Cochlear implant electrode array

• US 20040122501A1
• Filed: 11/13/2003
• Published: 06/24/2004
• Est. Priority Date: 10/04/2000
• Status: Active Grant

• Current Assignee: Cochlear Limited
• Original Assignee: Cochlear Limited
• Inventors: Gibson, Peter, Treaba, Claudiu, Darley, Ian, Parker, John, Dadd, Fysh
• Granted Patent: US 7,272,449 B2
• Time in Patent Office: Days
• US Class Current: 607/137
• CPC Class Codes: A61F 11/20 Ear surgery
• CPC Class Codes: A61N 1/0541 Cochlear electrodes

Abstract

A cochlear implant electrode assembly (10) comprising an elongate electrode carrier member (11), a bioresorbable stiffening element (15) and an outer layer (16) surrounding the stiffening element (15). The carrier member (11) is made of a resiliently flexible first material and has a plurality of electrodes (12) mounted thereon and has a first configuration selected to allow it to be inserted into an implantee'"'"'s cochlea, and at least a second configuration wherein it is curved to match a surface of the cochlea. The bioresorbable stiffening element (15) has a configuration selected for biassing the elongate member (11) into the first configuratin and is made of a second material relatively stiffer than the first material and which dissolves or softens on exposure to cochlear fluids to permit the elongate member (11) to at least approach or adopt the second configuration. The outer layer (16) surrounding the stiffening element (15) is made of a material sufficiently resiliently flexible to allow the elongate member (11) to at least approach or adopt the second configuration. The outer layer (16) has a first rate of cochlear fluid ingress therethrough and has at least one fluid ingress means (21) formed therein. The rate of cochlear fluid ingress through the fluid ingress means (21) is greater than the first rate of cochlear fluid ingress through the outer layer (16).

Claims

1. An implantable tissue-stimulating device comprising:

an elongate member having a plurality of electrodes mounted thereon and having a first configuration selected to allow said member to be inserted into an implantee'"'"'s body and at least a second configuration wherein said elongate member is adapted to apply a preselected tissue stimulation with the electrodes, said elongate member being made of a resiliently flexible first material;

a bioresorbable stiffening element having a configuration selected for biassing said elongate member into said first configuration, said stiffening element being made of a second material relatively stiffer than said first material and which dissolves or softens on exposure to a fluid to permit said elongate member to at least approach or adopt said second configuration; and

an outer layer surrounding the stiffening element, the layer being made of a material sufficiently resiliently flexible to allow said elongate member to at least approach or adopt said second configuration, the outer layer having a first rate of fluid ingress therethrough and having at least one fluid ingress means formed therein, the rate of fluid ingress through the fluid ingress means being greater than the first rate of fluid ingress through the outer layer.

2. An implantable tissue-stimulating device of claim 1 wherein the second configuration of the elongate member is curved.

3. An implantable tissue-stimulating device of claim 2 wherein the elongate member adopts a spiral configuration when in the second configuration.

4. An implantable tissue-stimulating device of claim 1 wherein the fluid is a body fluid of the implantee.

5. A cochlear implant electrode assembly comprising:

an elongate electrode carrier member having a plurality of electrodes mounted thereon and having a first configuration selected to allow said member to be inserted into an implantee'"'"'s cochlea and at least a second configuration wherein said elongate member is curved to match a surface of said cochlea, said elongate member being made of a resiliently flexible first material;

a bioresorbable stiffening element having a configuration selected for biassing said elongate member into said first configuration, said stiffening element being made of a second material relatively stiffer than said first material and which dissolves or softens on exposure to cochlear fluids to permit said elongate member to at least approach or adopt said second configuration; and

an outer layer surrounding the stiffening element, the layer being made of a material sufficiently resiliently flexible to allow said elongate member to at least approach or adopt said second configuration, the outer layer having a first rate of cochlear fluid ingress therethrough and having at least one fluid ingress means formed therein, the rate of cochlear fluid ingress through the fluid ingress means being greater than the first rate of cochlear fluid ingress through the outer layer.

6. A cochlear implant electrode assembly of claim 5 wherein the elongate member is preformed from a plastics material with memory and is preformed in the second configuration.

7. A cochlear implant electrode assembly of claim 5 wherein the elongate member has a first end that is firstly inserted into the implantee.

8. A cochlear implant electrode assembly of claim 5 wherein the first configuration is at least substantially straight.

9. A cochlear implant electrode assembly of claim 5 wherein the elongate member is formed from a biocompatible material.

10. A cochlear implant electrode assembly of claim 5 wherein the bioresorbable material of the stiffening element is selected from the group comprising polyacrylic acid (PAA), polyvinyl alcohol (PVA), polylactic acid (PLA) and polyglycolic acid (PGA).

11. A cochlear implant electrode assembly of claim 5 wherein the outer layer is in turn surrounded by another layer formed from a material selected from the group comprising a lubricious material and a non-lubricious material.

12. A cochlear implant electrode assembly of claim 11 wherein the outer layer is formed from a biocompatible material.

13. A cochlear implant electrode assembly of claim 7 wherein the stiffening element is positionable in a lumen extending within the elongate member.

14. A cochlear implant electrode assembly of claim 13 wherein the lumen has at least one opening at an end of the lumen distal the first end of the elongate member, the opening being closable by a closure means.

15. A cochlear implant electrode assembly of claim 14 wherein the closure means comprises a plug or cap.

16. A cochlear implant electrode assembly of claim 5 wherein the stiffening element comprises a sheath that at least partially surrounds the elongate member.

17. A cochlear implant electrode assembly of claim 16 wherein an annular channel is formed in the elongate member to receive the sheath.

18. A cochlear implant electrode assembly of claim 14 wherein the opening is closable by a sealing layer bonded to the elongate member.

19. A cochlear implant electrode assembly of claim 7 wherein a plurality of the fluid ingress means in the form of slits are provided in the outer layer.

20. A cochlear implant electrode assembly of claim 19 wherein the slits are formed so as to have substantially the same or the same rate of ingress of fluid through the outer layer.

21. A cochlear implant electrode assembly of claim 19 wherein at least one slit has a different rate of progress of fluid through the outer layer compared to the other slits in the outer layer.

22. A cochlear implant electrode assembly of claim 21 wherein a slit most distal the first end of the elongate member allows a greater rate of fluid ingress through the outer layer than its adjacent slit positioned closer to said first end, such that the bioresorbable material of the stiffening element beneath this slit preferably begins to dissolve or soften before the remainder of the stiffening element so allowing the elongate member to begin to firstly move from its first configuration to its second configuration at or adjacent the position of this most distal slit.

23. A cochlear implant electrode assembly of claim 22 wherein the rate of ingress provided by each slit can follow this pattern along the length of the device towards the first end, with the next closer slit to the first end providing a relatively lesser rate of ingress than its adjacent more distal slit.

24. A cochlear implant electrode assembly of claim 19 wherein the slits are sealable with a bioresorbable material.

25. A cochlear implant electrode assembly of claim 5 wherein a plurality of fluid ingress means are provided in the outer layer and each comprise regions of silicone having a thickness less than that of the remainder of the outer layer.

26. A cochlear implant electrode assembly of claim 7 wherein a resiliently flexible tip member extends forwardly from the first end of the elongate member.

27. A cochlear implant electrode assembly of claim 26 wherein the tip member has a plurality of metallic particles dispersed therethrough.