Glasgow Coma Scale

The Glasgow Coma Scale[1] (GCS) is a clinical scale used to reliably measure a person's level of consciousness after a brain injury.

Not to be confused with Glasgow Outcome Scale.
Glasgow Coma Scale
MeSHD015600
LOINC35088-4

The GCS assesses a person based on their ability to perform eye movements, speak, and move their body. These three behaviors make up the three elements of the scale: eye, verbal, and motor. A person's GCS score can range from 3 (completely unresponsive) to 15 (responsive). This score is used to guide immediate medical care after a brain injury (such as a car accident) and also to monitor hospitalized patients and track their level of consciousness.

Lower GCS scores are correlated with higher risk of death. However, the GCS score alone should not be used on its own to predict the outcome for an individual person with brain injury.

Scoring

The Glasgow Coma Scale is used for people above the age of two and composed of three tests: eye, verbal, and motor responses. The scores for each of these tests are indicated in the table below.

Glasgow Coma Scale [2]
Not Testable (NT) 123456
Eye Ex: severe trauma to the eyes Does not open eyes Opens eyes in response to pain Opens eyes in response to voice Opens eyes spontaneously N/A N/A
Verbal Ex: Intubation Makes no sounds Makes sounds Words Confused, disoriented Oriented, converses normally N/A
Motor Ex: Paralysis Makes no movements Extension to painful stimuli Abnormal flexion to painful stimuli Flexion / Withdrawal to painful stimuli Localizes to painful stimuli Obeys commands

The Glasgow Coma Scale is reported as the combined score (which ranges from 3 to 15) and the score of each test (E for eye, V for Verbal, and M for Motor). For each test, the value should be based on the best response that the person being examined can provide.[3] For example, if a person obeys commands only on their right side, they get a 5 for motor. The scale also accounts for situations that prevent appropriate testing (Not Testable). When specific tests cannot be performed, they must be reported as "NT" and the total score is not reported.

The results are reported as the Glasgow Coma Score (the total points from the three tests) and the individual components. As an example, a person's score might be: GCS 12, E3 V4 M5. Alternatively, if a patient was intubated, their score could be GCS E2 V NT M3.

Eye response (E)

There are four grades starting with the most severe:

  1. No opening of the eye
  2. Eye opening in response to pain stimulus. A peripheral pain stimulus, such as squeezing the lunula area of the person's fingernail is more effective than a central stimulus such as a trapezius squeeze, due to a grimacing effect.[4]
  3. Eye opening to speech. Not to be confused with the awakening of a sleeping person; such people receive a score of 4, not 3.
  4. Eyes opening spontaneously

NT (Not testable). Examples for this would include severe damage to the eyes, sedation from drugs, and paralysis.

Verbal response (V)

There are five grades starting with the most severe:

  1. No verbal response
  2. Incomprehensible sounds. Moaning but no words.
  3. Inappropriate words. Random or exclamatory articulated speech, but no conversational exchange. Speaks words but no sentences.
  4. Confused. The person responds to questions coherently but there is some disorientation and confusion.
  5. Oriented. Person responds coherently and appropriately to questions such as the person’s name and age, where they are and why, the year, month, etc.

NT (Not testable). Examples for this would include intubation, deafness, language barrier, sedation from drugs, and paralysis

Motor response (M)

There are six grades starting with the most severe:

  1. No motor response. Lack of any motor response should raise suspicion for spinal cord injury.
  2. Abnormal Extension in response to pain. Different guidelines report different evaluation of abnormal extension. While some sources indicate extension at the elbow is sufficient,[5] other sources use the language "decerebrate posturing".[6] It is important to note that the original publication of the Glasgow Coma Scale explicitly avoided the term "decerebrate extension" because it implied specific anatomical findings.[1] I
  3. Abnormal Flexion in response to pain. Different guidelines report different evaluation. While some sources focus on arm movements,[5] other sources use the term "decorticate posturing".[6]
  4. Normal Flexion (absence of abnormal posturing; unable to lift hand past chin with supraorbital pain but does pull away when nailbed is pinched)
  5. Localizes to pain (purposeful movements towards painful stimuli; e.g., brings hand up beyond chin when supraorbital pressure applied)
  6. Obeys commands (the person does simple things as asked)

NT (Not testable). Examples for this would include spinal cord injury, sedation from drugs, and paralysis

Scoring (Pediatrics)

Children below the age of two struggle with the tests necessary for assessment of the Glasgow Coma Scale. As a result, a version for children has been developed, and is outlined below.

Pediatric Glasgow Coma Scale [7]
Not Testable (NT) 123456
Eye Ex: severe trauma to the eyes Does not open eyes Opens eyes in response to pain Opens eyes in response to sound Opens eyes spontaneously N/A N/A
Verbal Ex: Intubation Makes no sounds Moans in response to pain Cries in response to pain Irritable/Crying Coos/Babbles N/A
Motor Ex: Paralysis Makes no movements Extension to painful stimuli (decerebrate response) Abnormal flexion to painful stimuli (decorticate response) Withdraws from pain Withdraws from touch Moves spontaneously and purposefully

Interpretation

Individual elements as well as the sum of the score are important. Hence, the score is expressed in the form "GCS 9 = E2 V4 M3 at 07:35". Patients with scores of 3-8 are usually considered to be in a coma.[8] Generally, brain injury is classified as:

  • Severe, GCS < 8–9
  • Moderate, GCS 8 or 9–12 (controversial)[9]
  • Minor, GCS ≥ 13.

Tracheal intubation and severe facial/eye swelling or damage make it impossible to test the verbal and eye responses. In these circumstances, the score is given as 1 with a modifier attached (e.g. "E1c", where "c" = closed, or "V1t" where t = tube). Often the 1 is left out, so the scale reads Ec or Vt. A composite might be "GCS 5tc". This would mean, for example, eyes closed because of swelling = 1, intubated = 1, leaving a motor score of 3 for "abnormal flexion".

The GCS has limited applicability to children, especially below the age of 36 months (where the verbal performance of even a healthy child would be expected to be poor). Consequently, the Paediatric Glasgow Coma Scale was developed for assessing younger children.

Glasgow Coma Scale (GCS) was developed by Sir Graham Teasdale, Emeritus Professor of Neurology, University of Glasgow.

History

Much of the below section is based on a recent article[10] that summarized period publications as well as personal communications with Dr. Graham Teasdale.

During the 1960s, assessment and management of head injuries became a topic of interest. The number of head injuries was rapidly increasing, in part because of increased use of automobiles. Also, doctors recognized that after head trauma, many patients had poor recovery. This led to a concern that patients were not being assessed or medically managed correctly.[11] Appropriate assessment is a critical step in medical management for several reasons. First, a reliable assessment allows doctors to provide the appropriate treatment. Second, assessments let doctors keep track of how a patient is doing, and intervene if the patient is doing worse. Finally, a system of assessment allows researchers to define categories of patients. This makes it possible to determine which treatments are best for different types of patients.

A number of assessments for head injury (“coma scales”) were developed, though none were widely adopted. Of 13 scales that had been published by 1974, all involved linear scales that defined levels of consciousness.[12][13][14][15][16][17][18][19][20] These scales posed two problems. First, levels of consciousness in these scales were often poorly defined. This made it difficult for doctors and nurses to evaluate head injury patients. Second, different scales used overlapping and obscure terms that made communication difficult.[10]

In this setting, Dr. Bryan Jennett and Dr. Graham Teasdale began work on what became the Glasgow Coma Scale. Based on their experiences, they aimed to make a scale satisfying several criteria. First, it needed to be simple, so that it could be performed without special training. Second, it needed to be reliable, so that doctors could be confident in the results of the scale. Third, the scale needed to provide important information for managing a patient with head injury.[10]

Their work resulted in the 1974 publication of the first iteration of the GCS.[1] The original scale involved three exam components (eye movement, motor control, and verbal control). These components were scored based on clearly defined behavioral responses. Clear instructions for administering the scale and interpreting results were also included. The original scale is identical to the current scale except for the motor assessment. The original motor assessment included only five levels, combining "flexion" and "abnormal flexion". This was done because Graham and Teasdale found that many people struggled in distinguishing these two states.[1]

In 1976, Dr. Graham Teasdale updated the motor component of the Glasgow Coma Scale to differentiate flexion movements.[2] This was because trained personnel could reliably distinguish flexion movements. Further research also demonstrated that normal and abnormal flexion have different clinical outcomes.[21] As a result, the six-point motor scale is now considered the standard.

Dr. Graham Teasdale did not originally intend to use the sum score of the GCS components.[10] However, later work demonstrated that the sum of the GCS components, or the Glasgow Coma Score, had clinical significance. Specifically, the sum score was correlated with outcome (including death and disability).[21] As a result, the Glasgow Coma Score is used in research to define patient groups. It is also used in clinical practice as shorthand for the full scale.

The Glasgow Coma Scale was initially adopted by nursing staff in the Glasgow neurosurgical unit.[10] Especially following a 1975 nursing publication, it was adopted by other medical centers.[22] True widespread adoption of the GCS was attributed to two events in 1978.[10] First, Tom Langfitt, a leading figure in neurological trauma, wrote an editorial in Journal of Neurosurgery strongly encouraging neurosurgical units to adoption the GCS score.[23] Second, the GCS was included in the first version of Advanced Trauma Life Support (ATLS), which expanded the number of centers where staff were trained in performing the GCS.[24]

Controversy

The GCS has come under pressure from some researchers who take issue with the scale's poor inter-rater reliability and lack of prognostic utility.[25] Although there is no agreed-upon alternative, newer scores such as the Simplified motor scale and FOUR score have also been developed as improvements to the GCS.[26] Although the inter-rater reliability of these newer scores has been slightly higher than that of the GCS, they have not gained consensus as replacements.[27]

See also

References

Citations
  1. Teasdale, Graham; Jennett, Bryan (1974). "Assessment of Coma and Impaired Consciousness". The Lancet. 304 (7872): 81–84. doi:10.1016/s0140-6736(74)91639-0. ISSN 0140-6736.
  2. Teasdale, G.; Jennett, B. (1976). "Assessment and prognosis of coma after head injury". Acta Neurochirurgica. 34 (1–4): 45–55. doi:10.1007/BF01405862. ISSN 0001-6268. PMID 961490. S2CID 32325456.
  3. Hutchinson’s clinical methods 22nd edition
  4. Iankova, Andriana (2006). "The Glasgow Coma Scale: clinical application in Emergency Departments". Emergency Nurse. 14 (8): 30–5. doi:10.7748/en2006.12.14.8.30.c4221. PMID 17212177.
  5. Teasdale, Graham (2015). "GLASGOW COMA SCALE : Do it this way" (PDF).
  6. "Glasgow Coma Scale".
  7. Borgialli, Dominic A.; Mahajan, Prashant; Hoyle, John D.; Powell, Elizabeth C.; Nadel, Frances M.; Tunik, Michael G.; Foerster, Adele; Dong, Lydia; Miskin, Michelle; Dayan, Peter S.; Holmes, James F. (2016). "Performance of the Pediatric Glasgow Coma Scale Score in the Evaluation of Children With Blunt Head Trauma". Academic Emergency Medicine. 23 (8): 878–884. doi:10.1111/acem.13014. ISSN 1553-2712. PMID 27197686.
  8. Bates' Guide to Physical Examination and History Taking, Twelfth Edition. Lynn S. Bickley. p. 791. ISBN 978-1-4698-9341-9.
  9. "Resources data" (PDF). www.cdc.gov.
  10. Mattei, Tobias A.; Teasdale, Graham M. (2020-02-01). "The Story of the Development and Adoption of the Glasgow Coma Scale: Part I, The Early Years". World Neurosurgery. 134: 311–322. doi:10.1016/j.wneu.2019.10.193. ISSN 1878-8750. PMID 31712114.
  11. Mckissock, Wylie; Taylor, JulienC.; Bloom, WilliamH.; Till, Kenneth (1960). "Extradural Hæmatoma". The Lancet. 276 (7143): 167–172. doi:10.1016/s0140-6736(60)91322-2. ISSN 0140-6736.
  12. "NEUROSURGICAL WATCH SHEET FOR CRANIOCEREBRAL TRAUMA : Journal of Trauma and Acute Care Surgery". LWW. Retrieved 2020-12-14.
  13. Marrubini, M. L. Bozza (1964-04-01). "Resuscitation treatment of the different degrees of unconsciousness". Acta Neurochirurgica. 12 (2): 352–365. doi:10.1007/BF01402103. ISSN 0942-0940.
  14. Fischgold, H.; Schwartz, B. A.; Dreyfus-Brisac, C. (1959-02-01). "Indicateur de l'état de présence et tracés électroencéphalographiques dans le sommeil nembutalique". Electroencephalography and Clinical Neurophysiology (in French). 11 (1): 23–33. doi:10.1016/0013-4694(59)90004-5. ISSN 0013-4694.
  15. "The Neurological Examination of the Comatose Patient". Acta Neurologica Scandinavica. 45 (S36): 5–56. 1969. doi:10.1111/j.1600-0404.1969.tb04785.x. ISSN 1600-0404.
  16. Mollaret, P.; Goulon, M. (1959). "[The depassed coma (preliminary memoir)]". Revue Neurologique. 101: 3–15. ISSN 0035-3787. PMID 14423403.
  17. "Acute Injuries of the Head. By G. F. Rowbotham. Fourth edition. 9⅝ × 6¾ in. Pp. 604, with 271 illustrations. 1964. Edinburgh: E. & S. Livingstone Ltd. £5". British Journal of Surgery. 52 (2): 158–158. February 1965. doi:10.1002/bjs.1800520221.
  18. OMMAYA, A. K.; SADOWSKY, D. (September 1966). "A SYSTEM OF CODING MEDICAL DATA FOR PUNCHED-CARD MACHINE RETRIEVAL". The Journal of Trauma: Injury, Infection, and Critical Care. 6 (5): 605–617. doi:10.1097/00005373-196609000-00006. ISSN 0022-5282.
  19. Overgaard, Jørn; Hvid-Hansen, Ole; Land, Anne-Marie; Pedersen, KnudK.; Christensen, Steen; Haase, Jens; Hein, Ole; Tweed, WilliamA. (September 1973). "PROGNOSIS AFTER HEAD INJURY BASED ON EARLY CLINICAL EXAMINATION". The Lancet. 302 (7830): 631–635. doi:10.1016/S0140-6736(73)92477-X.
  20. Plum, F.; Posner, J. B. (1972). "The diagnosis of stupor and coma". Contemporary Neurology Series. 10: 1–286. ISSN 0069-9446. PMID 4664014.
  21. Teasdale, G.; Murray, G.; Parker, L.; Jennett, B. (1979), Brihaye, J.; Clarke, P. R. R.; Loew, F.; Overgaard, J. (eds.), "Adding up the Glasgow Coma Score", Proceedings of the 6th European Congress of Neurosurgery, Vienna: Springer Vienna, 28 (1), pp. 13–16, doi:10.1007/978-3-7091-4088-8_2, ISBN 978-3-7091-4090-1, PMID 290137, retrieved 2020-12-08
  22. Teasdale, G.; Galbraith, S.; Clarke, K. (1975-06-19). "Acute impairment of brain function-2. Observation record chart". Nursing Times. 71 (25): 972–973. ISSN 0954-7762. PMID 1144086.
  23. Langfitt, Thomas W. (1978-05-01). "Measuring the outcome from head injuries". Journal of Neurosurgery. 48 (5): 673–678. doi:10.3171/jns.1978.48.5.0673. PMID 641547.
  24. Collicott, P. E.; Hughes, I. (1980-03-21). "Training in advanced trauma life support". JAMA. 243 (11): 1156–1159. doi:10.1001/jama.1980.03300370030022. ISSN 0098-7484. PMID 7359667.
  25. Green S. M. (2011). "Cheerio, Laddie! Bidding Farewell to the Glasgow Coma Scale". Annals of Emergency Medicine. 58 (5): 427–430. doi:10.1016/j.annemergmed.2011.06.009. PMID 21803447.
  26. Iver, VN; Mandrekar, JN; Danielson, RD; Zubkov, AY; Elmer, JL; Wijdicks, EF (2009). "Validity of the FOUR score coma scale in the medical intensive care unit". Mayo Clinic Proceedings. 84 (8): 694–701. doi:10.4065/84.8.694. PMC 2719522. PMID 19648386.
  27. Fischer, M; Rüegg, S; Czaplinski, A; Strohmeier, M; Lehmann, A; Tschan, F; Hunziker, PR; Marschcorresponding, SC (2010). "Inter-rater reliability of the Full Outline of UnResponsiveness score and the Glasgow Coma Scale in critically ill patients: a prospective observational study". Critical Care. 14 (2): R-64. doi:10.1186/cc8963. PMC 2887186. PMID 20398274.

General sources
  • Teasdale G, Murray G, Parker L, Jennett B (1979). "Adding up the Glasgow Coma Score". Acta Neurochir Suppl (Wien). 28 (1): 13–6. doi:10.1007/978-3-7091-4088-8_2. ISBN 978-3-7091-4090-1. PMID 290137.
  • Meredith W, Rutledge R, Fakhry SM, Emery S, Kromhout-Schiro S (1998). "The conundrum of the Glasgow Coma Scale in intubated patients: a linear regression prediction of the Glasgow verbal score from the Glasgow eye and motor scores". J Trauma. 44 (5): 839–44, discussion 844–5. doi:10.1097/00005373-199805000-00016. PMID 9603086.
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