In 2005, the legal case of Terri Schiavo, a Florida woman who had become comatose after suffering massive brain damage following full cardiac arrest in 1990, caught the attention of the world. The highly publicized legal challenges surrounding the case centered on patients’ rights, but the media attention it drew also started a public conversation about what it means to be in a state of coma.
A coma, sometimes called a persistent vegetative state, is a profound or deep state of unconsciousness. A person who is in a state of coma is alive, but unable to move or respond to his or her environment.
He or she loses their thinking abilities but may retain non-thinking body functions, such as breathing and circulation. He or she may move spontaneously, his or her eyes may open in response to external stimuli, or grimace, cry or laugh.
Some individuals in a persistent vegetative state may appear normal, although they are unable to speak or respond to commands, according to the National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health.
The body doesn’t just decide to go into a state of coma. It typically occurs because of some traumatic assault — an underlying medical condition, drug overdose, or as a result to an injury, such as head trauma. Sometimes doctors induce a coma, such as with Arizona Congresswoman Gabrielle Giffords, who was shot in the head in 2011 during an alleged assassination attempt.
A medically induced coma effectively shuts down brain function and gives the brain time to heal without having to expend energy to perform cognitive tasks. This helps reduce swelling and protects the injured part of the brain most at risk when no other treatment has worked.
It's important to note a medically induced coma is not the same thing as sedation. A medically induced coma is a very deep unconscious state, whereas sedation, as used in surgery or in other medical procedures to keep a patient comfortable, is a semi-conscious state with minimal side effects.
Some underlying medical conditions can cause a person to become comatose.