Glasgow Coma Scale/Score (GCS)
- Designed for use in serial assessments of patients with coma from either medical or surgical causes to be widely applicable.
- The GCS is commonly used in the pre-hospital and acute care setting as well as over a patient’s hospital course to evaluate for mental status assessment in both traumatic and non-traumatic presentations.
- The GCS allows providers in multiple settings and with varied levels of training to communicate succinctly about a patient’s mental status.
- The GCS has been shown to have statistical correlation with a broad array of adverse neurologic outcomes, including brain injury, need for neurosurgery, and mortality.
- The GCS score has been incorporated into numerous guidelines and assessment scores (e.g. ACLS, ATLS, APACHE I-III, TRISS and WNS SAH Grading Scale).
Points to keep in mind:
- Correlation with outcome and severity is most accurate when applied to an individual patient over time; the patient’s trend is important.
- A GCS of 8 should not be used in isolation to make a determination of whether to intubate a patient, but does suggest a level of obtundation that should be evaluated carefully.
- Reproducibility can be low; if individual institutions have concerns about agreement between providers, training and education are available from the GCS creators at www.glasgowcomascale.org.
- There are simpler scores that have been shown to perform as well as the GCS in the prehospital and emergency department setting (for initial evaluation); these are often contracted versions of the GCS itself (the SMS uses the Motor portion of the GCS only). These are less well studied than the GCS for outcomes like long-term mortality, and the GCS has been studied trended over time, while the SMS has not.
The Glasgow Coma Scale is an adopted standard for mental status assessment in the acutely ill trauma and non-trauma patient and assists with predictions of neurological outcomes (complications, impaired recovery) and mortality.
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The GCS score can be indicative of how critically ill a patient is.
- Trauma patients presenting with a GCS of < 15 warrant close attention and reassessment.
- A declining GCS is concerning in any setting and should prompt assessment of the airway and possible intervention.
Conversely, a GCS of 15 should not be taken as an indication that a patient (trauma or medical) is not critically ill. Decisions about the aggressiveness of the management and treatment plans should be made based on clinical presentation and context and not in any way overridden by the GCS score.
- Clinical management decisions should not be based solely on the GCS score in the acute setting.
- If a trauma patient has a GCS of ≤ 8 and there is clinical concern that they are unable to protect their airway or that they have an expected worsening clinical course based on exam or imaging findings, then intubation can be considered.
- In any patient, a rapidly declining or waxing and waning GCS is concerning and intubation should be considered in the context of the patient's overall clinical picture.
- Although it has been adopted widely and in a variety of settings, the GCS score is not intended for quantitative use.
- Clinical management decisions should not be based solely on the GCS score in the acute setting.
From the creators of the GCS:
“We have never recommended using the GCS alone, either as a means of monitoring coma, or to assess the severity of brain damage or predict outcome.” (Teasdale G 2014)
Addition of the selected points:
Facts & Figures
|EYE||Eyes open spontaneously||+4|
|Eye opening to verbal command||+3|
|Eye opening to pain||+2|
|No eye opening||+1|
|Not assessable (Trauma, edema, etc)||C|
|No verbal response||+1|
|Withdrawal from pain||+4|
|Flexion to pain||+3|
|Extension to pain||+2|
|No motor response||+1|
- The Modified Glasgow Coma Scale (the 15-point scale that has been widely adopted, including by the original unit in Glasgow, as opposed to the 14 point original GCS Scale) was developed to be used in a repeated manner in the inpatient setting to assess and communicate changes in mental status and to measure the duration of coma. (Teasdale G 1974)
- In the acute care setting, it has been shown to have highly variable reproducibility and inter-rater reliability (i.e. 56% among neurosurgeons in one study, 38% among ED physicians in another). In its most common usage, the three sections of the scale are often summed to provide a summary of severity. The authors themselves have explicitly objected to the score being used in this way, and analysis has shown that patients with the same total score can have huge variations in outcomes, specifically mortality (GCS score of 4 predicts a mortality rate of 48% if calculated 1+1+2 for eye, verbal, and motor, a mortality of 27% if calculated 1+2+1, but a mortality of only 19% if calculated 2+1+1. (Healey C 2014)
In summary, the Modified Glasgow Coma Scale provides a nearly universally accepted method of assessing patients with acute brain damage. Summation of its components into a single overall score loses information and provides only a rough guide to severity. In some circumstances, such as early triage of severe injuries, assessment of only a contracted version of the motor component of the scale, as in the Simplified Motor Scale (SMS) can perform as well the GCS and is significantly less complicated. However the SMS may be less informative in patients with lesser injuries.
Original/Primary ReferenceTeasdale G, Jennett B.Assessment of coma and impaired consciousness. A practical scale. Lancet. 1974 Jul 13;2(7872):81-4.
ValidationMoore L, Lavoie A, Camden S, Le Sage N, Sampalis JS, Bergeron E, Abdous B. Statistical validation of the Glasgow Coma Score.J Trauma. 2006 Jun;60(6):1238-43; discussion 1243-4.
Other ReferencesTeasdale G, Jennett B. Assessment of coma and severity of brain damage. Anesthesiology. 1978;49:225-226.Teasdale G, Jennett B, Murray L, Murray G. Glasgow coma scale: to sum or not to sum. Lancet. 1983 Sep 17;2(8351):678.Healey C, Osler TM, Rogers FB, Healey MA, Glance LG, Kilgo PD, Shackford SR, Meredith JW. Improving the Glasgow Coma Scale score: motor score alone is a better predictor. J Trauma. 2003 Apr;54(4):671-8; discussion 678-80.Green SM. Cheerio, laddie! Bidding farewell to the Glasgow Coma Scale. Ann Emerg Med. 2011 Nov;58(5):427-30. doi: 10.1016/j.annemergmed.2011.06.009. Epub 2011 Jul 30.Middleton PM. Practical use of the Glasgow Coma Scale; a comprehensive narrative review of GCS methodology. Australas Emerg Nurs J. 2012 Aug;15(3):170-83. doi: 10.1016/j.aenj.2012.06.002. Epub 2012 Aug 3. Review.Yeh DD. Glasgow Coma Scale 40 years later: in need of recalibration? JAMA Surg. 2014 Jul;149(7):734. doi: 10.1001/jamasurg.2014.47. No abstract available.Teasdale G. Forty Years on: Updating the Glasgow Coma Scale. Nursing Times. 2014; 110(42).Gill M, Windemuth R, Steele R, Green SM. A comparison of the Glasgow Coma Scale score to simplified alternative scores for the prediction of traumatic brain injury outcomes. Ann Emerg Med. 2005 Jan;45(1):37-42.Haukoos JS, Gill MR, Rabon RE, Gravitz CS, Green SM. Validation of the Simplified Motor Score for the prediction of brain injury outcomes after trauma. Ann Emerg Med. 2007 Jul;50(1):18-24. Epub 2006 Nov 16.Thompson DO, Hurtado TR, Liao MM, Byyny RL, Gravitz C, Haukoos JS. Validation of the Simplified Motor Score in the out-of-hospital setting for the prediction of outcomes after traumatic brain injury. Ann Emerg Med. 2011 Nov;58(5):417-25. doi: 10.1016/j.annemergmed.2011.05.033. Epub 2011 Jul 30.
From the Creator
- Why did you develop the Glasgow Coma Scale? Was there a clinical experience that inspired you to create this tool for clinicians?
- As a junior doctor in the early 1970s I saw that crucial decisions on patients with an acute brain injury were being on taken on the findings of a chaotic mixture of many different, ill-defined systems for assessing their so-called “conscious level.” I saw how this created confusion about the severity of a patient's condition, how it undermined communication, and how this led to delays in detecting and acting on clinical changes and, most importantly, to avoid morbidity and mortality.
- A better system of assessment was also needed to support Bryan Jennett's interests in prognosis by relating a patient's early severity to their outcome. We aimed for a method that would be widely acceptable, covering the spectrum of degrees of injury from many causes – beyond specialist neurosurgical units where only a minority of patients are managed. The result was deliberately called simply, “A practical scale for assessment of impaired consciousness and coma.”
- What pearls, pitfalls and/or tips do you have for users of the Glasgow Coma Scale? Are there cases in which it has been applied, interpreted, or used inappropriately?
- First: distinguish between the use of the Scale and its derived total or sum Score.
- The purpose of the Scale is to describe and communicate the condition of an individual patient by separate, multidimensional rating of their eye, verbal and motor responses. It remains the appropriate method for this purpose.
- The Score came a couple of years later. We had assigned numbers to the steps in each response so that they could be readily used in research; the temptation to aggregate the 3 into a total score became irresistible! The total score is very useful as a summary of severity in groups and in classification. It does provide a rough index in an individual but conveys less information than the scale. If one or other response cannot be assessed, a total score cannot be derived but the information in the remaining responses of the scale can still inform management.
- Second: the reliability of the scale can be high but cannot be assumed nor left to chance.
- In the course of a review of the scale I became aware that over the years of the emergence of quite wide variations both in how it is assessed and in the level of reproducibility. Consistent assessment is promoted by training and experience and to support these we have set up a website containing a video setting out a standard, structured approach (GlasgowComaScale.org).
- Are there any adjustments or updates you would make to the scale given recent changes in medicine like imaging, or the data and research we now have on concussion?
- I've often considered the need for changes and am aware of many proposals. Derivatives from the scale have been described but have reflected limited perspectives. A view that it is too complex has led to an assessment limited to only 3 steps in the motor scale, the Simplified Motor Scale; this may have application in immediate triage in severe injuries but is inadequate for the great majority of patients with lesser injuries. Views that a more elaborate system incorporating more features is needed, for example in neuro intensive care, overlook that it was always intended that other signs should be assessed, but alongside the scale, not lumped into even more complex scores.
- The scale seems still to be valuable in providing a common language across the full spectrum of responsiveness in a wide range of clinical circumstances. I have not been persuaded that changes are appropriate, apart from simplifying and tidying up some of the terms.
- Assessment of a patient with the scale and the use of other investigations such as imaging have interacting and overlapping places in management. The findings of the scale provide indications for performing imaging and for then interpreting the clinical implications of its findings. A scan doesn't tell you what the patient is like.
- The challenge in working on concussion is the lack of an independent, biologically sound, way of separating it out sharply and definitely within the spectrum of mild, trauma-induced brain disturbances. Agreement on practical, operational thresholds, perhaps based on degrees and durations of impairment of orientation and eye opening, might help research and clinical care.
- Other comments? Any new research or papers on this topic in the pipeline? Having developed the tool in 1974, any thoughts on how widespread its use has become (even being applied to atraumatic changes in consciousness)?
- The 40th birthday of the scale was the lever used by some colleagues to stimulate me to join them in conducting a thorough review of how it had fared, where it is now and what might be appropriate in future.
- The outputs from this include:
- Teasdale G, Maas A, Lecky F, Manley G, Stocchetti N, Murray G. The Glasgow Coma Scale at 40 years: standing the test of time. The Lancet Neurology 2014; 13: 844 – 54.
- Reith F, Brennan P, Maas AIR, Teasdale GM. Lack of standardization in applying painful stimuli for assessment the GCS. J. Neurotrauma 2014, in press.
- Teasdale G. Forty Years on: Updating the Glasgow Coma Scale. Nursing Times. 2014; 110(42).
- GlasgowComaScale.org - A web site, based around an instructional video , to promote communication about the scale and good practice in its use
- Perhaps the most eloquent confirmation that the scale has found value and widespread acceptance for many purposes came in the finding in a survey, done as part of the review, that it is now used by neurosurgeons in more than 80 countries across the world and has been translated into some 60 languages.
About the Creator
Sir Graham Teasdale, MBBS, is an honorary professor at the Institute of Health and Wellbeing, University of Glasgow. He was previously Professor of Neurosurgery, Head of the Department of Neurosurgery and Associate Dean for Medical Research. Sir Teasdale was President of the Royal College of Physicians and Surgeons of Glasgow (2003-2006), and he was knighted in 2006 for his services to neurosurgery.
To view Dr. Graham Teasdale's publications, visit PubMed