Medicine:Glasgow Coma Scale

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Short description: Neurological scale for recording the conscious state of a person
Glasgow Coma Scale
Medical diagnostics
MeSHD015600
LOINC35088-4

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

The GCS assesses a person based on their ability to perform eye movements, speak, and move their body. These three behaviours 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 hospitalised 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 is 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]
Test Not Testable (NT): Examples 1 2 3 4 5 6
Eye
(ocular response) 		Severe trauma to the eyes, enucleation Does not open eyes Opens eyes in response to pain[lower-alpha 1] Opens eyes in response to voice Opens eyes spontaneously N/A N/A
Verbal
(oral response) 		Intubation, non-oral language disability, linguistic barrier Makes no sounds Incomprehensible sounds Inappropriate words Confused and disoriented, but able to answer questions Oriented to time, person, and place, converses normally N/A
Motor
(motoric response) 		Paralysis/hemiparesis (acquired causes such as post-stroke, post-neurological injury; congenital/innate such as cerebral palsy) Makes no movements Abnormal extension (decerebrate posture)[lower-alpha 2] Abnormal flexion (decorticate posture) Flexion / Withdrawal from painful stimuli Moves to localise pain 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.[6]

For example, if a person obeys commands only on their right side, they get a 6 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.

Pediatric scoring

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) 1 2 3 4 5 6
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 to 8 are usually considered to be in a coma.[8] Generally, brain injury is classified as:

  • Severe, GCS ≤ 8
  • Moderate, GCS 9–12
  • Minor, GCS ≥ 13.[9]

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 (when 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.

History

Pre-GCS assessment

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 motorised transport. Also, doctors recognised that after head trauma, many patients had poor recovery. This led to a concern that patients were not being assessed or medically managed correctly.[10] 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.[11][12][13][14][15][16][17][18][19] 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.[20]

Origin

In this setting, Bryan Jennett and Graham Teasdale of the University of Glasgow Medical School 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 a head injury.[20]

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 behavioural 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 Jennett and Teasdale found that many people struggled in distinguishing these two states.[1]

Updates to the Glasgow Coma Scale

In 1976, 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.

Teasdale did not originally intend to use the sum score of the GCS components.[20] 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.

Adoption in clinical use

The Glasgow Coma Scale was initially adopted by nursing staff in the Glasgow neurosurgical unit.[20] Especially following a 1975 nursing publication, it was adopted by other medical centres.[22] True widespread adoption of the GCS was attributed to two events in 1978.[20] First, Tom Langfitt, a leading figure in neurological trauma, wrote an editorial in Journal of Neurosurgery strongly encouraging neurosurgical units to adopt the GCS score.[23] Second, the GCS was included in the first version of Advanced Trauma Life Support (ATLS), which expanded the number of centres 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 yet gained consensus as replacements.[27]

See also

References

Citations

  1. ↑ 1.0 1.1 1.2 1.3 "Assessment of coma and impaired consciousness. A practical scale". The Lancet 2 (7872): 81–4. July 1974. doi:10.1016/s0140-6736(74)91639-0. PMID 4136544. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(74)91639-0/fulltext. 
  2. ↑ 2.0 2.1 "Assessment and prognosis of coma after head injury". Acta Neurochirurgica 34 (1–4): 45–55. 1976. doi:10.1007/BF01405862. PMID 961490. 
  3. ↑ "The Glasgow Coma Scale: clinical application in emergency departments". Emergency Nurse 14 (8): 30–5. December 2006. doi:10.7748/en2006.12.14.8.30.c4221. PMID 17212177. 
  4. ↑ "Glasgow Coma Scale: Do it this way". Institute of Neurological Sciences NHS Greater Glasgow and Clyde. 2015. https://www.glasgowcomascale.org/downloads/GCS-Assessment-Aid-English.pdf. 
  5. ↑ "Glasgow Coma Scale". Geeky Medics. 31 October 2018. https://geekymedics.com/glasgow-coma-scale-gcs/. 
  6. ↑ Hutchinson's clinical methods (23rd ed.). India: Elsevier. 2012. ISBN 9788131232880. https://books.google.com/books?id=xYyvYATHxacC. [page needed]
  7. ↑ "Performance of the Pediatric Glasgow Coma Scale Score in the Evaluation of Children With Blunt Head Trauma". Academic Emergency Medicine 23 (8): 878–84. August 2016. doi:10.1111/acem.13014. PMID 27197686. 
  8. ↑ Bates' Guide to Physical Examination and History Taking, Twelfth Edition. Wolters Kluwer. 2017. pp. 791. ISBN 978-1-4698-9341-9. 
  9. ↑ "Resources Data: Glasgow Coma Scale". Centers for Disease Control and Prevention. U.S. Department of Health & Human Services. https://www.cdc.gov/masstrauma/resources/gcs.pdf. 
  10. ↑ "Extradural Hæmatoma". The Lancet 276 (7143): 167–172. 1960. doi:10.1016/s0140-6736(60)91322-2. ISSN 0140-6736. 
  11. ↑ "Neurosurgical watch sheet for craniocerebral trauma". The Journal of Trauma 8 (1): 29–31. January 1968. doi:10.1097/00005373-196801000-00004. PMID 5293834. 
  12. ↑ "Resuscitation treatment of the different degrees of unconsciousness". Acta Neurochirurgica 12 (2): 352–65. 1 April 1964. doi:10.1007/BF01402103. PMID 14293386. 
  13. ↑ "Indicateur de l'état de présence et tracés électroencéphalographiques dans le sommeil nembutalique" (in fr). Electroencephalography and Clinical Neurophysiology 11 (1): 23–33. February 1959. doi:10.1016/0013-4694(59)90004-5. PMID 13630229. 
  14. ↑ "The neurological examination of the comatose patient". Acta Neurologica Scandinavica 45 (S36): 5–56. 1969. doi:10.1111/j.1600-0404.1969.tb04785.x. PMID 5781179. 
  15. ↑ "[The depassed coma (preliminary memoir)"]. Revue Neurologique 101: 3–15. July 1959. PMID 14423403. https://pubmed.ncbi.nlm.nih.gov/14423403. 
  16. ↑ "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" (in en). British Journal of Surgery 52 (2): 158. February 1965. doi:10.1002/bjs.1800520221. https://bjssjournals.onlinelibrary.wiley.com/doi/abs/10.1002/bjs.1800520221. 
  17. ↑ "A system of coding medical data for punched-card machine retrieval. II. As applied to head injuries". The Journal of Trauma 6 (5): 605–17. September 1966. doi:10.1097/00005373-196609000-00006. PMID 5928631. 
  18. ↑ "Prognosis after head injury based on early clinical examination". Lancet 2 (7830): 631–5. September 1973. doi:10.1016/S0140-6736(73)92477-X. PMID 4125617. 
  19. ↑ "The diagnosis of stupor and coma". Contemporary Neurology Series 10: 1–286. 1972. PMID 4664014. https://pubmed.ncbi.nlm.nih.gov/4664014. 
  20. ↑ 20.0 20.1 20.2 20.3 20.4 "The Story of the Development and Adoption of the Glasgow Coma Scale: Part I, The Early Years". World Neurosurgery 134: 311–322. February 2020. doi:10.1016/j.wneu.2019.10.193. PMID 31712114. 
  21. ↑ 21.0 21.1 "Adding up the Glasgow Coma Score". Proceedings of the 6th European Congress of Neurosurgery. 28. Vienna: Springer Vienna. 1979. 13–6. doi:10.1007/978-3-7091-4088-8_2. ISBN 978-3-7091-4090-1. 
  22. ↑ "Acute impairment of brain function-2. Observation record chart". Nursing Times 71 (25): 972–3. June 1975. PMID 1144086. https://pubmed.ncbi.nlm.nih.gov/1144086. 
  23. ↑ "Measuring the outcome from head injuries" (in en-US). Journal of Neurosurgery 48 (5): 673–8. May 1978. doi:10.3171/jns.1978.48.5.0673. PMID 641547. 
  24. ↑ "Training in advanced trauma life support". JAMA 243 (11): 1156–9. March 1980. doi:10.1001/jama.1980.03300370030022. PMID 7359667. 
  25. ↑ "Cheerio, laddie! Bidding farewell to the Glasgow Coma Scale". Annals of Emergency Medicine 58 (5): 427–30. November 2011. doi:10.1016/j.annemergmed.2011.06.009. PMID 21803447. 
  26. ↑ "Validity of the FOUR score coma scale in the medical intensive care unit". Mayo Clinic Proceedings 84 (8): 694–701. August 2009. doi:10.4065/84.8.694. PMID 19648386. 
  27. ↑ "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): R64. 2010. doi:10.1186/cc8963. PMID 20398274. 

General sources

Notes

  1. ↑ 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, as the latter tends to make the patient close their eyes and grimace instead.[3]
  2. ↑ Different guidelines report different evaluation of abnormal extension. While some sources indicate extension at the elbow is sufficient,[4] other sources use the language "decerebrate posturing".[5] 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]



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