RADIOLOGY: HEAD: Case# 33060: SUBARACHNOID HEMORRHAGE (LARGE). There is extensive acute subarachnoid hemorrhage slightly more severe on the left and in the suprasellar cistern. Low attenuation present in the left parietal convexity consistent with ischemic change of indeterminate age. There is no hydrocephalus. Small amount of hemorrhage present in the fourth ventricle. Regarding etiology the most likely probability based on CT findings is ruptured left posterior communicating artery aneurysm.