Neuroimaging of hemorrhage and vascular malformations.

Nontraumatic spontaneous intracranial hemorrhage occurs most commonly into the subarachnoid space and brain parenchyma, in contrast to subdural and epidural hematomas that are usually traumatic. The differential diagnosis of nontraumatic subarachnoid hemorrhage includes intracranial aneurysm rupture and vascular malformations, both of which may be investigated noninvasively with computed tomography and magnetic resonance imaging. An isolated intraparenchymal hematoma may be caused by hypertensive vasculopathy, amyloid angiopathy, vascular malformations, or by primary or secondary neoplasms. Knowledge of the appearance of intracerebral vascular malformations will help clinicians request appropriate further imaging and direct treatment.