ARTERIOVENOUS MALFORMATIONS AVM Incidence

ARTERIOVENOUS MALFORMATIONS AVM Incidence Since only 12% of AVMs cause symptoms, the incidence of AVM in the United States is not fully known. The incidence is thought to be around 1 per 100,000, equaling 300,000 cases. As technology advances and early detection increases, these numbers may rise. The average age of AVM diagnosis is 33 years, with 64% being identified before age 40 (Greenburg, 2001). Untreated AVMs represent a threat to patients, because they have an annual major hemorrhage rate of anywhere from 2% to 17% (Bollet et al., 2004). AVMs account for 8.6% of all subarachnoid hemorrhages (SAHs) (Hickey & Buckley, 2003). The average rate of hemorrhage increases by 3% annually in unruptured vessels. This risk increases to 6% to 18% the first year after hemorrhage but has been shown to decrease to 4% annually thereafter (Greenburg, 2001; Greene et al., 1995).Although ruptured AVMs cause only 2% of all hemorrhagic strokes, the results can be devastating (Choi & Mohr, 2005). Lethal results from intracerebral AVM hemorrhages have been reported in as many as 29% of cases (Bollet et al.). Fortunately, thanks to advances in technology, twice as many AVMs are being identified before rupture than in years past (Choi & Mohr).