Transcranial Magnetic and Intraoperative Electrical Stimulation of the Trigeminal and Facial Nerves: Sites and Mechanisms of Excitation

Summary

Currents induced by a rapidly varying magnetic field were applied to the parietooccipital scalps of patients undergoing neurosurgical operations to stimulate simultaneously the ipsilateral facial and trigeminal nerve, as well as other caudal motor cranial nerves. The magnetic stimulation was assumed to generate electrical currents in the cerebrospinal fluid (CSF). The stimulating currents were assumed to pass through the foramina of the respective cranial nerves distal to the CPA, where the nerves are still surrounded by CSF. Thus, the point of excitation for the facial nerve was within the labyrinthine segment of the facial canal; and for the trigeminal nerve was probably within Meckel’s cave.