Question 22

College Answer

General introduction

The GCS is a neurological scoring system used to assess conscious level after head injury. It is now usually scored out of 15 and is comprised of 3 categories, best eye response, best vocal response and best motor response. It has recently been used to categorise traumatic brain injury into mild, moderate and severe.

Advantages

It is the most widely recognised of all conscious level scoring systems in the world. It is quick and reproducible. It is 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.

Disadvantages

• It fails to incorporate brain-stem reflexes
• It is unreliable in patients in the middle range of 9-12
• There is poor inter-observer reliability
• It is difficult for untrained staff to apply properly, especially distinguishing between M= 3,4,5
• Variation in scoring V in intubated patients
• M score does not factor in unilateral pathology

Controversy in the literature

• There is little evidence demonstrating validity and reliability of the GCS
• There are numerous other neurological scoring systems that have demonstrated greater validity and reliability e.g. the FOUR score
• Debates within the literature as to when GCS can be first applied after TBI, i.e when is the first post-resuscitation GCS applicable

How I use GCS in my practice.

• A statement of when and how GCS is used in TBI
• An appreciation of the need for all staff on the intensive Care Unit to be aware of the same criteria for its use and application
• An appreciation that on-going education is needed to make sure that it is used correctly

Discussion

The college answer is fairly comprehensive.

A thorough discussion of the advantages and disadvantages of the GCS can be found elsewhere.

It forms a part of the greater topic, the Assessment of the Unconscious Patient.

In brief, the major disadvantages are:

• It was never meant as an assessment tool for trauma.
• It is unreliable in patients in the middle range of 9-12
• People dont know how to use it correctly.
• It has high inter-observer variability
• It is inadequate to assess higher cortical functions.
• It is inadequate to assess brainstem reflexes.
  • Therefore, it cannot be used as a trigger for intubation (GCS of 8)
• The eye score is unreliable if the eyes are damaged.
• The eye score may be meaningless (it is possible to score an E4 even if one is braindead)
• The total score is meaningless:
  • The components are more important individually
  • Depending on the individual component score, the prognosis may be very different for patients with the same total score.
• It is affected by drugs and alcohol.
  • However, it is still used in assessing drug overdose patients.
• It is affected by language barriers
• Intubation makes a mockery of its verbal conponent
• It needs to be modified for use in young children.

The article by Green (2011) is the definitive resource on this topic, as it is a comprehensive review, in spite of being one person's opinion. 

Green, Steven M. "Cheerio, laddie! Bidding farewell to the Glasgow Coma Scale." Annals of emergency medicine 58.5 (2011): 427-430.

Gill, Michelle R., David G. Reiley, and Steven M. Green. "Interrater reliability of Glasgow Coma Scale scores in the emergency department." Annals of emergency medicine 43.2 (2004): 215-223.

Riechers, Ronald G., et al. "Physician knowledge of the glasgow coma scale."Journal of neurotrauma 22.11 (2005): 1327-1334.