• Gábor Nagy, Ottó Major, Jeremy G Rowe, Matthias W R Radatz, Timothy J Hodgson, Stuart C Coley, and Andras A Kemeny.
• The National Centre for Stereotactic Radiosurgery, Royal Hallamshire Hospital, Sheffield, United Kingdom.
• Neurosurgery. 2012 Jun 1;70(6):1458-69; discussion 1469-71.

BackgroundRadiosurgery is widely used to treat deep eloquent arteriovenous malformations (AVMs).ObjectiveTo evaluate how anatomic location, AVM size, and treatment parameters define outcome.MethodsRetrospective analysis of 356 thalamic/basal ganglia and 160 brainstem AVMs treated with gamma knife radiosurgery.ResultsMedian volume was 2 cm (range, 0.02-50) for supratentorial and 0.5 cm (range, 0.01-40) for brainstem AVMs; the marginal treatment doses were 17.5 to 25 Gy. After single treatment, obliteration was achieved in 65% of the brainstem, in 69% of the supratentorial, and 40% of the peritectal AVMs. Obliteration of lesions <4 cm was better in the brainstem (70%) and in the supratentorium (80%), but not in the peritectal region (40%). Complications were rare (6%-15%) and mild (≤ modified Rankin scale [MRS] 2). Rebleed rate increased with size, but was not higher than before treatment. AVMs >4 cm in the brainstem were treated with unacceptable morbidity and low cure rate. Obliteration of large supratentorial AVMs was 65% to 47% with more complications ≥ MRS3. Repeat radiosurgical treatment led to obliteration in 66% of the cases with minor morbidity.ConclusionDeep eloquent AVMs <4 cm can be treated safely and effectively with radiosurgery. Obliteration of peritectal AVMs is significantly lower after a single treatment. However, morbidity is low, and repeat treatment leads to good obliteration. Radiosurgical treatment >4 cm in the brainstem is not recommended. Supratentorial deep AVMs >8 cm can be treated with radiosurgery with higher risk and lower obliteration rate. However, these lesions are difficult to treat with other treatment modalities, and a 50% success rate makes radiosurgery a good alternative even in this challenging group.

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