Transcranial magnetic stimulation.

Multiple techniques are vying for establishing the new gold standard for functional cortical mapping, displacing that of the currently invasive and risk-prone techniques of subdural electrode arrays and intraoperative electrical stimulation mapping. Transcranial magnetic stimulation holds promise for functional localization of primary motor areas and speech areas, and possibly even other higher cortical functions. The technique is economical, especially when compared with the cost of functional magnetic resonance imaging and positron emission tomography. It can be performed effectively and safely in patients with epilepsy.