Introduction: Gamma-knife radiosurgery (GKRS) is a well-established modality in the management of inaccessible, recurrent or incompletely resected benign skull base meningiomas close to critical structures. Most series report clinical outcome parameters and complications in 5 years. Reports of longterm tumor control and neurological status are still sparse and limited. We report the presentation, treatment, and longterm outcome after GKRS.

Methods: A retrospective review was undertaken. 135 patients, 54.1% males (n=73) form the cohort. All included patients had a WHO grade I skull base meningioma treated with a single-session GKRS and a minimum of 60 months follow up. Median age was 54 years (19-80). Median tumor volume was 4.7 cm3 (0.5-23). Median margin dose was 15 Gy (7.5-36). The median follow up was 102.5 months (60.1-235.4 months). Patient and tumor characteristics were assessed to determine predictors of new or worsening neurological function and tumor progression following GKRS.

Results: At last follow up, tumor volume control was achieved in 88.1% (n=119), post-GKRS clinical improvement was reported in 61.5% Favorable outcome (both parameters combined) was attained in 60.8% (n=79). Intermittent headaches were reported in 34.8% (n=47), followed by dizziness (15.6%, n=21) and permanent cranial neuropathies (14.8%, n=20). Pre-GKRS KPS was shown to influence tumor progression (p=0.0001) and post-GKRS improvement (p=0.003).

Conclusions: GKRS offers a high and durable rate of tumor control for WHO-I skull base meningiomas, with an acceptably low incidence of neurological deficits. The performance status (KPS) at the time of radiosurgery serves as the most reliable longterm predictor of outcome.

Patient Care: Better longterm outcome helps in decision making and better patient education.

Learning Objectives: In the present study, we reviewed the presenting features, treatment parameters as well as clinical and radiological outcome in patients treated with single-session Gamma Knife radiosurgery (GKRS) for benign WHO-I skull base meningiomas having a minimum follow-up of 60 months.

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