Risk factors for recurrence of surgically treated conventional spinal schwannomas: Analysis of 169 patients from a multicenter international database

Study Design. A retrospective analysis of 169 adult patients operated for a conventional spinal schwannoma from the AOSpine Multicenter Primary Spinal Tumors Database. Objective. The aim of this study is to identify risk factors for local recurrence of conventional spinal schwannoma in patients who had surgery. Summary of Background Data. Schwannomas account for up to 30% of all adult spinal tumors. Total resection is the gold standard for patients with sensory or motor deficits. Local recurrence is reported to be approximately 5% and usually occurs several years after surgery. Methods.. Rates and time of local recurrence of spinal schwannoma were quantified. Predictive value of various clinical factors was assessed, including age, gender, tumor size, affected spinal segment, and type of surgery. Descriptive statistics and univariate regression analyses were performed. Results. Nine (5.32%) out the 169 patients in this study experienced local recurrence approximately 1.7 years postoperatively. Univariate analyses revealed that recurrence tended to occur more often in younger patients (39.33±14.58 versus 47.01±15.29 years) and in the lumbar segment (55.56%), although this did not reach significance [hazard ratio (HR) 0.96, P=0.127; and P=0.195, respectively]. Recurrence also arose in the cervical and sacral spine (22.22%, respectively) but not in the thoracic area. Tumors were significantly larger in patients with recurrence (6.97±4.66cm versus 3.81±3.34cm), with extent in the cranial caudal direction posing the greatest hazard (HR=1.321, P=0.002). The location of the tumor, whether epidural, intradural, or both (P=0.246), was not significantly related to recurrence. Regarding surgical technique, over 4 times as many patients who underwent intralesional resection experienced a recurrence proportionally to patients who underwent en bloc resection (HR=4.178, P=0.033). Conclusion. The pre-operative size of the conventional spinal schwannoma and intralesional resection are the main risk factors for local postoperative recurrence.