Progress in development of a multichannel acoustic nerve stimulation prosthesis for the totally deaf

Abstract

Neurophysiological and anatomical studies in cats have been directed toward determining the feasibility of development of a multichannel acoustic nerve stimulation prosthesis with potential application as an aid for profoundly deaf individuals with surviving acoustic nerve. From recording experiments taking advantage of the binaural frequency response characteristics of neurons within the central nucleus of the inferior colliculus, the pattern of excitation across the acoustic nerve array can be defined for any intracochlear electrode array. These single-unit studies reveal that it is possible to excite a series of restricted sectors of the acoustic nerve array from within the scala tympani, with appropriately positioned electrodes mounted in silastic carriers that fill the scala (displace perilymph). Precisely constructed electrode arrays in carriers molded to fill the scala can be fabricated using dies of the scala made from soft-metal cochlear casts. Implantation of these multichannel electrode arrays does not lead to significant direct destruction of the acoustic nerve in prior normal or prior neomycin-deafened ears, over a time course of many months. [Supported by NIH Grant NS-11804.]