Long-term follow-up results of electrogustometry and subjective taste disorder after middle ear surgery

Objectives. The present study compares the long-term follow-up results of e lectrogustometry with patient reports of taste dysfunction after middle ear surgery. Study Design: Retrospective review of 371 patients who underwent middle ear surgery. Methods: Patients were divided into the following group s depending on the degree of manipulation or surgical damage to the chorda tympani nerves: the no-touch group (group 1 [n = 109]); the touch group (gr oup 2 [n = 149]); and the severed nerve group (group 3 [n = 113]). Electrog ustometry was periodically performed over the course of several years. Resu lts: The incidences of postoperative subjective taste disorder in groups 1, 2, and 3 were 2.8%, 25.5%, and 38.9%, respectively. Although the subjectiv e taste disorder usually recovered within 1 to 2 years after surgery in all groups, it persisted for more than 2 years in 2.7% of the touch group and 5.3% of the severed nerve group. Concerning postoperative electrogustometri c results, in the no-touch group, 8.3% of patients showed threshold elevati on on electrogustometry, but the elevated thresholds completely recovered i n all cases. In the touch group, 45% of patients exhibited elevated electro gustometric thresholds on their first postoperative test, including 32.9% w ho subsequently had complete electrogustometric recovery, 10.1% who subsequ ently had incomplete recovery, and 2% who failed to recover during the foll ow-up period. In the severed nerve group, none of the patients was responsi ve to the electrical stimulus on the first postoperative test, including 8. 8% of patients who subsequently exhibited complete electrogustometric recov ery, 32.7% who later had incomplete electrogustometric recovery, and 58.4% who never recovered any electrogustometric responsiveness. Nerve repair in the severed nerve group produced better recovery, as measured electrically. Conclusions: The incidence of postoperative subjective taste disorder was low, although inconsistent with the high incidence of threshold elevation o n electrogustometry, especially in the severed nerve group. Preservation or repair of the chorda tympani nerve is recommended in order to maintain or recover gustatory function.