The CT pattern of a ruptured P3 posterior cerebral artery aneurysm.

A 48-year-old male smoker with a history of significant alcohol use developed thunderclap headache during sexual intercourse. On neurological exam, he was confused and agitated with a Glasgow Coma Score of 11 (E3, M6, V2). Computed tomography (CT) of the brain revealed diffuse subarachnoid hemorrhage (SAH) with blood notably present in the quadrigeminal and supracerebellar cisterns (Figure 1). Cerebral angiogram demonstrated a distal P3 posterior cerebral artery (PCA) aneurysm (Figure 2). The PCA aneurysm was successfully treated with endovascular coil occlusion.