Coma is a profound or deep state of unconsciousness. An individual in a state of 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 head trauma.
A coma rarely lasts more than 2 to 4 weeks. People in such a state have lost their thinking abilities and awareness of their surroundings, but retain non-cognitive function and normal sleep patterns. Sadly, some people will never progress beyond very basic responses, but many recover full awareness. Recovery usually occurs gradually, with some acquiring more and more ability to respond.
Even though those in a persistent vegetative state lose their higher brain functions, other key functions such as breathing and circulation may remain. Spontaneous movements may occur, and the eyes may open in response to external stimuli.
Although peoples in a persistent vegetative state may appear to be normal, they can’t speak and are unable to respond to commands.
The outcome for coma and persistent vegetative state depends on the cause, severity, and site of neurological damage. Individuals may emerge from coma with a combination of physical, intellectual, and psychological difficulties that need special attention..
Recovery from a coma requires close medical supervision.. Some patients may regain a degree of awareness after persistent vegetative state. Others may remain in that state for years or even decades. The most common cause of death for someone in a persistent vegetative state is infection, such as pneumonia.