Eye opening (E, 1–4). 4 spontaneous · 3 to sound · 2 to pressure · 1 none · NT not testable. The 2014 revision of the scale replaced "to speech" with "to sound" and, importantly, replaced a painful stimulus with pressure — supraorbital pressure, trapezius squeeze or sternal rub — because pain cannot be inferred from a motor response in a patient with a spinal injury.

Verbal response (V, 1–5). Adult: 5 orientated · 4 confused · 3 words but not coherent · 2 sounds but no words · 1 none. Pre-verbal child: 5 smiles, oriented to sounds, follows objects, interacts · 4 cries but consolable · 3 inconsistently consolable, moaning · 2 inconsolable, agitated · 1 none.

Motor response (M, 1–6). 6 obeys commands · 5 localising · 4 normal flexion (withdrawal) · 3 abnormal flexion (decorticate) · 2 extension (decerebrate) · 1 none. The motor component is the single most predictive of the three, which is why it is the one carried into abbreviated scores.

Total 3–15. 15 is normal; 13–14 mild brain injury; 9–12 moderate; 8 or below severe, and the "less than 8, intubate" heuristic comes from that band — though the decision is clinical, not arithmetic. Record the components, never the total alone: "GCS 8" tells the next clinician nothing that "E2 V2 M4" does not tell them better.

Why NT is not zero. A component scored 1 means you tested it and got nothing. A component scored NT means you could not test it — an intubated patient has no verbal response to score, a swollen eye cannot be opened, a limb in a splint cannot localise. Adding zero for an untestable component produces a falsely low total that looks like a deteriorating patient. This tool reports NT components explicitly and refuses to sum them, writing the total as, for example, "E4 V-NT M6 (maximum possible with the testable components is 10)" instead of a number that means something else. If you need a single comparable figure for an intubated patient, document the tube and use the motor score.

Deterioration thresholds (NICE head injury guidance). A drop of 1 or more in the total score, a drop of 1 or more in the motor score, or a drop of 2 or more in the verbal or eye score counts as deterioration and needs urgent reassessment. A single GCS is a snapshot; the trend is the clinical information.

Reliability limits. GCS is confounded by sedation, intubation, alcohol and drugs, language barrier, deafness, pre-existing dementia or learning disability, hypoxia, hypoglycaemia and hypothermia — record those alongside it. Inter-observer agreement is only moderate, which is why the same person should reassess where possible and why the structured assessment matters more than the number. It does not detect focal neurological signs: pupil size and reactivity, limb weakness and focal seizures need separate examination, and a GCS of 15 does not exclude an intracranial bleed. In children under about 5 the verbal and motor components are developmentally limited, so the paediatric scale is an adaptation, not an equivalent measurement.

Disclaimer. A scoring aid for qualified clinicians — not medical advice and not a substitute for the examination. Sources: Teasdale, Maas et al., The Lancet Neurology 2014 (40-year revision) · NICE NG232 head injury. Last reviewed: 2026-09-21.