Subdural Hematoma without Subarachnoid Hemorrhage Caused by the Rupture of Middle Cerebral Artery Aneurysm.

Pure subdural hematomas caused by a ruptured intracranial aneurysm are extremely rare. We describe the case of a 42-year-old woman who presented with headache without evidence of head trauma. Magnetic resonance angiography and conventional cerebral angiography revealed a ruptured aneurysm at the right middle cerebral artery bifurcation. The patient underwent surgical treatment and had a good outcome without any neurological deficit. The mechanisms and clinical characteristics of this condition are discussed.