Treatment of relevant nerve roots involved in nerve sheath tumors: Removal or preservation?

OBJECTIVE: Surgery for the treatment of patients with spinal nerve sheath tumors can require complete resection of the nerve roots involved in the tumor. The purpose of the present study is to analyze the risks of resection of eloquent roots as compared with the risks of incomplete tumor removal. METHODS: The pertinent literature on spinal nerve sheath tumors was reviewed. A single-institution series of 26 patients who underwent operations for 27 spinal schwannomas or neurofibromas, which were removed together with functionally relevant nerve roots (C5-C8 or L3-S1), was studied. RESULTS: Worsening of preoperativc radicular motor function was observed at follow-up in 4 (14.8%) of the 27 divided nerve roots, but the motor deficit was permanent and disabling in only 2 cases (7.4%). In the four patients who experienced worsened radicular motor function, the roots were cervical, and histological analysis revealed that the tumor was a schwannoma. Three-of these patients were neurologically negative before surgery. Of the two patients with severe radicular weakness, the location of the tumor was extradural and extraradicular in one patient, who had normal preoperative root function, and the tumor was intraextradural in the other patient, who had a preoperative root deficit. CONCLUSION: After resection of a single eloquent nerve root involved in a nerve sheath tumor, the incidence of radicular dysfunction is low but severe weakness is possible. The main risk factors, seem to be the pathological pattern (schwannoma versus neurofibroma) of tumor the preoperative status (with versus without deficit) of the root, and, for extradural nerve sheath tumors, the location (cervical and extraradicular versus lumbosacral and intraradicular) of growth. Deafferentation pain does not occur. Unlike schwannomas with neurofibromatosis Type 2 and neurofibromas, the radicality of removal seems to be the main factor with regard to the recurrence of solitary schwannomas, although recurrent tumors often appear later in follow-up.