[Transcranial magnetic stimulation in perioperative damage to the facial nerve]

5 patients (3 men, 2 women, aged from 28 to 51 years) with unilateral facial palsy after surgery of a cerebellopontine angle tumour have been investigated by transcranial magnetic stimulation. The purpose was to evaluate the prognostic aspects of this method, which was compared with the electrical stimulation of the facial nerve and the elicitation of an orbicularis-oculi reflex. The components of the blink reflex were absent in all cases. In 3 patients electrical stimulation was possible (compound muscle action potentials were delayed). With transcranial magnetic stimulation ipsilateral short-latency and contralateral long-latency responses (stimulation of the cortex) were elicited and registered from the M. mentalis as well as 3 times from the M. orbicularis oculi. The short-latency response revealed no prognostic aspects. Despite the missing response, a recovery was possible. Long-latency responses could be evoked in all patients. The extent of delay in latency was strongly correlated with clinical improvement of the paresis. Interestingly, this correlation could also be observed in the single rami of the facial nerve when two muscles were investigated in a patient. Transcranial magnetic stimulation is an important improvement in electrophysiological diagnosis of perioperative lesion of facial nerve to prove continuity of the nerve and to evaluate the clinical course.