The Glasgow Coma Scale (GCS) is the most common scoring system used to describe the level of consciousness in a person following a traumatic brain injury. Basically, it is used to help gauge the severity of an acute brain injury. The test is simple, reliable, and correlates well with outcome following severe brain injury.
The GCS is a reliable and objective way of recording the initial and subsequent level of consciousness in a person after a brain injury. It is used by trained staff at the site of an injury like a car crash or sports injury, for example, and in the emergency department and intensive care units.
The GCS measures the following functions:
Eye Opening (E)
- 4 = spontaneous
- 3 = to sound
- 2 = to pressure
- 1 = none
- NT = not testable
Verbal Response (V)
- 5 = orientated
- 4 = confused
- 3 = words, but not coherent
- 2 = sounds, but no words
- 1 = none
- NT = not testable
Motor Response (M)
- 6 = obeys command
- 5 = localizing
- 4 = normal flexion
- 3 = abnormal flexion
- 2 = extension
- 1 = none
- NT = not testable
Clinicians use this scale to rate the best eye opening response, the best verbal response, and the best motor response an individual makes. The final GCS score or grade is the sum of these numbers.
Using the Glasgow Coma Scale
A patient's Glasgow Coma Score (GCS) should be documented on a coma scale chart. This allows for improvement or deterioration in a patient's condition to be quickly and clearly communicated.
Individual elements, as well as the sum of the score, are important. The individual elements of a patient's GCS can be documented numerically (e.g. E2V4M6) as well as added together to give a total Coma Score (e.g E2V4M6 = 12). For example, a score may be expressed as GCS 12 = E2 V4 M6 at 4:32.
Every brain injury is different, but generally, brain injury is classified as:
- Severe: GCS 8 or less
- Moderate: GCS 9-12
- Mild: GCS 13-15
Mild brain injuries can result in temporary or permanent neurological symptoms and neuroimaging tests such as CT scan or MRI may or may not show evidence of any damage.
Moderate and severe brain injuries often result in long-term impairments in cognition (thinking skills), physical skills, and/or emotional/behavioral functioning.
Limitations of the Glasgow Coma Scale
Factors like drug use, alcohol intoxication, shock, or low blood oxygen can alter a patient’s level of consciousness. These factors could lead to an inaccurate score on the GCS.
Children and the Glasgow Coma Scale
The GCS is usually not used with children, especially those too young to have reliable language skills. The Pediatric Glasgow Coma Scale, or PGCS, a modification of the scale used on adults, is used instead. The PGCS still uses the three tests — eye, verbal, and motor responses — and the three values are considered separately as well as together.
Here is the slightly altered grading scale for the PGCS:
Eye Opening (E)
- 4 = spontaneous
- 3 = to voice
- 2 = to pressure
- 1 = none
- NT = not testable
Verbal Response (V)
- 5 = smiles, oriented to sounds, follows objects, interacts
- 4 = cries but consolable, inappropriate interactions
- 3 = inconsistently inconsolable, moaning
- 2 = inconsolable, agitated
- 1 = none
- NT = not testable
Motor Response (M)
- 6 = moves spontaneously or purposefully
- 5 = localizing (withdraws from touch)
- 4 = normal flexion (withdraws to pain)
- 3 = abnormal flexion (decorticate response)
- 2 = extension (decerebrate response)
- 1 = none
- NT = not testable
Pediatric brain injuries are classified by severity using the same scoring levels as adults, i.e. 8 or lower reflecting the most severe, 9-12 being a moderate injury and 13-15 indicating a mild TBI. As in adults, moderate and severe injuries often result in significant long-term impairments.
Posted on BrainLine February 13, 2018. Reviewed June 8, 2022.
Reviewed and revised 12 October 2019 OVERVIEW CALCULATION OF GCS Eye response (E) Verbal response (V) Motor response (M) USES ADVANTAGES
- most widely recognised of all conscious level scoring systems in the world
- has face validity (looks like it should work)
- quick
- reproducible (this is controversial, in one study 38% of the cases the GCS scores were the same and in 33% of cases the scores varied with more than two points)
- skewed towards motor score, which is good since this is the most reliable measure of short-term prognosis in TBI
- the distinction between a motor score of 2, 3 and 4 is a very useful clinical indicator of the severity of TBI, and the area of brain function that has been affected
- correlates with adverse neurological outcomes such as brain injury, neurosurgical intervention, and mortality
DISADVANTAGES
Problems with the use of GCS
- not originally intended to be converted into a single score — the components (E4,V5, M6) are more important than the total score
- does not incorporate brain-stem reflexes
- M score does not factor in unilateral pathology
- unreliable in patients in the middle range of 9-12
- The same GCS score will predict different TBI mortality depending on the components
— GCS of 4 with the components 1+1+2 (E+V+M) predicts a mortality rate of 48%
— GCS of 4 with the components 2+1+1 (E+V+M) predicts a mortality rate of 19% - grossly predictive but cannot accurately predict outcomes in individual patients (on par with weather presenters predicting rain or WBC predicting appendicitis!)
Problems with performing GCS
- designed as a tool for repeated bedside assessment of various neurological functions in patients in a neurosurgical ward, not for use in TBI
- It is difficult for untrained staff to apply properly, especially distinguishing between M= 3,4,5 (even neurosurgeons get it wrong ~50% of the time)
- Variation in scoring V in intubated patients
- subject to language barriers
- cannot be applied to small children
- may be affected by other factors influencing level of consciousness, e.g. drugs such as alcohol and sedatives
- GCS is often used in settings such as toxicology where it is unvalidated
- Debates within the literature as to when GCS can be first applied after TBI, i.e when is the first post-resuscitation GCS applicable
Problems with accuracy and validity of GCS
- Controversy in the literature
- There is poor inter-observer reliability
- Reproducibility is poor (only 50% in neurosurgeons!)
- There is little evidence demonstrating validity and reliability of the GCS
- Not proven to be better than unstructured clinical judgement
- There are numerous other neurological scoring systems that have demonstrated similar or greater validity and reliability e.g. the FOUR score, AVPU in children
- GCS 8 does not reliably correlate with the presence or absence of airway reflexes
‘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 and Jennet in 1978
ALTERNATIVES
- FOUR score
- AVPU
- Simplified Motor Score (aka TROLL: Test Responsiveness: Obeys, Localizes, or Less)
- unstructured clinical judgement
MY APPROACH
- Due to widespread adoption I still use GCS in TBI in conjunction with other clinical information and investigations in the assessment of TBI severity, to guide monitoring and management and as an aid to prognostication
- However, because of its limitations, GCS must be used cautiously
- all staff need to be aware of the same criteria for its use and application and have a standardised approach to its assessment
- on-going education is needed to make sure that it is used correctly
VIDEOS
Videos by Jake Timothy (Consultant Neurosurgeon) and Sir Graham Teasdale (professor of Neurosurgery) on the history and use of GCS:
References and Links
Journal articles
- Chou R et al. Predictive Utility of the Total Glasgow Coma Scale Versus the Motor Component of the Glasgow Coma Scale for Identification of Patients With Serious Traumatic Injuries. Ann Emerg Med. 2017 Aug;70(2):143-157 [PMID 28089112]
- Green SM. Cheerio, laddie! Bidding farewell to the Glasgow Coma Scale. Ann Emerg Med. 2011 Nov;58(5):427-30. PMID: 21803447.
- Teasdale G, Jennett B. Assessment of coma and impaired consciousness. A practical scale. Lancet. 1974 Jul 13;2(7872):81-4. PMID: 4136544.
- Teasdale G, Jennett B, Murray L, Murray G. Glasgow coma scale: to sum or not to sum. Lancet. 1983 Sep 17;2(8351):678 PMID: 6136811.
- Zuercher M, Ummenhofer W, Baltussen A, Walder B. The use of Glasgow Coma Scale in injury assessment: a critical review. Brain Inj. 2009 May;23(5):371-84. PMID: 19408162.
FOAM and web resources
- Glasgow Coma Scale website
- ScanCrit — Why the Glasgow Coma Scale has got to go (2011)
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of three amazing children.
On Twitter, he is @precordialthump.
| INTENSIVE | RAGE | Resuscitology | SMACC
Which score is awarded to a patient who is the best motor response is abnormal extension according to the Glasgow Coma Scale?
Sign | Glasgow Coma Scale | Score |
Motor response | Localizes pain | 5 |
Withdraws | 4 | |
Abnormal flexion to pain | 3 | |
Abnormal extension to pain | 2 |