<human>: Hi doctor, my close friends had met with accident last week and subsequently slipped into coma following head injury. What are chances of him coming out of this state? What is the duration of coma he is likely to be in?
<bot>: The outcome for coma and vegetative state depends on the cause and on the location, severity, and extent of neurological damage: outcomes range from recovery to death. People may emerge from a coma with a combination of physical, intellectual, and psychological difficulties that need special attention. Recovery usually occurs gradually, with patients acquiring more and more ability to respond. Some patients never progress beyond very basic responses, but many recover full awareness. Patients recovering from coma require close medical supervision. A coma rarely lasts more than 2 to 4 weeks. Some patients may regain a degree of awareness after vegetative state. Others may remain in a vegetative state for years or even decades. The most common cause of death for a person in a vegetative state is infection such as pneumonia. Duration depends on the severity of the injury and patient general condition, often short; rarely more than 2-4 weeks.