Tight Sylvian Cisterns Associated With Hyperdense Areas Mimicking Subarachnoid Hemorrhage on Computed Tomography. Four Case Reports.

Abstract

Four patients with supratentorial mass lesions (two chronic subdural hematomas, one acute epidural hematoma, and one acute subdural hematoma) showed hyperdense sylvian cisterns on computed tomography (CT). Association of subarachnoid hemorrhage was suspected initially, but was excluded by intraoperative observation or postoperative lumbar puncture. CT showed disappearance of the hyperdense areas just after evacuation of the mass lesions. The hyperdense areas are probably a result of the partial volume phenomenon or concentrations of calcium deposits rather than abnormally high hematocrit levels, which were not found in these patients.

Bilateral chronic subdural hematoma presenting with pseudo-subarachnoid hemorrhage sign on computed tomography

“…Pseudo-SAH is a false-positive sign whereby cisterns are demonstrated as high-density areas on CT, mimicking SAH. Pseudo-SAH has been reported in patients with chronic subdural hematoma (CSDH), [1][2][3][4] acute subdural hematoma, [2] acute epidural hematoma, [2] postresuscitation encephalopathy, [5,6] intracranial hypotension, [7] and chronic hypoxemia. [8] We encountered a patient with bilateral CSDHs whose CT showed high-density areas in the bilateral Sylvian fissures and a mesencephalic cistern mimicking SAH.…”