Cochlear implantation of totally deaf ears. Histologic evaluation of candidacy.

Successful cochlear implantation depends on the presence of stimulatable neural elements, which are believed to be the spiral ganglion, neurons, or their axons. We examined the 1,152 temporal bones in our laboratory to determine how many with a total sensorineural hearing loss would be implantable. We defined implantable as having 3,500 neurons or more, as determined by successful implant stimulation in two ears from our collection with less than 3,500 neurons. Of 46 bones with deafness, 37 had 3,500 neurons or more and would be considered implant candidates. The types of deafness in the potentially implantable ears and in ears with sufficient neural elements will be discussed.