Surgical Management of Peripheral Nerve Schwannomas in Non-Neurofibromatosis Type 2 Schwannomatosis.

BACKGROUND AND

OBJECTIVES

Pain is the cardinal symptom of non-neurofibromatosis type 2 schwannomatosis (non- NF2 -SWN), and peripheral nerve schwannomas are the most frequent tumors encountered in this condition. The role of surgery in alleviating schwannoma-associated pain in schwannomatosis remains a matter of debate in the literature.

METHODS

We conducted a retrospective chart review of all non- NF2 -SWN patients followed up at our Schwannomatosis Reference Center and included all patients operated from a peripheral nerve tumor. NF2 -related schwannomatosis was excluded on the basis of germline genetic study and/or absence of suggestive tumors on brain and spine MRIs.

RESULTS

Fifty-nine patients were included, suffering mostly from a nonfamilial (50/59, 85%) and diffuse (40/59, 68%) non- NF2 -SWN. A germline genetic study of the NF2 , LZTR1 , and SMARCB1 genes was performed in 38 patients (64%) and demonstrated a LZTR1 gene variant in 19 cases (50%). The patients were operated from 103 peripheral nerve tumors, mainly located in major nerves (n = 67, 65%) compared with subcutaneous (n = 17, 16%) and intramuscular (n = 17, 16%) cases. Most tumors were classical discrete tumors (n = 88, 85%), while multinodular cases represented only 15% (n = 15) of cases. Pathological analysis confirmed the diagnosis of schwannoma except 2 cases of hybrid neurofibroma/schwannoma tumors. A complete resection was performed in 89% of cases with a complete relief of preoperative pain in 87% of cases. Postoperative motor and sensory deficits were encountered in 8 (8%) and 14 (14%) cases, respectively. Multinodular schwannomas were characterized by a decreased rate of complete pain relief (64% vs 90%, P = .007) and an increased rate of postoperative motor deficit (3% vs 35%, P < .001) compared with discrete tumors.

CONCLUSION

Nerve-sparing surgery using intraoperative neuro-monitoring remains effective in treating pain of non- NF2 -SWN-associated peripheral nerve schwannomas, with the notable exception of multinodular tumors, also characterized by an increased rate of postoperative motor deficits.