Magnetic stimulation can be directed to the intracranial part of the facial nerve, whereas the conventional electric stiumli are dilivered extracranially to a more peripheral part of the nerve. To estabilish the normal values for transcranial facial nerve stimulation, 24 healthy volunteers were examined.
The coil of magnetic stimulator was located so that its center was 3 cm posterior and 6 cm lateral to the vertex. Responses were recorded on nasalis muscle. The mean latency of responses was 4.5⁑0.45 msec. The mean difference between the sides, 0.26⁑0.23 msec, was stastistivally not significant (p>0.05). On stylomastoid foramen stimulation, there were no significant differences between latencies of magnetically induced responses and those of electrically induced ones. But the electric stimulation was more comfortable, and elecited more sharp waves. Also twelve cases with Bell's palsy were examined using this method. The studies for 2 acute patients, which did not revealed any abnormalities on conventional electrodiagnostic study, showed definite evidence of conduction defects on transcranial magnetic stimulation.
