The "hypernormal" CT scan in dementia: bilateral isodense subdural hematomas.

Enlarged ventricles and prominent sulci are common findings on computed tomography (CT) in elderly demented patients. Three such patients were found to have small, symmetric ventricles and minimal sulci on tomography; these CT scans were considered "hypernormal" for the patients' ages and clinical syndromes. Bilateral isodense subdural hematomas were subsequently diagnosed by isotope brain scans in two cases and by angiography in the third. A "hypernormal" CT scan in an elderly demented patient suggests the possibility of bilateral isodense subdural hematomas, and requires further evaluation with isotope brain scan and, if necessary, angiography.