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DOI: 10.1055/s-0034-1384187
Vestibular Schwannoma Growth Patterns in Long-Term Follow-Up following Stereotactic Radiotherapy
Objective: Stereotactic radio surgery (SRS) is a well-recognized and utilized treatment used mainly for growing or medium-sized vestibular schwannomas (VS). Although, most VS will respond positively to SRS, the expected change in size is unknown, because of the lack in relevant literature. The aim of this study, was to quantify the growth patterns after SRS. Method: A retrospective analysis of patients with VS managed in a tertiary referral center was performed. The computerized radiology imaging system was used to analyze the magnetic resonance imaging (MRI) of all patients who had received SRS. The tumor was measured on axial contrastT1-weighted MRI before, 1year after SRS, and on the most recent scan. All growth rates were calculated. Significant change in size was deemed as a change of greater than 1 mm. Results: In a 15-year period 157 patients with VS were identified. Overall 46 patients with unilateral large or growing VS received SRS;18tumors (39%) had no significant change, 22 (48%) decreased, and 6 (13%) increased in size. Overall there was a mean reduction in size of 0.2 mm/y following SRS. This rate reached 1mm/y when we measured only the tumors that have responded positively to SRS. Conclusion: Our results show a trend for a decrease in tumor size in long-term follow -up for most patients receiving SRS. For those VS that respond positively to SRS, this decrease rate is significantly higher.