Effects of the single-electrode cochlear implant on the vestibular system of the profoundly deaf adult.

Twenty-two profoundly deafened adults, implanted with the single-electrode cochlear implant, were involved in a study to observe the effects of cochlear electrical stimulation on the vestibular system. Previous investigators had found evidence that the implant might disrupt postural stability. As there had been no general complaints of dizziness or dysequilibrium by the implant subjects, a study was undertaken to replicate the earlier study and to compare the results to more standardized procedures. A Sono-postural Test was devised from the Ataxia Test Battery for the testing of balance with and without an auditory prosthesis. Electronystagmography was also performed on the subjects before and after surgery as a means of monitoring vestibular status over time. Results from the these tests indicate that the single-electrode implant does not disrupt the balance system to any significant degree. In fact, evidence indicates that postural stability may actually improve with the cochlear implant activated.