Ten-Year Outcomes of Gamma Knife Radiosurgery for Vestibular Schwannomas: Single-Center Study

Introduction: Gamma knife (RS) has now been accepted as a treatment option for Vestibular Schwannoma (VS), either in combination with surgery or alone since last past two decades. The ultimate aim has therefore been to achieve maximum tumor control along with preserved neurological functioning. There have been only few reports evaluating the long-term treatment outcome of RS for VS; all but two limited to 5-year follow-up.

Objective: To present the 10-year follow-up data on patients treated with RS for VS. We also wanted to assess the factors responsible for failure of RS and worsening neurology.

Results: A total of 73 patients treated with Gamma Knife from the year 1997 to 2005 and available for follow-up were ambispectively reviewed. Majority of them were treated with primary GK (73%) and most of them were Koo’s grade 3 (12%) and 4 (56%). Ten-year tumor control rates with Gamma Knife radiosurgery (RS) were at 81 to 100%. The tumor marginal dose was 12 Gy and revealed 10-year tumor control rates of 89%, hearing preservation rates of 50%, facial nerve preservation rates of 96% and trigeminal preservation rates of 93%. The tumor control rate was affected by the nature of the tumor, solid vs cystic. The neurology of patient’s post RS largely depended on the Koos grading of the tumor. No secondary malignancy or long-term radiation adverse effects were observed in these patients.

Conclusion: RS remains a viable option for treatment of VS, with a good tumor control rate even on long-term follow-up. It may be used as a primary modality of treatment for small to medium sized lesions. However, for larger Koos grade tumor, a careful patient selection is required because of the chances of worsening cranial nerve functioning.

No conflict of interest has been declared by the author(s).