Predictors of Vestibular Schwannoma Growth and Clinical Implications

Objective: Vestibular schwannomas exhibit variable and unpredictable patterns of growth. We evaluated the extent to which tumor growth influences the management of these benign tumors, and we explored symptom markers present at diagnosis that may be predictive of tumor growth. Study Design: Retrospective case review. Setting: Tertiary care hospital center. Patients: One hundred eighty patients with unilateral vestibular schwannomas diagnosed between 1997 and 2007 who were initially managed conservatively by serial observation. Intervention(s): Serial observation versus eventual microsurgical or radiosurgical treatment. Main Outcome Measure( s): Tumor growth, defined as a 1 mm/year or greater increase in tumor size. Results: We observed that tumor growth was the most important predictor of a change in treatment strategy from serial observation to microsurgical or radiosurgical treatment. We further noted in multivariate analyses that larger tumor size at diagnosis was associated with higher odds of tumor growth, such that each 1-mm increment in tumor size at presentation increased the odds of growth by 20%. We also found that the symptom marker of tinnitus at diagnosis significantly increased the odds of tumor growth nearly 3-fold. Conclusion: Tumor growth plays a significant role in guiding the management of vestibular schwannomas. Assessment of tumor size at diagnosis and for the presence of tinnitus may allow for risk stratification of patients with newly diagnosed vestibular schwannomas and for a more rational application of the conservative management approach.