Accumulation of blood in the cranial epidural space due to rupture of the middle meningeal artery or rarely the meningeal vein, often associated with a temporal or parietal bone fracture. The hematoma tends to expand rapidly, compressing the dura and underlying brain. Clinical features include the acute or subacute onset of HEADACHE; VOMITING; alterations of mentation, and HEMIPARESIS. The natural history of the process is progression to COMA and eventually DEATH. (Adams et al., Principles of Neurology, 6th ed, p885).