Gamma Knife Radiosurgery for the Management of Vestibular Schwannomas in Neurofibromatosis Type 2 Patients: Tumor Control and Hearing Preservation

Background: Gamma knife radiosurgery GKS for the treatment of the patients with Neurofibromatosis type 2 (NF 2) is used for many years to achieve better tumor control, and to avoid postoperative neurological deficits. Objective: This study aimed at exploring the effect of GKS on the control rate, factors affecting such control, neurological morbidity, and the hearing preservation with such management. Patients and Methods: Between February 2002 and October 2012, seventy-nine patients with vestibular schwannomas associated with NF 2 were treated by gamma knife radiosurgery at our center. Fifty-five patients harboring 91 tumors were available for follow up for a minimum of 12 months after treatment. The follow up duration ranged from 12 to 126 months (median 40 months). The mean age was 26.8 years (range 9-56 years). The median target volume was 2.7 cc (range 0.1 to 27.5 cc). The median marginal dose was 12 Gy (range 8 to 13 Gy), with a median isodose of 50% (range 40-95%), and a median percent coverage of 94% (range 77-100%). Results: Regarding the overall radiological response, the tumor control rate was 89%. Progression free survival at 3, 5, and 10 years were (99%, 91.8%, and 42.9%). The hearing preservation rate was 60%. The actuarial hearing preservation rates were 79.8%, 67.5% and 50.6% at 3, 5 and 7 years, respectively. Better tumor control correlated with older age, smaller lesion size and follow up duration. Hearing preservation correlated with younger age, smaller lesions and hearing grade. Edema developed in only four lesions (4.4%). Three patients complained of facial palsy, which was temporary and resolved after medical treatment in less than a year. Conclusion: Gamma knife radiosurgery for NF 2 patients is a safe and effective treatment modality that can achieve excellent tumor control with preserved hearing and low risk of neurological morbidity.