Vestibular schwannoma radiosurgery after previous surgical resection or stereotactic radiosurgery

Objective: To evaluate radiosurgery outcomes in vestibular schwannoma (VS) patients who have undergone prior tumor treatment. Methods: Retrospective review of 55 consecutive VS patients having radiosurgery for recurrent (n = 22) or residual tumors (n = 33) after prior microsurgery. The median time from the patients' last surgery was 60 months (range, 2-463). Forty-seven patients (84%) had enlarging tumors at the time of radiosurgery. Results: The majority of patients (67%) had facial weakness prior to radiosurgery; 52 patients (95%) were deaf. The median tumor volume was 3.0 cm3 (range, 0.1-18.1). The median tumor margin dose was 14 Gy (range, 12-20). Fifty patients had follow-up available at a median of 47 months (range, 5-148) after radiosurgery. The tumor control rate was 94%. Trigeminal deficits developed in 2 patients (4%). Four of 42 patients (10%) with normal to moderate facial nerve function before radiosurgery developed facial weakness. Three of these 4 patients received a tumor margin dose of 20 Gy. Conclusion: Radiosurgery is effective for patients with recurrent or residual VSs after prior surgical removal. Repeat radiosurgery after initial failed radiosurgery can be considered, but little information is available to evaluate this approach. Staged treatment involving subtotal tumor removal and radiosurgery is an option for patients with large VSs to facilitate both cranial nerve preservation and long-term tumor control.