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Coma: Definition, Symptoms, Diagnosis, Treatment, and Evolution

A coma is defined as an altered state of consciousness in which the patient cannot respond to stimuli. Despite the lack of awareness, vital functions are preserved.

A coma may be due to trauma affecting the brain, drug intoxication (in the case of alcohol, it is called alcohol poisoning), a brain tumor, or a even a stroke.


There are different symptoms of a coma depending on its stage. The Glasgow Coma Scale is used to quantify the severity of the coma by developing a score from 3 (deep coma) to 15 (awake and normal consciousness).

This score evaluates: eye opening, assessed out of 4, with 4 points for spontaneous opening, 3 for opening on demand, 2 for opening in reaction to pain, and 1 for the total absence of eye opening; speech, scored out of 5, with 5 for oriented speech, 4 for confused speech, 3 for a few incoherent words with some recognized words, 2 for sounds without understandable words, and 1 for total silence without verbal response; motor response, scored out of 6, with 6 for correctly executed motions on command, 5 for localized movement in response to pain, 4 for a non-adapted avoidance movement, 3 for a bending movement in response to pain, 2 for an extending movement in response to pain, and 1 for the total lack of movement.


Diagnosis is based on the above scale as well as on a clinical evaluation. Additional tests — including blood tests; CT scans; MRIs; and lumbar punctures, if meningitis is suspected — are performed in the case of a coma in order to search for the cause.


In the case of a coma, medical care is urgently needed. The subject should be placed under surveillance to ensure the maintenance of vital functions (i.e. blood circulation and therefore pulmonary respiration and heartbeat).

A score below 8 requires intubation to ensure respiratory function. If the patient is unable to feed himself, they can be fed by blood perfusion or by gastrointestinal probe if the coma persists. It is essential to avoid pressure sores and cerebral edema.


The course of a coma is unpredictable and mainly depends on the cause. Comas due to drug intoxication generally have a good outcome. The evolution of comas due to trauma depends mostly on age — younger people are more likely to see improvement in their condition.

It is possible to see people that remain in a coma for several years. Comas can sometimes be artificially maintained by using sedative molecules.

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