Coma: a new strategy for quantifying the level of consciousness in patients

Publié le : 9 September 2013

 On 14 August, the Science Translational Medicine journal revealed that a team of American and European scientists had just developed a strategy for quantifying the level of consciousness in patients incapable of communicating because of an anaesthetic or coma. Traditionally, doctors have evaluated levels of consciousness in these patients "by assessing [their] ability […] to respond to external commands". In order to this, doctors ask patients "to open their eyes or press the hand of the person holding their hand". The extent of coma differs from one person to the next: patients can be "completely unconscious, in an almost vegetative state" or, in an intermediate, less serious condition in which they "may be aware of external stimuli but cannot move or talk".    

The principle of the new method developed by American and European scientists is as follows: "an external magnetic device sends strong stimuli to the brain and an electroencephalogram directly registers the way in which the neurons react". Depending on the type of reaction, "a computer calculates a ‘score’, which assesses whether or not the patient is conscious". For Steven Laureys, coma specialist at Liège University and team member, "this method is entirely objective and does not depend on the patient’s sensory or motor capacities". Scientists take two parameters into account when making their assessment, namely "the amount of information and the level of integration", once the magnetic impulse enters the brain.            
This technique has been tested on "subjects who are awake, sleeping or chemically anaesthetised as well as coma patients whose condition is well known to doctors". Consistent results have been obtained.

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