Electrogustometry of the soft palate as a topographic diagnostic method for facial paralysis

Electrogustometry (EGM) of the soft palate, innervated by the gustatory fibers running via the greater petrosal nerve, was performed in 10 cases with facial paralysis due to suprageniculate lesions to evaluate its clinical validity as a topographic diagnostic method. Lacrimal function was also examined for comparison. The results obtained from EGM showed a significantly increased threshold on the affected side in 90% of the cases. However, the lacrimal secretion decreased only in 40% using Schirmer No. 2 test. The results of the present study strongly suggest that EGM of the soft palate reflects the function of this nerve better than Schirmer test, and EGM is clinically useful for the topographic diagnosis of peripheral facial nerve lesions.