Traumatic aneurysm of the middle meningeal artery presenting as delayed onset of acute subdural hematoma.

A case is presented in which recurrence of acute subdural hematoma developed 29 days after head trauma. An emergency craniotomy was complicated by intraoperative profuse bleeding, which was caused by the rupture of a large false aneurysm of the middle meningeal artery. A pitfall in the surgical treatment of this rare lesion is discussed.