How the Glasgow Coma Scale is calculated
GCS assesses level of consciousness across three components — eye opening, verbal response, and motor response — each scored independently and summed.
| Eye opening (1–4) | Verbal response (1–5) | Motor response (1–6) |
|---|---|---|
| 4 = Spontaneous 3 = To voice 2 = To pain 1 = None | 5 = Oriented 4 = Confused 3 = Inappropriate words 2 = Incomprehensible sounds 1 = None | 6 = Obeys commands 5 = Localises pain 4 = Withdraws from pain 3 = Abnormal flexion 2 = Extension 1 = None |
If the patient is intubated, verbal response can't be assessed — this is recorded as "T" (e.g. "9T") rather than assigning a numeric verbal score.
Normal values & severity
| Total GCS | Severity |
|---|---|
| 15 | Normal / fully alert |
| 13 – 15 | Mild traumatic brain injury |
| 9 – 12 | Moderate traumatic brain injury |
| 3 – 8 | Severe traumatic brain injury |
Clinical use
GCS is used to grade the severity of traumatic brain injury, track neurological trend over time, and trigger key decisions — most notably, a score of 8 or below is a widely used threshold for considering airway protection ("GCS ≤8, intubate"), because airway reflexes are often unreliable at this level. It's also used more broadly to describe consciousness in non-trauma settings (e.g. sepsis, overdose, metabolic encephalopathy), though the AVPU scale is a faster screening alternative when full GCS isn't practical.
Frequently asked questions
What is the Glasgow Coma Scale?
A 3–15 point scale assessing level of consciousness across eye opening, verbal response, and motor response — used to grade traumatic brain injury severity and track neurological status over time.
What GCS score requires intubation?
A GCS of 8 or below is a widely used threshold for considering airway protection ("GCS ≤8, intubate"), since airway reflexes are often unreliable at this level — though the decision always depends on the full clinical picture.
What does a GCS of 15 mean?
15 is the maximum score, indicating a fully alert, oriented patient with normal eye, verbal, and motor responses.
How is GCS scored if a patient is intubated?
Verbal response can't be assessed in an intubated patient, so it's recorded as "T" (e.g. "9T") instead of a numeric verbal score, and the total isn't given a numeric severity category on verbal grounds alone.
References
- Teasdale G, Jennett B. Assessment of coma and impaired consciousness: a practical scale. Lancet. 1974;2:81–84.
- Teasdale G, et al. The Glasgow Coma Scale at 40 years: standing the test of time. Lancet Neurol. 2014;13:844–854.