Clinical Use of Magnetic Stimulation of Facial Nerve.

Magnetic stimulation of the peripheral facial nerve with Magstim model 200 was performed in normal human subjects without any history of facial nerve disorders. Contractions of the orbicularis oris and the orbicularis oculi muscles were evoked by magnetic stimulation around the auricle and were compared with those produced by extratemporal electrical stimulation.1) Infra-auricular stimulation with Magstim caused configurations and latency similar to those caused by electrical stimulation at the stylomastoid foramen.2) Contralateral stimulation of any site around the auricle never induced motor evoked potentials of both muscles.3) Changing the site of stimulation from the supra-auricular to the infra-auricular area tended to shorten the latency period.4) Ipsilateral stimulation of the right and left sides resulted in different latencies.Thus, the site of excitation was not defined clearly. We conclude that it is too early to use this method to diagnose conduction block of the facial nerve.