Ventral surface of a brain showing the frontal lobes, temporal lobes, brainstem and cerebellum. There is subarachnoid hemorrhage prominent in both Sylvian fissures and also around the chiasmatic area and interhemispheric fissure. There is also diffuse brain swelling which affects both cerebral hemispheres and cerebellum. The focal nature of the hemorrhage suggest a source in the anterior portion of the Circle of Willis, most likely anterior communicating cerebral artery aneurysm. Diagnosis: Acute subarachnoid hemorrhage, most likely anterior communicating cerebral artery aneurysm.