Reinforced sensing and stimulation leads and use in detection systems

• US 20030195602A1
• Filed: 04/15/2002
• Published: 10/16/2003
• Est. Priority Date: 04/15/2002
• Status: Active Grant

• Current Assignee: Neuropace Inc.
• Original Assignee: Neuropace Inc.
• Inventors: Boling, C. Lance
• Granted Patent: US 7,146,222 B2
• Time in Patent Office: Days
• US Class Current: 607/122
• CPC Class Codes: A61B 5/31 for electroencephalography [EEG]
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/0529 Electrodes for brain stimulation
• CPC Class Codes: A61N 1/0531 Brain cortex electrodes
• CPC Class Codes: A61N 1/0534 Electrodes for deep brain stimulation
• CPC Class Codes: A61N 1/0539 Anchoring of brain electrode systems, e.g. within burr hole
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing
• CPC Class Codes: Y10T 29/53204 Electrode

Abstract

A reinforced medical electrical lead for neurological applications has a reinforced construction for resisting the detachment of electrodes and lead connection terminals, thereby improving the robustness of the lead and extending the life of the lead by reducing the likelihood that a further surgical procedure will be required to remove the lead for repair or replacement thereof. The present reinforced lead construction maintains the integrity of the electrical connection between the conductor and the respective electrode and lead connection terminal by incorporating several reinforcing features in the lead construction in contrast to conventional lead constructions where it is possible to pull the electrodes and lead connection terminals away from their contact points with relatively little force.

Claims

1. A reinforced medical electrical lead adapted to be at least partially implanted in a human patient, the lead comprising:

a proximal portion having a lead connection area;

a distal portion having at least one electrode;

at least one conductor providing communication between the at least one electrode and the lead connection area;

a reinforcing member disposed at one of the proximal portion and the distal portion for enhancing the rigidity of the lead; and

a body interconnecting the proximal portion and the distal portion, wherein the at least one conductor is disposed between the reinforcing member and the body.

2. The medical electrical lead of claim 1, wherein the reinforcing member comprises a stiffening sheath.

3. The medical electrical lead of claim 2, wherein the stiffening sheath is a tube formed of a polymeric material.

4. The medical electrical lead of claim 3, wherein the stiffening sheath is formed of polyimide.

5. The medical electrical lead of claim 1, wherein the at least one conductor is arranged longitudinally within the body and in at least one of a distal end segment of the distal portion and a proximal end segment of the proximal portion.

6. The medical electrical lead of claim 1, wherein the at least one conductor is arranged in a helical coil around the reinforcing member and within the body.

7. The medical lead of claim 1, wherein the at least one conductor is arranged in a helical coil within the body and longitudinally within at least one of a distal end segment of the distal portion and a proximate end segment of the proximal portion.

8. The medical electrical lead of claim 1, wherein the body comprises a flexible biocompatible shaft and the at least one electrode comprises a biocompatible conductive electrode at least partially embedded within the biocompatible shaft.

9. The medical electrical lead of claim 1, wherein the at least one electrode comprises a biocompatible conductive circumferential metallic ring.

10. The medical electrical lead of claim 9, wherein the biocompatible conductive electrode is fabricated from one of platinum and a platinum-iridium alloy.

11. The medical electrical lead of claim 9, wherein the biocompatible conductive electrode has a surface area between approximately 0.75 mm² and approximately 15 mm².

12. The medical electrical lead of claim 1, wherein the reinforcing member is a stiffening sheath disposed at the distal portion and the distal portion further includes a core member at least partially inserted into a lumen defined by the sheath and a reinforcing sleeve disposed around the sheath such that the sleeve surrounds at least a portion of the inserted core member, the sleeve being crimped around the sheath and the core member to enhance the structural rigidity of the distal portion and disperse stress longitudinally along the distal portion.

13. The medical electrical lead of claim 12, wherein the body comprises a flexible biocompatible shaft and the distal portion terminates in a relatively rigid tip that is formed around one end of the core member which extends beyond a distal end of the reinforcing member that is disposed at the distal portion.

14. The medical electrical lead of claim 12, wherein the distal portion includes a plurality of electrodes, at least one of the electrodes surrounding the reinforcing sleeve.

15. The medical electrical lead of claim 14, wherein at least a portion of the at least one conductor is disposed around the reinforcing sleeve.

16. The medical electrical lead of claim 12, wherein the reinforcing sleeve is fabricated from a biocompatible metal that can be crimped.

17. The medical electrical lead of claim 16, wherein the reinforcing sleeve is fabricated from one of platinum and a platinum-iridium alloy.

18. The medical electrical lead of claim 1, wherein the lead connection area is a dapted for external connection to a neurological diagnostic or treatment apparatus.

19. The medical electrical lead of claim 1, wherein the lead connection area is adapted for connection to an internal neurostimulator.

20. The medical electrical lead of claim 1, wherein the lead connection area includes at least one circumferential lead connection terminal.

21. The medical electrical lead of claim 1, wherein the reinforcing member is a stiffening sheath disposed at the proximal portion and the proximal portion further includes a bushing disposed at a proximal end, a proximal end of the sheath being coupled to one end of the bushing, the bushing having a bore formed therein and the sheath defining an inner lumen which is axially aligned with the bore for providing stylet access along a longitudinal length of the lead.

22. The medical electrical lead of claim 12, wherein the stiffening sheath has a length of about 2.25 inch.

23. The medical electrical lead of claim 21, wherein the lead connection area comprises a plurality of circumferential lead connection terminals, at least one of the lead connection terminals being disposed around the bushing.

24. The medical electrical lead of claim 23, further including a proximal reinforcing element disposed between the at least one lead connection terminal and the bushing.

25. The medical electrical lead of claim 24, wherein the proximal reinforcing element is fabricated from a reinforcing fiber structure.

26. The medical electrical lead of claim 25, wherein the proximal reinforcing element is fabricated from polyester in the form of multi-strand fibers that are arranged to form a twisted cable structure.

27. The medical electrical lead of claim 25, wherein the bushing includes a radial groove and an axial slot substantially perpendicular to the radial groove, the reinforcing element being circumferentially wrapped around the bushing within the radial groove and disposed within the axial slot.

28. The medical electrical lead of claim 1, wherein the distal portion includes at least four coaxial conductive electrodes spaced apart from one another and the lead connection area includes at least four coaxial lead connection terminals, each of the conductive electrodes being in communication with a corresponding one of the lead connection terminals, and wherein the at least one conductor comprises at least four conductors, one conductor for each electrode/lead connection terminal pair.

29. The medical electrical lead of claim 1, wherein the reinforcing member defines a longitudinal lumen adapted to receive a stylet.

30. The medical electrical lead of claim 1, wherein the distal portion includes a rigid distal tip having an outer diameter and wherein the at least one electrode is disposed adjacent the distal tip, the at least one electrode having an outer diameter that is substantially equal to the outer diameter of the distal tip so as to produce an iso-diametric distal portion with a substantially seamless transition between the distal tip and the at least one electrode.

31. A reinforced medical electrical lead adapted to be at least partially implanted in a human patient, the lead comprising:

a proximal portion having a lead connection area;

a distal portion having at least one electrode in communication with the lead connection area of the proximal portion;

a first reinforcing sheath disposed at the proximal portion for enhancing the rigidity of the proximal portion

a second reinforcing sheath disposed at the distal portion for enhancing the rigidity of the distal portion; and

a body interconnecting the proximal portion and the distal portion;

wherein the distal portion includes a core member at least partially inserted into the second reinforcing sheath and a reinforcing sleeve disposed around the second reinforcing sheath such that the sleeve surrounds at least a portion of the inserted core member, the sleeve being crimped around the second reinforcing sheath and the core member to enhance the structural rigidity of the distal portion and retain the core member in place and disperse stress longitudinally along the distal portion.

32. A reinforced medical electrical lead adapted to be at least partially implanted in a human patient, the lead comprising:

a proximal portion having a lead connection area;

a distal portion having at least one electrode in communication with the lead connection area of the proximal portion;

a first reinforcing sheath disposed at the proximal portion for enhancing the rigidity of the proximal portion

a second reinforcing sheath disposed at the distal portion for enhancing the rigidity of the distal portion; and

a body interconnecting the proximal portion and the distal portion;

wherein the proximal portion includes a bushing having a bore formed therethrough, one end of the bushing being coupled to a proximal end of the first reinforcing sheath, the bore being axially aligned with a longitudinal lumen defined by the first reinforcing sheath to permit a stylet to be received into and extended longitudinally along the lumen, wherein at least a portion of the lead connecting area surrounds a section of the bushing.

33. The medical electrical lead of claim 32, wherein the lead connection area comprises a plurality of circumferential lead connection terminals, at least one of the lead connection terminals being disposed around the section of the bushing.

34. The medical electrical lead of claim 33, further including a proximal reinforcing element disposed between the at least one lead connection terminal and the bushing.

35. The medical electrical lead of claim 34, wherein the proximal reinforcing element is fabricated from a reinforcing fiber structure.

36. The medical electrical lead of claim 35, wherein the bushing includes a radial groove and an axial slot formed substantially perpendicular to the radial groove, the proximal reinforcing element being circumferentially disposed around the bushing within the radial groove while also being disposed within the axial slot.

37. The medical electrical lead of claim 35, wherein the reinforcing element is fabricated from polyester in the form of multi-strand fibers that are arranged to form a twisted cable structure that is wrapped around and secured to the bushing.

38. The medical electrical lead of claim 32, wherein the distal portion includes at least four coaxial conductive electrodes spaced apart from one another and at least partially embedded within the body and the lead connection area includes at least four coaxial lead connection terminals at least partially embedded within the body, each of the conductive electrodes being in communication with a corresponding one of the lead connection terminals, and wherein the at least one conductor comprises at least four conductors, one conductor for each electrode/lead connection terminal pair.

39. A reinforced medical electrical lead adapted to be at least partially implanted in a human patient, the lead comprising:

a proximal portion having a lead connection area;

a distal portion;

at least one reinforcing sheath disposed in at least the proximal portion and the distal portion for enhancing the rigidity of the lead, the reinforcing sheath defining a longitudinal lumen; and

a body extending from the proximal portion to a point prior to the distal portion;

wherein the distal portion includes a lower electrode strip having at least one electrode in communication with the lead connection area of the proximal portion and a cover that mates with the lower electrode strip to enclose the reinforcing sheath that is disposed in the distal portion, one end of the body being captured between first ends of the lower electrode strip and the cover.

40. The medical electrical lead of claim 39, wherein the lower electrode strip is a substantially planar member with a portion of the at least one electrode being exposed.

41. The medical electrical lead of claim 39, further including at least one conductor connecting the at least one electrode to the lead connection area.

42. The medical electrical lead of claim 41, wherein the at least one conductor extends from the proximal portion beyond the one end of the body to the distal portion.

43. The medical electrical lead of claim 42, wherein the at least one conductor is arranged in a helical coil around the reinforcing sheath, a section of the at least one conductor being disposed between the reinforcing sheath and the body.

44. The medical electrical lead of claim 39, wherein the distal portion includes a core member at least partially inserted into the longitudinal lumen of the reinforcing sheath and a reinforcing sleeve disposed around the reinforcing sheath such that the sleeve surrounds at least a portion of the inserted core member, the sleeve being crimped around the reinforcing sheath and the core member to enhance the structural rigidity of the distal portion and retain the core member in place and disperse stress longitudinally along the distal portion away from a distal end thereof.

45. The medical electrical lead of claim 39, wherein the body is a tubular shaft and the first end of the lower electrode strip has a groove formed therein for receiving the one end of the shaft and the first end of the cover has a step-shaped construction such that the one end of the shaft is received with a cavity defined by a first segment of the cover a the first end thereof, the longitudinal movement of the one end of the shaft being restricted by a first shoulder formed in the cover, wherein an inner end of the groove and the first shoulder are substantially aligned with one another.

46. The medical electrical lead of claim 45, wherein a section of the reinforcing sheath extends beyond the one end of the body, the section being disposed in a second segment of the cover which extends from the first shoulder to a second shoulder that prevents the reinforcing sheath from longitudinal movement beyond the second shoulder.

47. The medical electrical lead of claim 46, wherein the cover includes a third segment that extends from the second shoulder to a second end of the cover, the third segment being disposed flush against a second end of the lower electrode strip.

48. The medical electrical lead of claim 39, wherein the proximal portion includes a bushing disposed at a proximal end of the lead, one end of the reinforcing sheath being coupled to one end of the bushing, the bushing having a bore formed therein and the reinforcing sheath defining a longitudinal lumen which is axially aligned with the bore for providing stylet access along a longitudinal length of the lead.

49. The medical electrical lead of claim 48, wherein the reinforcing sheath is disposed in both the distal and proximal portions and extends therebetween.

50. The medical electrical lead of claim 48, wherein the lead connection area comprises a plurality of circumferential lead connection terminals, at least one of the lead connection terminals being disposed around the bushing.

51. The medical electrical lead of claim 50, further including a proximal reinforcing element disposed between the at least one lead connection terminal and the bushing.

52. The medical electrical lead of claim 51, wherein the proximal reinforcing element is fabricated from a reinforcing fiber structure.

53. The medical electrical lead of claim 52, wherein the reinforcing element is fabricated from polyester in the form of multi-strand fibers that are arranged to form a twisted cable structure.

54. The medical electrical lead of claim 39, wherein the distal portion includes at least four coaxial conductive electrodes spaced apart from one another and the lead connection area includes at least four coaxial lead connection terminals, each of the conductive electrodes being in communication with a corresponding one of the lead connection terminals via a conductor.

55. The medical electrical lead of claim 39, wherein the at least one electrode comprises a cortical electrode.

56. A method of fabricating a reinforced medical electrical lead, the method comprising the steps of:

providing at least one conductor;

disposing a flexible shaft around the at least one conductor, the at least one conductor having first and second end sections that extend beyond ends of the flexible shaft;

electrically connecting at least one electrode to the first end section of the at least one conductor;

electrically connecting at least one lead connection terminal to the second end section of the at least one conductor;

providing a first longitudinal reinforcing sheath, the first reinforcing sheath defining a first longitudinal lumen;

inserting a section of a core member within the first longitudinal lumen at a distal end of the first reinforcing sheath;

disposing a reinforcing sleeve around a length of the reinforcing sheath, the reinforcing sleeve surrounding the inserted section of the core member;

compressing selected sections of the reinforcing sleeve around the first reinforcing sheath and the inserted section of the core member to enhance the rigidity at the distal end and retain the core member in place;

disposing the crimped first reinforcing sheath through an inner channel defined by the first end section of the at least one conductor; and

extending the flexible shaft so that the at least one conductor and the at least one lead connection terminal are at least partially embedded within the body.

57. The method of claim 56, wherein the step of compressing selective sections of the reinforcing sleeve comprises:

crimping the reinforcing sleeve around the first reinforcing sheath and the inserted section of the core member.

58. The method of claim 56, wherein the step of disposing the crimped first reinforcing sheath through an inner channel defined by the first end section of the at least one conductor results in the at least one conductor being helically arranged around the first reinforcing sheath.

59. The method of claim 56, further comprising the steps of:

providing a second longitudinal reinforcing sheath, the second reinforcing sheath defining a second longitudinal lumen;

coupling a proximal end of the second reinforcing sheath to a bushing having a longitudinal bore extending therethrough and in communication with the second longitudinal lumen; and

disposing the second longitudinal reinforcing sheath through the inner channel of the at least one conductor at the second end section thereof.

60. The method of claim 59, further comprising the step of:

disposing a proximal reinforcing element between the at least one lead connection terminal and the bushing.

61. The method of claim 60, wherein the proximal reinforcing element comprises an elongated reinforcing cable formed of arranged fibers, and the method further including the step of:

wrapping and retaining the reinforcing cable around the bushing within a radial groove formed therein and disposing the reinforcing cable within an axial slot formed in the bushing substantially perpendicular to the radial groove, the reinforcing cable serving to enhance the robustness of the proximal portion.

62. The method of claim 56, further comprising the step of:

molding a relatively rigid distal tip around a head of the core member that extends beyond the distal end of the first reinforcing element.

63. The method of claim 56, wherein the step of extending the flexible shaft includes the step of:

injecting a material around the at least one electrode and the at least one lead connection terminal in a mold such that the length of the tubular shaft is extended to surround the first and second end sections of the at least one conductor, resulting in the at least one electrode and the at least one lead connection terminal being partially embedded in the extended flexible shaft.