epidural hematoma
May be intracranial (in the skull) or in the spine.
  1. In this type of hematoma, a blood vessel outside the brain, usually in a groove on the inner side of the skull bursts. Because it is usually an artery that is involved, blood begins to rapidly accumulate between the inside of the skull and the strong outer covering of the brain (called dura mater). The pressure of the blood clot strips the dura mater away from its normal firm attachment to the inside of the skull. The blood clot then can press on the brain, causing injury, and if not diagnosed and treated promptly, may be fatal.
  2. In spinal epidural hematoma, the bleeding into the space between the spinal column and the outer lining of the spinal cord may be a result of trauma, bleeding disorders, underlying vascular abnormalities or may occur spontaneously.