Unanswered questions concerning the indication for cochlear implant.

In a discussion of the function of cochlear implant (CI), the following criteria should be mentioned: (1) If possible, all deaf persons (including the prelingually deaf and children) should benefit from CI. (2) Since the number of patients with late deafness is doubtlessly decreasing with better prevention and medical care (elimination of ototoxic damage, decrease of iatrogenic deafness), the percentage distribution of the deaf will be displaced in favor of the prelingually deaf. At present, the ratio of cases of late deafness to those of prelingual deafness among our CI candidates is 1:3.

Extracochlear sixteen-channel electrode system.

This article summarizes 10 years of work by the Cologne-Düren Research Group. The purpose of our research was to develop a noninvasive operation technique and to avoid opening the inner ear cavities (extracochlear technique). On the basis of empiric experience, a 16-channel electrode system was developed.

Extracochlear eight-channel electrode system.

The Cologne-Düren research group has developed a new extracochlear eight-channel electrode system. The first observations on six cases have shown encouraging psychoacoustic results.