Pseudo-Subarachnoid Hemorrhage: A Potential Imaging Pitfall Associated with Hypoxic Encephalopathy

Results The CT images in each patient revealed diffuse hyperdensity in the basal cisterns in an appearance similar to aneurysmal SAH. None of the patients had the typical distribution of nonaneurysmal perimesencephalic-SAH. In two of the patients, the prospective CT interpretation by the radiologist cited true SAH as the etiology of this increased attenuation within the subarachnoid spaces. In the remaining three cases, a pseudo-SAH appearance of the basal cisterns was prospectively suspected. All of the five patients were proven to lack true SAH: three patients underwent an autopsy, one patient had a negative lumbar puncture, and one patient had two normal cerebral arteriograms.