Predicting Extent of Microsurgical Resection of Sporadic Vestibular Schwannoma.

Abstract

Develop a predictive model for incomplete microsurgical resection of sporadic vestibular schwannoma (VS). Historical cohort. Tertiary referral center. Patients with sporadic VS. Microsurgery with preoperative intent of gross total resection. Patient and tumor characteristics that influence extent of resection. Among 603 patients, 101 (17%) had intracanalicular tumors and 502 (83%) had tumors with cerebellopontine angle (CPA) extension. For patients with CPA tumors, 331 (66%) underwent gross total resection and 171 (34%) underwent near-total or subtotal resection (NTR-STR). Multivariable modeling identified older age at surgery, larger linear tumor size, and absence of a fundal fluid cap as predictive of NTR-STR ( p < 0.001). From this model, one can estimate that a 20-year-old with a tumor that has less than 10 mm of CPA extension and a present fundal fluid cap has a predicted probability of NTR-STR of 0.01 (or 1%), whereas a 70-year-old with a tumor that has 30 mm or greater CPA extension and absence of a fundal fluid cap has a predicted probability of NTR-STR of 0.91 (or 91%). Among the 171 patients who underwent NTR-STR, 24 required secondary treatment at the time of last follow-up. The primary predictors of incomplete microsurgical resection of VS include older age at surgery, larger linear tumor size, and absence of a fundal fluid cap. These factors can be used to estimate the likelihood of NTR-STR, aiding in preoperative discussions regarding future surveillance and potential need of secondary treatment, as well as shared clinical decision making.