STEREOTAXIC TRANSCRANIAL MAGNETIC STIMULATION - CORRELATION WITH DIRECT ELECTRICAL CORTICAL STIMULATION

OBJECTIVE: To evaluate stereotactic transcranial magnetic stimulation (TMS) as a tool for presurgical functional mapping of human motor cort ex. METHODS: Transcranial magnetic stimulation using a frameless stere otactic system was performed in two patients with tumors near the cent ral sulcus. TMS motor function maps were plotted on the patients' thre e-dimensional volumetric magnetic resonance imaging data and compared with direct electrical cortical stimulation at surgery with the patien t under local anesthesia. RESULTS: Stereotactic TMS was well tolerated by both patients and was consistent with known somatotopic representa tion of human motor cortex. The results demonstrated a good correlatio n between the TMS and electrical cortical stimulation maps, with all T MS responses eliciting more than 75% of the maximum motor evoked poten tial falling within 1 cm of the electrical cortical stimulation site. CONCLUSIONS: Our findings indicate that stereotactic TMS is feasible a nd can provide accurate noninvasive localization of cortical motor fun ction. It may prove to be a useful method for presurgical planning.