Significance of contrast enhancement in cranial computerized tomography after subarachnoid hemorrhage

Eighty patients with subarachnoid hemorrhage underwent computerized tomography (CT) scanning before and after administration of Conray contrast medium. Abnormal enhancement was seen in visual evaluation of the CT scans in 26 cases, in the regions bordering the subarachnoid spaces. Abnormal enhancement was associated with a poor clinical condition, angiographic spasm, and a poor outcome. Measurements of absorption values in the thalamus revealed significant increases in density after contrast enhancement in those patients whose scans showed abnormal enhancement in the regions bordering the subarachnoid spaces on visual evaluation. The authors suggest that the abnormal enhancement is parenchymal, in the gyri, and is not "subarachnoid." They suggest that it is due to gyral hyperemia or extravasation of contrast material into the cortex resulting from breakdown of the blood-brain barrier, or a combination of both factors.