1.2 The Glasgow Coma Scale

1.2.1 Description, Strengths and Weaknesses

Describe the Glasgow Coma Scale (GCS).

  • GCS score is a quick, simple and objective tool used during the initial examination to estimate severity of TBI.
     
  • The assessment is based on eye opening, verbal response, and motor response.
     
  • The rating scale consisting of 15 items in three basic categories: motor response (6 items), verbal response (5 items) and eye opening (4 items).
  • The Glasgow Coma Scale (GCS) is a quick, simple and objective score to be used during the initial examination to estimate severity of TBI. The assessment is based on eye opening, verbal response, and motor response.
     
  • The rating scale consisting of 15 items in three basic categories: motor response (6 items), verbal response (5 items) and eye opening (4 items)1.
     
  • The lowest total score 3 is likely fatal damage, especially if both pupils fail to respond to light and oculovestibular responses are absent.
     
  • The score < 8 is typically regarded as coma 5

     

  • Other categorical divisions are: scores of 13 – 15 represent mild injury, scores of 9 – 12 represent moderate injury and scores of 8 or less represent severe injury 1.

Appendix: The Glasgow Coma Scale

 

What are the strengths of the GCS?

  • Simple, straightforward and brief bedside assessment.
     
  • The most familiar, most widely used instrument in the assessment of level of consciousness.
     
  • Established categories related to the presence of coma and severity of injury.
     
  • Significant predictor of outcome following head injury.
     
  • Can be used by various groups of healthcare professionals regardless of level of education or ICU experience.

What are the limitations of the GCS?

  • The application of painful stimulus is controversial.
     
  • Assessment of all components is comprised by aggressive, early interventions such as intubation and sedation.
     
  • Use of global score may result in a loss of information that adversely affects the predictive accuracy of the GCS.
     
  • Motor response has the greatest influence on the summary.
     
  • Individuals with the same GCS scores in varying permutations can have significantly difference risks for mortality.
     
  • Lack of experience and variability may result in inaccurate assessment.

1.2.2   Glasgow Coma Scale as a Predictor of Outcome

Is the Glasgow Coma Scale as determined in the field predictive of outcome?

  • Higher initial GCS scores tend to predict better recovery.
     
  • However, prediction of prognosis and severity may be improved by considering the CT scan results and other factors.
     
  • Hypoxia and hypotension can decrease the GCS; therefore, GCS values after resuscitation from cardiopulmonary insults are more specific.
     
  • Sedative medicationscan decrease GCS values and should be used only after full neurological evaluation.5

The GCS score has been shown to have a significant correlation with outcome following severe TBI, both as the sum score 6;7 or as just the motor component 6;8-10.

 

For a more detailed discussion of the GCS please see ERABI/Assessment of Outcomes Following Acquired/Traumatic Brain Injury.