or prior to extraction of the delivery sheath from the patient, wherein separating the delivery device into at least two parts involves splitting the delivery sheath into at least two parts.

[0159] The delivery device may be the delivery device of the preceding aspect.

[0160] Prior to insertion, the electrode lead may extend through the handle. The housing portion of the implant may be located outside of the delivery device, opposite the delivery sheath, alternately, the housing portion may be received within the delivery device (e.g., withinthe handle). In other examples, prior to insertion, the electrode lead, may extend out of the side slot of the delivery sheath.

[0161] Separating the delivery device into at least two parts may involve a user separating the parts of the handle and continuing to apply a separating force tear the delivery sheath in two, separating it along the connector until the two parts of the delivery device are completely separated from one another.

[0162] Once the two parts are completely separated, they may be pulled out of the patient’s tissue by pulling the handle. The delivery device parts can either be extracted simultaneously or sequentially. By separating the delivery sheath the friction between the sheath and the electrode lead when the sheath is removed can be reduced. This may help to more reliably maintain the electrode lead in its implanted position proximal to the target nerve.

[0163] In other examples, the sheath may be retracted from the patient’s skin while the two parts are pulled part.

[0164] Once the delivery device is fully extracted, the free end of electrode lead may remain in the implanted position with an opposing portion of the electrode lead and the housing portion extending outside of the patient’s skin. The housing portion may then be inserted under the patient’s skin through an incision. For example, the incision may be made before the delivery sheath is inserted, after the delivery sheath is inserted and before it is withdrawn, or after the delivery sheath is withdrawn. Once the housing portion is inserted, both the housing portion and the electrode lead may be positioned beneath the patient’s skin. Optionally, once the implant is implanted, the incision may be closed (e.g., using sutures and / or a dermal adhesive).BRIEF DESCRIPTION OF THE DRAWINGSEmbodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

[0165] FIG. 1 illustrates a first example of an implantable neurostimulation device.

[0166] FIG. 2 illustrates implant delivery apparatus and the implantable neurostimulation device of FIG. 1.

[0167] FIG. 3 illustrates an enlarged view of a front section of the implant delivery apparatus of FIG. 2.

[0168] FIG. 4A illustrates a front end of the implant delivery apparatus of FIG. 2.

[0169] FIG. 4B shows a cross-sectional view of the front end of the implant delivery apparatus of FIG. 2.

[0170] FIG. 5 illustrates a second example of an implantable neurostimulation device.

[0171] FIG. 6A illustrates a perspective view of a front end of the implantable neurostimulation device of FIG. 5 when the first needle is partly retracted.

[0172] FIG. 6B the implantable neurostimulation device of FIG. 6A when the first needle is not retracted.

[0173] FIG. 7 illustrates an implantable neurostimulation device similar to that of FIG. 5, with an end cap having two tapered sections.

[0174] FIG. 8A illustrates a third example of an implantable neurostimulation device.

[0175] FIG. 8B illustrates the implantable neurostimulation device of FIG. 8A when the first needle is partly retracted.

[0176] FIG. 9 a front-end view of the implantable neurostimulation device of FIG. 8A.

[0177] FIG. 10 illustrates an expanded front-end view of a delivery device and the implantable neurostimulation device of FIG. 8A.

[0178] FIG. 11 illustrates an expanded perspective view of a portion of the implantable neurostimulation device of FIG. 8 A.

[0179] FIG. 12 illustrates a perspective view of the implantable neurostimulation device of FIG. 8A during deployment when the first needle is almost completely retracted.

[0180] FIG. 13 illustrates a cross-sectional view of the implantable neurostimulation device of FIG. 8A.

[0181] FIG. 14A-D illustrate example electrode lead configurations.

[0182] FIG. 15A to FIG. 15G illustrate a method of implanting the implantable neurostimulation device of FIG. 1 using the implant delivery apparatus of FIG. 2.

[0183] FIG. 16A to FIG. 16F illustrate a further method of implanting an implantable neurostimulation device, in particular an electrode lead.

[0184] FIG. 17A to FIG. 17F illustrate a further method of implanting an implantable neurostimulation device, in particular an electrode lead.

[0185] FIG. 18A to FIG. 18F illustrate a further method of implanting an implantable neurostimulation device, in particular an electrode lead.

[0186] FIG. 19A to FIG. 19C illustrate a further method of implanting an implantable neurostimulation device, in particular an electrode lead.

[0187] FIG. 20A illustrates an implantable neurostimulation device and an implant delivery device.

[0188] FIG. 20B illustrates a method of implanting the implantable neurostimulation device of FIG. 20A using the implant delivery device of FIG. 20A.

[0189] FIG. 21 A illustrates an implantable neurostimulation device and an implant delivery device.

[0190] FIG. 2 IB illustrates a method of implanting the implantable neurostimulation device of FIG. 21 A using the implant delivery device of FIG. 21 A.

[0191] FIG. 22A illustrates an implantable neurostimulation device and an implant delivery device.

[0192] FIG. 22B illustrates a method of implanting the implantable neurostimulation device of FIG. 22A using the implant delivery device of FIG. 22A.DETAILED DESCRIPTION

[0193] FIG. l is a schematic illustration of an implantable neurostimulation device 100. The implantable neurostimulation device 100 may be a neural implant, for example a neurostimulator implant for treating sleep apnea. In this example the implantable neurostimulation device 100 is a medical device for treating sleep apnea.

[0194] As described further hereinafter, the implantable neurostimulation device 100 is implantable in a patient and operable to stimulate and optionally sense at least one target nerve and / or surrounding muscles.

[0195] As shown in FIG. 1, the implantable neurostimulation device 100 comprises an electrode lead 110 having a free end 112 and one or more electrodes 111 for stimulating the target nerve (not shown). The electrode lead 110 is preferably at least partially flexible to accommodate movement of the patient post-implantation.

[0196] In this example, the electrode lead 110 comprises four electrodes 111 which are spaced along the electrode lead 110. In other examples the electrode lead 110 may comprise one, two,three, five or more electrodes. The electrodes 111 may be disposed towards the free end 112 of the electrode lead 110.

[0197] The implantable neurostimulation device 100 comprises a projection at the free end 112 of the electrode lead 110 for penetrating the patient’s tissue. In this example, the projection comprises an end cap 120. As shown in FIG. 1, in this example the end cap 120 is wider than a diameter of the electrode lead 110.

[0198] In this example the implantable neurostimulation device 100 also comprises a housing portion 101 operably connected to the electrode lead 110 opposite the free end 112. In this example the housing portion 101 and the electrode lead 110 are integrally formed and implanted in the same procedure. However, it will be appreciated that the electrode lead 110 may be provided, and implanted, without the housing portion 101. For example, the electrode lead 110 may be implanted without the housing portion 101, which may be connected after implantation of the electrode lead 110. In some examples, the housing portion 101 may be an implantable pulse generator (IPG). In some examples, the implantable neurostimulation device 100 only comprises the electrode lead 110 and does not comprise a housing portion 101.

[0199] In the illustrated example the housing portion 101 includes an electronics assembly (not shown) connected to the electrodes 111. The electronics assembly may include a printed circuit board, a wireless communications receiver / transmitter, and optionally sensor electronics. The electronics assembly may also include a power supply, such as a battery, capacitor and / or a wireless power receiver, for powering the electrodes to generate electrical impulses. In some examples, the housing portion 101 and / or the electrode lead 110 may include a wireless power antenna for receiving wireless power transmission from an external device, such as a wearable device.

[0200] The housing portion 101 comprises a casing 102, such as a tubular casing, for receiving some or all of the electronics assembly therein. In some examples, the electronics assembly may be hermetically sealed within the casing 102. In examples, the casing 102 may comprise a ceramic material such as zirconia. In examples, the casing 102 may comprise a metallic material such as titanium. The housing portion 101 includes housing portion end caps 130. The housing portion end caps 130 may be flat or rounded.

[0201] The implantable neurostimulation device 100 may comprise a connector 104 which connects the electrode lead 110 to the housing portion 101. In this example, the connector 104consists of a flexible elongate lead connected between the electronics assembly of the housing portion 101 and the electrode lead 110.

[0202] In some examples, the electrode lead 110 comprises a first portion 106 and a second portion 108. The first portion 106 includes the free end 112 and the electrodes 111, and the second portion 108 connects the first portion 106 to the housing portion 101. The first portion 106 has a higher stiffness than the second portion 108. The first portion 106 may have a larger diameter than the second portion 108, providing a higher stiffness, or the first portion 106 may be made from a different (stiffer) material than the second portion 108, or the first portion 106 may include a stiffening member (e.g., a rigid member extending therethrough). The first portion 106 may be rigid or essentially rigid, and the second portion 108 may be flexible. The rigidity of the first portion 106 may assist with advancement of the electrode lead 110 through the patient's tissue during blunt dissection, while the flexibility of the second portion 108 may permit the housing portion 101 to be implanted at a different orientation to the first portion 106.

[0203] FIG. 2 illustrates an implant delivery apparatus 300 having a delivery device 200. As illustrated, an implantable neurostimulation device 100 as described with reference to FIG. 1 is received in the delivery device 200, which is operated to implant the implantable neurostimulation device 100 within the patient.

[0204] The delivery device 200 comprises a delivery sheath 210 for insertion into the patient's tissue, and a handle portion 220 which remains external to the patient's tissue during insertion. The handle portion 220 includes a grip 222 which is adapted to be held by an operator.

[0205] The delivery sheath 210 carries the implantable neurostimulation device 100 during percutaneous delivery into the patient' tissue. In particular, the delivery sheath 210 comprises a first needle 211 having a lumen for receiving the electrode lead 110 therein. In this example, the delivery sheath 210 also includes a second needle 212 having a lumen for receiving the housing portion 101 therein. As shown in FIG. 2, the first needle 211 has a higher gauge than the second needle 212 (i.e., the first needle 211 has a smaller diameter than the second needle 212).

[0206] In examples, the second needle 212 may have a gauge of between 6 gauge and 15 gauge, for example 10 gauge. In examples, the first needle 211 may have a gauge of between 15 gauge and 25 gauge, for example 20 gauge.

[0207] The first and second needles 211, 212 are parallel and both extend in a longitudinal direction. The first needle 211 extends further than the second needle 212. In particular, the second needle 212 has a tip 212a, such as a bevel tip, and the first needle 211 extends past the tip 212a of the second needle 212. The first needle 211 also has a tip 21 la which forms a terminal end of the delivery device 200. As illustrated, the first needle 211 and the second needle 212 are axially offset. In particular, a central axis of the first needle 211 is offset from a central axis of the second needle 212. In the illustrated example, the first needle 211 extends into the second needle 212 (in particular into the lumen of the second needle 212), such that the first needle 211 is partly accommodated within the second needle 212 alongside the housing portion 101.

[0208] The second needle 212 is fixed with respect to the grip 222. In contrast, the first needle 211 is retractable to allow an operator to move the first needle 211 relative to the second needle 212. The delivery device 200 may include an actuation tab 221 for retracting and / or extending the first needle 211. The actuation tab 221 may include a gripping handle at the handle portion220 for the operator to grip when actuating the first needle 211.

[0209] In this example, the first needle 211 is fixedly connected to the actuation tab 221. The first needle 211 is retractable by pulling the actuation tab 221 in a direction away from the patient. In other examples the first needle 211 may be retracted by pushing the actuation tab221 in a direction towards the patient. For example the actuation tab 221 may be connected to the first needle 211 by a rack and pinion system.

[0210] As will be discussed in further detail below, retracting the first needle 211 deploys the electrode lead 110 in the patient's tissue.

[0211] A locking device (not shown) may be provided to selectively lock the first needle 211 to the handle portion 220 and or the second needle 212.

[0212] The delivery device 200 may include a deployment member, such as a pusher, adapted to push the housing portion 101 out of the second needle 212 to deploy the housing portion 101 at an appropriate anatomical site. In some examples, the implant delivery device 200 may include a retaining member arranged to hold the housing portion 101 in the second needle prior to deployment. The retaining member may be operable to release the housing portion 101 before the delivery sheath 210 is removed from a patient's tissue.

[0213] FIG. 3 illustrates an enlarged view of a front section of the implant delivery apparatus 300 prior to insertion into the patient's tissue.

[0214] As shown, the electrode lead 110 is received in the first needle 211 and extends along a substantial part of the first needle 211 towards the tip 211a.

[0215] The first needle 211 includes a side slot 213 through which the connector 104 can project to connect the electrode lead 110 to the housing portion 101. The side slot 213 may extend from the tip 21 la of the first needle 211 along a length of the first needle 211. In some examples, the side slot 213 may project along a full length of the first needle 211.

[0216] In this example, the second needle 212 also includes a side opening 214. The side opening 214 extends from the tip 212a of the second needle which exposes part of the housing portion 101. The second needle 212 includes a side slot 213 through which the connector 104 can project to connect the electrode lead 110 to the housing portion 101. The side slot 213 may extend from the tip 21 la of the first needle 211 along a length of the first needle 211. In some examples, the side slot 213 may project along a full length of the first needle 211. Due to the side slot 213 the first needle 211 may be termed a half-pipe needle. The side slot 213 may span less than half of the diameter of the first needle 211, such that the electrode lead 110 is retained within the first needle 211 and cannot exit through the side slot 213.

[0217] In the illustrated example the implantable neurostimulation device 100 is received in the delivery device 200 such that the electrode lead 110 extends from a proximal end of the housing portion 101 when the housing portion 101 is received in the second needle 212. In this arrangement the electrode lead 110 overlies the housing portion 101 before entering the first needle 211. In other examples, the housing portion 101 may be oppositely arranged, with the electrode lead 110 extending from a distal end of the second needle 212 and into the first needle 211.

[0218] During use, an incision may be made in the patient's skin and the delivery sheath 210 inserted through the incision into the patient’s tissue. As the delivery sheath 210 is advanced through the patient's tissue, the end cap 120 acts to penetrate the patient's tissue.

[0219] The end cap 120 may be shaped to penetrate the patient's tissue by blunt dissection. For example, the end cap 120 may terminate in an apex 121, which may be pointed, rounded or substantially flat. In the illustrated example, the end cap 120 comprises an outer surface 122 which terminates in a substantially pointed apex 121. The apex 121 may have an angle of greater than: 30 degrees, 40 degrees, 50 degrees or 60 degrees. In some examples, the angle of the apex 121 may be obtuse. The outer surface 122 may be conical and / or may be at least partially rounded.

[0220] Compared with hypodermic needles, which typically have a sharp bevelled tip, the end cap 120 may cause less damage to the surrounding tissue during insertion.

[0221] Beneficially, use of such an end cap 120 may facilitate improved patient outcomes and faster recovery times. As damage to the surrounding tissue may be minimised, the electrode lead 110 may be positioned closer to a target nerve than would otherwise be possible, while avoiding nerve, tissue and / or vasculature damage.

[0222] During implantation the delivery sheath 210 delivers the housing portion 101 to a first depth, and the electrode lead 110 to a second depth, deeper within the patient's tissue. Once the electrode lead 110 is correctly positioned the operator may retract the first needle 211 to deploy the electrode lead 110. During retraction, the connector 104 may travel along the side slot 213 allowing the first needle 211 to be retraced without retracting the electrode lead 110.

[0223] After the electrode lead 110 has been deployed, the housing portion 101 may then be deployed from the second needle 212 by pulling the implant delivery device 200 away from the patient.

[0224] Advantageously, the end cap 120 acts as an anti-migration feature to anchor the free end 112 of the electrode lead 110 in the patient's tissue such that when the delivery device 200 is withdrawn, the housing portion 101 is pulled out of the second needle 212 and left within the patient's tissue.

[0225] The end cap 120 is best seen in FIG. 4A and FIG. 4B which show a side and a cross- sectional view of a front end of the implant delivery apparatus 300 respectively.

[0226] In FIG. 4A and FIG. 4B the first needle 211 is shown in a partly retracted position. In this position a small length of the electrode lead 110 is exposed to the surrounding tissue.

[0227] Prior to retraction of the first needle 211, the electrode lead 110 is received within the lumen 231 of the first needle 211.

[0228] The end cap 120 projects outwardly from the electrode lead 110 to extend beyond a diameter of the electrode lead 110. In this example, the end cap 120 extends about the entire circumference of the first needle 211 and completely covers an end of the lumen 231. The end cap 120 protrudes beyond the outer surface of the first needle 211 and covers the tip 21 la of the first needle 211.

[0229] In this example, the end cap 120 is at least partially hollow and a terminus 113 of the electrode lead 110 extends into the hollow body. In particular, an annular cavity 124 is definedbetween the terminus 113 of the electrode lead 110 and the end cap 120. The annular cavity 124 accommodates an end section 21 lb of the first needle 211, including the tip 211a. As the first needle 211 is advanced through the patient's tissue, the end cap 120 completely covers the tip 21 la of the first needle 211. As such, the needle tip 21 la is shielded from the surrounding tissue while it is advanced, and the end cap 120 provides for blunt dissection of the tissue during advancement of the delivery device 200.

[0230] The end cap 120 comprises a rigid material. For example, the end cap 120 may comprise or essentially consist of a biocompatible polymer, such as polyurethane. Using a rigid material may beneficially allow the end cap 120 to retain its shape as it is pushed through the tissue by blunt dissection. In contrast, it is preferable that the electrode lead 110 be at least partially flexible to accommodate patient movement. E.g., flexing of the surrounding tissue, post-implantation.

[0231] Because the end cap 120 is wider than the electrode lead 110, the end cap 120 may act as an anti-migration feature to help to fix the position of the electrode lead 110 in the tissue after deployment from the first needle 211. In examples, the end cap 120 may be the only antimigration feature on the electrode lead 110. In this way, once implanted, the free end 112 of the electrode lead 110 is anchored in position, holding the electrodes 111 in proper position relative to the target nerve, while the remainder of the electrode lead 110 may move or flex as the surrounding tissue moves (e.g., due to patient movements).

[0232] FIG. 4B shows a cross-sectional view of the front end of the implant delivery apparatus 300.

[0233] As shown in FIG. 4B, in this example the end cap 120 is wider than the first needle 211 i.e., a maximum diameter 123 of the end cap 120 is greater than the outer diameter of the first needle 211.

[0234] In examples, an external diameter of the end cap 120 may increase away from the apex 121 of the end cap 120 reaching a maximum diameter 123 at or near a rear end 125 of the end cap 120. In this example, the maximum diameter 123 is spaced from the rear end 125 of the end cap 120 such that the external diameter decreases from the maximum diameter 123 to the rear end 125. Such a taper may minimise tissue damage during repositioning of the implant delivery apparatus 300. For example, prior to deployment when the end cap 120 is positioned on the first needle 211, the implant delivery apparatus 300 may be moved in a direction substantially opposite to the insertion direction without end cap 120 catching on the surrounding tissue.

[0235] The end cap 120 may be attached to or co-mounded with the terminus 113 of the electrode lead 110. For example the end cap may be over-moulded onto the electrode lead 110 or the end cap 120 may be attached to the electrode lead 110 by welding or by an adhesive.

[0236] In some examples the point of attachment between the electrode lead 110 and the end cap 120 may be a designated failure point. That is, the attachment between the electrode lead 110 and the end cap 120 may have a breaking force that is less than a breaking force of the electrode lead 110 itself. In this way, when the electrode lead 110 is removed from the patient (e.g., at the end of its serviceable life), the risk of any part of the electrode lead 110 remaining in the patient is reduced. This may be preferable, for example, if the electrode lead 110 comprises a metal (e.g., the electrodes 111). In this example the end cap 120 preferably comprises a biocompatible polymer.

[0237] As shown in FIG. 4B, the end cap 120 may comprise a rim 126 for engaging the tip 21 la of the first needle 211. Prior to insertion of the implant delivery apparatus 300, the tip 211a contacts the rim 126 of the end cap 120. During insertion of the first needle 211 in the tissue, the tip 21 la bears upon the rim 126 forcing the end cap 120 forwards through the tissue by blunt dissection. As the end cap is coupled to the electrode lead 110, the electrode lead 110 is prevented from being pushed backwards along the first needle 211 during insertion and advancement.

[0238] In examples, the rim 126 may project radially away from a central axis 127 of the end cap 120. In other examples, the rim 126 may be angled with respect to the central axis 127. For example, the rim 126 makes an acute angle with the central axis 127. After deployment of the electrode lead 110 when the first needle 211 is retracted, the rim 126 may act as an antimigration feature preventing rearward movement of the end cap 120 through the tissue.

[0239] The tip 21 la of the first needle 211 may comprise a 2D annular surface for engaging the rim 126 of the end cap 120. For example, tip 21 la of the needle may be substantially flat, substantially perpendicular to the longitudinal axis of the first needle 211.

[0240] In examples, the end cap 120 may comprise a flange 128 which extends from the rim 126 towards the rear end 125 of the end cap 120 i.e. away from the apex 121. The flange 128 and the end section 211b of the electrode lead 110 define the annular cavity 124 therebetween.

[0241] FIG. 5 shows a second example of an implantable neurostimulation device 400. The implantable neurostimulation device 400 is substantially similar to the implantable neurostimulation device 100 described with reference to FIG. 1 to FIG. 4B, with the exceptionof the shape of the end cap. In the example FIG. 5 the implantable neurostimulation device 400 is shown alongside the delivery device 200, the details of which are described above and will not be repeated here.

[0242] As shown in FIG. 5, the implantable neurostimulation device 400 comprises an electrode lead 410 having one or more electrodes 411 for stimulating the target nerve (not shown). In this example, the electrode lead 410 comprises four electrodes 411 which are spaced along the electrode lead 110. In other examples the electrode lead 410 may comprise one, two, three, five or more electrodes. In this example, an electrode 411 closest to a free end 412 of the electrode lead 410 is spaced from the free end 112. Beneficially, this configuration may ensure the tissue can contact a full length of the electrode 411 after the electrode lead 410 is deployed in a patient's tissue. This may enable more effective stimulation of the target nerve by the electrode 411.

[0243] Like the implantable neurostimulation device 100, the implantable neurostimulation device 400 comprises a projection in the form of an end cap 420 which is provided at the free end 412 of the electrode lead 410 for penetrating the patient’s tissue. In this example, the end cap 420 is substantially conical in shape. The shape of the end cap 420 is best seen in FIG. 6A and FIG. 6B which show perspective views of the front end of the implantable neurostimulation device 400.

[0244] As with the previous examples, the electrode lead 510 may comprise a first portion 536 and a second portion 538. The first portion 536 includes the end cap 420 and the electrodes 411, and the second portion 538 connects the first portion 536 to the housing portion 501. The first portion 536 has a higher stiffness than the second portion 538. The first portion 536 may have a larger diameter than the second portion 538, providing a higher stiffness, or the first portion 536 may be made from a different (stiffer) material than the second portion 538, or the first portion 536 may include a stiffening member (e.g., a rigid member extending therethrough). The first portion 536 may be rigid or essentially rigid, and the second portion 538 may be flexible. The rigidity of the first portion 536 may assist with advancement of the electrode lead 510 through the patient's tissue during blunt dissection, while the flexibility of the second portion 538 may permit the housing portion 501 to be implanted at a different orientation to the first portion 536.

[0245] In this example, the end cap 420 progressively widens towards a rear end 425 of the end cap 420. An external diameter of the end cap 420 increases away from the apex 421reaching a maximum diameter at the rear end 425. The rear end 425 of the end cap 420 forms a rim 426 around the terminus 413 of the electrode lead 410 for engaging the tip 21 la of the first needle 211.

[0246] FIG. 6B shows the front end of the implantable neurostimulation device 400 prior to insertion of the implant delivery apparatus 300. As shown, the end cap 420 protrudes beyond the first needle 211 and covers the tip 21 la of the first needle 211. In use, the tip 21 la contacts the rim 426 of the end cap 420.

[0247] In this example, the maximum diameter of the end cap 420 is the same as the diameter of the first needle 211. The rim 426 covers the whole of the tip 21 la ensuring it is shielded from the surrounding tissue while the first needle 211 is advanced. Unlike the end cap 120 of the previous example, the end cap 420 is not hollow and does not comprise a rearwardly projecting flange or annular cavity for accommodating an end section of the electrode lead.

[0248] The end cap 420 is wider than a diameter of the electrode lead 410 so the end cap 420 may act as an anti-migration feature to help to fix the position of the electrode lead 410 in the tissue after deployment from the first needle 211.

[0249] FIG. 7 shows a similar example to FIG. 5 to FIG. 6B. In this example the free end 412 of the electrode lead 410 has a first tapered part 415 and a second tapered part 417 joined together and forming the end cap 420. The second tapered part 417 includes the apex 421, as described above, and the first tapered part 415 defines the rear end 425 and rim 426 as described above.

[0250] Providing an end cap 420 with more than one tapered part may increase the anchoring provided by the end cap 420 in the patient's tissue.

[0251] It will be appreciated that a similar arrangement to that shown in FIG. 7 may be provided with the shape of the end cap 120 of FIG. 1. In other examples, the end cap 420, in particular the rear end 425 of the first tapered part 415, may include an annular cavity as illustrated in FIGS. 4A and 4B.

[0252] In the examples of FIG. 5 to FIG. 7 the attachment between the electrode lead 410 and the end cap 420 may be a designated failure point. That is, the attachment between the electrode lead 410 and the end cap 420 may have a breaking force that is less than a breaking force of the electrode lead 410 itself. In this way, when the electrode lead 410 is removed from the patient (e.g., at the end of its serviceable life), the risk of any part of the electrode lead 410 remaining in the patient is reduced. This may be preferable, for example, if the electrode lead410 comprises a metal (e.g., the electrodes 411). In this example the end cap 420 preferably comprises a biocompatible polymer.

[0253] FIG. 8A to FIG. 9 show a third example of an implantable neurostimulation device 500. The implantable neurostimulation device 500 is substantially similar to the implantable neurostimulation device 400 described with reference to FIG. 5, with the exception of the configuration of the projection as will be discussed below. The implantable neurostimulation device 500 is shown alongside the delivery device 200. In this example the tip 211a' of the first needle 211 is shaped for sharp dissection of the tissue, as will be described in more detail below. All other features of the delivery device 200 are the same as described previously.

[0254] As shown in FIG. 8A the implantable neurostimulation device 500 comprises an electrode lead 510 and an end cap 520 provided at a free end 512 of the electrode lead 510. Unlike the example end caps 120, 420 described above, the end cap 520 is configured to fit within the first needle 211. In particular, the end cap 520 comprises a body portion 533 which covers a terminus 513 of the electrode lead 510. The body portion 533 is configured to be received within the lumen 231 of the first needle 211. The body portion 533 may have the same width as the diameter of the electrode lead.

[0255] The end cap 520 is shaped to penetrate the patient's tissue by blunt dissection. For example, the end cap 520 may terminate in an apex 521 which is pointed, rounded or substantially flat. In the illustrated example, the end cap 520 comprises an outer surface which terminates in a rounded apex 521. The apex 521 may have an angle of greater than: 30 degrees, 40 degrees, 50 degrees or 60 degrees. In some examples, the angle of the apex 521 may be obtuse. The outer surface may be conical and / or may be at least partially rounded. In this example, the end cap 520 progressively widens to a rear end of the end cap 520. An external diameter of the end cap 520 increases away from the apex 521 reaching a maximum diameter at the rear end 425.

[0256] As shown in FIG. 8A, the end cap 520 comprises a projection 534 which projects outwardly (i.e. away from the axis of the end cap 520) to extend beyond a diameter of the electrode lead 510. Therefore, in this example only a part of the end cap 520 projects outwardly from the electrode lead 510, in particular the projection 534.

[0257] In FIG. 8A, the electrode lead 510 is shown when fully received within the first needle 211. As shown, in this position the end cap 520 does not extend beyond the tip 21 la'. The tip 211a' of the first needle 211 is shaped for sharp dissection of the patient's tissue. For example,the tip 211a' may be bevelled as shown in FIG. 8 A or may have any other suitable shape for sharp dissection of the patient's tissue. In use, the first needle 211 may be inserted into the tissue while the electrode lead 510 is received within the first needle 211 as shown in FIG. 8 A. The rigidity of the first needle 211 and the sharp tip 211a' allow the first needle 211 to be easily advanced through the tissue to a location proximal to the target nerve. Such sharp insertion may be beneficial in cases where the needle tip 211a' needs to be progressed through tough layers of tissue such as muscle. In contrast, blunt dissection through tough tissue may require a large amount of force to progress the implant. This large progression force may increase the difficulty in accurately positioning the needle without causing unnecessary damage to the surrounding tissue. By shielding the end cap 520 with the first needle 211 during initial insertion, tough layers of tissue may be more easily passed through to accurately position the first needle 211 proximal to the target nerve.

[0258] In alternative examples, particularly where the first needle 211 does not include the side slot 213, or where the side slot 213 is not aligned with the projection 534, the projection 534 may include a cavity formed on its rear side, similar to the example illustrated in FIGS. 4A and 4B. The cavity may define a rim. The cavity may receive a part of the tip 211a’ of the first needle 211. This may negate dissection by this part of the first needle 211 and also stiffen the electrode lead 510 where it protrudes beyond the tip 211a’ of the first needle 211.

[0259] As discussed previously, nerves and other anatomical structures (vasculature, glands, tissues) may be easily damaged by sharp needles. To avoid damage it is preferable that once the needle tip 211a' is in the general vicinity of the target nerve, the soft tissue immediately surrounding the nerve be progressed through by blunt dissection.

[0260] To achieve this, the first needle 211 may be partially retracted to expose the end cap 520 to the surrounding tissue, as shown in FIG. 8B. In this position it can be seen that the end cap 520 extends beyond the needle tip 21 la'. Once the first needle 211 is in this position, the delivery device 200 can be progressed closer to the target nerve with the leading surface of the end cap 520 acting to bluntly dissect the tissue immediately surrounding the target nerve. In this way, the electrode lead 510 may be located closer to the target nerve without risking damage to the target nerve and / or other sensitive tissue or structures.

[0261] Movement of the first needle 211 thereby allows a practitioner implanting the implantable neurostimulation device 500 to switch between sharp and blunt dissection. Thismay assist with achieving accurate implantation while reducing damage to nerves and other sensitive tissue or structures.

[0262] As shown in FIG. 8B, the projection 534 comprises a rearwardly facing surface 535. Once the free end 512 of the electrode lead 510 has been deployed, the rearwardly facing surface 535 acts to anchor the free end 512 of the electrode lead 510 in the tissue. In this way, the end cap 520 acts as an anti-migration feature helping to ensure that when the first needle 211 and / or the entire delivery device 200 is withdrawn the electrode lead stays in place in the tissue and the housing portion 101 is pulled out of the second needle 212.

[0263] In this example, the rearwardly facing surface 535 is perpendicular to the central axis 527 of the end cap 520. In other examples, the rearwardly facing surface 535 may be angled with respect to the central axis 527. For example, the rearwardly facing surface 535 makes an acute angle with the central axis 527. An angle of less than or equal to 90 degrees may help to prevent rearward movement of the end cap 120 through the tissue (i.e. generally opposite to the insertion direction).

[0264] FIG. 9 illustrates a front-end view of the first needle 211 and end cap 520. As shown, prior to deployment the projection 534 sits within the side slot 213 of the first needle 211.

[0265] The projection 534 may extend outside of a profile 531 of the lumen 231. The further the projection 534 extends beyond the electrode lead 510, the greater the anchoring effect once deployed.

[0266] In this example, the projection 534 does not extend beyond an outer profile 532 of the first needle 211. Beneficially, a projection 534 which lies within the outer profile 532 of the first needle 211 may be effectively shielded by the first needle 211 from the surrounding tissue during insertion. This may ease repositioning of the first needle 211 allowing forward and backward movement of the delivery device 200 without the projection 534 catching on the surrounding tissue.

[0267] By providing a projection 534 which extends beyond the profile of the lumen 231 but lies inside the outer profile 532 of the first needle 211, the needle may be repositioned without the projection 534 damaging the surrounding tissue, and the projection 534 can still achieve effective anchoring once deployed.

[0268] Advantageously, in the present invention the projection 534 is fixed with respect to the end cap 520 to fixedly connect the projection 534 to the electrode lead 510. For example, the projection 534 may be integral or co-mounded with the end cap 520. This contrasts withknown anti-migration features which change conformation when the electrode lead is deployed from a needle to achieve a greater anchoring effect.

[0269] Instead, in the present invention, the projection 534 is fixed and sized to fit within the side slot 213 of the first needle 211. Beneficially, this may allow the first needle 211 to be reversibly retracted and extended to deploy and then re-house the electrode lead 510 without fouling the projection 534.

[0270] In some examples the point of attachment between the electrode lead 510 and the end cap 520 may be a designated failure point. That is, the attachment between the electrode lead 510 and the end cap 520 may have a breaking force that is less than a breaking force of the electrode lead 510 itself. In this way, when the electrode lead 510 is removed from the patient (e.g., at the end of its serviceable life), the risk of any part of the electrode lead 510 remaining in the patient is reduced. This may be preferable, for example, if the electrode lead 510 comprises a metal (e.g., the electrodes 511). In this example the end cap 520 preferably comprises a biocompatible polymer.

[0271] In some examples, the electrode lead 510 may include two end caps 520, in particular with two projections 534.

[0272] FIG. 10 shows a front-end view of the delivery device 200 and implantable neurostimulation device 500 prior to deployment.

[0273] The implantable neurostimulation device 500 comprises a connector 504 which connects the electrode lead 510 to a housing portion 501 for housing the electronics assembly (not shown).

[0274] The first needle 211, in particular the side slot 213, is configured to prevent translation of the electrode lead 510 through the side slot 213. In this way, the first needle 211 may provide structural rigidity to the flexible electrode lead 510 during blunt advancement through the tissue.

[0275] In examples, the electrode lead 510 may have a greater diameter than the connector 504. As shown, a diameter of the connector 504 may be smaller than or equal to a width of the side slot 213 such that the connector 504 can slide along the side slot 213 as the first needle 211 is moved relative to the electrode lead 510. A diameter of the electrode lead 510 may be greater than the width of the side slot 213 to ensure that the electrode lead 110 cannot exit the first needle 211 via the side slot 213.

[0276] Alternatively or additionally, as shown in FIG. 11, the electrode lead 510 may comprise a sleeve 540 which at least partially surrounds a circumference of the electrode lead 510. The sleeve 540 may be positioned at a rear end of the electrode lead 510, proximal to the connector 504.

[0277] Alternatively or additionally, the electrode lead 510 may include one or more side projections (not shown) configured to fit within corresponding grooves in the first needle 211. The side projections and the corresponding grooves may act in combination to confine the electrode lead 510 such that it is only able to translate axially along the first needle 211 prior to deployment. For example, the one or more side projections may comprise two projections disposed on opposite sides of the electrode lead 510. The side projections may extend along the full length of electrode lead or may only extend along part of the electrode lead 510.

[0278] FIG. 12 shows a perspective view of the delivery device 200 and the electrode lead 510 during deployment when the first needle 211 is almost completely retracted.

[0279] As shown, the implantable neurostimulation device 500 may comprise one or more anti-migration members 550. Each anti-migration member may comprise a sloped leading surface and a rear facing surface for anchoring the electrode lead 510 post deployment.

[0280] At least one electrode 511 of the electrode lead 510 may be located closer to the free end 512 than the anti-migration members 550. In some examples, all of the electrodes 511 may be located closer to the free end 512 of the electrode lead 510 than the anti-migration members 550. This may allow the first needle 211 to be partially retracted to expose some or all of the electrodes 511, for example to test the implant position of the electrodes 511, without exposing the anti-migration members 550 to the surrounding tissue.

[0281] The electrode lead 510 may comprise multiple sets 551 of anti-migration members 550 spaced along a length of the electrode lead 510. In this example, the electrode lead 510 comprises fourteen sets 551 of anti-migration members 550 and each set 551 comprises eleven individual anti-migration members 550. It will be understood that the present example is only illustrative and the electrode lead 510 may comprise any number of sets 551 and that each set 551 may contain any number of anti-migration members 550. For example, each set 551 may contain one or more anti-migration members 550 such as 2, 3, 4, 5 or more anti-migration members 550.

[0282] The anti-migration members 550 may extend at least partially around the circumference of the electrode lead 510. Each set 551 may comprise a series anti-migrationmembers 550 spaced at intervals around part or all of the circumference of the electrode lead 510.

[0283] As shown in FIG. 12, the anti-migration members 550 may be unevenly spaced around the circumference of the electrode lead. For example, the anti-migration members 550 may be configured to be covered by the first needle 211 when the electrode lead 510 is received within the first needle 211. This is best shown in FIG. 13 which illustrates a cross-sectional view of the first needle 211 and the electrode lead 510 prior to deployment.

[0284] As shown, in this example the anti-migration members 550 are disposed along a part of the circumference of the electrode lead 510 which is covered by the first needle 211. No antimigration members 550 are located on the part of the electrode lead 510 which is exposed to the surrounding tissue through the side slot 213. In this way, the first needle 211 may shield the surrounding tissue from the anti-migration members 550 prior to deployment of the electrode lead 510.

[0285] The anti-migration members 550 may extend around at least 10% of the circumference of the electrode lead 510. For example, the anti-migration members 550 may extend around more than 20%, 40% or 60% of the circumference of the electrode lead 510. In examples, the anti-migration members 550 may extend around less than 20%, 40%, 60% or 80% of the circumference of the electrode lead 510. In this example, the anti-migration members 550 extend around approximately 70% of the circumference of the electrode lead 510.

[0286] The anti-migration members 550 may be fixed with respect to the electrode lead 510, i.e. they do not change conformation when the electrode lead 510 is deployed. For example, the anti-migration members 550 may be integral or co-mounded with the electrode lead 510.

[0287] As shown in FIG. 13, the anti-migration members may be configured to lie completely within the profile 531 of the lumen 231. This may allow the first needle 211 to be reversibly retracted and extended to deploy and then re-house the electrode lead 510 without fouling the anti-migration members 550.

[0288] In the example shown in FIG. 12 and FIG. 13, the anti-migration members 551 are located on a length of the electrode lead proximal to the housing portion. In some examples, the implant delivery apparatus may include anti-migration members closer to the free end 112 i.e., on a part of the electrode lead which is exposed to the surrounding tissue during testing. This is best illustrated in FIG. 14A to FIG. 14D which illustrate several example configurations of the anti-migration members and electrodes on the electrode lead.

[0289] FIG. 14A shows a first example configuration an electrode lead 110a for the implantable neurostimulation device 100. The electrode lead 110a comprises a first portion 631 extending along a first length of the electrode lead 110a which includes the free end 112 and a second portion which extends along a second length of the electrode lead 110a from the housing portion (not shown) to the first portion 631. The first portion 631 may have a higher stiffness than the second portion 632.

[0290] The implantable neurostimulation device may comprise one or more anti-migration members. The one or more anti-migration members may extend at least partially around the circumference of the electrode lead. In examples, the one or more anti-migration members may be positioned on the first portion of the electrode lead. The one or more anti-migration members may be proximal to or at the free end of the electrode lead. As shown in FIG. 14A, the implantable neurostimulation device may comprise a first set of anti-migration members 621 and a second set of anti-migration members 622, each comprising one or more antimigration members. As shown, the first set of anti-migration members 621 are spaced from the second set of anti-migration members 622 along the length of the electrode lead 110a. In particular, the first set of anti-migration members 621 are closer to the free end 112 of the electrode lead 110 than the second set of anti-migration members 622.

[0291] The anti-migration members of the first set 621 of anti-migration members and / or the second set 622 of anti-migration members may be moveable with respect to the electrode lead 110. They may be deployable from a closed configuration to a deployed configuration in which the anti-migration members extend further from the electrode lead 110a than in the closed configuration. For example, the anti-migration members may be tines which pivot away from the electrode lead 110a.

[0292] In the closed configuration, prior to deployment, the anti-migration members of the first set 621 of anti-migration members and / or the second set of anti-migration members 622 may be configured to be received within a profile of the lumen of the first needle. In examples, the anti-migration members 621, 622 may be covered by the first needle, prior to deployment (when the electrode lead 110a is fully received within the lumen of the first needle). As the electrode lead is deployed, the anti-migration members 621, 622 deploy, pivoting outwards to extend further from the electrode lead 110a and adopt a deployed configuration as shown in FIG. 14 A.

[0293] As illustrated in FIG. 14A. the first set of anti-migration members 621 may act in an opposite direction to the second set of anti-migration members 622. In particular, the first set of anti-migration members 621 may act to resist movement of the electrode lead 110a towards its free end (i.e., against movement of the electrode lead 110a deeper into the tissue). The second set of anti-migration members 622 may act to resist retraction of the electrode lead 110a towards the skin. In examples, in the deployed configuration the anti-migration members of the first set 621 extend further (measured radially) from the electrode lead 110a as the distance from the free end 112 decreases. In contrast, in the deployed configuration the anti-migration members of the second set 622 extend further (measured radially) from the electrode lead 110a as the distance from the free end 112 increases.

[0294] The first set of anti-migration members 621 may define a (virtual or physical) boundary between: a distal side 634 of the electrode lead 110a which is distal from the housing portion; and a proximal side 636 of the electrode lead 110a which is proximal to the housing portion, the free end 112 of the electrode lead 110a forming part of the distal side 634. As shown, an electrode I l li is provided on the distal side 634 of the electrode lead 110a e.g., at or proximal to the free end 112.

[0295] At least one electrode 11 lii may also be provided on the proximal side 636 of the electrode lead 110a between the first set of anti-migration members 621 and the second set of anti-migration members 622.

[0296] In use, the electrode lead 110a may be partially deployed to expose the distal side 634 of the electrode lead 110 and the first set of anti-migration members 621. Once exposed, the first set of anti-migration members 621 adopt the deployed configuration to anchor the free end 112 of the electrode lead 110. Preferably, the electrode lead 110a is deployed until the electrode(s) 11 lii positioned between the first set of anti-migration members 621 and the second set of anti-migration members 622 are exposed and the second set of anti-migration members 622 are not exposed (i.e., they are still within the first needle. The delivery device may be configured to provide tactile feedback when the electrode lead 110a is deployed to this extent. Alternately, the delivery device may comprise a locking mechanism to inhibit deployment of the electrode I l li beyond this extent without unlocking the locking mechanism. This may prevent a user from inadvertently deploying the second set of anti-migration members 622 before the position of the free end 112 of the electrode lead 110a within the subject's anatomy has been tested. The electrodes I l li, 111 ii, which are exposed can be used to test theposition of the electrode lead 110a relative to the target site. For example, the efficacy of the stimulation on the target nerve or muscle may be tested.

[0297] If the electrode lead 110a needs to be re-positioned, the first needle can be pushed forwards to re-sheath at least part of the electrode lead 110a and force the first set of antimigration members 621 back into the closed configuration within the first needle. In the example of FIG. 14A, an end cap 120i is provided at a terminal end of the electrode lead 110a. The end cap 120ii comprises one or more projections 654 which each act as an anti-migration feature. In this example, the end cap comprises two projections 654. The projections 654 may be aligned at a same circumferential position around the electrode lead 110a and / or end cap 120i. Providing such aligned projections 654 may allow each of the projections 654 to be accommodated within a single slot in the needle prior to deployment (or following resheathing).

[0298] When the electrode lead 110a is re-sheathed within the first needle, at least the rearwardly facing surface of the or each projection 654 is received within the side slot or lumen of the first needle. Beneficially, this may prevent or ameliorate damage to the subject's tissue as the first needle is repositioned.

[0299] Once the first needle has been re-positioned with the subject's anatomy, the electrode lead 110a may then be re-deployed and its position re-tested as needed. Once the electrode lead 110a is in the appropriate position, the electrode lead 110a can be fully deployed to expose the second set of anti-migration members 622. This may be achieved by retracting the first needle to a greater extent than during testing. The second set of anti-migration members 622 may deploy automatically once exposed, adopting a deployed configuration as shown in FIG. 14 A. In this configuration, the second set of anti-migration members 622 inhibit retraction of the electrode lead 110a towards the skin as the first needle is retracted thereby ensuring appropriate anatomical positioning of the electrode lead 110a is maintained during needle retraction. Where present, the end cap 120i and the projections 654 thereon further assist in inhibiting the retraction of the electrode lead 110a towards the skin as the first needle is retracted and withdrawn.

[0300] As shown, one or more further electrodes may be provided on the electrode lead between the second set of anti-migration members 622 and the housing portion.

[0301] FIG. 14B illustrates a further example of an electrode lead 110b. The electrode lead is substantially the same as the electrode lead 110a of FIG. 14A with the exception that no endcap 120i is provided. Instead, the terminal electrode I l li defines a penetrating surface for blunt dissection of a patient’s tissue. The omission of an end cap may ease re-insertion of the electrode lead back into the first needle during re-sheathing.

[0302] FIG. 14B illustrates a further example of an electrode lead 110c. The electrode lead 110c is substantially the same as the electrode lead 110a of FIG. 14A with the exception that two electrodes 11 lii are provided between the first set of anti-migration members 621 and the second set of anti-migration members 622 as opposed to one in FIG. 14A. Beneficially, such an arrangement increases the number of electrodes that are exposed when the anatomical position of the electrode lead 110c is tested. This configuration may be particularly suited for intraoperative stimulation allowing greater functionality of the electrodes to be tested. For example, the efficacy of bi-polar stimulation can be tested with multiple different electrode pairs, or tri- polar stimulation can be tested.

[0303] FIG. 14B illustrates a further example of an electrode lead HOd. The electrode lead 1 lOd is substantially the same as the electrode lead 110c of FIG. 14C with the exception that the and end cap 120i has been omitted. Instead, the terminal electrode I l li defines a penetrating surface for blunt dissection of a subject’s tissue.

[0304] FIG. 15A to FIG. 15G illustrate a method of implanting an implantable neurostimulation device 1414 in a patient using the implant delivery apparatus 300 described above, illustrated as delivery device 1418. The implantable neurostimulation device 1414 may be any of the implantable neurostimulation devices 100, 400, 500 described above. In this example, the implantable neurostimulation device 1414 is implanted to target a nerve branch 1404 of a target nerve 1406.

[0305] As shown in FIG. 15 A, initially the implantable neurostimulation device 1414 is provided in the delivery device 1418. In particular, the first needle 1420 is in an extended position and the electrode lead 1416 is received within the first needle 1420. The housing portion 1426 is received in the second needle 1422 of the delivery device 1418. As shown in this example, an ultrasound device 1402 is used to guide the first needle 1420 towards the nerve branch 1404 of the target nerve 1406 during implantation. In other examples, other images devices can be used to guide the first needle 1420 towards the target nerve 1406.

[0306] In an example, the first needle 1420 enters the patient's tissue at an insertion point that is in the submandibular area, close to the posterior edge of the mandibular symphysis at the midline.

[0307] In the example of FIG. 8 A to FIG. 11, the first needle 211 may be in a fully extended position such that the sharp tip 211a of the first needle 211 punctures the patient's skin 1408 and / or dissects the patient's subcutaneous tissue 1410. In the examples of FIG. 1 to FIG. 6B, the first needle 211 may be extended to engage the end cap 120, 420 to provide rigidity to the electrode lead 110, 410 during advancement.

[0308] The first needle 1420 is advanced into the patient's tissue, through the skin 1408 and into the subcutaneous tissue 1410, as shown in FIG. 15B. The first needle 1420 is pushed towards the muscle 1412 and specifically the nerve branch 1404 of the target nerve 1406. The ultrasound device 1402 provides an image of the position of the first needle 1420 and can be used to guide the first needle 1420 into proximity with the nerve branch 1404. In examples, the first needle 1420 is advanced at an intramuscular angle (approximately 90 degrees to the skin surface), particularly if the target nerve is a deep nerve.

[0309] During this advancement, the end cap of the electrode lead 1416 (as described with reference to previous examples) provides blunt dissection for at least some of the movement of the electrode lead 1416 through the tissue, particularly as the electrode lead 1416 approaches the target nerve. In the examples of FIG. 1 to FIG. 6B the end cap 120, 420 forms the leading point during advancement and provides blunt dissection. In the example of FIG. 8 A to FIG. 11 the physician performing the implantation may switch between sharp dissection using the first needle 211 and blunt dissection using the end cap 520 of the electrode lead 510. The physician may use sharp dissection for an initial stage of advancement, and then switch to blunt dissection as they approach the target nerve.

[0310] In the position shown in FIG. 15C the implantation position of the electrode lead 1416 can be tested by at least partially retracting the first needle 1420 and powering the implantable neurostimulation device 1414.

[0311] When the first needle 1420 is retracted the end cap 120, 420, 520 acts as an antimigration member, anchoring the free end of the electrode lead 1416 proximate to the target nerve.

[0312] The implantable neurostimulation device 1414 may be powered by a power system provided in the delivery device 1418, or by an external device (not shown), for example a wearable. The implantable neurostimulation device 1414 can be powered and controlled to provide sensing or stimulation to determine if the electrode lead 1416 is properly positioned withrespect to the nerve branch 1404. This testing may include monitoring a reaction of the patient to stimulation by the implantable neurostimulation device 1414.

[0313] As shown in FIG. 15D, if the position of the electrode lead 1416 is determined to be unacceptable, the first needle 1420 can be re-extended, specifically by moving the actuation tab 1424. The delivery device 1418 can then be manipulated to move the first needle 1420 into a better position relative to the nerve branch 1404, for example as shown in FIG. 15D. Repositioning the first needle 1420 may include rotating the delivery device 1418 so that the first needle 1420 is closer to parallel with the nerve branch 1404.

[0314] Preferably, the end of the electrode lead 1416 with the electrodes is approximately parallel with the nerve branch 1404 so that each of the electrodes can be operated to sense and / or stimulate the nerve branch 1404. Repositioning the first needle 1420 may also include percutaneously positioning the tip of the second needle 1422 in the patient, for example in the skin 1408, as shown, or in subcutaneous tissue 1410. However, in preferred examples the second needle 1422 remains exterior to the patient.

[0315] During this process, the anti-migration function of the end caps 120, 420, 520 can be disabled by reextending the first needle 211 to abut or surround the end cap 120, 420, 520, allowing the electrode lead 1416 to be retracted and moved.

[0316] Once the first needle 1420 is determined to be appropriately positioned relative to the nerve branch 1404 within the muscle 1412, as shown in FIG. 15E, the first needle 1420 can be more fully retracted to implant the electrode lead 1416. The first needle 1420 can be fully retracted by moving the actuation tab 1424.

[0317] As described previously, when the first needle 1420 is retracted the end cap 120, 420, 520 acts as an anti-migration member, anchoring the free end of the electrode lead 1416 proximate to the target nerve.

[0318] In some examples, retraction of the first needle 1420 may also deploy anti-migration tines to anchor the electrode lead 1416 in position.

[0319] As illustrated in FIG. 15F, once the electrode lead 1416 has been implanted and preferably anchored, the delivery device 1418 is partially withdrawn from the patient such that the second needle 1422 is removed from the subcutaneous tissue 1410 and skin 1408. In some examples, the second needle 1422 is already external to the patient and such withdrawal is not performed. The delivery device 1418 can be simultaneously or subsequently rotated. In particular, the delivery device 1418 may be rotated from an intramuscular angle to a subcutaneousangle (approximately 45 degrees or less to the skin surface). Slack in the electrode lead 1416 permits the retraction and rotation of the delivery device 1418 without applying pulling or bending stress to the electrode lead 1416, particularly the end of the electrode lead 1416 that has been positioned proximate to the target nerve. Advantageously, this prevents dislodgement of the electrode lead 1416 from the implanted position. The end cap 120, 420, 520 acts to hold the end of the electrode lead 1416 in position.

[0320] As shown in FIG. 15F and FIG. 15G, the delivery device 1418 is rotated so that the second needle 1422 is closer to parallel with the skin 1408. That is, the delivery device 1418 is rotated into a subcutaneous injection angle. Advantageously, this permits the housing portion 1426 to be implanted at a different angle to the electrode lead 1416, particularly at an angle closer to parallel with the skin 1408.

[0321] As shown in FIG. 15G, once the delivery device 1418 has been rotated, the second needle 1422 is percutaneously repositioned for implanting the housing portion 1426.

[0322] As shown in FIG. 15H, the second needle 1422 is pushed into the patient's skin 1408 and subcutaneous tissue 1410 to a position for implanting the housing portion 1426. During this movement, the electrode lead 1416 bends such that the housing portion 1426 is at an angle with respect to the electrode lead 1416.

[0323] FIG. 15H illustrates ejection of the housing portion 1426 from the second needle 1422. The housing portion 1426 may be ejected from the second needle 1422 by moving the actuation tab 1424 to push the housing portion 1426 out of the second needle 1422. The operator may gradually withdraw the delivery device 1418 from the patient's tissue as they push the actuation tab 1424 so that the housing portion 1426 is implanted in the space created by the second needle 1422.

[0324] The delivery device 1418 can then be removed from the patient. As shown, the end of the electrode lead 1416 with the electrodes has been implanted and anchored proximal to the nerve branch 1404 within the muscle 1412. The housing portion 1426 has been implanted in the skin 1408, and the electrode lead 1416 is bent between the housing portion 1426 and the electrodes.

[0325] Advantageously, the housing portion 1426 is oriented approximately parallel to the skin 1408, which may be beneficial for wireless power transfer and / or wireless communications between the housing portion 1426 and an external device. This orientation may also be more comfortable and require less tissue damage to implant the relatively larger housing portion 1426.Additionally, this implantation position enables the implantable neurostimulation device 1414 to target the nerve branch 1404 within the muscle 1412, where there is minimal tissue suitable for implanting the housing portion 1426.

[0326] Accordingly, the method described with reference to FIG. 15A to FIG. 15G advantageously allows the implantable neurostimulation device 1414 to target the nerve branch 1404 within the muscle 1412 using a minimally invasive procedure.

[0327] FIG. 16A to FIG. 16F illustrate an implantation method that is similar to that of FIG. 15A to FIG. 15G. In this example the first needle 1506 is implanted in the subcutaneous tissue 1410 of the patient separately to any housing portion. In particular, in this example method only an electrode lead 1502 is implanted. The electrode lead 1502 comprises an elongate lead with a plurality of electrodes, similar to as described with reference to previous examples. The electrode lead 1502 may include at least a part of an antenna extending at least partly along the electrode lead 1502, for example for receiving wireless power and / or communications from an external device. The electrode lead 1502 may comprise a connector for connection with an electronics housing after implantation of the electrode lead 1502. The electronics housing may be implantable. For example, an implantable pulse generator (IPG) may be connected to the electrode lead 1502 and implanted in the subcutaneous tissue 1410 after implantation of the electrode lead 1502.

[0328] The method of FIG. 16A to FIG. 16F uses a delivery device 1504 that is the same as the delivery device 1418 described above. The delivery device 1504 includes a first needle 1506 and a second needle 1508. The first needle 1506 is sized to receive the electrode lead 1502. The second needle 1508 is larger than the first needle 1506 and the first needle 1506 is retractable relative to the second needle 1508.

[0329] As shown in FIG. 16A, in an initial state the electrode lead 1502 is received in the first needle 1506 and extends into the second needle 1508.

[0330] In the described example method of FIG. 16A to FIG. 16F the electrode lead 1502 may include an end cap 120, 420, 520 as described above, or alternatively it may not comprise an end cap 120, 420, 520 for blunt dissection, and the tip of the first needle 1506 may provide sharp dissection during implantation.

[0331] As shown in FIG. 16B, the first needle 1506 penetrates the patient's tissue and is advanced into the subcutaneous tissue 1410 towards the nerve branch 1404 of the target nerve 1406. In this way the electrode lead 1502, and in particular the electrodes on the electrode lead1502, are positioned proximate to the nerve branch 1404 of the target nerve 1406. The first needle 1506 may be inserted at an intramuscular injection angle (approximately 90 degrees to the skin surface), or a subcutaneous injection angle (approximately 45 degrees to the skin surface), depending on the location of the target nerve 1406 and the surrounding tissue.

[0332] As shown in FIG. 16C, the first needle 1506 is retracted relative to the second needle 1508, which is the same as described previously. In this way, the electrode lead 1502 is deployed in position proximate to the nerve branch 1404 of the target nerve 1406. In the deployed state, as illustrated, the end of the electrode lead 1502 proximate to the target nerve 1406 (and with the electrodes) extends in a first orientation in the subcutaneous tissue 1410.

[0333] As shown in FIG. 16D and FIG. 16E, the delivery device 1504 is then rotated towards the plane of the skin, so that the second needle 1508 is closer to parallel with the skin surface 1510. In particular, the delivery device 1504 may be rotated into a subcutaneous injection angle (approximately 45 degrees to the skin surface, or less). Once rotated, the delivery device 1504 is pushed into the tissue a small amount to form a kink in the electrode lead 1502 close to the end that is received in the delivery device 1504.

[0334] Subsequently, as shown in FIG. 16F, the delivery device 1504 is removed and the electrode lead 1502 remains implanted. Once implanted, the end of the electrode lead 1502 with the electrodes (distal end) is proximate to the nerve branch 1404 of the target nerve 1406 and the other end (connection end 1514, proximal end) is approximately parallel to the skin surface 1510, with the kink 1512 in between. This permits an IPG to be implanted at a shallow depth in the tissue, with the IPG oriented approximately parallel to the skin surface 1510, and connected to the electrode lead 1502. In this way, the implantation procedure may be minimally invasive. Additionally, the orientation of the IPG may be beneficial for wireless power transfer from an external wearable on the skin.

[0335] FIG. 17A to FIG. 17F illustrate a further implantation procedure. Like the example of FIG. 16A to FIG. 16F, this procedure is to implant only an electrode lead 1502. After implantation of the electrode lead 1502 an IPG (not shown) can be implanted and connected to the electrode lead 1502. The electrode lead 1502 may optionally include an end cap 120, 420, 520, as described above, and the implantation procedure may use sharp and / or blunt dissection as previously described.

[0336] As shown in FIG. 17A, in this example the electrode lead 1502 is initially received in a needle 1602. The needle 1602 may include an opening extending along one side (a half-pipeneedle), or it may be a full needle (with a fully enclosed lumen). The electrode lead 1502 may extend out of the needle 1602 at a proximal end (end opposite the insertion tip).

[0337] As shown in FIG. 17B, the needle 1602 is advanced into the subcutaneous tissue 1410 to carry the electrode lead 1502 into position with one end (with the electrodes) proximate to the nerve branch 1404 of the target nerve 1406. The needle 1602 may be advanced at an intramuscular injection angle (approximately 90 degrees to the skin surface), or at a subcutaneous injection angle (approximately 45 degrees to the skin surface), depending on the location of the target nerve 1406 and the surrounding tissue.

[0338] As shown in FIG. 17C, the needle 1602 is then withdrawn, leaving the electrode lead 1502 implanted with one end (with the electrodes) proximate to the nerve branch 1404 of the target nerve 1406 and the connection end 1514 external of the patient.

[0339] As shown in FIG. 17D, the connection end 1514 of the electrode lead 1502 is then inserted into the needle 1602, and as shown in FIG. 17E and FIG. 17F, the needle 1602 is used to implant the connection end 1514 of the electrode lead 1502 at a different angle to the remainder of the electrode lead 1502. Specifically, the connection end 1514 is implanted at a shallow tissue depth, approximately parallel with the skin surface 1510. In particular, the needle 1602 may be rotated into a subcutaneous injection angle (approximately 45 degrees to the skin surface, or less).

[0340] An IPG can then be connected to the connection end 1514 of the electrode lead 1502. In particular, an IPG can be implanted at a shallow depth in the tissue, with the IPG oriented approximately parallel to the skin surface 1510, and connected to the electrode lead 1502. In this way, the implantation procedure may be minimally invasive. Additionally, the orientation of the IPG may be beneficial for wireless power transfer from an external wearable on the skin.

[0341] FIG. 18A to FIG. 18F illustrate a further example implantation procedure for implanting an electrode lead 1702. Like the examples of FIG. 16A to FIG. 17F, this procedure is to implant only the electrode lead 1702. After implantation of the electrode lead 1702 an IPG can be implanted and connected to the electrode lead 1702. The electrode lead 1702 has a connection end 1704 (proximal end) for connection of the IPG after implantation of the electrode lead 1702. The electrode lead 1702 may include a distal end that is implanted proximate to the nerve branch 1404 and a proximal end comprising the connection end 1704.

[0342] As shown in FIG. 18 A, in this example the implantation procedure uses a needle 1710. The needle 1710 preferably does not have a lumen, i.e., the needle 1710 is preferably solid. Theneedle 1710 includes a hook 1712 at or near one end. The electrode lead 1702 includes a loop 1706 at an end of the electrode lead 1702 proximate to the electrodes, and a loop 1708 at the connection end 1704 of the electrode lead 1702. The hook 1712 on the needle 1710 can engage either of the loops 1706, 1708.

[0343] As shown in FIG. 18B to FIG. 18C, to implant the electrode lead 1702 the hook 1712 on the needle 1710 is engaged with the loop 1706 at the end of the electrode lead 1702 proximate to the electrodes and the electrode lead 1702 is used to advance the electrode lead 1702 through the patient's skin 1408 and into the subcutaneous tissue 1410 such that the electrodes on the electrode lead 1702 are positioned proximate to the nerve branch 1404 of the target nerve 1406. At this time, the connection end 1704 of the electrode lead 1702 remains outside of the patient's tissue. The needle 1710 may be advanced at an intramuscular injection angle (approximately 90 degrees to the skin surface), or at a subcutaneous injection angle (approximately 45 degrees to the skin surface), depending on the location of the target nerve 1406 and the surrounding tissue.

[0344] Once the electrode lead 1702 has been positioned, the needle 1710 can be withdrawn, at which point the hook 1712 disengages from the loop 1706 so that the needle 1710 is withdrawn and the electrode lead 1702 remains in the implanted position.

[0345] Once the needle has been withdrawn the hook 1712 can be engaged with the loop 1708 at the connection end 1704 as shown in FIG. 18D.

[0346] As shown in FIG. 18E and FIG. 18F, the needle 1710 can then be used to implant the connection end 1704 of the electrode lead 1702 at a different angle to the end of the electrode lead 1702 that includes the electrodes. Specifically, the connection end 1704 can be implanted such that it extends approximately parallel to the skin 1408. In particular, the needle 1710 may be rotated into a subcutaneous injection angle (approximately 45 degrees to the skin surface, or less).

[0347] An IPG can then be connected to the connection end 1704 of the electrode lead 1702. In particular, an IPG can be implanted at a shallow depth in the tissue, with the IPG oriented approximately parallel to the skin surface, and connected to the electrode lead 1702. In this way, the implantation procedure may be minimally invasive. Additionally, the orientation of the IPG may be beneficial for wireless power transfer from an external wearable on the skin.

[0348] FIG. 18A to FIG. 18C illustrate a further example of an implantation procedure for an implantable neurostimulation device. In this example the electrode lead 1802 compriseselectrodes towards one end of the electrode lead 1802 and an expandable antenna 1804 at or towards the opposite end. The expandable antenna 1804 may comprise a coiled wire, or a shape memory alloy (such as Nitinol), or similar. In particular, the expandable antenna 1804 may comprise a bundle of wires, a spring, and / or a memory alloy. Preferably, the expandable antenna 1804 comprises a ferrous material for magnetic resonance during wireless power transfer.

[0349] As shown in FIG. 18A, the electrode lead 1802 is initially received in a needle 1806. When the electrode lead 1802 is positioned within the lumen of the needle 1806 the expandable antenna 1804 is held, by the needle 1806, in a collapsed or compressed state.

[0350] As shown in FIG. 18B, the needle 1806 is then advanced into the patient's tissue until the electrodes are positioned proximate to the nerve branch 1404 of the target nerve 1406. The needle 1806 may be advanced at an intramuscular injection angle (approximately 90 degrees to the skin surface), or at a subcutaneous injection angle (approximately 45 degrees to the skin surface), depending on the location of the target nerve 1406 and the surrounding tissue.

[0351] As shown in FIG. 18C, the electrode lead 1802 is deployed by retracting the needle 1806 such that the electrode lead 1802 is implanted. At this location the expandable antenna 1804 is at a shallow depth within the patient, for example under the skin 1408 or in a shallow position within the subcutaneous tissue 1410. When the needle 1806 is retracted beyond the expandable antenna 1804 the expandable antenna 1804 expands to increase a size of the expandable antenna 1804. The expandable antenna 1804 may thereby provide a receiving antenna that can receive power and / or communications from a wearable device on the skin 1408. The expanded state of the expandable antenna 1804 improves the efficiency of the antenna and it extends at least partially substantially parallel to the skin surface. In addition, when expanded, the expandable antenna 1804 may act as an anti-migration member to hold the electrode lead 1802 in position.

[0352] FIG. 20A-FIG.20B illustrate a further example of an implantation procedure for an implantable neurostimulation device 1900. In this example the electrode lead 1902 comprises electrodes towards one end of the electrode lead 1902 and a housing portion 1910 operably connected to another end of the electrode lead 1902, opposite the electrodes. The housing portion 1910 comprises an electronics assembly (not shown) connected to the one or more electrodes for stimulating a target nerve during use. The electronics assembly may comprise a power supply for powering the electrodes to generate electrical impulses and may behermetically sealed within the housing portion 1910. In this example, the housing portion 1910 is tubular in shape with both ends of the housing portion 1910 having an end cap. The end caps are rounded to improve ease of insertion.

[0353] As illustrated in FIG. 20 A a delivery device 1904 comprising a handle 1914 and a needle 1906 is used during the implantation procedure. The needle 1906 has a lumen configured to receive the electrode lead 1902 therein.

[0354] FIG. 20A shows the housing portion 1910 and the electrode lead 1902 prior to insertion. The needle 1906 includes a side slot 1903 which extends along the length of the needle 1906. As shown in FIG. 20A, prior to insertion, part of the electrode lead 1902 extends out of the side slot 1903 of the needle 1906 to the housing portion 1910.

[0355] In this example, the side slot 1903 extends around half a circumference of the needle 1906. In some examples, the side slot 1903 may extend around more than half of the circumference of the needle 1906. In other examples, the side slot 1903 may extend around less than half of the circumference of the needle 1906. In such examples the electrode lead 1902 may have a diameter that is less than or equal to a width of the side slot 1903. Alternately or in addition, the electrode lead 1902 may include a narrowed portion where the electrode lead 1902 extends out of the side slot 1903. The narrowed portion having a smaller diameter than the remainder of the electrode lead 1902.

[0356] The electrode lead 1902 may be configured to prevent translation of the electrode lead 1902 through the side slot 1903 during insertion of the needle 1906. For example, the electrode lead 1902 may have a greater diameter than the side slot 1903. The electrode lead 1902 may include one or more side projections configured to fit within corresponding grooves in the needle 1906 for retaining the electrode lead 1902 within the needle 1906.

[0357] As shown in FIG. 20A, the electrode lead further comprises a protrusion 1907 for anchoring the free end of the electrode lead 1902 within the patient’s tissue. The protrusion 1907 is located at the free end of the electrode lead 1902 (proximal the electrodes). In this example, the protrusion 1907 is located at a terminus of the electrode lead 1906. As shown in FIG. 20 A, prior to insertion, the protrusion 1907 is aligned within the side slot 1903.

[0358] FIG. 20B shows the delivery device 1904 and the implantable neurostimulation device 1900 following initial insertion. As shown, to implant the electrode lead 1902 the handle 1914 is used to advance the electrode lead 1902 through the patient's skin 1408 and into the subcutaneous tissue 1410 such that the electrodes on the electrode lead 1902 are positionedproximate to the nerve branch 1404 of the target nerve 1406. At this time, the housing portion 1910 and part of the electrode lead 1902 opposite the free end remains outside of the patient's tissue. The needle 1906 may be advanced at an intramuscular injection angle (approximately 90 degrees to the skin surface), or at a subcutaneous injection angle (approximately 45 degrees to the skin surface), depending on the location of the target nerve 1406 and the surrounding tissue.

[0359] Once the electrode lead 1902 has been positioned, the needle 1906 can be withdrawn. The needle 1906 is withdrawn by pulling the handle 1914 of the delivery device 1904 away from the patient’s skin 1408. As the needle 1902 is withdrawn, the electrode lead 1902 passes through a tip 1908 of the needle 1906 out of the lumen of the needle 1906. The protrusion 1907 acts to anchor the electrode lead 1902 within the patient’s tissue preventing the electrode lead 1902 from being withdrawn along with the needle 1906. Once the delivery device 1904 is fully extracted, the free end of electrode lead 1902 remains in the implanted position with a small portion of the electrode lead 1902 and the housing portion 1910 extending outside of the patient’s skin 1408.

[0360] The housing portion 1910 is then inserted under the patient’s skin through an incision (not shown). For example, the incision may be made before the needle 1906 is inserted, after the needle 1906 is inserted and before it is withdrawn, or after the needle 1906 is withdrawn. Once the housing portion 1910 is inserted, both the housing portion 1910 and the electrode lead 1902 are positioned beneath the patient’s skin 1408 and implantation of the implant 1900 is complete. Optionally, once the implant is implanted, the incision may be closed (e.g., using sutures and / or a dermal adhesive).

[0361] FIG. 21 A and FIG. 2 IB illustrate a further example of a delivery device 2004 for implanting an implantable neurostimulation device 2000. The implantable neurostimulation device 2000 may be substantially similar to and of the previous implantable neurostimulation devices described herein.

[0362] In this example the delivery device 2004 is a peel-away introducer comprising a sheath 2006 and a handle 2014. The sheath 2006 has a lumen configured to receive an electrode lead 2002 of the implantable device 2000 therein.

[0363] FIG. 21 A shows the delivery device 2004 prior to insertion. As shown, in this example the electrode lead 2002 extends through the handle 2014 and a housing portion 2010 is located outside the delivery device 2004, opposite the sheath 2006. In other examples, the housing portion 2010 may be received within the delivery device 2004 (e.g., within the handle 2014).

[0364] To implant the electrode lead 2002 the handle 2014 is used to advance the electrode lead 2002 through the patient's skin and into the subcutaneous tissue such that the electrodes on the electrode lead 2002 are positioned proximate to a nerve branch of a target nerve. At this time, the housing portion 2010 and part of the electrode lead 2002 adjacent the implant remains outside of the patient's tissue. The sheath 2006 may be advanced at an intramuscular injection angle (approximately 90 degrees to the skin surface), or at a subcutaneous injection angle (approximately 45 degrees to the skin surface), depending on the location of the target nerve and the surrounding tissue.

[0365] Once the electrode lead 2002 has been positioned, the sheath 2006 must be withdrawn. To prevent the electrode lead 2002 from being withdrawn along with the delivery device 2004, the delivery device 2004 is designed to split into at least two parts. This is illustrated by comparison of FIG. 21 A and FIG. 21B which shows the delivery device 2004 as it is being split apart.

[0366] As shown, the delivery device 2004 is divided into two parts: a first part 2004a and a second part 2004b. In this example the two parts 2004a, 2004b are symmetric and each define half of the delivery device 2004. In other examples the split between the two parts 2004a, 2004b may be asymmetric and / or the delivery device 2004 may be split into more than two parts (e.g., three or four parts).

[0367] The two parts 2004a, 2004b are connected together via a connector 2030 illustrated by a dashed line in FIG. 21A and FIG. 21B. In this example, the connector 2030 is a frangible connector which allows the delivery device 2004 to come apart when a splitting force is applied to separate the two parts 2004a, 2004b. In particular the frangible connector 2030 includes a line of weakness in the delivery sheath 2006 that defines a line of breakage of the delivery device 2004. For example, a wall of the delivery sheath 2006 may have two opposing continuous or discontinuous lines of weakness along its length (e.g., opposing sides of the wall may comprise thinned portions to define opposing aligned lines of weakness). In examples where the delivery sheath 2006 includes a side slot, the side slot may be aligned with and extend from the frangible connector 2030.

[0368] The handle 2014 may include an extension of the line of weakness. In some examples a body of the handle 2014 may have a continuous or discontinuous line of weakness, such as a thinned portion or a line of perforations, aligned with the length of the sheath 2006. In otherexamples the handle 2014 may comprise two independent parts which are reversibly coupled together e.g., via a clip or another fastener.

[0369] FIG. 2 IB shows the shows the delivery device 2004 as it is being split apart following insertion of the electrode lead 2002. As shown, to remove the delivery device 2004, the user separates the two parts of the handle 2014 and continues to apply a separating force tear the delivery sheath 2006 in two, separating it along the frangible connector 2030 until the two parts of the delivery device 2004a, 2004b are completely separated from one another.

[0370] Once the two parts 2004a, 2004b are completely separated, they can be pulled out of the patient’s tissue by pulling the handle 2014. The two parts 2004a, 2004b can either be extracted simultaneously or sequentially. By separating the delivery sheath 2006 the friction between the sheath 2006 and the electrode lead 2002 when the sheath 2006 is removed can be reduced. This helps to more reliably maintain the electrode lead 2002 in its implanted position proximal to the target nerve (not shown).

[0371] In other examples, the sheath 2006 may be retracted from the patient’s skin while the two parts 2004a, 2004b are pulled part.

[0372] Once the delivery device 2004 is fully extracted, the free end of electrode lead 2002 remains in the implanted position with a small portion of the electrode lead 2002 and the housing portion 2010 extending outside of the patient’s skin.

[0373] The housing portion 2010 is then inserted under the patient’s skin through an incision. For example, the incision may be made before the delivery sheath 2006 is inserted, after the delivery sheath is inserted and before it is withdrawn, or after the delivery sheath 2006 is withdrawn. Once the housing portion 2010 is inserted, both the housing portion 2010 and the electrode lead 2002 are positioned beneath the patient’s skin and implantation of the implant 2000 is complete. Optionally, once the implant is implanted, the incision may be closed (e.g., using sutures and / or a dermal adhesive).

[0374] FIG. 21 A and FIG. 21 B illustrate an alternative example of the delivery method using the delivery device 2004. FIG. 21 A shows the delivery device 2004 prior to insertion while FIG. 21 B shows the delivery device 2004 as it is being split apart following insertion of the electrode lead 2002. In FIG. 21A and FIG. 21B, the side slot 2003 of the delivery sheath 2006 is visible. The side slot 2003 is aligned with the opposing lines of weakness in the wall of the delivery sheath 2006. In particular, a front line of weakness 2030a in the front of the delivery sheath 2006 only extends along part of the length of the delivery sheath 2006 from the handle2014 to the side slot 2003. The side slot 2003 extends between the front line of weakness and the tip 2008 of the delivery sheath 2006. In other examples, the side slot 2003 may instead extend along the full length of the delivery sheath 2006.

[0375] The side slot 2003 may be particularly advantageous in examples where the free end of the electrode lead 2002 comprises a protrusion for anchoring the free end in the tissue. In such examples, prior to insertion the protrusion may be received within the side slot 2003.

[0376] As shown, prior to insertion, rather than the electrode lead 2002 extending through the handle 2014 as in FIG. 21 A, in this example the electrode lead 2002 extends out of the side slot 2003 of the delivery sheath 2006. As before, the housing portion 2010 and part of the electrode lead 2002 proximal thereto remain outside of the patient’s skin during insertion of the free end of the electrode lead 2002. Once the free end of the electrode lead 2002 in inserted, the delivery device is separated into two parts and extracted as described above in relation to FIG.21B.

Claims

CLAIMS1. An implantable neurostimulation device comprising an electrode lead having a free end shaped for blunt dissection of a patient’s tissue during implantation of the implantable neurostimulation device, the electrode lead comprising a first portion extending along a first length of the electrode lead and including the free end, and a second portion extending along a second length of the electrode lead, the first portion having a higher stiffness than the second portion.

2. The implantable neurostimulation device of claim 1, wherein the electrode lead comprises a projection which projects outwardly to extend beyond a diameter of the electrode lead, the projection being disposed at or proximate to the free end of the electrode lead.

3. The implantable neurostimulation device of claim 2, wherein the projection comprises a rearwardly facing surface for anchoring the free end of the electrode lead in the tissue.

4. The implantable neurostimulation device of claim 2 or 3, wherein the projection is wider than a diameter of the electrode lead and comprises a rim.

5. The implantable neurostimulation device of claim 4, wherein the electrode lead is receivable in a needle of a delivery device for implantation of the implantable neurostimulation device such that the free end of the electrode lead protrudes beyond a tip of the needle, and wherein the rim is sized to abut an end of the needle.

6. The implantable neurostimulation device of claim 4 or 5, comprising an annular cavity for accommodating the tip of the needle when the electrode lead is received in the needle of the delivery device.

7. The implantable neurostimulation device of any one of claims 2 to 6, wherein the projection is attached to, or co-mounded with, a terminus of the electrode lead.

8. The implantable neurostimulation device of any preceding claim, comprising an end cap and wherein the end cap has a penetrating outer surface terminating in an apex, optionally wherein the apex of the end cap is pointed, rounded or substantially flat.

9. The implantable neurostimulation device of claim 8, wherein an outer diameter of the end cap increases away from the apex to a maximum diameter at or near a rear end of the end cap, optionally wherein the outer surface of the end cap tapers.

10. The implantable neurostimulation device of claim 8 or 9, wherein the end cap is at least partially hollow for receiving the terminus of the electrode lead and is attached to, or comoulded with, a terminus of the electrode lead.

11. The implantable neurostimulation device of any preceding claim, wherein the electrode lead comprises one or more electrodes positioned at or near the free end.

12. The implantable neurostimulation device of claim 11, comprising a housing portion operably connected to the electrode lead, wherein the housing portion comprises an electronics assembly connected to the one or more electrodes for stimulating a target nerve during use.

13. An implant delivery apparatus comprising the implantable neurostimulation device of any preceding claim and a delivery device for implanting the implantable neurostimulation device within a patient, wherein the delivery device comprises a needle having a lumen for receiving the electrode lead such that the free end of the electrode lead protrudes beyond a tip of the needle.

14. The implant delivery apparatus of claim 13, when dependent on any one of claims 2 to 7, wherein the projection extends outside of a profile of the lumen.

15. The implant delivery apparatus of claim 14 or claim 13 when dependent on any one of claims 2 to 7, wherein the needle comprises a slot extending at least partially along the length of the needle and wherein the projection is received within the slot.

16. The implant delivery apparatus of claim 14, or claim 15, or claim 13 when dependent on any one of claims 2 to 7, wherein when the electrode lead is received within the needle, the projection extends to or lies within an outer profile of the needle.

17. The implant delivery apparatus of any one of claims 13 to 16, wherein the electrode lead comprises an end cap, and wherein when the electrode lead is received in the lumen of the needle the end cap protrudes beyond the needle and at least partially covers the tip of the needle.6318. The implant delivery apparatus of claim 17, wherein the end cap comprises a rim for engaging the tip of the needle and wherein the tip of the needle contacts the radially projecting rim of the end cap, optionally wherein a tip of the needle is substantially flat.

19. The implant delivery apparatus of any one of claims 13 to 18, wherein the electrode lead comprises one or more anti-migration members extending at least partially around the circumference of the electrode lead, optionally wherein the electrode lead comprises a plurality of anti-migration members spaced at intervals around a circumference of the electrode lead.

20. The implant delivery apparatus of any one of claims 13 to 19, comprising a first set of antimigration members and a second set of anti-migration members, the first set of anti-migration members being spaced from the second set of anti-migration members along a length of the electrode lead such that first set of anti-migration members are closer to the free end of the electrode lead than the second set of anti-migration members.

21. The implant delivery apparatus of claim 20, wherein the anti-migration members of the first set of anti-migration members and / or the second set of anti-migration members are moveable with respect to the electrode lead from a closed configuration to a deployed configuration, and wherein, in the deployed configuration, the anti-migration members of the first set of antimigration members extend further from the electrode lead as the distance from the free end decreases.

22. The implant delivery apparatus of claim 21, wherein, in the deployed configuration, the anti-migration members of the second set extend further from the electrode lead as the distance from the free end increases.

23. The implant delivery apparatus of claim 19, wherein the one or more anti-migration members are fixed with respect to the electrode lead and configured to be received within a profile of the lumen of the needle.

24. The implant delivery apparatus of any one of claims 19 to 23, wherein the one or more antimigration members are covered by the needle when the electrode lead is received within the lumen of the needle.

25. The implant delivery apparatus of any one of claims 13 to 24, wherein the delivery device comprises a second additional needle having a lumen adapted to receive a housing portion of64the implantable neurostimulation device, wherein the housing portion comprises an electronics assembly attached to one or more electrodes of the electrode lead for stimulating a target nerve during use.

26. The implant delivery apparatus of claim 25, wherein the implantable neurostimulation device comprises a connector which connects the electrode lead to the housing portion and wherein the needle comprises a slot extending at least partially along the length of the needle, wherein the electrode lead is configured to prevent translation of the electrode lead through the slot, optionally wherein the electrode lead has a greater diameter than the connector and / or the electrode lead includes one or more side projections configured to fit within corresponding grooves in the needle for retaining the electrode lead within the needle.

27. A method of implanting an implantable neurostimulation device using the implant delivery apparatus of any one of claims 13 to 26, the method comprising: inserting a portion of the needle in which the electrode lead is received, into a patient, such that the free end of the electrode lead provides blunt dissection of the patient’s tissue during insertion.

28. The method of claim 27, comprising testing the implantable neurostimulation device to determine if it is suitably located in the patient’s tissue.

29. The method of claim 27 or 28, wherein the method comprises at least partially retracting the needle to expose the free end of the electrode lead, optionally wherein at least partially retracting the needle to expose the free end of the electrode lead deploys the free end of the electrode lead at an implant location within a patient’s tissue.

30. The method of claim 29, wherein at least partially retracting the needle to expose the free end of the electrode lead exposes at least one of the one or more anti-migration members to the patient's tissue.

31. The method of any one of claims 27 to 30, comprising re-extending the needle such that the electrode lead is once again received within the needle and subsequently repositioning the electrode lead using the needle.

32. The method of claim 31, comprising at least partially retracting the needle to expose the free end of the electrode lead to deploy the free end of the electrode lead in a second implant65position in the patient’s tissue, wherein the second implant position is different to the implant position.66

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