Present Status and Future Development of the Cochlear Prosthesis

Abstract

Presently devised single channel devices generate relatively primitive sensation of hearing. They provide some enhancement of communication skills for the totally deaf. Definite psychological advantages for the totally deaf have been observed. Pitch discrimination is by the mechanism of "periodicity pitch." No "place" pitch encoding is possible. The recognition of complex sounds is not possible. Multiple segments of auditory nerve must be stimulated in a manner which will stimulate the complex patterns of neural activity necessary for speech discrimination. Electrodes can be optimized and the pathophysiological consequences of electrical stimulation can be determined in experimental animals. The perceptual consequences of electrical stimulation, however, can best be determined in man himself. How much we will have to rely on known and future methods of aural rehabilitation will depend upon how well perceptual speech patterns can be generated by electrical stimulation of the auditory nerve.

A Model for Cochlear Implant Electrode Insertion and Force Evaluation: Results with a New Electrode Design and Insertion Technique

“…The House group initially developed both single and 10‐electrode devices. However, when no difference in speech perception was initially noted in the multielectrode device, it was decided to focus on the more simple and reliable single channel option 11 . Since that time, outcomes with multichannel electrode cochlear implants have been found to be superior.…”

“…It also posed greater engineering design challenge. 6,19 Some centers experimented with both or used a percutaneous plug during the initial programming, then replacing it with a permanent transcutaneous link 11,15 . With engineering advances, the benefits of transcutaneous radio‐frequency transmission soon was established as the norm.…”

“…Many early investigators developed one of each device, or even a single device incorporating both extraand intracochlear components. 5,6,11,12 Simmons' original implant consisted of six electrodes implanted into the modiolus. 3 House used an intracochlear array in the scala tympani as early as 1969, whereas Banfai in Germany was using an extracochlear position for an array as recently as 1986.…”

“…How is the external device to communicate with the internal electrode? Two main options were pursued: a direct percutaneous connection between internal and external devices 4,6,11,15 or transmitting information transcutaneously. 7,8,[16][17][18][19][20][21][22] The latter option was preferred because it reduced the risk of scalp and device infection.…”

“…Should the electrodes be extracochlear or intracochlear? Many early investigators developed one of each device, or even a single device incorporating both extra‐ and intracochlear components 5,6,11,12 . Simmons' original implant consisted of six electrodes implanted into the modiolus 3 .…”