Lead wires for active implantable medical devices

Abstract

A lead (1) for an active implantable medical device, comprising: an elongated, biocompatible, non-conductive body (3) having a central section (4) between a first portion (7) and a body extension (11); a plurality of electrical connectors (6) at the first portion (7); a plurality of electrodes (8) at a second portion (9) of the elongated body (3), wherein the second portion (9) is located between the central section (4) and the body extension (11); and a plurality of conductive filaments (5) within the elongated body (3) for connecting the electrical connectors (6) to corresponding electrodes (8), wherein each of the plurality of conductive filaments (5) includes a corresponding filament extension (13) located in the body extension (11).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Australian Provisional Patent Application No. 2019903747 filed on October 4, 2019, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates to leads for active implantable medical devices (AIMDs) for implantation into patient tissue.

[0004] background

[0005] Medical devices with one or more active implantable components, generally referred to herein as active implantable medical devices (AIMDs), have provided a wide range of therapeutic benefits to patients in recent decades. AIMDs typically include an implantable sealed electronic module and an instrument (sometimes referred to as a tissue interface) that interfaces with patient tissue. The tissue interface may include, for example, one or more appliances, devices, sensors, or other functional components that are permanently or temporarily implanted in the patient's body. The tissue interface is used, for example, to diagnose, monitor, and / or treat a disease or injury, or to alter a patient's anatomical structure or physiological process.

[0006] In certain applications, the AIMD tissue interface includes one or more conductive contacts, called electrodes, which transmit electrical stimulation signals to or receive signals from patient tissue. The electrodes are typically disposed in a biocompatible non-conductive component and electrically connected to the electronic module. The electrodes and non-conductive components are collectively referred to herein as electrode assemblies.

[0007] For a neurostimulator, the tissue interface is a stimulation lead 1000 that delivers electrical pulses to a specific nerve or tissue. The lead 1000 may consist of a long, thin, non-conductive (and insulating) body 1004 and several conductive loops 1006, 1008 at both ends 1007, 1009 of the body 1004. Figure 5a , Figure 5b , Figure 6 and Figure 7 , the ring 1008 at the treatment end 1009 is called an electrode, and the ring 1006 at the connector end 1007 is called a contact, where the electrode is connected to the contact along the long and thin non-conductive body 1004. Figure 7 An example of a long, thin non-conductive body 1004 is shown in the cross section in FIG. 1 , which shows a conductor 1005 surrounded by a non-conductive body 1003. These conductors 1005 are sized to have a length that conducts signals between corresponding conductive loops, for example, the length of the conductor 1005' is between Figure 5a and Figure 5bA conductor 1005" of varying length spans between conductive loops 1006" and 1008".

[0008] Patients with implanted neurostimulators and associated leads may have problems when undergoing magnetic resonance imaging (MRI). MRI uses three types of fields to create images: static magnetic fields; radiofrequency (RF) magnetic fields; and gradient magnetic fields. Exposure to these fields may cause heating of the leads. This heating may cause tissue burns and damage (which the patient may not immediately feel). Another potential damaging effect is damage to the implant due to the RF energy transmitted from the leads. This can cause rearrangement, damage to the implant, or explantation of the implant. In addition, MRI may cause temporary involuntary stimulation due to induced voltages through components and systems.

[0009] Throughout this specification, the word "comprise" or variations such as "comprises" or "comprising" will be understood to mean the inclusion of stated elements, integers or steps, or groups of elements, integers or steps, but not the exclusion of any other elements, integers or steps, or groups of elements, integers or steps.

[0010] Any discussion of documents, acts, materials, devices, articles or the like contained in this specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.

[0011] Overview

[0012] Attempts have been made to provide designs for MRI-safe leads. U.S. Patent Publication US 8798767 B2 describes a method for reducing the heating caused by the conditions of MRI. The document suggests winding the conductor in a multilayer structure, with each winding layer electrically connected to the next winding layer to provide parallel conductive paths. However, this approach may result in high inductance when exposed to MRI radiation. U.S. Patent Publication US 9050457 B2 adopts a similar approach, having a lead body and a multilayer wound conductor within the length of the lead body. The stiffness of the multilayer wound conductor is similar to that of the lead body, ensuring that the mechanical properties of the lead are continuous. U.S. Patent Publication US 9302101 B2 adopts a different approach, where the lead body provides an additional path for accommodating conductive material. The path spans at least a portion of the length of the lead and is used to conduct induced RF energy away from the conductor of the lead.

[0013] In view of the above problems, it may be advantageous to have an electrode assembly, such as an electrode assembly for use in an implantable medical device, that can be implanted in a patient while the patient is undergoing magnetic resonance imaging. This can include providing an implantable electrode assembly that does not generate significant heat in the leads due to electromagnetic currents when exposed to the MRI environment. It may be further advantageous that the implantable medical device can operate during magnetic resonance imaging without or with reduced side effects as described above.

[0014] A lead for an active implantable medical device is disclosed, comprising: an elongated, biocompatible, non-conductive body having a central section between a first portion and a body extension; a plurality of electrical connectors at the first portion; a plurality of electrodes at a second portion of the elongated body, wherein the second portion is located between the central section and the body extension; and a plurality of conductive filaments within the elongated body for connecting the electrical connectors to corresponding electrodes, wherein each of the plurality of conductive filaments includes a corresponding filament extension section in the body extension.

[0015] In some examples, the length of each filament extension is 10 mm or more. In a further example, the length of each filament extension is in the range of 10 mm to 50 mm.

[0016] In some examples, the lead also includes a biocompatible, non-conductive seal at the body extension to insulate the filament extension.

[0017] In some examples of leads, each of the plurality of conductive filaments has a common overall physical length and / or an overall electrically equivalent length.

[0018] In further examples, each electrical distance between each electrical connector and a corresponding electrode is shorter than the common total length.

[0019] In some examples of the lead, each of the plurality of electrical connectors is spaced apart along the first length of the first portion.

[0020] In some examples of the lead, each of the plurality of electrodes is spaced apart along a length of the second portion.

[0021] In some examples of leads, the electrical connector and / or the electrode are ring-shaped.

[0022] In some examples, the lead also includes a central lumen for receiving a stylet.

[0023] Also provided is a method for manufacturing a lead for an active implantable medical device, comprising: forming a multi-cavity, elongated, biocompatible, non-conductive body, the elongated body having a central section located between a first portion and a body extension; placing a plurality of conductive filaments through the cavities of the elongated body, wherein the plurality of conductive filaments include corresponding filament extensions extending into the body extension; forming a plurality of electrical connectors at the first portion, wherein each electrical connector is electrically connected to a respective conductive filament; forming a plurality of electrodes at a second portion of the elongated body, wherein the second portion is located between the central section and the body extension, and the plurality of electrodes are connected to the corresponding electrical connectors via the corresponding conductive filaments.

[0024] In some examples, the method further includes sizing each of the plurality of conductive filaments to a common overall length.

[0025] In some examples, the elongated body is formed by extruding a biocompatible, non-conductive material having multiple lumens.

[0026] In some examples, the method also includes sealing the ends of the body extension to insulate the filament extension. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1a and Figure 1b An example of a lead wire for an active implantable medical device is shown, wherein Figure 1a shows the far end, and Figure 1b The proximal end is shown;

[0029] Figure 2a is a perspective view of a distal end of a lead including a body extension with corresponding filament extensions;

[0030] Figure 2b illustrates a cross section of the lead at a proximal end and through an electrical connector;

[0031] Figure 3a and Figure 3b are test results, showing the composite electric field strength at the distal end with and without the main body extension;

[0032] Figure 4 is a flow chart of a method of manufacturing a lead for an active implantable medical device;

[0033] Figure 5a and Figure 5b An example of a prior art lead is illustrated;

[0034] Figure 6 illustrates another view of a prior art lead; and

[0035] Figure 7 The diagram shows Figure 6 Cross section of a prior art lead in FIG.

[0036] Description of Embodiments

[0037] It will be appreciated by those skilled in the art that many variations and / or modifications may be made to the above-described embodiments without departing from the broad general scope of the present disclosure. Therefore, the embodiments presented are to be considered in all aspects as illustrative and not restrictive.

[0038] Aspects of the present disclosure generally relate to electrode assemblies for active implantable medical devices (AIMDs). The AIMD may include an implantable electronics module and a tissue interface. The electrode assembly at least partially forms the tissue interface.

[0039] The electrode assembly can be used with a type of AIMD, a neurostimulator, more specifically, a deep brain stimulator or a spinal cord stimulator. A deep brain stimulator is a special type of AIMD that delivers electrical stimulation to the patient's brain, while a spinal cord stimulator delivers electrical stimulation to the patient's spine. As used herein, deep brain stimulators and spinal cord stimulators refer to instruments that deliver electrical stimulation alone or in combination with other types of stimulation. It should be understood that embodiments of the present disclosure can be implemented in any brain stimulator (deep brain stimulator, cortical stimulator, etc.), spinal cord stimulator, or other neurostimulator now known or later developed, such as a pacemaker / defibrillator, a functional electrical stimulator (FES), a pain stimulator, etc. Embodiments of the present disclosure can also be implemented in AIMDs that address acute conditions with relatively short implant times, as well as in AIMDs that address chronic conditions with relatively long implant times.

[0040] The electrode assembly according to an embodiment of the present disclosure is not limited to an apparatus for transmitting electrical stimulation signals to a patient. For example, in some embodiments, the electrode assembly can be used to receive, record or monitor the physiological response of patient tissue (e.g., to treatment). In such an embodiment, the electrode receives a signal representing a physiological response from the patient tissue. The electrode assembly of the present disclosure that transmits electrical stimulation signals to patient tissue or receives signals from patient tissue may also include one or more other components connected to the patient tissue, such as a therapeutic agent delivery system, a sensor, etc.

[0041] exist Figure 1a and Figure 1b An example of a lead 1 for an active implantable medical device is shown in FIG. Figure 1a and Figure 1b denoting opposite ends of the same lead 1). The lead 1 comprises an elongated, biocompatible, non-conductive body 3. The elongated body 3 extends from a first portion 7 to a central section 4, to a second portion 9, and finally to a body extension 11.

[0042] A plurality of electrical connectors 6 are located at a first portion 7 near the proximal end, whereby the connectors 6 are used to electrically connect to an active implantable medical device. A plurality of electrodes 8 are located at a second portion 9 near the distal end of the elongated body 3, such that the electrodes 8 are located between the central section 4 and the body extension 11. The electrodes 8 deliver therapy to the patient.

[0043] A plurality of conductive filaments 5 (indicated by dashed lines) are disposed inside the elongated body 3 to connect the electrical connector 6 to the respective electrodes 8. Furthermore, the plurality of conductive filaments 5 include respective filament extensions 13 in the body extension 11.

[0044] The filament extensions 13 in the body extension 11 cause the reflection point 16 of the electromagnetic waves to move along the elongated body 3, away from the distal-most electrode 10 at the second portion 9. Such electromagnetic waves are excited along the lead 1 during an MRI scan.

[0045] Examples of specific components of the lead 1 will now be described in detail.

[0046] Part 17

[0047] The first part 7 includes a plurality of connectors 6, which are configured to be inserted into the AIMD, whereby the connectors 6 are electrically connected to corresponding connectors inside the AIMD. In one example, the connectors 6 are configured to be received in a medical-grade connector / contact system, such as those systems provided by "Bal Seal Engineering" under the trade name "Bal Conn". The connectors 6 are substantially annular (i.e., ring-shaped) and are typically made of biocompatible and conductive materials. The annular structure allows good electrical contact to be formed with the receiving contacts in the AIMD. Suitable materials for the connectors 6 may include, but are not limited to, platinum, iridium and / or alloys thereof. In other examples, the connectors 6 may include a core of a highly conductive material (e.g., cobalt, chromium, molybdenum or an alloy thereof) having a metal coating (e.g., platinum, tantalum, niobium, titanium or an alloy thereof).

[0048] The connectors 6 are spaced apart along the axial length L1 of the first portion 7. Figure 1b , for purposes of illustration, this includes three connectors 6 spaced apart along the first portion 7. However, it should be understood that additional connectors 6 may be used for additional channels. In some examples, this may include up to a dozen or more channels (with corresponding dozen connectors 6, conductive filaments 5, and electrodes 8). The entire length L1 of the first portion 7 is typically inserted into the AIMD.

[0049] In addition to the connector 6, the first portion 7 comprises a non-conductive portion supporting the connector 6. In some examples, this comprises the same material and may be part of the elongated, biocompatible, non-conductive body 3.

[0050] Now refer to Figure 2b Describe a specific example, Figure 2b 1 is a cross section of the first portion 7 of the twelve channel lead 1 through one of the connectors 6. This comprises a biocompatible non-conductive body 3 having a central lumen 35 and a dozen outer lumens 15. The central lumen 35 is configured to receive a stylet to aid insertion and implantation of the lead 1, after which the stylet is removed. The outer lumens 15 house conductive filaments 5, in this case comprising a dozen conductive filaments 5.

[0051] Now refer to Figure 2b A specific example of electrically connecting the connector 6' to the conductive filament 5' is described. A portion of the non-conductive body 3 is thinned 18 or removed to expose a specific outer cavity 15'. This allows the conductive filament 5' within the outer cavity 15' to make electrical contact with the electrical conductor 6' disposed around the periphery of the body 3. It should be understood that the order in which these components are assembled can vary.

[0052] In one example, the conductive filament 5 is inserted into the outer cavity 15 (e.g., by a drawnfilled tubing process), and the connector 6 is then attached to the first portion 7 of the body 3. In other examples, the connector 6 is positioned on the body 3 before the conductive filament 5 is inserted into the outer cavity 15.

[0053] In the above example, the body 3 and the conductive filaments 5 extend to and are part of the first portion 7. In alternative examples, separate materials or components may form the first portion 7. This may include separate conductive filaments in the first portion 7 that are electrically connected to the conductive filaments 5 in the central portion 4. Similarly, the body of the first portion 7 may be manufactured separately but connected to the central portion 4 of the body 3.

[0054] Main body 3 and center section 4

[0055] The central section 4 of the body 3 comprises a biocompatible, non-conductive body 3 and a conductive filament 5 in an outer lumen 15. In the example where a stylet is used, the central section 4 also has a central lumen 35 to receive the stylet.

[0056] The central segment 4 has a length L2, which is typically the longest portion of the elongated body 3. In a typical example, the central segment 4 surrounds the conductive filaments 5 to minimize conduction from the conductive filaments 5 to the tissue immediately surrounding the central segment 4.

[0057] The body 3 is made of a biocompatible, non-conductive material, which may include thermoplastic polyurethane (TPU), such as those provided by The Lubrizol Corporation under the trade name "pellethane". In some examples, the body 3 is made by extruding a flexible material having a plurality of cavities. In some examples, the body 3 and the conductive filament 5 are mated together by a drawn filling line method.

[0058] The conductive filament 5 is preferably selected from a construction of biocompatible materials. This may include a single core or multiple strands. In another example, this may include a composite material of a medical grade alloy, provided by Fort Wayne Metals under the trade name "35NLT", with a silver core. In another specific example, the conductive filament 5 includes a wire sheath of 35N LT (nickel-cobalt-chromium alloy) in accordance with ASTM F562 standard, and the wire sheath composition includes ≤0.01wt% titanium, and a silver wire core accounting for 28% of the cross-sectional area of ​​the conductive filament 5.

[0059] Part 9

[0060] The second portion 9 comprises a plurality of electrodes 8, 10 to deliver therapy to the patient. In some examples, the number of electrodes 8 is the same as the number of corresponding connectors 6, and in turn the same as the number of conductive filaments 5 forming an electrical connection.

[0061] The size and spacing of the electrodes 8 disposed along the length L3 are selected based on the intended treatment of the patient. Typically, each electrode 8 has a longer axial length than the corresponding connector 6.

[0062] In some examples, the electrode 8 can be assembled to the lead 1 in a manner similar to the way the connector 6 is assembled to the first portion 7. Thus, in some examples, Figure 2b The structure shown similarly reflects the structure in the second portion 9. Furthermore, the electrodes 8 may be made of the same or similar biocompatible, electrically conductive material.

[0063] The non-conductive portion of the second portion 9 may be integrally formed with the body 3 of the central segment 4 and the first portion 7. Similarly, the conductive filaments 5 are integrally formed and extend from the central segment 4 into the second portion 7. The conductive filaments 5 continue through the second portion 9 and to the body extension 11 discussed below.

[0064] It will be appreciated that in alternative examples, the conductive filaments 5 in the second portion 9 may be formed separately but electrically connected to the conductive filaments 5 in the central segment 4. Similarly, in alternative examples, the non-conductive portion of the second portion may be formed separately but connected to the central segment 4.

[0065] Main body extension 11

[0066] refer to Figure 1a and Figure 2a , the main body extension 11 is located at the distal end of the lead 1 and adjacent to the second portion 9. The purpose of the main body extension 11 is to pass through the most distal electrode 10 of the plurality of electrodes 8 and extend the conductive filament 5 by the length L4 of the filament extension 13. The length L4 moves the reflection point 16 of the electromagnetic wave propagating along the lead 1 away from the most distal electrode 10.

[0067] In some examples, the body extension 11 is formed as part of the biocompatible, non-conductive body 3 that constitutes the first portion 7, the central segment 4, and the second portion 9. This may include an extrusion of a flexible material having multiple lumens, whereby the ends are sealed with a non-conductive seal 14. The seal 14 isolates the filament extension 13 from the immediately surrounding tissue (to some extent).

[0068] In some examples, the seal 14 can be a plug of material injected into the cavity 15, 35. In other examples, the end of the body extension 11 can be immersed in the sealing material. In yet another example, the seal 14 is formed by welding (e.g., heat, ultrasonic welding, resistance welding, laser welding, etc.) to close the cavity 15, 35 in the material of the non-conductive body 3. A similar seal can be provided at the first portion to close the end of the outer cavity 15 at the proximal end.

[0069] Configuration of the main body extension 11

[0070] In some examples, the filament extension 13 has a length L4 of 10 mm or more. In some examples, the length L4 is in the range of 10 mm to 50 mm (including end values).

[0071] In some examples, each conductive filament 5 is sized to have a common total length. In some examples, this common total length is a physical total length. In other examples, the common total length is an electrical equivalent total length. In a further example, the conductive filaments share a common physical total length and an electrical equivalent total length. The common total length can help minimize the generation of differential electromagnetic modes and minimize the propagation of induced differential voltages between the filaments 5 in the body 3.

[0072] In some examples, the common total length of the conductive filaments 5 is the sum of L1 , L2 , L3 , and L4 .

[0073] In some examples, the electrical distance between each electrical connector 6 and the corresponding electrode 8 is shorter than the common total length. Typically, the length difference is at least the length L4 of the filament stretch 13.

[0074] Lead 1 is selected to be suitable for the length of treatment and patient characteristics. In some examples, the length of lead 1 is in the range of 600mm to 900mm. In other examples, the length of lead is in the range of 500mm to 1200mm.

[0075] Test data

[0076] Figure 3a and Figure 3b The composite electric field strength at the distal end (ie the main body near the second portion 9) of a 600 mm long lead 1 having a dozen electrodes 9 (and correspondingly a dozen conductive filaments 5 and electrical connectors 6) is shown. Figure 3a The graph 300 of FIG. 3 illustrates the composite electric field strength at the distal end without the main body extension 11. In particular, the highest strength corresponds to the first electrode 301 disposed at the most distal portion (i.e., about 600 mm from the proximal end), which has a strength of about 14 V / m. The other electrodes 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312 have smaller strengths, with the twelfth electrode 312 (closer to the proximal end) having the smallest strength.

[0077] Figure 3b Graph 400 illustrates the composite electric field strength at the distal end with body extension 11 ranging from 10 mm to 50 mm. These different lengths are represented by different lines in the figure. The highest intensity corresponds to the first electrode 401 disposed at the most distal portion (i.e., about 600 mm from the proximal end), which has an intensity of about 9.5 V / m. The other electrodes 402, 403, 404, 405, 406, 407, 408, 409, 410, 411, 412 have lesser intensities, with the twelfth electrode 412 (closer to the proximal end) having the smallest intensity.

[0078] In both cases (i.e., with body extension 11 and without body extension 11), the distal end was stimulated using a plane electromagnetic wave with an axial electric field of 1 V / m at 128 MHz. The lead and AIMD (in the form of an implantable pulse generator) were placed in a gelled saline solution to simulate tissue. In this test, the composite electric field strength of the lead 1 with body extension 11 at the distal end was reduced by more than 30%.

[0079] manufacture

[0080] refer to Figure 4, also discloses a method for manufacturing a lead 1 for an active implantable medical device. This includes 110: forming a multi-lumen 15 elongated, biocompatible, non-conductive body 3, wherein the elongated body 3 has a central section 4 located between a first portion 7 and a body extension 11. In some examples, this includes extruding an elongated body 3 having multiple lumens. The method also includes 120: placing a plurality of conductive filaments 5 through the lumens 15 of the elongated body 3, wherein the plurality of conductive filaments 5 include corresponding filament extensions 13, and the filament extensions 13 extend into the body extension 11. As described above, some examples include placing and fixing the conductive filaments 5 using a drawn filling line technique. The method also includes 130: forming a plurality of electrical connectors 6 at the first portion 7, wherein each electrical connector 6 is electrically connected to a respective conductive filament 5. The method 100 also includes 140: forming a plurality of electrodes 8 at a second portion 9 of the elongated body 3, wherein the second portion 9 is located between the central section 4 and the body extension 11, and the plurality of electrodes 8 are connected to the corresponding electrical connectors 6 via the corresponding conductive filaments 5.

[0081] In some examples, some of these steps may be performed in other orders. For example, step 140 of forming electrodes may precede step 130 of forming connectors.

[0082] The method 100 may also include additional steps. For example, this may include the steps of sealing one or more ends of the lead wires and / or adjusting the length of the conductive filament 5 .

[0083] It will be appreciated by those skilled in the art that many variations and / or modifications may be made to the above-described embodiments without departing from the broad general scope of the present disclosure. Therefore, the embodiments presented are to be considered in all aspects as illustrative and not restrictive.

Claims

1. A lead wire (1) for an active implantable medical device, comprising: an elongated, biocompatible, non-conductive body (3) having a central section (4) between a first portion (7) at a proximal end and a body extension (11) at a distal end; a plurality of electrical connectors (6) at said first portion (7); a plurality of electrodes (8) at a second portion (9) of the elongated, biocompatible and non-conductive body (3), wherein the second portion (9) is located between the central section (4) and the body extension (11); and a plurality of electrically conductive filaments (5) within the elongated, biocompatible and non-conductive body (3) to connect the electrical connector (6) to respective electrodes (8), wherein each of the plurality of conductive filaments (5) comprises a corresponding filament extension segment (13) in the main body extension portion (11), the filament extension segment (13) extending toward the distal end beyond the most distal electrode (10) of the plurality of electrodes (8), The length of each of the filament extension segments (13) is 10 mm or greater than 10 mm.

2. The lead wire (1) according to claim 1, wherein: The length of each of the filament extension segments (13) is in the range of 10 mm to 50 mm.

3. The lead (1) according to claim 1 further includes a biocompatible and non-conductive seal (14) at the main body extension (11) to insulate the filament extension section (13).

4. The lead wire (1) according to claim 1, wherein: Each of the plurality of conductive filaments (5) has a common total physical length and / or an electrically equivalent total length.

5. The lead wire (1) according to claim 4, wherein: Each electrical distance between each electrical connector (6) and the corresponding electrode (8) is shorter than the common total length.

6. The lead wire (1) according to any one of claims 1 to 5, wherein: Each of the plurality of electrical connectors (6) is spaced apart along a first length of the first portion (7).

7. The lead wire (1) according to any one of claims 1 to 5, wherein: Each of the plurality of electrodes (8) is spaced apart along the length of the second portion (9).

8. The lead wire (1) according to any one of claims 1 to 5, wherein: The electrical connector (6) and / or the electrode (8) are annular in shape.

9. The guide wire (1) according to any one of claims 1 to 5, further comprising a central lumen (35) for receiving a stylet.

10. A method for manufacturing a lead (1) for an active implantable medical device, comprising: An elongated, biocompatible, non-conductive body (3) forming a multi-lumen (15), the elongated, biocompatible, non-conductive body having a central section (4) between a first portion (7) at a proximal end and a body extension (11) at a distal end; A plurality of electrical connectors (6) are formed at the first portion (7), wherein each of the electrical connectors (6) is electrically connected to a respective conductive filament (5); forming a plurality of electrodes (8) at a second portion (9) of the elongated, biocompatible and non-conductive body (3), wherein the second portion (9) is located between the central section (4) and the body extension (11), and the plurality of electrodes (8) are connected to respective electrical connectors (6) via respective plurality of conductive filaments (5); as well as a plurality of electrically conductive filaments (5) disposed through a lumen (15) of the elongated, biocompatible and non-conductive body (3), wherein the plurality of electrically conductive filaments (5) include respective filament extensions (13) extending toward the distal end and into the body extension (11) beyond the most distal electrode (10) of the plurality of electrodes (8); The length of each of the filament extension segments (13) is 10 mm or greater than 10 mm.

11. The method according to claim 10, further comprising: Each of the plurality of electrically conductive filaments (5) is sized to have a common overall length.

12. The method according to claim 10 or 11, wherein: The elongated, biocompatible and non-conductive body (3) is formed by extruding a biocompatible, non-conductive material having the multiple lumens (15).

13. A method according to claim 10 or 11, further comprising sealing the ends of the body extension (11) to insulate the filament extension (13).

14. The method of claim 12, further comprising sealing the ends of the body extension (11) to insulate the filament extension (13).

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