What is the Glasgow Coma Scale?
The Glasgow Coma Scale (GCS) is the most widely used tool for assessing level of consciousness, originally described by Teasdale and Jennett in The Lancet in 1974. It scores three independent components — eye opening, verbal response, and motor response — and is used across emergency medicine, neurosurgery, intensive care, and prehospital settings to track conscious level over time and communicate it consistently between clinicians.
How to calculate GCS
Add the best response observed in each of the three categories:
| Eye Opening (1–4) | Verbal Response (1–5) | Motor Response (1–6) |
|---|---|---|
| 4 = Spontaneous | 5 = Oriented | 6 = Obeys commands |
| 3 = To voice | 4 = Confused | 5 = Localising |
| 2 = To pain | 3 = Inappropriate words | 4 = Withdrawal |
| 1 = No response | 2 = Incomprehensible | 3 = Flexion (decorticate) |
| 1 = None | 2 = Extension (decerebrate) | |
| 1 = No response |
The total ranges from 3 (deep coma) to 15 (fully alert), and is usually reported with the breakdown, e.g. "GCS 13 (E3 V4 M6)" — the breakdown matters as much as the total, since the same total can come from very different combinations.
Interpretation
| Score | Severity | Note |
|---|---|---|
| 13–15 | Mild | Routine monitoring |
| 9–12 | Moderate | Close neurological monitoring; consider CT |
| 3–8 | Severe | Intubation often indicated (GCS ≤8) |
Special considerations
Intubated patients can't be scored verbally — this is usually recorded as "VT" (verbal, tube) rather than assigning a numeric verbal score. A separate, age-adapted Pediatric GCS exists for infants and young children who can't yet follow the standard verbal and motor commands.
References
Teasdale G, Jennett B. Assessment of coma and impaired consciousness: a practical scale. The Lancet. 1974.
See also: Cranial Nerves OSCE Guide.