Glasgow Coma Scale

Article Author:
Shobhit Jain
Article Editor:
Lindsay Iverson
Updated:
10/27/2018 12:31:36 PM
PubMed Link:
Glasgow Coma Scale

Introduction

The Glasgow Coma Scale was first published in 1974 at the University of Glasgow by neurosurgery professors Graham Teasdale and Bryan J. Jennett. The Glasgow Coma Scale (GCS) is used to objectively measure coma severity in all acute medical and trauma patients. The scale measures the mental status of patients according to three categories of responsiveness: eye opening, motor, and verbal responses.

Glasgow Coma Scale use became more widespread in 1980 when the first edition of the Advanced Trauma and Life Support recommended its use in all trauma patients. Additionally, the World Federation of Neurosurgical Societies (WFNS) used it in its scale for grading patients with subarachnoid hemorrhage in 1988. The Glasgow Coma Scale has since been incorporated in numerous clinical guidelines and scoring systems for victims of trauma or critical illness. This includes patients of all ages, including the preverbal children. Additionally, the Glasgow Coma Scale is used in more than 75 countries.

Function

Scoring and Parameters

The Glasgow Coma Scale is scored between three and 15, three being the worst and 15 being the best. 

It is divided into three parameters: best eye response (E), best verbal response (V) and best motor response (M).

Modification of the Glasgow Coma Scale to pediatric patients has been a vital advancement in the assessment of verbal and pre-verbal children. Best eye response (4)

  1. No eye opening
  2. Eye opening to pain
  3. Eye opening to verbal command
  4. Eyes open spontaneously

Best verbal response (5)

  1. No verbal response
  2. Incomprehensible sounds
  3. Inappropriate words
  4. Confused
  5. Orientated

Best motor response (6)

  1. No motor response.
  2. Abnormal extension to pain (decerebrate posturing)
  3. Abnormal flexion to pain (decorticate posturing)
  4. Withdrawal from pain
  5. Localizing pain
  6. Obeys commands

Application of Glasgow Coma Scale in Pediatrics

The Glasgow Coma Scale can be used with to children older than 5 years with no modification. Younger children and infants are not able to provide the necessary verbal responses for the practitioner to use the scale to assess their orientation or obey the commands to evaluate their motor response. A Pediatric Glasgow Coma Scale was therefore described in Adelaide in which responses were modified. Below are commonly used versions for use in children.

Children less than 2 years old (pre-verbal)

Best eye response (4)

  1. No eye opening
  2. Eye opening to pain
  3. Eye opening to verbal command
  4. Eyes open spontaneously

Best verbal response (5)

  1. None
  2. Moans in response to pain
  3. Cries in response to pain
  4. Irritable/cries
  5. Coos and babbles

Best motor response (6)

  1. No motor response.
  2. Abnormal extension to pain (decerebrate posturing)
  3. Abnormal flexion to pain (decorticate posturing)
  4. Withdrawal to pain
  5. Withdraws to touch
  6. Moves spontaneously and purposefully

Children greater than 2 years old (verbal)

Best eye response (4)

  1. No eye opening
  2. Eye opening to pain
  3. Eye opening to verbal command
  4. Eyes open spontaneously

Best verbal response (5)

  1. None
  2. Incomprehensible sounds
  3. Incomprehensible words
  4. Confused
  5. Oriented/Appropriate

Best motor response (6)

  1. No motor response.
  2. Abnormal extension to pain (decerebrate posturing)
  3. Abnormal flexion to pain (decorticate posturing)
  4. Withdrawal to pain
  5. Localizes to pain
  6. Obeys commands

The score is expressed as the sum of the scores as well as the individual elements. For example, a score of 10 might be expressed as GCS10 = E3V4M3.

Issues of Concern

The following factors may interfere with the Glasgow Coma Scale assessment:

  1. Pre-existing factors
    • Language barriers
    • Intellectual or neurological deficit
    • Hearing loss or speech impediment
  2. Effects of current treatment
    • Physical (e.g., intubation): If a patient is intubated and unable to speak, they are evaluated only on motor and eye-opening response and the suffix T is added to their score to indicate intubation.
    • Pharmacological (e.g., sedation) or paralysis: If possible, the clinician should obtain the score before sedating the patient.
  3. Effects of other injuries or lesions
    • Orbital/cranial fracture
    • Spinal cord damage
    • Hypoxic-ischemic encephalopathy after cold exposure

There are instances when the Glasgow Coma Scale cannot be obtained despite efforts to overcome the issues listed above. It is important that the total score is not reported without testing and including all of the components because the score will be low and could cause confusion.

Clinical Significance

The Glasgow Coma Scale is frequently used for field triage decisions, including emergent management such as securing the airway, to the determine the proper destination for a patient transfer. Glasgow Coma Scale also is used in the acute care settings as a widely applied scoring system for all trauma patients. Glasgow Coma Scale as a mental status assessment method has been adopted into numerous guidelines and assessment scores. This includes trauma guidelines (such as Advanced Trauma Life Support), intensive care scoring systems (APACHE II, SOFA) and Advanced Cardiac Life Support. Serial Glasgow Coma Scale measurements also have value in the evaluation of the clinical course of a patient. In addition to blunt traumatic brain injury, Glasgow Coma Scale has been linked to the prognosis for several nontraumatic conditions, including subarachnoid hemorrhage and bacterial meningitis.

The use of Glasgow Coma Scale as an accurate marker for clinically important traumatic brain injury (i.e., injury requiring neurosurgical intervention, intubation for over 24 hours, hospitalization for more than two nights, or causing death) has been thoroughly established in both preverbal and verbal pediatric patients. 

Traumatic brain injury is often classified as follows: 

  • Severe, with GCS 3 to 8
  • Moderate, with GCS 9 to 12
  • Mild, with GCS 13 to 15

Glasgow Coma Scale Pupils Score

The Glasgow Coma Scale Pupils Score (GCS-P) was described by Paul Brennan, Gordon Murray, and Graham Teasdale in 2018 as a strategy to combine the two key indicators of the severity of traumatic brain injury into a single simple index. 

The GCS-P is calculated by subtracting the Pupil Reactivity Score (PRS) from the Glasgow Coma Scale (GCS) total score:

  • GCS-P = GCS – PRS

The Pupil Reactivity Score is calculated as follows.

Pupils unreactive to light - Pupil Reactivity Score

  • Both pupils - 2
  • One pupil - 1
  • Neither pupil - 0

Other Issues

Some authors have raised a concern about poor inter-rater reliability and lack of prognostic utility of the Glasgow Coma Scale. Although there is no agreed-upon alternative, newer scores such as the FOUR score have also been developed as improvements to the Glasgow Coma Scale. "FOUR" in this context is an acronym for "Full Outline of UnResponsiveness." It was developed by Dr. Eelco F.M. Wijdicks and colleagues at the Mayo Clinic in Rochester, Minnesota.

The FOUR Score is a 17-point scale (with potential scores ranging from 0 to 16). Decreasing FOUR Score is associated with worsening level of consciousness.

  • The FOUR Score assesses four domains of neurological function: eye responses, motor responses, brainstem reflexes, and breathing pattern.
  • The FOUR score may have a better sensitivity, specificity, accuracy and positive predictive value as compared to the Glasgow Coma Scale.