Delayed Rebleeding of Cerebral Aneurysm Misdiagnosed as Traumatic Subarachnoid Hemorrhage.

An intracranial saccular aneurysm is uncommonly diagnosed in a patient with closed head trauma. We herein present a patient with delayed rebleeding of a cerebral aneurysm misdiagnosed as traumatic subarachnoid hemorrhage (SAH). A 26-year-old female visited our emergency department because of headache after a motorcycle accident. Brain computed tomography (CT) showed a right-side dominant SAH in Sylvian fissure. Although traumatic SAH was strongly suggested because of the history of head trauma, we performed a CT angiogram to exclude any vascular abnormalities. The CT angiogram showed no vascular abnormality. She was discharged after conservative treatment. One day after discharge, she returned to the emergency department because of mental deterioration. Brain CT showed diffuse SAH, which was dominant in the right Sylvian fissure. The CT angiogram revealed a right middle cerebral artery bifurcation aneurysm. During operation, a non-traumatic true saccular aneurysm was found. The patient recovered fully after successful clipping of the aneurysm and was discharged without neurologic deficit. Normal findings on a CT angiogram do not always exclude aneurysmal SAH. Follow-up vascular study should be considered in trauma patients who are highly suspicious of aneurysmal rupture.