The brain is surrounded by three linings, and the outermost is the dura mater. Head trauma can result in bleeding in the space between the dura and the brain. The bleeding normally occurs from injured veins in the dura. As the bleeding continues it causes pressure on the brain resulting in the symptoms and damage to the brain. Bleeding can be recognized immediately, an acute subdural, or many weeks after the initial injury, a chronic subdural. Symptoms can vary from complete paralysis and coma to mild alterations in behavior. This disorder is most commonly found between the ages of 50-70 and any disorder that prevents normal blood clotting increases the risk of this disorder.