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 electrogustometry 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 groups 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 (group 2 [n = 149]); and the severed nerve group (group 3 [n = 113]). Electrogustometry was periodically performed over the course of several years. Results: The incidences of postoperative subjective taste disorder in groups 1, 2, and 3 were 2.8%, 25.5%, and 38.9%, respectively. Although the subjective 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 electrogustometric results, in the no-touch group, 8.3% of patients showed threshold elevation on electrogustometry, but the elevated thresholds completely recovered in all cases. In the touch group, 45% of patients exhibited elevated electrogustometric thresholds on their first postoperative test, including 32.9% who subsequently had complete electrogustometric recovery, 10.1% who subsequently had incomplete recovery, and 2% who failed to recover during the follow-up period. In the severed nerve group, none of the patients was responsive to the electrical stimulus on the first postoperative test, including 8.8% of patients who subsequently exhibited complete electrogustometric recovery, 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 on 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.