Conservative Management of Vestibular Schwannoma: Expectations Based on the Length of the Observation Period

Objective: Evaluate long-term prevalence of tumor growth and need for further treatment in patients with a vestibular schwannoma treated with conservative management. Study Design: Retrospective chart review. Setting: Private neurotologic tertiary referral center. Patients: Vestibular schwannoma patients undergoing conservative management and previously studied (N = 114). Mean time to last magnetic resonance imaging was 4.8 years and to last follow-up was 6.4 years (maximum, 18.5 yr). Intervention: Serial gadolinium-enhanced magnetic resonance imaging with size measurement. Main Outcome Measures: Change in maximum tumor dimension of 2 mm or higher (growth), further treatment, audiologic measures-pure-tone average, word recognition, AAO-HNS (American Academy of Otolaryngology-Head and Neck Surgery) hearing class. Results: Thirty-eight percent of tumors demonstrated growth; an average of 6.5 mm (SD, 3.8) at a mean rate of 3.1 mm per year. Of patients with no growth at 1 year or less, 20% grew by last follow-up. Overall, 31% had further treatment after a mean of 3.8 years (SD, 3.5; maximum, 18.5 yr). Of those followed for 5 to 10 years, 18% eventually had further treatment. Only 56% of growing tumors had further treatment by last follow-up; 14.8% with nongrowing tumors also had further treatment. Pure-tone average declined more in tumors that grew (mean Delta = 28.8 dB) than those that did not (mean Delta = 16.5 dB) (p <= 0.025), but there was no correlation between the amount of change in hearing and in the size of the tumor. Of patients with an initial AAO-HNS hearing Class A, 85.7% retained serviceable hearing. Conclusion: For patients electing an observation approach to treatment of vestibular schwannoma, about 31% may eventually undergo further treatment. Of those followed for 5 to 10 years, 18% eventually had further treatment. However, some patients are followed with radiologic evaluations for many years without necessity for further treatment.