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Coma
ICD-10 R40.2
ICD-9 780.01

In medicine, a coma (from the Greek κῶμα koma, meaning deep sleep) is a profound state of unconsciousness. A person in a coma cannot be awakened, fails to respond normally to pain, light or sound, does not have sleep-wake cycles, and does not take voluntary actions. A person in a state of coma can be described as comatose.

Coma may result from a variety of conditions, including intoxication, metabolic abnormalities, central nervous system diseases, acute neurologic injuries such as stroke, and hypoxia. A coma may also result from head trauma caused by mechanisms such as falls or car accidents. It may also be deliberately induced by pharmaceutical agents in order to preserve higher brain function following another form of brain trauma, or to save the patient from extreme pain during healing of injuries or diseases. The underlying cause of coma is bilateral damage to the Reticular formation of the hindbrain, which is important in regulating sleep.[1]

If the cause of coma is not clear, various investigations (blood tests, medical imaging) may be performed to establish the cause and identify reversible causes. Coma usually necessitates admission to a hospital and often the intensive care unit.

Contents

Signs and symptoms

The severity and mode of onset of coma depends on the underlying cause. For instance, deepening hypoglycemia (low blood sugar) or hypercapnia (increased carbon dioxide levels in the blood) initially cause mild agitation and confusion, then progress to obtundation, stupor and finally complete unconsciousness. In contrast, coma resulting from a severe traumatic brain injury or subarachnoid hemorrhage can be instantaneous. The mode of onset may therefore be indicative of the underlying cause.

In the initial assessment of coma, it is common to gauge the level of consciousness by spontaneously exhibited actions, response to vocal stimuli ("Can you hear me?"), and painful stimuli; this is known as the AVPU (alert, vocal stimuli, painful stimuli, unconscious) scale. More elaborate scales, such as the Glasgow coma scale (see below), quantify individual reactions such as eye opening, movement and verbal response on a scale.

In those with deep unconsciousness, there is a risk of asphyxiation as the control over the muscles in the face and throat is diminished. As a result, those presenting to a hospital with coma are typically assessed for this risk ("airway management"). If the risk of asphyxiation is deemed to be high, doctors may use various devices (such as an oropharyngeal airway, nasopharyngeal airway or endotracheal tube) to safeguard the airway.

Diagnosis

Once a person in a coma is stable, investigations are performed to assess the underlying cause. These may be simple; a computed tomography scan of the brain, for example, is performed to identify specific causes of the coma, such as hemorrhage.

A diagnosis will direct the appropriate therapy, however it does not reduce the need for generic supportive care, such as that offered on intensive care. Sometimes, the diagnosis allows the withdrawal of care, if the cause of coma is untreatable and the brain damage is irreversible.

Classification

The severity of coma impairment is categorized into several levels. Patients may or may not progress through these levels. In the first level, the brain responsiveness lessens, normal reflexes are lost, the patient no longer responds to pain and cannot hear.

Two scales of measurement often used in Traumatic Brain Injury (TBI) diagnosis to determine the level of coma are the Glasgow Coma Scale (GCS) and the Ranchos Los Amigos Scale (RLAS). The GCS is a simple 3 to 15-point scale (3 being the worst and 15 being that of a normal person) used by medical professionals to assess severity of neurologic trauma, and establish a prognosis. The RLAS is a more complex scale that has eight separate levels, and is often used in the first few weeks or months of coma while the patient is under closer observation, and when shifts between levels are more frequent.

Prognosis

Outcomes range from recovery to death. Comas generally last a few days to a few weeks. They rarely last more than 2 to 5 weeks but some have lasted as long as several years. After this time, some patients gradually come out of the coma, some progress to a vegetative state, and others die. Some patients who have entered a vegetative state go on to regain a degree of awareness. Others remain in a vegetative state for years or even decades (the longest recorded period being 37 years).[2]

The outcome for coma and vegetative state depends on the cause, location, severity and extent of neurological damage. A deeper coma alone does not necessarily mean 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.

People may emerge from a coma with a combination of physical, intellectual and psychological difficulties that need special attention. Recovery usually occurs gradually—patients acquire more and more ability to respond. Some patients never progress beyond very basic responses, but many recover full awareness. Regaining consciousness is not instant: in the first days, patients are only awake for a few minutes, and duration of time awake gradually increases. This is unlike the situation in many movies where people who awake from comas are instantly able to continue their normal lives. In reality, the coma patient awakes sometimes in a profound state of confusion, not knowing how they got there and sometimes sufferering from dysphasia, the inability to articulate any speech, and with many other disabilities.

Predicted chances of recovery are variable owing to different techniques used to measure the extent of neurological damage. All the predictions are based on statistical rates with some level of chance for recovery present: a person with a low chance of recovery may still awaken. Time is the best general predictor of a chance of recovery: after 4 months of coma caused by brain damage, the chance of partial recovery is less than 15%, and the chance of full recovery is very low.[3][4]

The most common cause of death for a person in a vegetative state is secondary infection such as pneumonia which can occur in patients who lie still for extended periods.

Occasionally people come out of coma after long periods of time. After 19 years in a minimally conscious state, Terry Wallis spontaneously began speaking and regained awareness of his surroundings.[5] Similarly, Polish railroad worker Jan Grzebski woke up from a 19-year coma in 2007.

A brain-damaged man, trapped in a coma-like state for six years, was brought back to consciousness in 2003 by doctors who planted electrodes deep inside his brain. The method, called deep brain stimulation (DBS) successfully roused communication, complex movement and eating ability in the 38-year-old American man who suffered a traumatic brain injury. His injuries left him in a minimally conscious state (MCS), a condition akin to a coma but characterized by occasional, but brief, evidence of environmental and self-awareness that coma patients lack.[6]

Society and culture

Research by Dr. Eelco Wijdicks on the depiction of comas in movies was published in Neurology in May 2006. Dr. Wijdicks studied 30 films (made between 1970 and 2004) that portrayed actors in prolonged comas, and he concluded that only two films accurately depicted the state of a coma victim and the agony of waiting for a patient to awaken: Reversal of Fortune (1990) and The Dreamlife of Angels (1998). The remaining 28 were criticised for portraying miraculous awakenings with no lasting side effects, unrealistic depictions of treatments and equipment required, and comatose patients remaining muscular and tanned[7].

In the 2005 novel The Coma by Alex Garland, a man assaulted in the London Underground tries to put his life back into order from his comatose state. Extraordinary Means, a 1987 novel by Donna Levin, is a literary fantasy in which a comatose woman is able to overhear her family dispute over whether to end life support. Coma, published in 1977 by Robin Cook, is a medical thriller in which a med student unravels a plot to purposely induce comas in patients in order to harvest their organs.

In the film Just Like Heaven, a doctor who was seriously injured in a car accident falls into a coma that lasts for three months. Meanwhile, the woman's spirit goes back to her apartment, to find that it has been rented out to someone else. Together, the spirit and the man occupying her house find her body and bring her back to life.

In Rocky II, Adrian, Rocky's wife falls into a coma after giving birth, she wakes up and survives.

In the novel, Girlfriend in a Coma by Douglas Coupland, one of the main characters, Karen, falls into a coma after consuming alcohol and valium.

In the Stephen King novel The Dead Zone, Johnny Smith falls into a coma after a car accident, waking five years later with minor brain damage and psychic powers.

In the film Miss March a man wakes up from a four year coma, to find out that his high school sweetheart became a playboy bunny.

See also

References

  1. ^ Sundsten, John W.; Nolte, John (2001). The human brain: an introduction to its functional anatomy. St. Louis: Mosby. ISBN 0-323-01320-1. 
  2. ^ According to the Guinness Book of Records, the longest period spent in coma was by Elaine Esposito. She did not wake up after being anaesthetized for an appendectomy on August 6, 1941, at age 6. She died on November 25, 1978 at age 43 years 357 days, having been in a coma for 37 years 111 days.
  3. ^ Formisano R, Carlesimo GA, Sabbadini M, et al. (May 2004). "Clinical predictors and neuopleropsychological outcome in severe traumatic brain injury patients". Acta Neurochir (Wien) 146 (5): 457–62. doi:10.1007/s00701-004-0225-4. PMID 15118882. 
  4. ^ brain injury .com | Coma traumatic brain injury - Brain Injury Coma
  5. ^ Mother stunned by coma victim's unexpected words - smh.com.au
  6. ^ "Electrodes stir man from six-year coma-like state". Cosmos Magazine. 2 August 2007. http://www.cosmosmagazine.com/node/1513. 
  7. ^ Eelco F.M. Wijdicks, MD and Coen A. Wijdicks, BS (2006). "The portrayal of coma in contemporary motion pictures". Neurology 66: 1300-1303. http://www.neurology.org/cgi/content/abstract/66/9/1300. Retrieved 2009-11-25. 

1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

COMA (Gr. K&/la,? from Kowav, to put to sleep), a deep sleep; the term is, however, used in medicine to imply something more than its Greek origin denotes, namely, a complete and prolonged loss of consciousness from which a patient cannot be roused. There are various degrees of coma: in the slighter forms the patient can be partially roused only to relapse again into a state of insensibility; in the deeper states, the patient cannot be roused at all, and such are met with in apoplexy, already described. Coma may arise abruptly in a patient who has presented no pre-existent indication of such a state occurring. Such a condition is called primary coma, and may result from the following causes: - (I) concussion, compression or laceration of the brain from head injuries, especially fracture of the skull; (2) from alcoholic and narcotic poisoning; (3) from cerebral haemorrhage, embolism and thrombosis, such being the causes of apoplexy. Secondary coma may arise as a complication in the following diseases: - diabetes, uraemia, general paralysis, meningitis, cerebral tumour and acute yellow atrophy of the liver; in such diseases it is anticipated, for it is a frequent cause of the fatal termination. The depth of insensibility to stimulus is a measure of the gravity of the symptom; thus the conjunctival reflex and even the spinal reflexes may be abolished, the only sign of life being the respiration and heart-beat, the muscles of the limbs being sometimes perfectly flaccid. A characteristic change in the respiration, known as CheyneStokes breathing occurs prior to death in some cases; it indicates that the respiratory centre in the medulla is becoming exhausted, and is stimulated to action only when the venosity of the blood has increased sufficiently to excite it. The breathing consequently loses its natural rhythm, and each successive breath becomes deeper until a maximum is reached; it then diminishes in depth by successive steps until it dies away completely. The condition of apnoea, or cessation of breathing, follows, and as soon as the venosity of the blood again affords sufficient stimulus, the signs of air-hunger commence; this altered rhythm continues until the respiratory centre becomes exhausted and death ensues.

Coma Vigil is a state of unconsciousness met with in the algide stage of cholera and some other exhausting diseases. The patient's eyes remain open, and he may be in a state of low muttering delirium; he is entirely insensible to his surroundings, and neither knows nor can indicate his wants.

There is a distinct word "coma" (Gr. hair), which is used in astronomy for the envelope of a comet, and in botany for a tuft.


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Simple English

Coma is a medical term. It is a state of deep unconsciousness. People who are in that state can not be woken up. They also do not react to pain or light. Coma can result from various conditions. Some of these are intoxication, poisons or damages or diseases of the nervous system. It can also be the result of certain drugs. Doctors sometimes put patients that have very bad injuries into a coma. There are different levels of coma. Comas usually do not last more than several weeks, but those several weeks could be disastrous. Sometimes only basic bodily functions are left over. Intensive hospital care is often needed to recover some of these functions. Some comas can last years, but these are usually not woken up from. The family of a coma victim (or whoever has the power of attorney) can sign papers so that they are taken off of life support and die.








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