[Masseteric responses following electrical stimulation of the scalp]

Electromyographic responses of the masseter muscles following electric transcranial stimulations by a conventional constant current stimulator were recorded with surface and needle electrodes. Ipsilateral motor evoked responses following both anodic and cathodic bipolar electrical stimulations performed at 7 and 11 cm laterally to the vertex on the biauricular line were recorded, with latencies ranging from 2 to 3.6 ms. Contralateral responses were not elicited. The ipsilateral responses to stimuli were ascribed to direct stimulation of the trigeminal nerve, probably its intracisternal portion.