The main risk is intracranial hemorrhage. This risk is difficult to quantify since many patients with asymptomatic AVMs will never come to medical attention. Small AVMs tend to bleed more often than do larger ones, the opposite of<unk>  aneurysms. If a rupture or bleeding incident occurs, the blood may penetrate either into the brain tissue<unk>  hemorrhage) or into the subarachnoid space, which is located between the sheaths (meninges) surrounding the brain (subarachnoid hemorrhage). Bleeding may also extend into the ventricular system (intraventricular hemorrhage).<unk>  hemorrhage appears to be most common. One long-term study (mean follow up greater than 20 years) of over 150 symptomatic AVMs (either presenting with bleeding or seizures) found the risk of<unk>  hemorrhage to be approximately 4% per year, slightly higher than the 2-3% seen in other studies. A simple, rough approximation of a patient's lifetime bleeding risk is 105 - (patient age in years), assuming a 3% bleed risk annually. For example, a healthy 30-year-old patient would have approximately a 75% lifetime risk of at least one bleeding event. Ruptured AVMs are a significant source of morbidity and mortality; post rupture, as many as 29% of patients will die, and only 55% will be able to live independently.
Cerebral arteriovenous malformation
Cavernous venous malformation
Arteriovenous malformation
Chiari malformation
Central nervous system cavernous hemangioma
Meningioma
Glioma
Brain metastasis