In medicine, a coma (from the Greek koma, meaning deep sleep) is a profound state of unconsciousness, which may result from a variety of conditions including intoxication (drug, alcohol or toxins), metabolic abnormalities (hypoglycemia, hyperglycemia, ketoacidosis, etc.), central nervous system diseases, stroke, head trauma, seizures, and hypoxia. The metabolic abnormalities are the most common causes of coma. Medicine is a branch of health science concerned with restoring and maintaining health. ... Unconsciousness is the absence of consciousness. ... This article or section should include material from drunkenness Intoxication is an impaired mental and physical state caused by ingesting alcoholic beverages or other psychoactive drugs. ... Many drugs are provided in tablet form. ... In general usage, alcohol (from Arabic al-khwl الكحول, or al-ghawl الغول) refers almost always to ethanol, also known as grain alcohol, and often to any beverage that contains ethanol (see alcoholic beverage). ... A toxin, in a scientific context, is a biologically produced substance that causes injury to the health of a living thing on contact or absorption, typically by interacting with biological macromolecules such as enzymes and receptors. ... Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος(metavallo), the Greek word for change), in the most general sense, is the ingestion and breakdown of complex compounds, coupled with the liberation of energy, and the consequent generation of waste... Hypoglycemia is a medical term referring to a pathologic state produced and usually defined by a lower than normal amount of sugar (glucose) in the blood. ... Hyperglycemia is the condition of having an excessive amount of glucose circulating in the blood plasma. ... Ketoacidosis is a type of metabolic acidosis which is caused by high concentrations of keto acids, formed by the deamination of amino acids. ... A stroke or cerebrovascular accident (CVA) occurs when the blood supply to a part of the brain is suddenly interrupted by occlusion (an ischemic stroke- approximately 90%of strokes) or by hemorrhage (a hemorrhagic stroke - approximately 10% of strokes). ... Head trauma is injury to the head from any cause. ... This article is about the medical condition. ... Hypoxia is a pathological condition in which the body as a whole (generalized hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. ...

A temporary coma is sometimes deliberately induced (using drugs) to reduce swelling of the brain after injury.

In layman's terms

"A coma is a profound state of unconsciousness. Patients are alive but unable to move or respond to their environment. There are several levels of coma and patients may, or may not, progress through them. The responsiveness of the brain lessens as the coma deepens and when it becomes more profound, normal body reflexes are lost and the patient no longer responds even to pain. The chances of recovery depend on the severity of the underlying cause. It is unclear whether a deeper coma alone necessarily means a slimmer chance of recovery because some people in deep coma recover well while others in a so-called milder coma sometimes fail to improve."

Contrasts to other conditions

The difference between coma and stupor is that a patient with coma cannot give a suitable response to either noxious or verbal stimuli, whereas a patient in a stupor can give a rough response (like screaming) to a noxious stimulus.

Coma is also to be distinguished from the persistent vegetative state which may follow it. This is a condition in which the individual has lost cognitive neurological function and awareness of the environment but does have noncognitive function and a preserved sleep-wake cycle. Spontaneous movements may occur and the eyes may open in response to external stimuli, but the patient does not speak or obey commands. Patients in a vegetative state may appear somewhat normal. They may occasionally grimace, cry, or laugh. A persistent vegetative state (or PVS) is a condition of patients with severe brain damage in whom coma has progressed to a state of wakefulness without awareness. The term was introduced by two doctors in 1972 to describe a syndrome that seemed to have been made possible by medicines... An eye is an organ that detects light. ...

Likewise, coma is not the same as brain death, which is the irreversible cessation of all brain activity. One can be in a coma but still exhibit spontaneous respiration; one who is brain-dead by definition cannot do so. Brain death is defined as a complete and irreversible cessation of brain activity. ... Respiration can refer to: Cellular respiration, which is the use of oxygen in the metabolism of organic molecules. ...

Coma is different from sleep: Sleep is always reversible. A girl quietly at sleep Sleep is the fundamental anabolic process common to all life forms, plant and animal. ...

Coma outcome

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. Gaining consciousness again is not instant: the first days, patients are only awake for a couple of minutes, then 15 minutes or so, 30 minutes etc. In Germany, Köln (music therapy) is used to quicken the awakening traject. In Belgium a project is set up to train dogs and cats's "sixth sense" to warn patients and medical staff someone is awake. Death is either the cessation of life in a living organism or the state of the organism after that event. ...

A coma rarely lasts more than 2 to 4 weeks. Some patients who have gone into vegetative state may go on to regain a degree of awareness. 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. An infection is the detrimental colonization of a host organism by a foreign species. ... Pneumonia (the ancient Greek word for lungs) is defined as an inflamation, usually caused by infection, involving the alveoli of the lungs. ...

Moral controversy

There have been controversies and legal cases over whether to keep comatose patients alive for long periods using life support equipment. One such case is that of Karen Ann Quinlan, who fell into a coma after ingesting sedatives and alcohol at a party in 1975. Her parents, in opposition to the doctors caring for her, eventually won the legal right to have her removed from her ventilator. She was able to breathe on her own, and lived in a vegetative state until her death from pneumonia on 11 June 1985. Life support is a term for a set of therapies to preserve a patients life when essential bodily systems are not working well enough to be relied upon. ... Karen Ann Quinlan (March 29, 1954–June 11, 1985) was an important figure in the history of the right to die debate. ... Pneumonia (the ancient Greek word for lungs) is defined as an inflamation, usually caused by infection, involving the alveoli of the lungs. ... June 11 is the 162nd day of the year in the Gregorian Calendar (163rd in leap years), with 203 days remaining. ... 1985 is a common year starting on Tuesday of the Gregorian calendar. ...

Glasgow Coma Scale

The Glasgow Coma Scale is used to quantify the severity of a coma. There are three components to the score: Eye opening response, Verbal response, and Motor response. The Glasgow Coma Scale (also known as Glasgow Coma Score or simply GCS) was devised by doctors to assess head trauma and, importantly, to help keep track of patients progress over a period of time. ...

• E1 = None; E2 = To pain; E3 = To speech; E4 = Spontaneous

• V1 = None; V2 = Incomprehensible; V3 = Inappropriate; V4 = Confused; V5 = Oriented

• M1 = None to pain; M2 = Extension to pain (decerebrate posturing); M3 = Flexion to pain (decorticate posturing); M4 = Withdrawal to pain; M5 = Purposeful movement/localized response to pain; M6 = Obeys commands.

A score of E4V5M6 indicates the normal state; a score of E1V1M1 indicates complete un-responsiveness.

External links

• Some of the information in this section is from the public domain resource provided by the National Institute of Neurological Diseases and Stroke at http://www.ninds.nih.gov/health_and_medical/disorders/coma_doc.htm