Long-Term Outcomes after Gamma Knife Surgery for Cavernous Sinus Meningiomas

Introduction: Meningiomas in the cavernous sinus confer high risk during resection due to proximity of cranial nerves and vascular structures. SRS is a non-invasive management strategy that can be used as a primary or adjuvant modality. However, the long-term outcome of cavernous sinus meningioma (CSM) after stereotactic radiosurgery (SRS) is unknown. The objective of this study is to investigate outcomes at 10 or more years after SRS for CSM patients.

Methods: From 1987 to 2022, 334 CSM patients underwent SRS. Ninety patients (71 female,78.9%) who had a minimum of 10 years of clinical follow-up were included in this analysis. Thirty-seven patients (41.1%) had undergone previous surgical resection, and 2 patients (2.2%) had a history of fractionated radiation therapy. The median tumor volume was 4.8cc (range, 0.02-23.4cc) and the median margin dose was 13 Gy (range,11-20 Gy). The five most prevalent preoperative symptoms were facial numbness (54.4%), diplopia (53.3%), headaches (48.9%), visual disturbance (41.1%), and ptosis (35.6%).

Results: Twenty-seven patients (30.0%) were deceased at the time of the study. Progression free survival rates at 10-, 15-, and 20-years were 88.9%, 65.6%, and 47.8%, respectively. Fifteen patients (16.67%) had local tumor progression at a median time of 10.1 years (range, 4.1-23.2 years). Local tumor control rates at 10-, 15-, and 20-years were 92.2%, 84.4%, and 77.8%, respectively. Ten patients underwent repeated SRS and one patient underwent additional surgical resection. Eighty-six patients had neurological function follow-up at 10 or more years after SRS. In total, 29.1% improved, 52.3% stabilized, and 18.6% worsened. No patients experienced malignant tumor transformation.

Conclusion : We report for the first time the long-term outcome of patients with CSM treated with SRS. This study confirms that at 10 or more years after SRS, most CSM patients had high tumor control and enjoyed excellent quality of life, establishing the long-term effectiveness of SRS for CSM.