Glasgow Koma Skala (GCS)

The Glasgow Coma Scale (GCS) is a clinical tool developed to assess the depth and duration of impaired consciousness and coma following acute brain injury¹. First introduced in 1974 by Graham Teasdale and Bryan Jennett, it has since become the most widely used instrument worldwide for evaluating levels of consciousness².

Target Population

Originally designed for traumatic brain injury (TBI) assessment, GCS is now applied to a broad range of conditions that cause reduced consciousness³, including:

• Stroke (subarachnoid hemorrhage, intracerebral hemorrhage, ischemic stroke)

• Infections (e.g., meningitis, encephalitis)

• Epileptic seizures

• Brain abscesses

• General trauma and ICU patients

• Non-traumatic coma

• Drug overdose or poisoning³

The scale can be administered pre-hospital, upon emergency admission, and repeatedly during hospitalization, enabling monitoring of changes in consciousness over time³.

Modified versions include:

• Glasgow Coma Scale – Extended (GCS-E): Includes an amnesia scale to avoid premature discharge of mild TBI patients⁴.

• Pediatric adaptations: Motor scale scoring is especially useful for older children and preverbal children with blunt trauma⁵.

Test Procedure

GCS follows four structured steps for evaluation⁷:

1. Check for factors that may influence response (e.g., medication, alcohol, hypoxia).

2. Observe for spontaneous behavior or responses to stimuli.

3. Stimulate using fingertip pressure, trapezius squeeze, or supraorbital pressure to elicit a response.

4. Evaluate by scoring responses in three categories: eye opening, verbal response, and motor response.

GCS Components and Scoring

GCS evaluates three domains, with higher scores indicating better neurological function⁷:

Eye Opening (E) (1–4 points):

• 4 = Spontaneous

• 3 = To verbal command

• 2 = To pain

• 1 = No response

Verbal Response (V) (1–5 points):

• 5 = Oriented and coherent

• 4 = Confused conversation

• 3 = Inappropriate words

• 2 = Incomprehensible sounds

• 1 = No response

Motor Response (M) (1–6 points):

• 6 = Follows commands

• 5 = Localizes pain

• 4 = Withdraws from pain

• 3 = Abnormal flexion (decorticate)

• 2 = Abnormal extension (decerebrate)

• 1 = No response

Total score = E + V + M (range: 3–15).

Score Interpretation

• Mild brain injury: GCS 13–15 (awake, may be confused but follows commands).

• Moderate brain injury: GCS 9–12 (drowsy, opens eyes, localizes pain).

• Severe brain injury: GCS 3–8 (often comatose, may show abnormal posturing)¹⁰.

NICE Clinical Guidelines

The National Institute for Health and Care Excellence (NICE) recommends⁸:

• GCS < 15: Monitor every 30 minutes until GCS reaches 15.

• At GCS = 15: Monitor every 30 minutes for 2 hours, then hourly for 4 hours, then every 2 hours.

• If GCS drops below 15: Resume 30-minute monitoring.

Evidence and Psychometric Properties

Reliability

• Inter-rater reliability (total GCS): p = 0.86¹¹.

• Subscale reliability:

  • Eye score: p = 0.76

  • Verbal score: p = 0.67

  • Motor score: p = 0.81

• Systematic review: Individual components are more reliable than the total score, with motor response (κ = 0.94) being the most reliable¹³.

Validity

• Challenge: Use in sedated or intubated patients can result in inaccurate scoring¹⁴.

• Motor score is the strongest predictor of survival¹⁶.

• In intubated patients, excluding verbal response does not reduce prognostic accuracy (r = 0.90 for verbal, r = 0.97 for total)¹⁵.

Sensitivity and Specificity

• Sensitivity: 56.1% (misses some severe cases).

• Specificity: 82.2% (low false positives)¹⁷.

Prognostic Value

• GCS at 24h post-injury: OR = 0.40 for hospital mortality.

• GCS at 72h post-injury: OR = 0.59 (better prediction)¹⁸.

• Functional outcome prediction:

  • 71% accuracy for functional independence.

  • Moderate correlations with Disability Rating Scale (-0.28) and Cognitive FIM (0.37)¹⁹.

Conclusion

The Glasgow Coma Scale is a standardized, internationally recognized tool for assessing consciousness in brain injury and coma. It demonstrates high specificity, good inter-rater reliability, and strong prognostic value of the motor component. However, limitations exist, particularly in intubated patients.

GCS remains an essential tool for monitoring neurological status but should be used in conjunction with other assessments for a comprehensive evaluation.

Sources:

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9. GCS at 40. Glasgow Coma Scale at 40 | The new approach to Glasgow Coma Scale assessment. Available from: https://www.youtube.com/watch?v=v6qpEQxJQO4

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18. McNett M, Amato S, Gianakis A, Grimm D, Philippbar S, Belle J et al. The FOUR Score and GCS as predictors of outcome after traumatic brain injury. Neurocritical Care 2014;21(1):52-57. doi:10.1007/s12028-013-9947-6

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