Acute spontaneous subdural hematoma of arterial origin.

Acute spontaneous subdural hematoma of arterial origin is very rare. We have encountered two such cases and verified the arterial origin of the bleeding at operation. Both patients had no history of head trauma and developed progressive neurological deficits, becoming comatose. The source of bleeding was identified as a cortical artery located on the temporal lobe near the Sylvian region. This type of lesion is reviewed in the literature and the etiology is discussed.