The yearly risk of hemorrhage associated with AVMs is 2-3%, with a mortality rate of 10% for the initial bleed and increasing up to 20% for subsequent bleeds. Neurological deficits occur approximately 50% of the time with each bleed, mainly due to mass effect. Patients with AVMs are at increased risk for cerebral aneurysms, specifically located on the arteries feeding the AVM. Treatment options include endovascular techniques as well as surgical resection. Endovascular treatment options are often used as surgical adjuncts. Embolization can be used pre-operatively to shrink the AVM, reduce intra-operative bleeding, and decrease surgical time. Embolization is also important in patients with either small AVMs, arterial feeders, or AVMs with rebleeding after surgery. The rebleeding rate of a ruptured AVM is 6% for the first year, and 2-4% each year thereafter, but there can be an “angiographic cure” with embolization of any remnant arterial feeders. Treatment itself is not completely benign, with one study indicating that the overall rate of new neurological deficits after surgical resection was 32% in patients with unruptured AVMs. Arteriovenous malformations are graded based on the Spetzler-Martin grading system, which predicts surgical resectability based on size of AVM, pattern of venous drainage, and eloquence of adjacent brain. High grade AVMs are more difficult to resect, and, therefore, may result in neurological deficits due to the surgery itself.