Predictors of clinical and structural outcomes after surgery for spinal nerve sheath tumor resection: a retrospective analysis
Authors: Levy Adam S. , Jamshidi Aria M. , Merenzon Martin A. , Levi David J. , Levi Allan D. 
Published: October 2023

OBJECTIVE
Resection of spinal nerve sheath tumors (SNSTs) typically necessitates laminectomy, often with facetectomy, for adequate exposure of tumor. While removal of bone affords a greater operative window and extent of resection, it places the patient at greater risk for spinal instability. Although studies have identified risk factors for fusion at the time of tumor resection, there has yet to be a study assessing long-term stability following SNST resection. In this study, the authors sought to identify preoperative and operative risk factors that predispose to long-term spinal instability and investigate clinical variables associated with greater risk for subsequent fusion in the time following initial SNST resection.

METHODS
An institutional registry of spinal surgeries was queried at a single institution over a 20-year period. Demographic, clinical, and operative variables were recorded retrospectively and investigated for predictive value of several postoperative sequelae.

RESULTS
A total of 122 SNST cases among 112 patients were included. At a mean follow-up time of 27.7 months, patients with a history of neurofibromatosis type 2 (NF2) (p = 0.014) and those who had undergone a laminectomy of ≥ 4 levels at the time of initial SNST resection (p = 0.028) were more likely to present with some degree of structural abnormality or neurological deficit following their initial surgery. The presence of facetectomy, degree of laminectomy, and level of spinal surgery were not found to be predictors of future instability. Ultimately, there was no significant predictor for true spinal instability following index surgery without fusion. A secondary analysis showed that an entirely extradural location (p = 0.044) and facetectomy at index surgery (p = 0.012) were predictive of fusion being performed at the time of tumor resection. Four of the 112 patients required fusion after their index SNST resection, 3 of whom underwent fusion for instability at the level of the index surgery. No variables were identified as predictive for future instrumentation.

CONCLUSIONS
Ultimately, the authors conclude that resection of SNSTs does not always necessitate fusion, and good outcomes can be obtained with motion-preserving techniques and minimizing facetectomy when possible. Patients with a history of NF2 and those with SNSTs that required ≥ 4-level laminectomy were more likely to exhibit some degree of structural abnormality and/or neurological deficit localized to the index level defined as either new or worsening spinal instability and/or new or worsening neurological deficit at last follow-up; however, no variable was found to be predictive of true spinal instability. Furthermore, a complete facetectomy at initial SNST resection and entirely extradural tumor location were noted to be associated with fusion at index surgery. Lastly, the authors were unable to identify a clinical predictor for future instrumentation.