Taste function after section of chorda tympani nerve in middle ear surgery

Abstract

Objectives: We already reported that taste disturbance occurred more frequently after preservation of chorda tympani nerve (CTN) than after section of CTN, especially in cases of otosclorosis, and that younger patients showed higher recovery rate of CTN function than older ones. In the present study, we examined taste function after the section of CTN in middle ear surgery. Methods: Fifty-nine patients were followed up more than 2 years after section of CTN on unilatreral side (42 ears) or on both sides (34 ears) from 1999 to 2002. They aged from 7 to 63 years with a mean of 46.2 years, and they consisted of 63 ears of cholesteatoma, 6 ears of adhesive otitis media and 7 ears of chronic otitis media. Taste function was evaluated by electrogustometry (EGM) and questionnaire. Results: The threshold of EGM was still much elevated 2 years after surgery either in unilatreral or bilateral section of CTN. Interestingly, the area with no response of EGM became smaller in patients below 10 years old with the time, but it was the same in middle and old aged patients. In the questionnaire, symptoms of taste disturbance or tongue numbness ceased 3–12 months (mean, 7.2 months) after unilateral section of CTN and they ceased 1–12 months (mean, 6.7 months) after bilateral section of CTN. Conclusion: These findings suggested that CTN of the opposite side might compensate taste function in case of unilatreral section, and that glossopharyngeal nerve might compensate it in case of bilateral section.