Abstract
Full consciousness is characterized by wakefulness, focused attention and normal cognitive function. A coma patient by definition has closed eyes, does not respond to commands and does not talk. If a patient is comatose, the cause needs to be found as soon as possible. Coma can be caused by damage to brain tissue (structural coma) or metabolic dysregulation. It can be due to a brain herniation syndrome. Herniation syndromes obey certain laws. Altered consciousness due to a metabolic disorder does not usually have a sudden onset. The prognosis for postanoxic coma depends on how long the patient has been unconscious. If there is no obvious cause of the coma, the possibility of non-convulsive status epilepticus should always be considered. Decrease in the level of consciousness without loss of consciousness is often indicative of a diffuse cortical disorder. Delirium patients have impaired attention to and perception of their surroundings. Frontal injuries can produce a state of ‘lack of will’ (abulia). Patients in a vegetative state have no contact with their surroundings. Cerebral death is a diagnosis that can only be made if strict conditions are met.