Hilger facial nerve stimulator: a 25-year update. Percutaneous nerve excitability testing using the Hilger facial nerve stimulator was introduced about 25 years ago. The test is reliable, easy to use, and inexpensive; it continues to be the most frequently used method for predicting prognosis of facial nerve disorders. Between 1966 and 1974, we recorded 10,243 nerve excitability tests on 865 patients with a mean of 3.29 tests for each peripheral branch and 3.43 for the trunk. Using a multiple regression model, we determined the effect on nerve stimulation values of age, sex, race, diabetes, hypertension, partial or complete clinical paralysis, diagnosis of herpes zoster, year of testing, and eventual facial paralysis recovery profile. We discuss statistical reliability, provide a table of interpretive results, and offer "tips and traps" invaluable to the practitioner. A prospective study of 25 patients with residual facial paralysis was evaluated by two separate otolaryngologists to determine intertester reliability. 