Keimyung Medical Journal, Vol.9(2) : 215-221, 1990
The primary receptor cells for the sense of taste are arranged in small groups called taste buds mostly located on the tongue. The taste buds over the anterior two-thirds of the tongue receive afferent fibers from the chorda tympani branch of the facial nerve. The aims of the present investigation were to measure the range of normal variation in electrogustometric thresholds and to study the effects of surgical injuries to the chorda tympani on the electrogustometric threshold, using a electrogustometer (Life-Tech model 4000). Forty healthy subjects were selected as a control group while a patient group was composed of 41 cases of chronic otitis media. In the former group normal range of the threshold were measured and analyzed. The latter goup was compared using various clinical characteristics of chronic otitis media and its surgical modalities in terms of taste thresholds. The normal range of electrogustometric thresholds of the control group was 0-22-μA High scores of the preoperative electrogustometric threshold were significantly relative to the duration of chronic otitis media and severity of hearing impaismenit (P<0.05), however it was within normal limits in chronic otitis media with or without cholesteatoma. The postoperative thresholds were elevated in cases of the surgically-cut and stretched chorda tympani (p<0.01), but it revealed normal limits in the well-preserved cases. In the weee-preserved cases of chorda tympani during surgery, the postoperative electrogustometric threshold was slightly higher in the open cavity mastoidectomy than in the closed cavity mastoidectomy. These results suggest that surgical injury to the chorda tympani is the leading factor decreasing the sense of taste postoperatively in chronic otitis media. Assordingly the issue of change in the taste threshold following ear surgery should have widespread interests in otologists.