State of the art of cochlear implants. The UCSF experience

Clinical trials with the University of California, San Francisco (UCSF)/Storz multichannel cochlear implant began in February 1985. A total of 16 patients were implanted with this four channel unit, a vocoder-based, compressed-analog system. Twelve of the 16 patients have had their 1-year postoperative evaluations, which permitted observations of their performance over time. Of these 12 patients, 10 (83%) are able to obtain a considerable degree of speech recognition. This represents the achievement of some level of auditory-only understanding in a very high proportion of the implant population. Results are measured with a battery of speech reception tests, including monosyllabic word recognition (the standard clinical "speech discrimination" list), the recognition of key words in sentences, and connected discourse tracking. Conventional audiologic test procedures are used. The objective of the clinical trial was to evaluate the strategies developed by the UCSF implant team through neurophysiologic, histopathologic, and psychophysical investigations over the past 18 years. The UCSF/Storz trials have helped to clarify and to define the specifications for our next generation implant, an electrically transparent eight (bipolar) or 16 (monopolar) channel system.