The Glasgow scale: how to measure unconsciousness

Not so long ago in the world of medicine and psychology there were a lot of issues with it identify signs of altered level of consciousness (At the beginning) of thousands of patients around the world, so that in many cases there were failures in diagnoses, and then negative consequences, because the treatment carried out in the same way was not the right one .

There was also no general consensus on what involved a “severe” head injury., And in different medical sections, there were different subjective cutoff medical terms and notes that weren’t entirely clear: mild coma, deep coma, semi-coma; “He is more conscious today”, etc.

Fortunately, that has all changed, as there is currently an internationally recognized scale that allows for a very accurate and objective assessment of a patient’s level of consciousness. This is the Glasgow scale.

    Features of this tool

    The Glasgow Coma Scale was created at the University of Glasgow in 1974 by English neurosurgeons Bryan Jennett and Graham Teasdale. This tool, in general terms, it allows you to assess the severity of the coma and assess the state of consciousness of the person through tests carried out on him, which revolve around 3 axes: ocular response, motor response and verbal response.

    On the other hand, this scale evaluates two aspects in a timely manner:

    1. Cognitive state

    is studied the level of understanding the person may haveThis is done by the execution or non-execution of the commands that the evaluator asks the evaluated person to carry out.

    2. The state of alert

    The degree of consciousness of the person is evaluated by the environment which surrounds him.

    Benefits of the Glasgow Coma Scale

    This instrument has properties of discrimination, evaluation and prediction that no other similar instrument has to date.

    • discrimination: Thanks to the scale, we know which treatment is best for the patient, depending on the type and severity of the injury (mild, moderate, etc.).
    • Evaluation: In the same way, it makes it possible to evaluate the progression, the stagnation and even the decrement that the patient has (this can be observed by the application and the qualification of the scale several times thereafter).
    • Prediction: You can also estimate a prognosis on the level of recovery that can be expected at the end of treatment.

    In terms of poor prognosis, the score obtained from this instrument, and the duration of the coma, would represent two very important measures to consider in order to be able to determine the risk of cognitive impairment it may exist. The probability of death is increased in the following cases: comas lasting more than 6 hours, in the elderly, and with scores below 8 (it can be obtained from three to fifteen points).

      Common error in its application and interpretation

      There are cases in which the patient’s limitations at the time of the assessment are not taken into account. sometimes verbal response is valued when the person encounters an obstruction in the area (tracheostomy or endotracheal intubation, for example). It would then be a mistake to apply it to that person, because obviously he will not be in condition.

      Another error, and which goes in the same direction as the previous one, is to evaluate the motor response when the person is sedated or has a neuromuscular blocker in your body.

      What is appropriate in these cases is not to assess with a specific figure, but rather to register as “not assessable”, because if it is applied and qualified as if it presents no obstacles, it is possible that in the medical report is the impression that the situation is very serious, because there would be a record of 1 point in this area, being that perhaps the assessed could obtain the 5 points, but not at this time- there it was applied, just from what we have already seen, there was an object that did not allow it to develop in the test in the best possible way; they were limitations beyond something neurological, And the subscales should be continued if they can be assessed.

      Basic features

      The Glasgow Coma Scale has two very valuable aspects which gave it the opportunity to be the most used instrument in various medical units to assess the level of consciousness:


      Being an easy-to-use tool, communication between different healthcare professionals (even people who were not specialists in the field, such as nurses, paramedics, etc.) has greatly improved, as the understanding between the parties was much greater, as they were all had “the same channel” of communication.


      Using a digital scale leaves aside any assessment which may be considered subjective, there is no room for different interpretations to be presented by different assessors; in this case it is rather to say if it presents the oculo-verbal-motor movement, or not, by adding points or by having a point in this heading.

      Bibliographical references:

      • Antoni, PP (2010). Introduction to neuropsychology. Madrid: McGraw-Hill.
      • Muñana-Rodríguez, JE, and Ramírez-Elies, A. (2014). Glasgow scale: origin, analysis and appropriate use. University Nursing, 11 (1), 24-35.

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