Successful enucleation of a large sciatic schwannoma with intraoperative neurostimulation-guided dissection: a case report

Advances in intraoperative neurophysiological monitoring (IONM) have enabled safer peripheral nerve tumor surgery. We report a patient in whom a large sciatic nerve schwannoma was successfully removed using intraoperative nerve stimulation. A 62-year-old male presented with a palpable mass in the right posterior upper thigh, just below the gluteal fold. Magnetic resonance imaging showed an approximately 9-cm encapsulated solid mass in the middle of the sciatic nerve. After a vertical skin incision with a laterally curved upper end extending to the inferior gluteal region, the proximal sciatic nerve was secured laterally to the biceps femoris and the distal nerve medial to the muscle. We avoided causing trauma to the viable nerve fascicles by dissecting through the “safe zone,” as confirmed by monitoring the distal muscle contractions induced by intraoperative nerve stimulation on the tumor surface. In this report, we present the details of our surgical approach to the middle portion of the sciatic nerve and the use of IONM for safe tumor excision.