Cochlear electrode implant assemblies with positioning system therefor

A self-positioning cochlear electrode implant assembly adapted to be implanted in the scala tympani of the spirally curved cochlea of a human ear for stimulating cells of the spiral ganglion, said assembly comprising:

• a rod-shaped cochlear electrode carrier made of a biocompatible plastic material and sufficiently flexible to be able to assume the spiral curvature of the cochlea, said electrode carrier having leading and trailing end regions and tapering in cross-section from said trailing end region to said leading end region;
• an array of cochlear electrode elements supported by said electrode carrier at respective longitudinally spaced locations thereon in a medial region of said electrode carrier between said leading and trailing end regions thereof, said electrode elements having respective contact faces exposed along a first longitudinal side region of said electrode carrier;
• a rod-shaped electrode carrier-positioning member made of a biocompatible plastic material and sufficiently flexible to be able to assume the spiral curvature of the cochlea, said positioning member having leading and trailing end regions and being juxtaposed to and extending lengthwise of said electrode carrier along a second longitudinal side region of the latter opposite said first longitudinal side region thereof so as to have said leading and trailing end regions of said positioning member located adjacent said leading and trailing end regions, respectively, of said electrode carrier;
• and means connecting said leading and trailing end regions of said positioning member to said leading and trailing end regions, respectively, of said electrode carrier so as to leave a medial region of said positioning member separated from said medial region of said electrode carrier and adapted to assume an arched configuration relative to said medial region of said electrode carrier upon insertion of the assembly into the cochlea;
• whereby, upon insertion of said assembly into the scala tympani with said positioning member engaging and closely following the curvature of the radially outer wall of the cochlea and with said electrode carrier juxtaposed to and closely following the curvature of said positioning member, said positioning member when assuming said arched configuration against the constraint of the radially outer wall of the cochlea exerts a force on said electrode carrier at said leading and trailing end regions thereof to shift said electrode carrier into engagement of said first longitudinal side region thereof with the radially inner wall of the cochlea so as to position said contact faces of said array of electrode elements in close proximity to the spiral ganglion cells of the cochlea;
• and said means connecting said trailing end region of said electrode carrier and said trailing end region of said positioning member further serves, when the insertion of said assembly into the cochlea has been completed and said positioning member is in said arched configuration thereof, to stabilize said assembly in and lock the same against inadvertent reverse movement out of the cochlea.