Neurostimulation leads with delivery systems and methods

Abstract

The present disclosure is directed to systems for providing occipital nerve stimulation (ONS), peripheral nerve stimulation (PNS), and / or spinal cord stimulation (SCS). Methods of delivery are also provided. Stimulator lead bodies as disclosed herein can include features designed to prevent lead migration and retention in tissue. Delivery systems are also provided to deliver these stimulator lead bodies. The delivery systems can include features to test placement of the stimulation lead bodies during delivery to ensure accurate placement of the electrode.

Description

NEUROSTIMULATION LEADS WITH DELIVERY SYSTEMS AND METHODSRELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 704,714, titled “NEUROSTIMULATION LEAD,” filed on October 8, 2024, which is incorporated herein by reference in its entirety.INCORPORATION BY REFERENCE

[0002] All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.FIELD

[0003] The present disclosure details novel implantable systems and methods for stimulating nerves. Specifically, this disclosure provides an implantable lead with features to reduce migration, and an accompanying delivery tool.BACKGROUND

[0004] Occipital nerves provide a favorable site for treating head and / or neck pain with neuromodulation, because an occipital nerve stimulation has level 1 evidence for acute treatment of refractory chronic migraine. However, the occipital nerves are too deep to permit stimulation with surface electrodes and instead require a permanent implant.

[0005] Prior art occipital nerve stimulators have required a long electrode-lead assembly, which in one study exhibited a lead migration rate of 24%. Another study showed a 32% revision rate for electrode migration or displacement, 3.6% removal rate for infection, and 21% removal rate for lack of efficacy. A third study demonstrated 35 serious hardware- related adverse events in 31 participants, including replacement of pulse generators for energy-source depletion; or dislocation, failure, or fracture of electrodes or leads. Yet another study reported 173 device- or procedure-related adverse events in 157 subjects, of which 8.6% required hospitalization and 40.7% required surgical intervention. FDA has not approved any permanent implant for ONS.

[0006] Electrical stimulation leads used for peripheral nerve targets like the greater and lesser occipital nerves can fail from mechanical and biological issues, with lead migration being the most frequent complication that degrades pain coverage and often necessitates revision surgery.- 1 -SG Docket No. 14972-701.600

[0007] Additional hardware problems include lead fracture, conductor or insulation damage, connector disconnection, and skin erosion, while biological complications include infection and wound problems, all of which can interrupt therapy or cause discomfort and require troubleshooting or reoperation.

[0008] Delivering leads to the occipital nerves is technically demanding due to the need for accurate placement on or near the target nerve to avoid muscular stimulation or superficial erosion.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The novel features of the invention are set forth with particularity in the claims that follow. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:

[0010] FIG. 1 illustrates a stimulation lead body.

[0011] FIG. 2 is one embodiment of a stimulation lead.

[0012] FIGS. 3A-3C are another embodiment of a stimulation lead.

[0013] FIGS. 4A-4B show a distal end of a stimulation lead having one or more retention features.

[0014] FIG. 5 shows one example of a delivery tool for implanting a stimulation lead.

[0015] FIGS. 6A-6C show additional embodiments of a delivery tool.

[0016] FIGS. 7A-7B show another embodiment of a delivery tool.

[0017] FIGS. 8A-8C show one example of a stimulation lead inside and outside of a delivery tool.

[0018] FIGS. 9A-9G show another embodiment of a stimulation lead and delivery tool.

[0019] FIG. 10 is a flowchart showing a method of implanting a stimulation lead into a patient.SUMMARY OF THE DISCLOSURE

[0020] A stimulation lead is provided, comprising: an insulated lead wire including a straight proximal portion and a coiled distal portion; and a stimulation electrode coupled to a distal end of the insulated lead wire, the stimulation electrode being a distinct component from the insulated lead wire and having a diameter greater than an outer diameter of the insulated lead wire.- 2 -SG Docket No. 14972-701.600

[0021] A stimulation lead, comprising: an insulated lead wire having an outer diameter, the insulated lead wire including a straight proximal portion and a coiled distal portion, the coiled distal portion having a helical axis aligned with a longitudinal axis of the straight proximal portion; a stimulation electrode disposed at a distal end of the insulated lead wire; wherein the coiled distal portion has a spring constant less than 0.7 Ibf / inch, to mechanically decouple the stimulation electrode from the lead wire proximal to the coiled distal portion.

[0022] A stimulation lead, comprising: an insulated lead wire having an outer diameter, the insulated lead wire including a straight proximal portion and a coiled distal portion, the coiled distal portion comprising less than 50% of a length of the insulated lead wire and having a helical axis aligned with a longitudinal axis of the straight proximal portion; a stimulation electrode disposed at a distal end of the insulated lead wire; wherein a coil diameter of the coiled distal portion of the insulated lead wire is at least three times the outer diameter of the insulated lead wire, to mechanically decouple the stimulation electrode from the insulated lead wire proximal to the coiled distal portion.

[0023] The following features listed below can be incorporated into or combined with any of the stimulation leads of this disclosure, including:

[0024] In some aspects, the coiled distal portion of the insulated lead wire has a pitch greater than the outer diameter of the insulated lead wire to promote tissue ingrowth into the coiled distal portion.

[0025] In one aspect, the insulated lead wire further comprises one or more retention features disposed near the stimulation electrode. In some aspects, the retention features comprise one or more tines, flanges, or scales. In some aspects, the retention features are absorbable in tissue.

[0026] In some aspects, the insulated lead wire further comprises a strain relief feature disposed between the stimulation electrode and the insulated lead wire. In some aspects, the stimulation electrode is attached to the strain relief feature. In one aspect, the strain relief feature is tapered away from the stimulation electrode. In other aspects, the strain relief feature is configured to cut tissue. In one aspect, the strain relief feature comprises a dissolvable or resorbable material. In other aspects, the strain relief feature includes one or more retention features.

[0027] In some aspects of the disclosure, the straight proximal portion comprises more than half of the length of the lead wire. In another aspect, the straight proximal portion comprises more than three-quarters of the length of the insulated lead wire.

[0028] In one aspect, a lead body connector is disposed at a proximal end of the insulated lead wire, the lead body connector being connectable to a stimulator to provide electrical- 3 -SG Docket No. 14972-701.600pulses to the stimulation electrode. In some aspects, the stimulator is implantable, or can be located external to the patient. In some aspects, the lead body connector has a connector diameter greater than the outer diameter of the insulated lead wire.

[0029] In some aspects, the insulated lead wire comprises a conductor and an insulator disposed thereon.

[0030] In other aspects, stimulation systems are provided, comprising: a lead body and an electrode assembly disposed at a distal end of the lead body; and a delivery tool configured to implant a part of the lead body and the electrode assembly, the delivery tool including a stylet, and a sheath slidably disposed over the stylet; wherein a distal end of the stylet is configured to push against the electrode assembly while the sheath releasably engages with the electrode assembly when the lead body and the electrode assembly are loaded onto the delivery tool.

[0031] Another stimulation system is provided, comprising: a lead body and an electrode assembly disposed at a distal end of the lead body; a delivery tool configured to implant part of the lead body and the electrode assembly, the delivery tool comprising a stylet and a sheath disposed over the stylet; wherein a distal end of the stylet is configured to push against the electrode assembly to provide blunt dissection of tissue with the electrode assembly while the sheath is configured to hold the electrode assembly on the delivery tool when the lead body and the electrode assembly are loaded onto the delivery tool.

[0032] In some aspects, another stimulation system is provided, comprising: a lead body and an electrode assembly disposed at a distal end of the lead body, the lead body having a helical portion disposed near its distal end; a delivery tool configured to implant part of the lead body and the electrode assembly, including: a stylet, a distal end of the stylet being configured to push against the electrode assembly to provide blunt dissection of tissue with the electrode assembly, while the helical portion of the lead body is coiled around the stylet; and a sheath disposed over the stylet, the sheath being configured to engage with the electrode assembly and cover the helical portion.

[0033] Additionally, a stimulation system is provided, comprising: a lead body and an electrode assembly disposed at a distal end of the lead body, the lead body having a helical portion disposed near the distal end of the lead body and a lead body connector disposed at a proximal end of the lead body; a delivery tool comprising: a stylet configured to receive the lead body, a distal end of the stylet being configured to apply pressure to the electrode assembly to provide blunt dissection of tissue while the helical portion of the lead body is coiled around the stylet; a sheath disposed over the stylet and having a distal end configured to engage with the electrode assembly; a handle assembly coupled to the stylet and sheath, - 4 -SG Docket No. 14972-701.600the handle assembly including a connector interface configured to receive the lead body connector; and an external stimulator having a stimulator connector configured to be electrically coupled to the lead body connector via the connector interface of the handle assembly, the external stimulator being configured to apply test pulses to an electrode in the electrode assembly, during delivery to confirm placement of the electrode.

[0034] The following features listed below can be incorporated into or combined with any of the stimulation systems of this disclosure, including:

[0035] In some aspects, the delivery tool further comprises a peelable sheath disposed over the stylet and translatable relative to the stylet. In some aspects, the sheath is configured to cover the helical portion of the lead body when the lead body is disposed on the stylet.

[0036] In another aspect, the lead body comprises a straight portion extending proximally from the helical portion. In some aspects, the straight portion is disposed between the stylet and the sheath.

[0037] In some aspects of the disclosure, the delivery tool has a locked configuration in which the sheath is axially locked relative to the stylet, and an unlocked configuration in which the sheath is translatable relative to the stylet. In some aspects, the delivery tool has a locking feature on the handle assembly configured to switch between the locked configuration and the unlocked configuration. In one aspect, the sheath is configured to be retracted without retracting the stylet so as to expose the helical portion of the lead body to tissue. In one aspect, at least a portion of the electrode assembly is exposed or outside of the sheath during delivery.

[0038] In some aspects, the distal end of the sheath engages with an outer surface of the electrode assembly.

[0039] In one aspect, the stylet has a reduced diameter portion configured to pass through the helical portion of the lead body. In another aspect, the stylet has an expanded diameter portion proximal to the reduced diameter portion, wherein a straight portion of the lead body extending proximally from the helical portion is positioned along the expanded diameter portion of the stylet. In one aspect, the stylet includes a groove within the expanded diameter portion of the stylet, the straight portion of the lead body being at least partially disposed within the groove. In some aspects, the stylet is retractable into the handle assembly without applying force to the electrode assembly.

[0040] In some aspects, the lead body has a first diameter and the helical portion has a second diameter, wherein the second diameter of the helical portion is at least three times the first diameter of the lead body.- 5 -SG Docket No. 14972-701.600

[0041] In some aspects, the helical portion of the lead body has a pitch greater than a diameter of the straight portion of the lead body, to promote tissue ingrowth into the helical portion.

[0042] In additional aspects, the lead further comprises retention features disposed near the electrode assembly. In some aspects, the retention features are absorbable in tissue.

[0043] In other aspects, the lead further comprises a strain relief feature disposed between the electrode assembly and the lead body. In some aspects, the strain relief feature is tapered away from the electrode assembly. In other aspects, the strain relief feature is configured to cut tissue. In one aspect, the strain relief feature comprises a dissolvable or resorbable material. In additional aspects, the strain relief feature forms an interference fit within the sheath.

[0044] Another stimulation system is provided, comprising: a delivery tool including: a stylet having a distal end; a sheath disposed over the stylet and translatable axially relative to the stylet; a lead body configured to be loaded onto the delivery tool, the lead body including a coiled portion disposed near its distal end and an electrode assembly disposed at the distal end of the lead body; wherein when the lead body is loaded onto the delivery tool; the electrode assembly extends at least partially beyond the distal end of the sheath; the stylet passes through the coiled portion and pushes against the electrode assembly; and the sheath is configured to be translated over the coiled portion to protect the coiled portion during delivery and retracted from the coiled portion to expose the coiled portion to tissue.

[0045] In some aspects, the electrode assembly has a larger diameter than the lead body. In one aspect, the electrode assembly is a spherical or hemispherical electrode.

[0046] In one aspect, the delivery tool further comprises a locking mechanism configured to selectively lock an axial position of the sheath relative to the stylet.

[0047] In some aspects, the lead both further comprises one or more retention features disposed near the electrode, and wherein retraction of the sheath from the coiled portion also exposes the retention features.

[0048] A method of implanting a stimulation lead is also provided, comprising: receiving a delivery tool with a stimulation lead body disposed therein, the stimulation lead body including a stimulation electrode at least partially exposed at a distal end of the delivery tool; electrically coupling a connector of the stimulation lead to an external stimulator; advancing the delivery tool to a target tissue site within a patient, the stimulation electrode providing blunt dissection through tissue with the delivery tool; applying test pulses to the stimulation electrode with the external stimulator; assessing a neurostimulation response resulting from the test pulses to confirm placement of the stimulation electrode; retracting a sheath of the - 6 -SG Docket No. 14972-701.600delivery tool to expose a coiled portion of the stimulation lead body while simultaneously maintaining a position of the stimulation electrode with a stylet of the delivery tool; retracting the stylet from the stimulation electrode without applying force to the stimulation electrode; and releasing the stimulation lead body from the delivery tool.DETAILED DESCRIPTION

[0049] The present disclosure is directed to stimulation leads for electrical stimulators, such as stimulators configured to stimulate nerves, including any number of peripheral nerves such as the occipital nerve. The stimulation leads and nerve stimulators are implantable within a patient adjacent to the target nerve, typically less than 25 cm away from the target nerve. This disclosure is also directed to delivery devices and systems for delivering and implanting these stimulation leads, and may include features that can confirm proper lead placement during delivery. This disclosure addresses the unmet need for stimulation leads that can resist migration and breakage, and can be delivered efficiently and accurately to a target tissue site such as a peripheral nerve.

[0050] Lead Body

[0051] FIG. 1 is a schematic view of a stimulation lead wire 100. The stimulation lead wire may be connectable to an electrical stimulator, such as a nerve or neuro stimulator, and may include other features described later in this disclosure such as electrodes and custom connectors to the stimulator. Details on such a stimulator may be found in International Patent Application No. PCT / US2024 / 023928, titled “Occipital Nerve Stimulator and Methods of Use”, incorporated herein by reference in its entirety. The lead wire may include a cable or conductor 101 and an insulator 102. In one embodiment, the cable may be constructed from 19 strands of 0.9 mil MP35N wire, resulting in a diameter of approximately 4.5 mils. The insulator may be, for example, polyurethane, silicone, Parylene, or ETFE, individually or in combination. The outer diameter (OD) of the lead wire with the insulation may be, for example, 5 to 15 mils in diameter.

[0052] FIG. 2 shows one example of a stimulation lead 204 configured to be connected to a stimulator. The stimulation lead 204 may include the aforementioned stimulation lead wire 100. As described above, this lead body includes a conductor / cable and an insulator. The stimulation lead body can include a coiled portion 206 positioned near the distal end of the lead body and a straight section 207 of wire extending proximally from the coiled portion. An electrode 208 may be attached to the distal end of the lead body. In any of the embodiments described herein the electrode is a distinct or separate component from the conductor / cable of the lead body (e.g., the electrode is not simply an extension or distal end - 7 -SG Docket No. 14972-701.600of the conductor / cable), and can have a diameter greater than an outer diameter of the conductor / cable. In some embodiments, the electrode comprises a spherical electrode. The electrode can be a platinum iridium (Pt / Ir) electrode. In one example, the exposed surface area of the electrode can be approximately 8 mm2.

[0053] The coiled portion 206 of the stimulation lead body is designed and configured to provide strain-relief for the electrode 208 when it is implanted near a target stimulation site (e.g., near or on a target nerve). The coiled portion therefore can prevent dislodgement or migration of the electrode if there is any traction proximal to the coiled section. As shown, the coiled portion can have a helical axis that is aligned with the longitudinal axis of the straight section of wire that extends proximally (i.e., the straight section and the coiled portion share the same axis, or are aligned along the same axis). This configuration facilitates delivery with the delivery tools described herein. Any coiled portion described herein can comprise less than 50% of the length of the lead body, to reduce an overall electrical resistance of the lead body. In another embodiment, the coiled portion comprises less than 25% of the length of the lead body. Put another way, the straight section of the lead body can comprise at least half of the length of the lead body, or at least three-quarters of the length of the lead body.

[0054] The proximal end of the stimulation lead can include a custom connector body 210 having a connector pin 212. As shown, the connector pin can include a tapered distal potion and a cylindrical proximal end. In some examples, the tapered distal portion can also comprise a strain relief. The connector pin is configured to connect to the stimulator, such as to a header of an implantable pulse generator (IPG). In some examples, the connector pin is connected in the IPG header with a terminal block and setscrew. As will be described in more detail below, the connector pin can also be electrically coupled to the stimulator when the lead body is within a delivery device, to allow the electrode of the lead to stimulate a nerve to verify placement during delivery, before the delivery device releases the lead into the subject.

[0055] FIGS. 3A-3C show detailed figures of another embodiment of a stimulation lead body 304. The stimulation lead comprises an electrode assembly 309a lead wire 300, and a connector body 310. The lead wire 300 (e.g., an insulated wire as discussed above) can have a coiled portion 306 near the distal end. An electrode assembly 309, includes an electrode 308 such as a spherical or hemispherical electrode, can be disposed on the distal end of the lead wire and include a strain relief 314 between the electrode and lead wire. Additionally, as shown, there may be a very short straight section 318 of insulated wire between the coiled portion 306 and the strain relief 314. The electrode 308 can be attached or coupled to the - 8 -SG Docket No. 14972-701.600strain relief 314. As shown, the coiled portion of the lead wire can have a helical axis that is aligned with the longitudinal axis of the straight section of wire that extends proximally (i.e., the straight section and the coiled portion share the same axis, or are aligned along the same axis). As with the embodiment of FIG. 2, the lead body 304 can include a connector body 310 having a connector pin 312 for mating with the header of the IPG and with the delivery device. The connector body can include an epoxy sealing surface 321 for the header O-ring. The connector body may include a strain relief 320 between the connector body and lead wire. The lead body may include an implantable sleeve 322 that runs along a length of the lead body to add abrasion resistance. The lead body includes a distance 324 between the sleeve and the coiled portion, as shown.

[0056] At the distal end of the lead body 304, shown in more detail in FIG. 3B, a strain relief feature 314 is included between the electrode 308 and the lead wire 300. The strain relief feature can be, for example, a compliant material such as silicone or polyurethane. The strain relief may include folds or bellows to allow for relative axial movement of the electrode 308 relative to the lead wire 300, to allow the lead body to resist migration.

[0057] The distal end of the lead body 304 may further include retention features 316 configured to enhance fixation. The retention features may be integrated into the electrode, the strain relief feature, the lead body, or be a separate component. In some embodiments, the retention features may be dissolvable, such that they dissolve or are absorbed by the body sometime after implantation but serve the purpose of enhancing fixation of the lead body immediately after implantation. As shown in FIGS. 3A-3B, the retention features may comprise spikes or barbs. Other retention features can be used, including but not limited to flanges, tines, scales, or the like. In some examples, the retention features may be deployable or expandable, so that the retention features can be collapsed or atraumatic during delivery but can expand or extend outwards after delivery to engage with tissue. As discussed above, the retention features can be incorporated or embedded into the strain relief feature 314, or alternatively can be a separate structure entirely that is coupled to the lead body on the proximal end and to the strain relief feature 314 on the distal end.

[0058] As described above, the coiled portion 306 provides strain relief for the lead body to prevent migration or electrode movement after implantation. To achieve this goal, the coiled portion of the stimulation lead body can have a very low spring constant, preferably up to 0.7 Ibf / inch. This provides a 2: 1 safety factor for preventing dislodgment of the lead body in an acute time frame. In some implementations, once the electrode is positioned, any traction on the lead body itself won’t result in migration of the electrode, either in the acute implant phase, or in the chronic implant phase. By creating a large spring portion, the - 9 -SG Docket No. 14972-701.600stimulation lead body of the present disclosure mechanically isolates the electrode from any traction proximal to the spring on the lead itself due to patient motion or other forces. In some embodiments, the coiled portion of the stimulation lead body can comprise a helical coil, having a ratio of coil diameter to wire diameter (e.g., diameter of the conductor and insulator) of at least 3 to 1. This ratio of coil diameter to wire diameter is configured to mechanically decouple the electrode from the lead body to improve electrode stability when implanted. As described above, the lead wire with insulation may have an OD of 5-15 mils. Therefore, in some embodiments, the coiled portion, at a ratio of 3 to 1 with the lead wire OD, may have an OD of at least 15-45 mils.

[0059] The coiled portion of the stimulation leads according to the present disclosure can be designed and configured to have a spring constant appropriate for the implantation site, length of the lead, and intended stimulation. Hooke’s law states that the force needed to extend or compress a spring is F = -kx where F is the force exerted by the spring in Ibf, k is the spring constant (stiffness) in Ibf / in, and x is the displacement in inches. The spring constant is affected by the material properties, wire diameter, coil diameter, number of turns, spacing between turns, and the type of spring. As discussed above, the coiled portion of the lead body herein can include a spring constant of up to 0.7 Ibf / inch.

[0060] Another important aspect of the coiled portion design is the pitch of the coils, which essentially describes the spacing between adjacent coils in the helix. In one embodiment, the pitch of the coiled portion (or the helix) can be greater than the diameter of the lead wire. This results in spacing or air gaps between adjacent coils of the coiled portion (as opposed to adjacent coils being in contact with another in the at-rest state). When the pitch of the coiled portion is greater than the diameter of the lead wire, the spacing or air gaps between adjacent coils can promote tissue ingrowth into the coiled portion after the acute time frame, which can assist in keeping the lead body in place after implantation.

[0061] The proximal end of the lead, including the connector body 310, is shown in more detail in FIG. 3C. As discussed above, the implantable sleeve 322 adds abrasion resistance and strain relief to the proximal portion of the insulated lead wire. It can be, for example, 0.005” thick. The connector pin 312 can have an increased diameter relative to the conductor of the lead wire. The epoxy sealing surface 321 provides a hermetic sealing surface for the O-ring of the IPG header.

[0062] FIGS. 4A-4B show additional embodiments of the distal end of the lead, including the electrode 408, strain relief feature 414, and retention features 416. As shown in FIGS.4A-4B, the retention features may be attached to or integrated into the strain relief feature. In FIG. 4A, the retention features may comprise individual retention features made from- 10 -SG Docket No. 14972-701.600dissolvable sutures. In the FIG. 4B embodiment, the retention features may comprise molded resorbable materials such as polylactic acid (PLA) or polydioxanone (PDO). The strain relief feature 414 may be tapered away from the electrode. In the illustrated example, the strain relief feature tapers, distally to proximally, to a diameter larger than that of the electrode, and then tapers back down to a narrower diameter as it approaches the lead wire. In some examples, the strain relief may include cutting or dilating features to cut or dilate tissue as the lead is retracted from tissue. In some embodiments, the strain relief itself may be dissolvable or resorbable.

[0063] Delivery Tool

[0064] This disclosure also provides delivery tool(s) used to deliver the lead described herein to a target location such as a target nerve. Additionally, the delivery tools described herein can include features that allow for stimulation with the electrode to verify placement before releasing the lead from the delivery tool.

[0065] Referring to FIG. 5, a delivery tool 501 is shown. The delivery tool can include an elongate cannula or hypo-tube 526. The lead body can be loaded into the delivery tool such that the electrode assembly 508 is positioned at the distal end of the hypo-tube 526, with the hypo-tube pushing or pressing against the electrode assembly such that a portion of the electrode assembly is exposed or outside the hypo-tube to provide blunt or atraumatic dissection as the tool and electrode assembly is inserted into tissue. The straight portion 500 and coiled portion 506 are shown contained within the hypo-tube, with the connector body 510 and connector pin 512 extending proximally beyond the delivery tool handle 528. The handle 528 is used to help position the electrode assembly under fluoroscopy or other realtime guidance.

[0066] Generally, the electrode assembly 508 can remain at the distal end of the delivery tool during implantation to provide an atraumatic tip for blunt dissection. To achieve this goal, the inner diameter of the cannula or hypo-tube can be smaller than, or precisely the same diameter as the electrode assembly, to prevent the electrode from moving into the cannula. Features may be included on the distal tip of the cannula to ensure an atraumatic mating between the electrode assembly and the cannula. In some examples, the electrode assembly is spherical or hemispherical, and the distal end of the cannula may be beveled or precisely machined or manufactured to match the curvature of the electrode to provide a flush connection between the electrode and cannula. In some examples, the distal tip of the cannula may include a compliant material, to provide additional friction and compliance between the electrode and the cannula.- 11 -SG Docket No. 14972-701.600

[0067] FIGS. 6A-6C show additional embodiments in which the delivery tool has features for maintaining the electrode in contact with, or attached to, the distal end of the delivery tool hypo-tube during delivery / manipulation. In FIG. 6 A, the delivery tool 601 can include a stylet, 630 releasably connected to the electrode. The stylet can be, for example, screwed into or temporarily attached to the electrode, thereby holding the electrode against the distal end of the hypo-tube. The stylet can be attached to a stylet handle 632. The stylet can be sized and configured such that, when the stylet is attached to the electrode, the stylet handle 632 is flush against or contacts the delivery tool handle 628. Unscrewing the stylet via stylet handle 632 can release the electrode and allow the hypo-tube to be withdrawn, over the connector body and connector pin.

[0068] The delivery tool 601 of FIG. 6B, alternatively, uses a stopper approach. In this embodiment, the electrode can be pulled into contact with the distal end of the delivery tool cannula, such as by applying sufficient tension to the lead wire. A stopper 634 having a tapered distal section can then be inserted into the delivery tool cannula to maintain the tension from the lead wire on the electrode and hold the electrode in place. The stopper can comprise, for example, a compliant material such as silicon or polyurethane. With the stopper applying sufficient tension on the lead body, the stopper can hold the electrode against distal end of the hypo-tube as the delivery tool is advanced and withdrawn during manipulation and delivery.

[0069] In the embodiment of FIG. 6C, the electrode can be held in place at the distal end of the delivery tool hypo-tube with a detent or locking feature. This can include, for example, corresponding detent / locking features on both the electrode and the cannula distal end. A stylet 630 and stylet handle 632 can again be used, however in this example the stylet is longer and extends further proximally than the proximal end of the cannula. Once the electrode is in the target location within the patient, the stylet 630 used to detach or decouple the electrode from the cannula when the desired electrode position is achieved, such as by pushing on the stylet handle 632.

[0070] Additional delivery tools are provided that use a stylet to push against the electrode assembly of the lead body, and a translatable sheath disposed over the stylet and lead body to protect the lead body during delivery and implantation. In some aspects, the delivery tool can allow for electrode placement at a target tissue site and real-time testing / confirmation of electrode placement prior to releasing the electrode from the delivery tool.

[0071] FIG. 7A illustrates a delivery tool 701 that includes a handle body and a stylet 734. The stylet can be rigid or semi-rigid. A tearaway or peelable sheath 736 is removably- 12 -SG Docket No. 14972-701.600coupled to the stylet and in this illustration, resides over and is translatable over the stylet. The sheath 736 can include tabs 737. The handle body can include a nose assembly 738 configured to lock the axial position of the sheath and stylet together while advancing the electrode assembly towards a target nerve and unlock the sheath and stylet to allow for retraction of the sheath over the stylet. The handle body 739 of the delivery tool can include a plurality of controls, including but not limited to a sheath retractor 740 for retracting the tearaway sheath and a stylet retractor 742 for retracting the stylet. When the lead body is installed or inserted into the delivery tool, the stylet 734 is configured to push against or apply pressure to the electrode, or optionally the strain relief feature, while the sheath is configured to engage with, attach to, and / or partially cover the electrode and / or strain relief feature to hold the electrode and / or strain relief in place against the stylet.

[0072] As shown in FIG. 7A, the delivery tool 701 can also be electrically connected at the handle body to stimulator 703, which can include a stimulator connector 705. The stimulator connector 705 can be electrically connected to the connector pin of the lead body when the lead body is disposed within the delivery tool, as will be discussed in more detail below.

[0073] Section A-A of FIG. 7A is a close-up view of the distal end of the stylet 734. As shown, the stylet 734 can include features that interface with the lead, including with the electrode and / or the strain relief, and also allows clearance for the lead body between the stylet 734 and sheath 736. In this example, the coiled portion 706 of the lead body is mounted over the stylet 734 (e.g., the stylet passes through the coiled portion), and the sheath is shown retracted to expose the coiled portion. As discussed above, the sheath is translatable over the stylet to enable the sheath to protect the coiled portion during delivery and to engage with the electrode and / or strain relief to hold the electrode and / or the strain relief against the stylet. Retraction of the sheath from the electrode and / or strain relief allows for delivery of the lead. In Section A-A, the tear-away sheath is shown retracted, and in section-view for illustrative purposes to allow a view of the coiled portion on the stylet.

[0074] At least a portion of the electrode 708 extends distally from the distal end of the stylet. The strain relief feature 714 contacts or interfaces the electrode to the stylet, as shown. The distal end of the stylet can include a groove or slot 744 which allows the straight section of the lead body (e.g., straight section 318 between the coiled portion and the electrode) to reside within the stylet. The stylet passes through the coiled portion 706, as shown, such that the coiled portion resides external or around the stylet. The proximal straight portion of the lead body then extends proximally along the length of the stylet between the stylet and the sheath as shown.- 13 -SG Docket No. 14972-701.600

[0075] FIG. 7B shows the stylet 734 without the lead body mounted thereon. Section B- B is a close-up view of the distal end of the stylet. As shown, the distal end can include a pocket 746 that mates with the proximal end of the strain relief near the electrode, to facilitate axial advancement of the electrode through tissue. The pocket also aids in holding the electrode and strain relief concentric with the tearaway sheath. The groove or slot 744 is also shown, allowing for the insulated conductor or lead wire to exit the strain relief from the electrode to be concentric with the strain relief, electrode, and sheath. The stylet can include sections of two different diameters. The distal section 748 can include a first or smaller diameter. This section can be sized to correspond with the length of the coiled portion of the lead body, to allow the coiled portion to reside over or around the stylet. The proximal section 750 can include a larger diameter to provide stability, and can included another slot or groove 752 to allow for clearance between the stylet and sheath and to accommodate the straight section of the lead body that extends proximally from the coiled portion.

[0076] FIGS. 8A-8C illustrate another embodiment of a sheath / stylet / el ectrode interface for a delivery system. In these examples, the lead body may include a dissolvable or resorbable bushing to form an interference fit between the lead body and the delivery tool (e.g., within the distal portion of the sheath 836 as shown). The bushing can be configured to dissolve over time to reduce the diameter of the lead for easier extraction from the patient. In FIG. 8A, the lead body is inserted into the stylet / sheath as described above. The lead body can include a dissolvable / resorbable bushing 854 positioned proximally to the electrode 808. The bushing 854 can be inserted into the distal end of the sheath to allow the sheath to hold the electrode assembly in place against the stylet.

[0077] FIG. 8B shows the lead body outside of the stylet after implantation. In this view, it can be seen how the bushing abuts or even partially covers or overlaps the proximal portion of the strain relief 814 near the electrode 808. Immediately after implantation, the bushing 854 is shown still intact in FIG.8B. However, the example of FIG. 8C shows the bushing at least partially dissolved sometime after implantation. It can be seen that the bushing has dissolved, or partially dissolved, reducing the diameter at the distal end of the lead body for easier removal from the patient.

[0078] FIGS. 9A-9C show additional details of the delivery tool 901, including how the connector pin 912 of the lead can be oriented within the handle body 939 for providing an electrical connection to the stimulator during implantation of the lead. In FIG. 9A, the proximal portion of the handle body is shown in cutaway view, with Section C-C showing a close-up view of the internals of the handle. In this view, it can be seen that handle body 939 includes a connector holder 956 configured to receive and hold the connector body 910- 14 -SG Docket No. 14972-701.600and / or connector pin 912 of the lead when the lead is disposed or loaded within the delivery tool 901. In some examples, the connector holder 956 can have a tapered portion as shown in Section C-C to receive a corresponding tapered portion in the connector body 910 of the lead. In some embodiments, the connector holder can be located in the handle such that, when the connector body 910 of the lead is disposed in the connector holder, tension is applied to the lead to hold the electrode against the distal end of the stylet of the delivery tool. FIG. 9A also shows the straight portion 900 of the lead body routed along a track within the handle body towards the stylet of the delivery tool.

[0079] In some examples, described in more detail below, the handle body 939 of the delivery tool can include a proximal end cap 958 which can be removed from the handle body to allow for loading of the lead body into the handle and of the lead connector into the connector holder, and the proximal end cap can then be re-installed onto the handle body to allow for an electrical connection between the lead and the stimulator.

[0080] FIGS. 9B-9C show additional details of the delivery tool including the proximal end cap 958 and the connection between the lead and the stimulator via stimulator connector 905. In FIG. 9B, the nose 938 is in a locked configuration to hold the sheath 936 and stylet 934 in a fixed position relative to another during implantation, with the sheath covering the stylet and engaged with the electrode and / or strain relief to hold the electrode and / or strain relief against the stylet. The electrode 908 is advanced through tissue to the target nerve site. In FIG. 9C, the nose 938 is in an unlocked configuration to allow retraction of the sheath 936 from the stylet 934 via sheath retractor 940, releasing the electrode assembly and exposing the coiled portion of the lead body. Tabs 937 of the sheath are shown moving closer to the handle body as a result of retracting the sheath. As discussed above, the straight portion of the lead body passes between the stylet and the inner diameter of the sheath. With the sheath partially retracted, the electrode and / or strain relief is no longer held in place against the stylet and the coiled portion 906 and / or retention features of the lead are exposed to engage with tissue during implantation. Even though the electrode assembly is not attached to the sheath, the stylet can maintain the position of the electrode at the nerve site.

[0081] In the configuration of FIG. 9C, the lead is still attached to the delivery tool 901, including providing support to the electrode and / or strain relief with the stylet 934. As shown, stimulator connector 905 of stimulator connection 903 is electrically connected to the lead body via the handle body of the delivery tool. While reference number 903 points to a stimulator connection, it should be understood that this is intended to convey a connection to an implantable or external stimulator that includes stimulation electronics and other features described above. In this arrangement, the placement of electrode 908 can be tested by- 15 -SG Docket No. 14972-701.600applying test stimulation pulses from the stimulator 903 to the electrode, and evaluating neurostimulation response resulting from the test pulses. If the electrode placement is confirmed, then the remaining steps of removing the delivery tool can be performed.

[0082] In FIG. 9D, the stylet is retracted with stylet retractor 942, disengaging from the strain relief and leaving the electrode 908, coiled portion 906, and / or retention features in place within the tissue. When the stylet is retracted from the electrode and / or strain relief, the stylet does not apply force to or push against the electrode assembly.

[0083] FIG. 9E shows how the lead body is removed from the delivery tool. In this example, stimulator connector 905 can be disconnected from the handle body. Proximal end cap 958 is shown removed from the handle body, exposing connector pin 912 within connector holder 956. The straight portion of the lead body was previously routed through the handle body via track, groove, or slot 962 towards and into the stylet of the delivery tool. With the proximal end cap removed from the handle body, the connector pin 912 can be removed from the connector holder 956, and the lead body can be removed from the handle body out of the track, groove, or slot 962.

[0084] FIG. 9F shows the lead body 904 removed from the stylet and delivery tool handle, with only the tearaway sheath 936 in place. To leave only the lead implanted within the patient, the tearaway sheath 936 can be removed from the lead at this stage in the procedure. The tearaway sheath can include perforations or other features that allow it to be split away from the lead for removal, as is known in the art. FIG. 9G shows the delivery tool 901 handle and stylet with the lead completely removed from the tool.

[0085] Implant procedure

[0086] A method and procedure for implanting a stimulation lead will now be described. This procedure is also illustrated in flowchart 1000 of FIG. 10, and with reference to delivery tool 901 and lead 904 and their associated components as described above in FIGS. 9A-9G.

[0087] At step 1002 of flowchart 1000, the delivery tool (e.g., delivery tool 901) can be furnished with a stimulation lead (e.g., lead 904) pre-loaded therein. The delivery tool as previously described can include a tearaway or peelable sheath (e.g., sheath 936) and a delivery stylet (e.g., stylet 934). The lead can be supplied preloaded in the delivery tool, with the electrode of the lead engaged near the distal end of the stylet and held in place with the sheath as discussed above.

[0088] At step 1004 of flowchart 1000, the method can include inserting the delivery tool into a patient and advancing the electrode towards a target tissue site, such as towards a target nerve, and preferably towards an occipital nerve of the patient. At least a portion of the- 16 -SG Docket No. 14972-701.600electrode can be positioned at the distal end of the delivery tool to provide blunt dissection of tissue.

[0089] Prior to inserting the delivery tool, the method can comprise rinsing the electrode in saline to ensure electrical conductivity with nerves and tissues, or alternatively using a sterile solution containing an antibiotic. The free end of the stimulator connection 903 can be passed outside the sterile field for connection to an external stimulator / programmer.

[0090] For occipital nerve implantation, after applying local anesthesia, the method can include making a stab incision over the target nerve site, optionally cutting through the outer layer of fascia.

[0091] The delivery tool and lead can be advanced toward the target tissue site by pushing the delivery tool handle, optionally under intermittent fluoroscopic guidance. In some examples, lateral and anteroposterior (AP) fluoroscopy views can be used to confirm the electrode position.

[0092] At step 1006 of flowchart 1000, the method can include applying test pulses from the external stimulator / programmer to the electrode while the lead remains loaded within the delivery tool to confirm placement of the electrode near or on the target nerve site, such as an occipital nerve. In some embodiments, the programmer provides test pulses at 20 Hz and 200 ps for confirming the electrode position.

[0093] At step 1008 of flowchart 1000, neurostimulation response resulting from the test pulses can be measured / evaluated / determined. After determining, confirming, or reconfirming the neurostimulation response, the method can include recording the threshold voltage, current, and impedance.

[0094] If the test pulses result in a determination that the electrode is not properly positioned on the target nerve site, then steps 1006-1008 can be repeated after repositioning the electrode.

[0095] At step 1010 of flowchart 1000, the stimulation lead can be released or removed from the delivery tool, leaving the lead implanted in the patient with the electrode positioned properly on or near the target nerve site (e.g., an occipital nerve). As discussed above, the lead can be removed from the delivery tool by holding the delivery tool, unlocking the sheath, then withdrawing the sheath from the electrode along the stylet, such as with the sheath retractor button. Retracting the sheath releases the electrode and / or strain relief from the delivery tool. The external programmer can be used throughout the procedure to confirm neurostimulation response. Next, the stylet can be withdrawn from the electrode and / or strain relief, such as with the stylet retractor button. After reconfirming neurostimulation response, the proximal end cap of the delivery tool can be removed, allowing for removal of- 17 -SG Docket No. 14972-701.600the lead connector pin from the delivery tool. The tearaway sheath can be removed from the delivery tool, such as by holding the delivery tool and rotating the winged tabs of the sheath. Finally, the tearaway sheath can be split and withdrawn from the lead, carefully avoiding tension on the lead. Once again, the programmer can be used to confirm neurostimulation response.

[0096] In some aspects, the method can include implanting multiple leads, such as a contralateral lead, and the same process described above can be repeated for each lead.

[0097] It should be noted that specific dimensions for lead wire diameters, insulation thicknesses, material selection, electrode shape, etc., may change depending on the desired application and implantation site, and are not limiting to the fundamental ideas conveyed by this disclosure.

[0098] As for additional details pertinent to the present invention, materials and manufacturing techniques may be employed as within the level of those with skill in the relevant art. The same may hold true with respect to method-based aspects of the invention in terms of additional acts commonly or logically employed. Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. Likewise, reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms “a,” “and,” “said,” and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. Unless defined otherwise herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The breadth of the present invention is not to be limited by the subject specification, but rather only by the plain meaning of the claim terms employed.- 18 -SG Docket No. 14972-701.600

Claims

CLAIMSWhat is claimed is:

1. A stimulation lead, comprising: an insulated lead wire including a straight proximal portion and a coiled distal portion; and a stimulation electrode coupled to a distal end of the insulated lead wire, the stimulation electrode being a distinct component from the insulated lead wire and having a diameter greater than an outer diameter of the insulated lead wire.

2. The stimulation lead of claim 1, wherein coiled distal portion of the insulated lead wire has a pitch greater than the outer diameter of the insulated lead wire to promote tissue ingrowth into the coiled distal portion.

3. The stimulation lead of claim 1, wherein the insulated lead wire further comprises one or more retention features disposed near the stimulation electrode.

4. The stimulation lead of claim 3, wherein the retention features comprise one or more tines.

5. The stimulation lead of claim 3, wherein the retention features comprise one or more flanges.

6. The stimulation lead of claim 3, wherein the retention features comprise one or more scales.

7. The stimulation lead of claim 3, wherein the retention features are absorbable in tissue.

8. The stimulation lead of claim 1, wherein the insulated lead wire further comprises a strain relief feature disposed between the stimulation electrode and the insulated lead wire.

9. The stimulation lead of claim 8, wherein the stimulation electrode is attached to the strain relief feature.- 19 -SG Docket No. 14972-701.60010. The stimulation lead of claim 8, wherein the strain relief feature is tapered away from the stimulation electrode.

11. The stimulation lead of claim 8, wherein the strain relief feature is configured to cut tissue.

12. The stimulation lead of claim 8, wherein the strain relief feature comprises a dissolvable or resorbable material.

13. The stimulation lead of claim 8, wherein the strain relief feature includes one or more retention features.

14. The stimulation lead of claim 1, wherein the straight proximal portion comprises more than half of the length of the lead wire.

15. The stimulation lead of claim 1, wherein the straight proximal portion comprises more than three-quarters of the length of the insulated lead wire.

16. The stimulation lead of claim 1, further comprising a lead body connector disposed at a proximal end of the insulated lead wire, the lead body connector being connectable to a stimulator to provide electrical pulses to the stimulation electrode.

17. The stimulation lead of claim 16, wherein the stimulator is implantable.

18. The stimulation lead of claim 16, wherein the lead body connector has a connector diameter greater than the outer diameter of the insulated lead wire.

19. The stimulation lead of claim 1, wherein the insulated lead wire comprises a conductor and an insulator disposed thereon.

20. A stimulation lead, comprising: an insulated lead wire having an outer diameter, the insulated lead wire including a straight proximal portion and a coiled distal portion, the coiled distal portion comprising less than 50% of a length of the insulated lead wire and having a helical axis aligned with a longitudinal axis of the straight proximal portion;- 20 -SG Docket No. 14972-701.600a stimulation electrode disposed at a distal end of the insulated lead wire; wherein a coil diameter of the coiled distal portion of the insulated lead wire is at least three times the outer diameter of the insulated lead wire, to mechanically decouple the stimulation electrode from the insulated lead wire proximal to the coiled distal portion.

21. The stimulation lead of claim 20, wherein coiled distal portion of the insulated lead wire has a pitch greater than the outer diameter of the insulated lead wire to promote tissue ingrowth into the coiled distal portion.

22. The stimulation lead of claim 20, wherein the insulated lead wire further comprises one or more retention features disposed near the stimulation electrode.

23. The stimulation lead of claim 22, wherein the retention features comprise one or more tines.

24. The stimulation lead of claim 22, wherein the retention features comprise one or more flanges.

25. The stimulation lead of claim 22, wherein the retention features comprise one or more scales.

26. The stimulation lead of claim 22, wherein the retention features are absorbable in tissue.

27. The stimulation lead of claim 20, wherein the insulated lead wire further comprises a strain relief feature disposed between the stimulation electrode and the insulated lead wire.

28. The stimulation lead of claim 27, wherein the stimulation electrode is attached to the strain relief feature.

29. The stimulation lead of claim 27, wherein the strain relief feature is tapered away from the stimulation electrode.

30. The stimulation lead of claim 27, wherein the strain relief feature is configured to cut tissue.- 21 -SG Docket No. 14972-701.60031. The stimulation lead of claim 27, wherein the strain relief feature comprises a dissolvable or resorbable material.

32. The stimulation lead of claim 27, wherein the strain relief feature includes one or more retention features.

33. The stimulation lead of claim 20, wherein the straight proximal portion comprises more than half of the length of the lead wire.

34. The stimulation lead of claim 20, wherein the straight proximal portion comprises more than three-quarters of the length of the insulated lead wire.

35. The stimulation lead of claim 20, further comprising a lead body connector disposed at a proximal end of the insulated lead wire, the lead body connector being connectable to a stimulator to provide electrical pulses to the stimulation electrode.

36. The stimulation lead of claim 35, wherein the stimulator is implantable.

37. The stimulation lead of claim 35, wherein the lead body connector has a connector diameter greater than the outer diameter of the insulated lead wire.

38. The stimulation lead of claim 20, wherein the insulated lead wire comprises a conductor and an insulator disposed thereon.

39. A stimulation lead, comprising: an insulated lead wire having an outer diameter, the insulated lead wire including a straight proximal portion and a coiled distal portion, the coiled distal portion having a helical axis aligned with a longitudinal axis of the straight proximal portion; a stimulation electrode disposed at a distal end of the insulated lead wire; wherein the coiled distal portion has a spring constant less than 0.7 Ibf / inch, to mechanically decouple the stimulation electrode from the lead wire proximal to the coiled distal portion.- 22 -SG Docket No. 14972-701.60040. The stimulation lead of claim 39, wherein coiled distal portion of the insulated lead wire has a pitch greater than the outer diameter of the insulated lead wire to promote tissue ingrowth into the coiled distal portion.

41. The stimulation lead of claim 39, wherein the insulated lead wire further comprises one or more retention features disposed near the stimulation electrode.

42. The stimulation lead of claim 41 wherein the retention features comprise one or more tines.

43. The stimulation lead of claim 41, wherein the retention features comprise one or more flanges.

44. The stimulation lead of claim 41, wherein the retention features comprise one or more scales.

45. The stimulation lead of claim 41, wherein the retention features are absorbable in tissue.

46. The stimulation lead of claim 39, wherein the insulated lead wire further comprises a strain relief feature disposed between the stimulation electrode and the insulated lead wire.

47. The stimulation lead of claim 46, wherein the stimulation electrode is attached to the strain relief feature.

48. The stimulation lead of claim 46, wherein the strain relief feature is tapered away from the stimulation electrode.

49. The stimulation lead of claim 46, wherein the strain relief feature is configured to cut tissue.

50. The stimulation lead of claim 46, wherein the strain relief feature comprises a dissolvable or resorbable material.- 23 -SG Docket No. 14972-701.60051. The stimulation lead of claim 46, wherein the strain relief feature includes one or more retention features.

52. The stimulation lead of claim 39, wherein the straight proximal portion comprises more than half of the length of the lead wire.

53. The stimulation lead of claim 39, wherein the straight proximal portion comprises more than three-quarters of the length of the insulated lead wire.

54. The stimulation lead of claim 39, further comprising a lead body connector disposed at a proximal end of the insulated lead wire, the lead body connector being connectable to a stimulator to provide electrical pulses to the stimulation electrode.

55. The stimulation lead of claim 54, wherein the stimulator is implantable.

56. The stimulation lead of claim 54, wherein the lead body connector has a connector diameter greater than the outer diameter of the insulated lead wire.

57. The stimulation lead of claim 39, wherein the insulated lead wire comprises a conductor and an insulator disposed thereon.

58. A stimulation system, comprising: a lead body and an electrode assembly disposed at a distal end of the lead body; and a delivery tool configured to implant a part of the lead body and the electrode assembly, the delivery tool including a stylet, and a sheath slidably disposed over the stylet; wherein a distal end of the stylet is configured to push against the electrode assembly while the sheath releasably engages with the electrode assembly when the lead body and the electrode assembly are loaded onto the delivery tool.

59. The system of claim 58, wherein the delivery tool further comprises a peelable sheath disposed over the stylet and translatable relative to the stylet.

60. The system of claim 59, wherein the sheath is configured to cover the helical portion of the lead body when the lead body is disposed on the stylet.- 24 -SG Docket No. 14972-701.60061. The system of claim 60, wherein the lead body comprises a straight portion extending proximally from the helical portion.

62. The system of claim 61, wherein the straight portion is disposed between the stylet and the sheath.

63. The system of claim 59, wherein the delivery tool has a locked configuration in which the sheath is axially locked relative to the stylet, and an unlocked configuration in which the sheath is translatable relative to the stylet.

64. The system of claim 63, further comprising a locking feature on the handle assembly configured to switch between the locked configuration and the unlocked configuration.

65. The system of claim 59, wherein the sheath is configured to be retracted without retracting the stylet so as to expose the helical portion of the lead body to tissue.

66. The system of claim 58, wherein at least a portion of the electrode assembly is exposed or outside of the sheath during delivery.

67. The system of claim 66, wherein the distal end of the sheath engages with an outer surface of the electrode assembly.

68. The system of claim 58, wherein the stylet has a reduced diameter portion configured to pass through the helical portion of the lead body.

69. The system of claim 68, wherein the stylet has an expanded diameter portion proximal to the reduced diameter portion, wherein a straight portion of the lead body extending proximally from the helical portion is positioned along the expanded diameter portion of the stylet.

70. The system of claim 69, further comprising a groove within the expanded diameter portion of the stylet, the straight portion of the lead body being at least partially disposed within the groove.- 25 -SG Docket No. 14972-701.60071. The system of claim 58, wherein the stylet is retractable into the handle assembly without applying force to the electrode assembly.

72. The system of claim 58, wherein the lead body has a first diameter, and the helical portion has a second diameter, wherein the second diameter of the helical portion is at least three times the first diameter of the lead body.

73. The system of claim 58, wherein the helical portion of the lead body has a pitch greater than a diameter of the straight portion of the lead body, to promote tissue ingrowth into the helical portion.

74. The system of claim 58, wherein the lead further comprises retention features disposed near the electrode assembly.

75. The system of claim 74, wherein the retention features are absorbable in tissue.

76. The system of claim 58, wherein the lead further comprises a strain relief feature disposed between the electrode assembly and the lead body.

77. The system of claim 76, wherein the strain relief feature is tapered away from the electrode assembly.

78. The system of claim 76, wherein the strain relief feature is configured to cut tissue.

79. The system of claim 76, wherein the strain relief feature comprises a dissolvable or resorbable material.

80. The system of claim 79, wherein the strain relief feature forms an interference fit within the sheath.

81. A stimulation system, comprising: a lead body and an electrode assembly disposed at a distal end of the lead body; a delivery tool configured to implant part of the lead body and the electrode assembly, the delivery tool comprising a stylet and a sheath disposed over the stylet;- 26 -SG Docket No. 14972-701.600wherein a distal end of the stylet is configured to push against the electrode assembly to provide blunt dissection of tissue with the electrode assembly while the sheath is configured to hold the electrode assembly on the delivery tool when the lead body and the electrode assembly are loaded onto the delivery tool.

82. A stimulation system, comprising: a lead body and an electrode assembly disposed at a distal end of the lead body, the lead body having a helical portion disposed near its distal end; a delivery tool configured to implant part of the lead body and the electrode assembly, including: a stylet, a distal end of the stylet being configured to push against the electrode assembly to provide blunt dissection of tissue with the electrode assembly, while the helical portion of the lead body is coiled around the stylet; and a sheath disposed over the stylet, the sheath being configured to engage with the electrode assembly and cover the helical portion.

83. A stimulation system, comprising: a lead body and an electrode assembly disposed at a distal end of the lead body, the lead body having a helical portion disposed near the distal end of the lead body and a lead body connector disposed at a proximal end of the lead body; a delivery tool comprising: a stylet configured to receive the lead body, a distal end of the stylet being configured to apply pressure to the electrode assembly to provide blunt dissection of tissue while the helical portion of the lead body is coiled around the stylet; a sheath disposed over the stylet and having a distal end configured to engage with the electrode assembly; a handle assembly coupled to the stylet and sheath, the handle assembly including a connector interface configured to receive the lead body connector; and an external stimulator having a stimulator connector configured to be electrically coupled to the lead body connector via the connector interface of the handle assembly, the external stimulator being configured to apply test pulses to an electrode in the electrode assembly, during delivery to confirm placement of the electrode.- 27 -SG Docket No. 14972-701.60084. The system of any of claims 81-83, wherein the delivery tool further comprises a peelable sheath disposed over the stylet and translatable relative to the stylet.

85. The system of claim 84, wherein the sheath is configured to cover the helical portion of the lead body when the lead body is disposed on the stylet.

86. The system of claim 85, wherein the lead body comprises a straight portion extending proximally from the helical portion.

87. The system of claim 86, wherein the straight portion is disposed between the stylet and the sheath.

88. The system of claim 84, wherein the delivery tool has a locked configuration in which the sheath is axially locked relative to the stylet, and an unlocked configuration in which the sheath is translatable relative to the stylet.

89. The system of claim 88, further comprising a locking feature on the handle assembly configured to switch between the locked configuration and the unlocked configuration.

90. The system of claim 84, wherein the sheath is configured to be retracted without retracting the stylet so as to expose the helical portion of the lead body to tissue.

91. The system of any of claims 81-83, wherein at least a portion of the electrode assembly is exposed or outside of the sheath during delivery.

92. The system of claim 91, wherein the distal end of the sheath engages with an outer surface of the electrode assembly.

93. The system of any of claims 81-83, wherein the stylet has a reduced diameter portion configured to pass through the helical portion of the lead body.

94. The system of claim 93, wherein the stylet has an expanded diameter portion proximal to the reduced diameter portion, wherein a straight portion of the lead body extending proximally from the helical portion is positioned along the expanded diameter portion of the stylet.- 28 -SG Docket No. 14972-701.60095. The system of claim 94, further comprising a groove within the expanded diameter portion of the stylet, the straight portion of the lead body being at least partially disposed within the groove.

96. The system of any of claims 81-83, wherein the stylet is retractable into the handle assembly without applying force to the electrode assembly.

97. The system of any of claims 81-83, wherein the lead body has a first diameter, and the helical portion has a second diameter, wherein the second diameter of the helical portion is at least three times the first diameter of the lead body.

98. The system of any of claims 81-83, wherein helical portion of the lead body has a pitch greater than a diameter of the straight portion of the lead body, to promote tissue ingrowth into the helical portion.

99. The system of any of claims 81-83, wherein the lead further comprises retention features disposed near the electrode assembly.

100. The system of claim 99, wherein the retention features are absorbable in tissue.

101. The system of any of claims 81-83, wherein the lead further comprises a strain relief feature disposed between the electrode assembly and the lead body.

102. The system of claim 101, wherein the strain relief feature is tapered away from the electrode assembly.

103. The system of claim 101, wherein the strain relief feature is configured to cut tissue.

104. The system of claim 101, wherein the strain relief feature comprises a dissolvable or resorbable material.

105. The system of claim 104, wherein the strain relief feature forms an interference fit within the sheath.

106. A stimulation lead and delivery system, comprising:- 29 -SG Docket No. 14972-701.600a delivery tool including: a stylet having a distal end; a sheath disposed over the stylet and translatable axially relative to the stylet; a lead body configured to be loaded onto the delivery tool, the lead body including a coiled portion disposed near its distal end and an electrode assembly disposed at the distal end of the lead body; wherein when the lead body is loaded onto the delivery tool; the electrode assembly extends at least partially beyond the distal end of the sheath; the stylet passes through the coiled portion and pushes against the electrode assembly; and the sheath is configured to be translated over the coiled portion to protect the coiled portion during delivery and retracted from the coiled portion to expose the coiled portion to tissue.

107. The system of claim 106, wherein the electrode assembly has a larger diameter than the lead body.

108. The system of claim 106, wherein the electrode assembly is a spherical electrode.

109. The system of claim 106, wherein the electrode assembly is a hemispherical electrode.

110. The system of claim 106, wherein the delivery tool further comprises a locking mechanism configured to selectively lock an axial position of the sheath relative to the stylet.

111. The system of claim 106, wherein the lead both further comprises one or more retention features disposed near the electrode, and wherein retraction of the sheath from the coiled portion also exposes the retention features.

112. A method of implanting a stimulation lead, comprising: receiving a delivery tool with a stimulation lead body disposed therein, the stimulation lead body including a stimulation electrode at least partially exposed at a distal end of the delivery tool; electrically coupling a connector of the stimulation lead to an external stimulator;- 30 -SG Docket No. 14972-701.600advancing the delivery tool to a target tissue site within a patient, the stimulation electrode providing blunt dissection through tissue with the delivery tool; applying test pulses to the stimulation electrode with the external stimulator; assessing a neurostimulation response resulting from the test pulses to confirm placement of the stimulation electrode; retracting a sheath of the delivery tool to expose a coiled portion of the stimulation lead body while simultaneously maintaining a position of the stimulation electrode with a stylet of the delivery tool; retracting the stylet from the stimulation electrode without applying force to the stimulation electrode; and releasing the stimulation lead body from the delivery tool.- 31 -SG Docket No. 14972-701.600

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