Gamma Knife Radiosurgery for Anterior Clinoid Process Meningiomas: A Series of 61 Consecutive Patients

Abstract

OBJECTIVE: Gamma Knife radiosurgery (GKRS) outcomes for anterior clinoid process (ACP) meningiomas have not been specifically reported within any meningioma series. We present the initial and largest series in the literature that describes the presenting features, radiosurgery parameters, and radiologic and long-term clinical outcomes for 61 patients with ACP meningiomas treated with GKRS. METHODS: Medical records were reviewed for 61 consecutive patients at a single center who underwent GKRS for ACP meningioma between 2008 and 2016. RESULTS: Of 61 patients with ACP meningiomas, 49 (80\%) were treated with GKRS as primary treatment, and 12 (20\%) were treated with GKRS as an adjuvant therapy. Before GKRS, 29 patients presented with visual impairment and 50 patients presented with headache. Median patient age was 54.9 years. Median tumor volume was 3.2 cm(3), and median margin dose was 12.0 Gy. The median radiologic follow-up time after GKRS was 75 months. During follow-up, tumor volume regressed in 37 cases (61\%) and remained unchanged in 24 cases (39\%). None of the patients experienced tumor volume progression. Tumor volume <3 cm(3) was an independent predictor of tumor volume regression after GKRS (univariate analysis, P = 0.047

multivariate analysis, P = 0.049). Of 29 patients who presented with visual impairment, 16 (55\%) improved after GKRS. None of the 61 patients developed new neurologic deficits after GKRS. CONCLUSIONS: GKRS provides a high rate of tumor volume control for ACP meningiomas as well as a low complication rate. Excellent tumor volume control was associated with smaller tumor size only.