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Hemorrhage and accumulation of blood in the subdural space associated with the acute onset of neurologic deficits, usually following CRANIOCEREBRAL TRAUMA. Hematoma formation occurs most frequently over the lateral and superior aspects of a cerebral hemisphere, but may also occur in the posterior fossa and spinal canal. Clinical manifestations may include hemiparesis, SEIZURES, third nerve palsy (see OCULOMOTOR NERVE DISEASES), mental status changes, and COMA. (From Adams et al., Principles of Neurology, 6th ed, p886)