Revised selection criteria for the multiple-channel cochlear implant

Abstract

The criteria of suitability for a cochlear implant have been extended from total deafness to include some individuals with residual hearing. The aim of the initial hearing evaluation is to define whether the speech discrimination is good enough to justify perseverance with a hearing aid. In adults, usually the pure tone audiogram and speech audiometry are accurate and consistent. In children, however, to achieve accuracy, free field testing must be complemented by repeated aided conditioned responses and objective evoked response audiometry. When a child has residual hearing it is more difficult to assess the potential for habilitation using an aid. For both adults and children, it is necessary to make a selection from a battery of tests on the basis of the subjects experience. This development highlights the need for otologists and audiologists to become familiar with the battery of tests used in evaluating severe deafness (Plant 1984) and to review decisions made about the management of people with severe to total deafness. In suitable people, the aim of treatment with the Cochlear multichannel implant and its multipeak speech processor is a significant score for open set speech discrimination tests using hearing alone. This cannot always be achieved but as long as the evaluation protocol has been used to warn patients before the operation, they will be satisfied with a result where the implant complements lip reading resulting in discrimination of running speech and detection of environmental sounds.