Whether gamma knife radiosurgery is really necessary for treatment of patients with vestibular schwannomas.

The present study was directed at establishing the role of Gamma Knife radiosurgery (GKS) in the management of vestibular schwannomas (VSs), particularly those that are large. We analyzed a consecutive series of 222 tumors operated on by a single neurosurgeon (T. Hori) at Tottori University (1981-1998) and Tokyo Women's Medical University (1998-2011). The surgical strategy for sporadic unilateral VSs was typically total or nearly total tumor removal with facial nerve preservation, whereas in some cases of neurofibromatosis type 2 intentional subtotal resection was performed. In all, 15 patients (8.6 %) in the series underwent GKS before (4 cases), after (9 cases), or before and after (2 cases) tumor removal. Overall, 211 patients (95 %) were cured by microsurgery alone. Of note, six patients underwent primary radiosurgery but were operated later on for regrowth of the neoplasm, and in four of them near-total resection led to good long-term tumor control. GKS was required in only 5 % of cases for management of residual VS or, more frequently, its regrowth. Radiosurgery resulted in volume reduction in one-third of these tumors. In other cases it stabilized the lesion, preventing further progression. Thus, GKS is considered a reasonable management option for residual or regrowing small VSs to obtain maximum tumor growth control after initially attempting complete surgical removal.