Many instances of total deafness are due to destruction of the organ of Corti, contrasting with the partial or complete preservation of the function of the cochlear nerve. In such cases, it is possible to restore some hearing by stimulating electrically the fibres of the cochlear nerve with the help of implanted electrodes. By means of several fenestrations, it is possible to construct electrically insulated compartments in the scala tympani of the cochlea, and to implant eight electrodes. This procedure allows discrimination of sound frequencies because the electrical stimulation of each electrode gives a sound sensation which depends on the electrode stimulated. This enabled us to elaborate a map of frequencies of the human cochlea and to make some physiological observations and achieve clinical results in seven cases of total bilateral deafness.

Adult↗

PubMedDate not supplied

Indications and results of the multichannel cochlear implant.

In the case of total deafness, the multichannel cochlear implant prosthesis constitutes a substantial improvement. It allows known words to be recognized without lip reading, with a great percentage of good responses. Clinical and phoniatric results are reported in 21 cases of patients with implants.

Acoustic Stimulation↗

PubMedDate not supplied

Auditory brainstem potentials in man evoked by electrical stimulation of the round window.

In normal subjects, round-window electrical stimulation provides a sound sensation and supplies brainstem-evoked responses whose form is just the same of those evoked by sound stimulation. This electrical stimulation also provides a sound sensation in more than 90% of cases of total deafness, which means that at least a few auditory nerve fibres are still present. Thus, this test is indispensable when considering surgical rehabilitation with a multichannel cochlear implant. The diagram of this response to an electrical stimulus differs completely in the case of total deafness and in normal subjects. The correlation between the form of these diagrams and the supposed etiology of the deafness is not significant.

Acoustic Stimulation↗