UCH/RNID single channel extracochlear implant: results in thirty profoundly deafened adults

The University College Hospital/Royal National Institute for the Deaf (UCH/RNID) Cochlear Implant Programme has now given single channel extracochlear implants to forty profoundly deafened adults. Audiological, psychophysical, speech perceptual and subjective results for the first thirty cases are described. The main findings can be summarised as follows: 1. Users of the single channel extracochlear implant gained considerable improvements in their lipreading and communication ability, as assessed by both objective testing and by the patients' own reports. All acquired useful awareness of environmental sounds and an improvement in their quality of life; some also showed improvements in their own speech. A small number were capable of some open-set speech discrimination without lipreading. 2. Extracochlear implantation was not found to destroy residual hearing, although it did cause slight deterioration in hearing thresholds in some cases. 3. Our results so far suggest that patients deafened by meningitis are likely to obtain less benefit from a single channel cochlear implant than those deafened by other causes. Better results were also achieved by younger, more recently deafened patients and those who were good lipreaders. Despite the emergence of these trends we have not yet found a reliable way to predict benefit from an implant on the basis of preoperative variables. 4. Self-reported measures of the benefits of the implant correlated well with the objective test results, but also revealed important information that was not available from the objective tests. In particular, they showed that the improvement in lipreading provided by the implant was reduced in noisy conditions.