Pseudo-subarachnoid hemorrhage in a patient with acute cerebellar infarction

Hyperdensity in the basal cisterns on computed tomography (CT) brain scan is a diagnostic feature in subarachnoid hemorrhage. However, false enhancement of the subarachnoid space on CT scan may be seen in diffuse neurological conditions with acute presentation. This is the first reported case of a 'focal lesion' (acute cerebellar infarct) producing a 'pseudo-subarachnoid hemorrhage' secondary to increased intracranial pressure.

A 42-year-old man presented with acute onset of left hemiataxia and neck pain. CT brain scan showed a left cerebellar infarct. During the admission, he had sudden onset of altered sensorium, and an emergency CT scan showed diffuse cerebral edema and hyperdensity of the basal cisterns. The patient then developed sudden cardiac arrest and all resuscitative measures failed. Autopsy showed no evidence of subarachnoid hemorrhage.

Pseudo-subarachnoid hemorrhage is a rare clinical entity. It should be considered as a possibility in the evaluation and management of patients presenting acutely with CT brain scan showing hyperdensity of the basal cisterns and vascular imaging revealing absence of any aneurysm or vascular malformation.