Follow-up investigations of peripheral facial palsy by transcranial magnetic stimulation.

Twenty-three patients (10 men, 13 women; age: from 23 to 81 years, mean 52 years) with Bell's palsy were investigated by magneto-electrical stimulation in order to evaluate the usefulness of this method for prognostication. At each examination the facial nerve was electrically stimulated, and an orbicularis-oculi-reflex was elicited. Follow-up investigations were possible in 13 patients. All patients showed pathological long- and short-latency responses at the first examination. The blink reflex examination revealed a pathological result in all cases. The responses to electrical stimulation were pathological only in 35%. The follow-up examinations revealed that the analysis of the short-latency response did not give a prognostic information. In contrast, maintained elicitation of the long-latency response pointed to a favourable prognosis. In follow-up investigations, the increase of amplitude and the decrease of latency of the long-latency response correlated with a complete recovery, while the decrease of amplitude and the increase of latency correlated with a partial recovery. The improvement of the responses in magnetic stimulation preceded the clinical improvement. By using magnetic stimulation, an early registration and evaluation of the course of Bell's palsy are possible.