Glasgow Coma Scale (GCS)

Purpose of the measure

The Glasgow Coma Scale (GCS) was developed to describe the depth and duration of impaired consciousness or coma. In this measure, three aspects of behaviour are independently measured: motor responsiveness, verbal performance, and eye opening. The GCS can be used with individuals with traumatic brain injury, stroke, non-traumatic coma, cardiac arrest, and toxic ingestions.

Available versions

The GCS was published in 1974 by Graham Teasdale and Bryan J. Jennett. In 1976, Teasdale and Jennett distinguished between “normal” and “abnormal” flexion, which increased the “best motor response” item by one point.

Features of the measure

Items:
The GCS is comprised of three components: 1) Best eye response, which is believed to indicate whether the arousal mechanisms in the brainstem are active; 2) Best verbal response, which is believed to be the most common definition of the end of a coma, or the recovery of consciousness; and 3) Best motor response, which is thought to be associated with central nervous system functioning. Each component has a number of grades starting with the most severe. Best eye response has 4 grades; Best verbal response has 5 grades; Best motor response has 6 grades.

Best eye response (E)

  1. No eye opening
  2. Eye opening in response to pain (patient responds to pressure on the patient’s
    fingernail bed; if this does not elicit a response, supraorbital and sternal pressure or rub may be used).
  3. Eye opening to speech (not to be confused with an awaking of a sleeping person; such patients receive a score of 4, not 3).
  4. Eyes opening spontaneously

Best verbal response (V)

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

Best motor response (M)

  1. No motor response
  2. Extension to pain (decerebrate response: rigid adduction and extension of the arms, legs stiffly extended, downward pointing of the toes, backward arching of the head, wrists pronated and fingers flexed).
  3. Flexion in response to pain (decorticate response: arms flexed, or bent inward on
    the chest, the hands are clenched into fists, and the legs extended).
  4. Withdraws from pain (pulls part of body away when pinched; normal flexion)
  5. Localizes to pain (purposeful movements towards changing painful stimuli; e.g. hand crosses mid-line and gets above clavicle when supra-orbital pressure applied).
  6. Obeys commands (the patient does simple things as asked).

Scoring:
In the GCS, each of the component scores as well as the sum of the components are considered. The total score is out of 15-points, with lower scores indicating more severe impairment. The lowest possible GCS total score is 3, indicating deep coma or death, and the highest possible score is 15, indicating a fully awake individual. The total score of the GCS is calculated by summing E + V + M.

The score is expressed in the form GCS (total score) = score on E + score on V + score on M. For example, GCS 9 = E2 V4 M3 indicates a total score of 9, a score of 2 on Best eye response (E), a score of 4 on Best verbal response (V), and a score of 3 on Best motor response (M).
Note: For a patient who is intubated, the V is expressed as V intubated.

Interpretation of the GCS total score is as follows:

  • Minor head injury = 13-15
  • Moderate head injury = 9-12
  • Severe head injury (coma) = 8 or less

Time:
Not reported.

Subscales:
The GCS has 3 subscales: Best eye response, Best motor response, and Best verbal
performance.

Equipment:
Only a pencil and the test are needed.

Training of administrator:
Although no training is required to administer the GCS, one study examined whether the GCS can be used reliably and accurately by inexperienced examiners and found that experienced medical personnel can use the measure with extremely high levels of accuracy and reliability, but inexperienced examiners may create significant errors, especially in the intermediate levels of consciousness, when the detection of neurologic changes is critical to patient monitoring (Rowley & Fielding, 1991). Thus, it is recommended that the inexperienced examiner be supervised by an expert when completing the GCS.

Alternative form of the GCS

The GCS cannot be used with children, especially below the age of 36 months. This is due to the verbal performance component which is likely to be poor in even a healthy child. Thus, the Pediatric Glasgow Coma Scale (Reilly, Simpson, Sprod, & Thomas, 1988) was developed as an alternative to the GCS.

The Pediatric Glasgow Coma Scale can be obtained at the following website:

https://www.mdcalc.com/pediatric-glasgow-coma-scale-pgcs

Client suitability

Can be used with:

The GCS can be used with clients with stroke. However, the National Institutes of Health Stroke Scale (NIHSS), developed specifically for use with a stroke population may be a more useful assessment of consciousness in this population.

Should not be used with:

    • Clients with dysphasia, aphasia, and clients who are intubated will have a reduced score on the verbal response scale resulting in a reduced total GCS score but a normal level of consciousness. This should be taken into account when interpreting the GCS results in these individuals. Although it has been suggested that the verbal score be omitted in these clients, and an 8-level (3 to 10) modified GCS be used (Prasad, 1996; Prasad & Menon, 1998), the results of a larger study has suggested that the verbal subscale still be included because it adds important prognostic information (Weir, Bradford, & Lees, 2003).
    • In clients with hemiparesis, ensure that the motor scale is being applied to the less affected arm so that a “best” response can be obtained.
    • The GCS should be administered prior to administration of a sedative or paralytic agent, or after these drugs have been metabolized. Airway, breathing, and circulation should be assessed and stabilized prior to administering the GCS.
In what languages is the measure available?

The GCS has been translated into Chinese and is available online at the following
website: http://www.coma.ulg.ac.be/medical/acute.html