Axial magnetic resonance imaging (MRI) of the brain of a 35-year-old male patient hospitalized in the neuro-surgical emergency department following violent headache attacks. The MRI scan shows the presence of a major arteriovenous malformation (AVM), located in the the left parietooccipital region and supplied by the the left posterior and middle cerebral arteries. An AVM is a type of congenital brain vascular malformation that can result in serious disability or death. AVMs can rupture (burst) and lead to bleeding inside the head.