Stereotactic radiosurgery for arteriovenous malformations located in deep critical regions

Radiosurgery is widely used to treat deep eloquent arteriovenous malformations (AVMs).

To evaluate how anatomic location, AVM size, and treatment parameters define outcome.

Retrospective analysis of 356 thalamic/basal ganglia and 160 brainstem AVMs treated with gamma knife radiosurgery.

Median 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.

Deep 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.