Of the first 100 patients implanted on the Midland Cochlear Implant Programme the commonest aetiologies of deafness were idiopathic 31 per cent, meningitis 28 per cent and cochlear otosclerosis 16 per cent.

The major complication rate was three per cent. The most severe was one individual who post-operatively developed a cerebral infarct and subsequently died. The minor complication rate was 39 per cent, all of which successfully resolved, and included 11 cases of wound infection, nine cases of vertigo, three transient facial palsies and two post-operative bleeds.

Older patients and men were most likely to have a post-operative medical complication. Women were more likely to have an abnormal electrode insertion. Meningitis and otosclerosis were the most complicated aetiologies in terms of cochlear ossification and electrode insertion. A non-patient cochlea was associated with fewer active electrodes. In six cases which had been reported pre-operatively as showing patent cochleas, some form of obstructional ossification was encountered. Patients functioning with greater than 15 active electrodes performed better on auditory tests than patients with fewer than 15 active electrodes.