The surgical complications for the first 153 multiple-channel cochlear implant operations carried out at the Medizinische Hochschule in Hannover and the first 100 operations at the University of Melbourne Clinic, The Royal Victorian Eye and Ear Hospital, are presented. In the Hannover experience the major complications were wound breakdown, wound infection, electrode tie erosion through the external auditory canal, electrode slippage, a persistent increase in tinnitus, and facial nerve stimulation. The incidence of wound breakdown requiring removal of the package was 0.6% in Hannover and 1.0% in Melbourne. The complications for the operation at both clinics were at acceptable levels. It was considered that wound breakdown requiring implant removal could be kept to a minimum by making a generous incision and suturing the flap without tension.

Electrically elicited stapedius reflexes were examined in 25 deaf patients who had received a 22-channel Clark/ NUCLEUS cochlear implant. Using an apical, a medial and a basal electrode pair, different stimulation positions within the cochlea and different stimulation modes were examined. For threshold determination, 10 reflexes were averaged with reflexes recorded on the nonoperated side. Reflexes were elicited in 19 of the 25 patients (76%); a saturation of reflex amplitude could be recorded in 14 (56%) subjects. In two additional cases, a reflex could be obtained by increasing the bipolar stimulation width (changing the stimulation mode). In comparison with different stimulation positions within the cochlea, the stimulation of apical electrodes produced more distinctive reflexes and required lower current levels. An increase in the bipolar stimulation width also decreased the intensity required for stapedius reflex threshold. Our data suggest that stapedius reflex evaluation may be a useful tool for speech processor fitting.

No abstract