coma
a state of deep unconsciousness from which a person cannot be roused. There may be an absence of pupillary and corneal reflexes and no movements of withdrawal when painful stimuli are applied. It may be accompanied by deep, noisy breathing and strong heart action, and is caused by a number of conditions. These include apoplexy, high fever, brain injury, diabetes mellitus, carbon monoxide poisoning and drug overdose. A comatose person may eventually die but can recover, depending on the nature of the coma and its cause.
A coma is a deep state of unconsciousness. An individual in a coma is alive but unable to move or respond to his or her environment. Coma may occur as a complication of an underlying illness, or as a result of injuries, such as brain injury.
A coma rarely lasts more than 2 to 4 weeks. The outcome for coma depends on the cause, severity, and site of the damage. People may come out of a coma with physical, intellectual, and psychological problems. Some people may remain in a coma for years or even decades. For those people, the most common cause of death is infection, such as pneumonia.
NIH: National Institute of Neurological Disorders and Stroke
coma