A Retrospective Analysis of the Role of Single-Session Gamma Knife Stereotactic Radiosurgery in Sporadic Vestibular Schwannomas with Tumor Volumes Greater Than 10 cm3: Is It Worth Stretching the Boundaries?

Objective: To evaluate the role of single-session Gamma Knife stereotactic radiosurgery (GK-SRS) in the treatment of vestibular schwannomas (VSs) with volumes of greater 10 cm3. Methods: A retrospective analysis was performed of 103 patients treated with single-session GK-SRS between 1993 and 2011 with a mean follow-up of 6.2 years ± 4.4 SD. Treatment, clinical and outcome details were recorded and assessed. Results: Eighty-one (78.6%) patients achieved radiological control with slow progression in a further 5 (4.9%) patients, who did not require further treatment. Linear measurements did not correlate well with volume, which can predict outcome following treatment more precisely. 2.9% of patients developed a new facial paresis, 5.8% trigeminal numbness and 2.9% facial pain. In all, 26 (25.2%) patients who were tested preserved some level of hearing following treatment. Conclusions: The overall radiological control rate in this study was 78.6%, while tumor volumes less than 20 cm3 can be safely treated with single-stage GK-SRS with an expected control rate of 83.2% without unacceptable morbidity rates. GK-SRS can be utilized as a first-line treatment option in patients with large-volume VSs especially in whom surgery is unattractive.