High Resolution MRI Can Help Determine Tumor Resectability in Cases of Benign Sciatic Notch Lesions

The operative management of patients with combined intra- and extrapelvic sciatic notch dumbbell tumors is challenging. Their relative rarity and varied extent of disease have made it difficult for surgeons to establish definitive surgical indications or predict favorable neurologic outcomes based on preoperative imaging.

Five patients with benign sciatic notch dumbbell tumors recently presented with radiating leg pain. Because of the extent and location of pathology and presumed direct neural involvement, they were initially thought to have unresectable lesions. High resolution MRI was utilized to analyze specifically the relationship of the tumor to the nerve with the aim of potentially predicting tumor resectability. A single radiologist prospectively then determined whether the tumor appeared discrete from the sciatic nerve within the notch (potentially “resectable”) or involved the sciatic nerve directly (“unresectable”).

Three patients were determined to have respectable tumors based on imaging criteria and underwent a combined one-stage transabdominal and posterior gluteal approach. Gross total resection was achieved in these cases and histology revealed 2 plexiform neurofibromas and 1 myxoma. These three patients maintained normal neurologic status postoperatively. At follow-up more than 1 year postoperatively, these patients had no recurrence radiographically. Two patients with NF-1 had “unresectable” lesions bilaterally (presumably, plexiform neurofibromas). Their tumors directly involved the sciatic nerves on MRI and tumor debulking or resection would have resulted in neurologic deficit and would not have addressed the neuropathic pain. They were treated pharmacologically and were recommended for life-long tumor surveillance for the possibility of malignant transformation.

High-resolution MRI is a useful adjunct to the management of patients with benign but extensive sciatic notch tumors. This method of preoperative imaging also has implications for the resection of the more common neurogenic or non-neurogenic tumors involving the sciatic notch which do not extend into the pelvis. This imaging technique allows visualization of the anatomic relationships of the tumor to the sciatic nerve so that surgeons can predict which sciatic notch tumors can be resected safely and completely.