Coma and Persistent Vegetative State
A 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 persistent vegetative state (commonly, but incorrectly, referred to as "brain-death") sometimes follows a coma. Individuals in such a state have lost their thinking abilities and awareness of their surroundings, but retain non-cognitive function and normal sleep patterns. Even though those in a persistent vegetative state lose their higher brain functions, other key functions such as breathing and circulation remain relatively intact. Spontaneous movements may occur, and the eyes may open in response to external stimuli. They may even occasionally grimace, cry, or laugh. Although individuals in a persistent vegetative state may appear somewhat normal, they do not speak and they are unable to respond to commands.
Once an individual is out of immediate danger, the medical care team focuses on preventing infections and maintaining a healthy physical state. This will often include preventing pneumonia and bedsores and providing balanced nutrition. Physical therapy may also be used to prevent contractures (permanent muscular contractions) and deformities of the bones, joints, and muscles that would limit recovery for those who emerge from coma.
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 usually occurs gradually, with some acquiring more and more ability to respond. Some individuals never progress beyond very basic responses, but many recover full awareness. Individuals 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 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.
Prepared by the National Institutes of Health