What is a Coma?

Also see www.waiting.com for support for those family members affected by a loved one in coma.

From Kosmix RightHealth web page (http://www.righthealth.com)

What is a Coma?
In medicine, a coma (from the Greek koma, meaning deep sleep) is a profound state of unconsciousness. A comatose patient cannot be awakened, fails to respond normally to pain or light, does not have sleep-wake cycles, and does not take voluntary actions. Coma may result from a variety of conditions, including intoxication, metabolic abnormalities, central nervous system diseases, acute neurological injuries such as stroke, and hypoxia. It may also be deliberately induced by pharmaceutical agents in order to preserve higher brain function following another form of brain trauma.

Severity
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.

Contrary to popular belief, a patient in a coma does not always lay still and quiet. They may talk, walk, and perform other functions that may sometimes appear to be conscious acts but are not.[1]

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 15-point scale 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.

Outcome
Outcomes range from recovery to death. Comas generally last a few days to a few weeks, rarely more than 2 to 5 weeks. After this time, some patients gradually come out of the coma, some progress to a vegetative state, and others die. Many 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 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.

Predicted chances of recovery are variable due 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 recovery is less than 15%, and of full recovery is very low.

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 coma, Terry Wallis spontaneously began speaking and regained awareness of his surroundings.

According to the Guinness Book of Records, the longest period spent in coma was by Elaine Esposito. She did not wake up after being anesthetized 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.

References
1. http://news.bbc.co.uk/2/hi/europe/6715313.stm
2. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstrac
t&list_uids=15118882&query_hl=5

3. http://www.braininjury.com/coma.html
4. http://www.smh.com.au/articles/2003/07/11/1057783356390.html

Brain Injury Association of America (BIAUSA). Types of Brain Injury.
This article contains text from the NINDS public domain pages on TBI at:
http://www.ninds.nih.gov/health_and_medical/disorders/tbi_doc.htm

Some of the information in this section is from the public domain resource provided by the
National Institute of Neurological Diseases and Stroke.