Middle Cerebral Artery Arrow Sign

A 54-year-old woman presented to the emergency department with sudden onset severe headache, nausea and vomiting upon waking that morning. On examination, she was alert and oriented, with a mild right facial droop and a right upper extremity pronator drift. A non-contrast computed tomography (CT) of the head revealed diffuse subarachnoid blood, with a prominent triangular focus projecting into the left Sylvian fissure (Figure).