The Chorimac-12. A multichannel cochlear implant for total deafness. Description and clinical results.

More than 90% of cases of patients suffering from acquired or congenital deafness may be provided with some sound sensation owing to the electrical stimulation of the few cochlear nerve fibers that are still present in the deaf cochlea. In order to obtain some speech discrimination without lip reading it is necessary to elicite different frequency sound sensations. Thus electrically proofs compartments must be performed all along the cochlear keyboard. The placement of 12 intra-cochlear electrodes is greatly facilitated by using an electrodes-bearer which is introduced through a very simple and classical surgical procedure. The indications for implanting depend on undiscussible criteria (total deafness, auditory response to electrical stimulation of the round window, patient's motivation). Clinical results consist of psychoaffective improvement and auditory possibilities. All patients are able to discriminate homosyllabic words in closed lists without lips reading, but the percentages of these performances greatly vary from one patient to the other. Some patients, generally suffering from acquired total deafness, are able to discriminate words or sentences without reference list and without help of lips reading. These results depend on the patient's socialization level, on the pre or post-lingual status of the deafness, on an eventual cochlear ossification, and on the value of several pre operative electro physiological data. Associated handicaps (autism, blindness, tetraplegia) are not contra indications and often represent supplementary reasons for implanting. The value of these post-operative results may be predicted owing to a series of electrical pre-operative tests and clinical data. Thus it is possible to determine the respective indications of multi and single channel cochlear implants.