PERIOPERATIVE LESIONS OF THE FACIAL-NERVE - FOLLOW-UP INVESTIGATIONS USING TRANSCRANIAL MAGNETIC STIMULATION

Peripheral facial palsy can occur after aural surgery and neurosurgery . Routine neurophysiological investigation (utilizing electrical stimu lation and the blink reflex) does not allow the direct assessment of t he site of a lesion. In the present study transcranial magnetic stimul ation (TMS) was applied in order to evaluate the usefulness of this me thod for prognosis. Twenty-three patients with postoperative facial pa reses (after removals of an acoustic neuroma in 12 patients and paroti d tumors in 11) were investigated. Ipsilateral short-latency and contr alateral long-latency responses (after cortex stimulation) were elicit ed. At the first examination (11.7 +/- 9 days after onset of the palsy ) the components of the blink reflex were absent in all cases. Respons es to electrical stimulation were abnormal in 80%. Ipsilateral short-l atency responses after TMS could be obtained in 7 patients. Pathologic al long-latency TMS responses were elicited in 17 patients. Follow-up investigations up to 2 years revealed no prognostic aspects from perip heral electrical stimulation, the blink reflex and the short-latency T MS response. The absence or extent of delay in long-latency responses at first examination was strongly correlated with final clinical outco mes. As improvements of the responses preceded clinical regressions of the paresis, TMS proved to be an important neurophysiological method for an early prognosis of recovery after perioperative lesions of the facial nerve.