Stereotactic radiosurgery of cerebral arteriovenous malformations: long-term follow-up in 164 patients of a single institution.

This retrospective study aimed to investigate long-term outcome in patients with arteriovenous malformations (AVM) treated with stereotactic radiosurgery (SRS). Between 1998 and 2008, 164 patients with AVM received SRS. Median age was 36 years (range 7-69 years). Before SRS, 39 % of the patients experienced haemorrhage and 27 % suffered from epileptic seizures, whereas 43 % received previously embolization, 7.9 % neurosurgery and 1.8 % proton radiotherapy. Primary SRS was applied in 51.2 % of the patients. Median single dose was 19 Gy (80 % isodose; range 18-20 Gy) and median target volume was 4 cc (range 0.1-24.4). Median follow-up was 93 months (range 12-140). Complete obliteration (CO) was observed in 100 (61 %) patients at a median time of 29 months (range 6.1-88.5). The 3 and 5-year CO rates were 61 and 88 %, respectively. In multivariate analysis, radiation dose ≥ 19 Gy (p = 0.044) and target volume <4 cc (p = 0.015) were associated with significantly higher rates of CO. Intracranial haemorrhage was seen in nine patients (5.5 %) after SRS, whereas three patients (1.8 %) died as a consequence of bleeding. The annual bleeding risk was 1.3 % after 1 year and 1.3 % after 2 years, respectively. In multivariate analysis, only target volume >4 cm(3) (p = 0.031) and Spetzler-Martin grade III-V (p = 0.046) retained significance for increased risk of intracranial bleeding. After SRS an improvement in epileptic episodes, headaches and motor-sensory deficits was found in 8.5, 14 and 15 % of patients, respectively. Our long-term follow-up data show that SRS is an effective treatment option in AVM with low toxicity and bleeding risk, depending on AVM size and Spetzler-Martin grade. An improvement of neurologic symptoms is achievable.