Evaluation of greater petrosal nerve function in patients with acute peripheral facial paralysis: comparison of soft palate electrogustometry and Schirmer's tear test.

We tested sensory and secretomotor function of the greater petrosal nerve (GPN) by means of electrogustometry (EGM) of the soft palate and Schirmer's tear test in 115 patients (59 males, 56 females) with acute peripheral facial paralysis. Facial paralysis was caused by Bell's palsy in 78 cases, Ramsay Hunt syndrome in 27 cases and zoster sine herpetic lesions in 10. All patients had dysfunction of the stapedial nerve. An electrogustometer was used to test taste (GPN sensory function), and elevation of the threshold by > 6 dB on the affected side was considered abnormal. Schirmer's test was used to evaluate lacrimal (GPN secretomotor) function, which was considered abnormal when tear secretion on the affected side was < 50% of secretion on the non-affected side. Of the 78 patients with Bell's palsy, 28.2% had altered taste on the soft palate (sensory dysfunction) and 10.3% had lacrimal dysfunction, indicating that EGM of the soft palate is more sensitive than Schirmer's test for identifying dysfunction of the GPN in patients with facial paralysis due to Bell's palsy. Of the total of 115 patients, 32 (28%) had taste dysfunction and 9 (28.1%) of these 32 patients also had lacrimal dysfunction. This finding indicates that facial paralysis has different effects on the sensory and secretory nerve fibers of the GPN. The results of Schirmer's test were more closely related to the severity of, and prognosis for, facial paralysis than the results of EGM.