Electrode for implantation into cochlea

• US 4,261,372 A
• Filed: 11/13/1978
• Issued: 04/14/1981
• Est. Priority Date: 11/22/1977
• Status: Expired due to Term

• Current Assignee: Carl C. Hansen, Ole M. Lauridsen
• Original Assignee: Carl C. Hansen, Ole M. Lauridsen
• Inventors: Hansen, Carl C., Lauridsen, Ole M.
• Primary Examiner(s): Cohen, Lee S.
• Application Number:
  US05/959,757
• Time in Patent Office: 883 Days
• Field of Search: 128/784-789, 128/799, 128/802, 128/419 R, 128/639, 128/642, 128/1 R, 179/107 R, 179/107 E
• US Class Current: 607/137
• CPC Class Codes: A61N 1/0541 Cochlear electrodes
• CPC Class Codes: H04R 25/606 acting directly on the eardrum, the ossicles or the skull, e.g. mastoid, tooth, maxillary or mandibular bone, or mechanically stimulating the cochlea, e.g. at the oval window

Abstract

An electrode in the form of a foil-like flexible, electrically insulating support member having nerve electrodes supported thereupon for implantation into the cochlea. The electrode establishes electrical communication to the acoustic nerves of the human ear, substantially in the area of the cochlea containing the auditory nerves pertaining to that part of the audible spectrum, which is relevant to the intelligibility of speech. The electrode is provided with two prongs and a shank, each prong having a length which corresponds to the length of the turn in the cochlea into which it is to be inserted during implantation and hence the two prongs are of different lengths. Further, each prong terminates in a bevelled pilot guiding member which guides each prong through its respective turn in the cochlea to thereby reduce damage to the auditory nerves. During implantation each prong passes through only a single turn of the cochlea and is prevented from gouging into the walls of the cochlea due to provision of the bevelled guiding member. The guiding member can be provided as a drop-shaped member secured to the end of each prong or by forming an eyelet in the distal ends of the prongs.

The present invention is related to an electrode for implantation into the cochlea in order to establish electrical communication to the acoustic nerves of the human ear, the electrode comprising an insulating support member having nerve contact points and associated supply lines.

Electrodes of this kind have been described by Martin Sonn and Wolfgang Feist in an article entitled "A prototype flexible microelectrode array for implant-prosthesis applications" in Medical and Biological Engineering, Nov. 1974, pages 778-790 and are illustrated in FIG. 1. This prior art electrode is disposed to be inserted through an aperture in a turn of a patient'"'"'s cochlea, whose internal ear is defective, in order to establish communication substantially in the area of cochlea containing the acoustic nerves pertaining to that part of the audible spectrum, which is relevant to the intelligibility of speech. Accordingly it has such an extension that it has to be introduced into about nearly two turns of cochlea. It has appeared, however, that a satisfactory result was not attained, in as much as it has certainly been possible to bring the patent to such a condition that she or he could interpret electrical signals supplied through the electrode as being sound but not as being intelligible speech. The present invention is based on the opinion that this fact is due to damaging of the patient'"'"'s acoustic nerves during the insertion of the electrode into the cochlea. Accordingly, it is an object of the present invention to provide an improved embodiment of an electrode of the kind discussed above, by means of which the damage of the acoustic nerves during the implantation can be avoided.

The present invention is based on the acknowledgement, that the entire area of cochlea which is relevant to speech cannot be contacted collectively, because an electrode having a sufficient extension for this purpose will act unavoidably as a chisel, which during the introduction gouges into cochlea and in this way damages the interior walls of cochlea and possibly the acoustic nerves too. Consequently it would be obvious to implant a number of shorter electrodes, but this will cause difficulties in practice. Partly, implantation of a number of electrodes would last a longer time than it would be permitted to keep the lymph-filled cochlea open and partly the attachment of a number of electrode ends or connection of lines to an external signal source would cause further difficulties compared to application of only a single electrode.

Claims

1. An implantable flexible electrode for implantation into the cochlea and disposed to establish electrical communication to the auditory nerves of the human ear comprising:

an elongated foil-like support member of a flexible electrically insulating material said support member having a planar surface extending along a substantial length thereof and a socket portion at one end thereof;

a pattern of electrically conductive paths of a material inert to body fluids and tissue integrally adhered to said planar surface of said support member;

a connecting point provided at one end of each of said paths in said socket portion of said support member;

one nerve electrode of an array of a plurality of nerve electrodes connected to the opposite end of each of said paths and arranged in an opposite end of said support member;

said opposite end of said support member divided into two prongs of uneven lengths each having distal ends and each corresponding to the lengths of particular turns of the cochlea into which said prongs are to be respectively inserted, said nerve electrodes secured to said prongs; and

pilot members bevelled with respect to the plane of said foil-like support member attached to said distal ends of said prongs for guiding said prongs through the turns of the cochlea during implantation to thereby reduce damage to the auditory nerves.

2. Am implantable flexible electrode according to claim 1, wherein:

said pilot members comprise drop-shaped members secured to each of said prongs.

3. An implantable flexible electrode according to claim 1, wherein:

said pilot members comprise eyelets formed in the distal ends of said prongs.

4. An implantable flexible electrode according to claim 1, wherein:

a different number of nerve electrodes are secured to each of said prongs.