The relevance of the corticographic median nerve somatosensory evoked potentials (SEPs) phase reversal in the surgical treatment of brain tumors in central cortex.

Tumors of the central brain cortex change the original anatomy of this important area and so an intraoperative localization of the perirolandic structures is crucial in decision concerning the way and the extent of tumor resection. The phase reversal of median nerve SEPs is an essential tool for neurosurgical procedures in and around the perirolandic gyri. This study examines the relevance of the method in a group of 62 patients having surgery of tumors in and around the central region. A success rate in obtaining the SEP phase reversal was 94%. In all groups of patients the complete resection of tumor was achieved in 58% , subtotal resection in 19% and partial or biopsy only in 23%. The long term impairment of neurological status was observed in 6% of patients. Compared to the recently published studies our results are acceptable both in completeness of tumor resection and relatively low ratio of impaired postoperative neurological deficit despite the fact, that in the majority of patients the phase reversal mapping was the only method guiding the surgical procedure. Our study supports the crucial role of the central cortex mapping using the SEP phase reversal method in the surgery for the tumors of the primary sensorimotor cortex.