Taste change following cochlear implantation

Taste change is a well documented but under emphasised complication of middle ear surgery and is usually related to damage to the chorda tympani nerve (CTN). However, the taste outcomes following cochlear implantation have not been previously recorded. One hundred and forty one patients who had received cochlear implants between January 1997 and April 2006 were questioned using a postal survey regarding changes in the sense of taste following cochlear implantation. Sixty seven per cent of questionnaires were returned. Forty three patients (45%) experienced changes in taste following their surgery. Eighteen patients (19%) said that their symptoms had not resolved by the end of the follow up period (mean 51 months). CTN division produced taste change in 86%. Fifty per cent of patients who had CTN preservation developed taste change, presumably related to occult trauma to the nerve. The difference in the number of patients describing taste change in the two groups was statistically significant (p < 0.05). Resolution of symptoms took a mean of 20 weeks. For those patients in whom taste change was noted, resolution of symptoms was more likely if the CTN was divided rather than preserved although the difference was not statistically significant (p < 0.5). This may reflect neuronal injury during surgery which then fails to heal normally. These results are comparable to taste outcomes in patients undertaking middle ear surgery for non-inflammatory disease such as stapedectomy. The symptoms can be extremely troublesome and may not resolve with time. Careful consideration of the CTN intra-operatively is recommended and in the event of injury, the taste outcome may be better if the nerve is divided rather than left in situ but damaged. These findings have significant implications for patients as bilateral implantation becomes more commonplace.