Subarachnoid hemorrhage is caused by the rupture of cerebral blood vessels due to various reasons, allowing blood to flow into the subarachnoid space. Common causes include trauma and rupture of congenital aneurysms. Subarachnoid hemorrhage caused by the rupture of congenital aneurysms typically presents on a CT scan with high-density appearances at the base of the skull in the brain pools, especially widespread columnar high-density appearances in the suprasellar cistern, lateral fissure cistern, anterior interhemispheric fissure, and around the circumferential pool. If the subarachnoid hemorrhage is due to trauma, the abnormalities are more localized, generally appearing in the brain pool or cerebral sulcus on the side of injury with high-density appearances, and may also be accompanied by hematomas within the ventricles or bleeding in other locations.