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Glasgow Coma Scale (GCS)

Glasgow Coma Scale — assess level of consciousness in acute brain injury. Always report components separately (E + V + M). GCS ≤ 8 indicates severe injury; airway protection strongly indicated.

Eye Opening (E)

Verbal Response (V)

Motor Response (M)

Pupil Reactivity (optional — for GCS-P)

Guidelines & Evidence

Clinical Details

Section 1

When to Use

Any patient with impaired or altered consciousness — traumatic or non-traumatic aetiology

Acute traumatic brain injury (TBI) — initial triage, severity classification, and serial monitoring

Non-traumatic causes: metabolic encephalopathy, DKA, endocrine crises, CO poisoning, severe intoxication

Subarachnoid haemorrhage — incorporated into WFNS grading scale

ICU monitoring — component of APACHE II and SOFA scores

Guiding airway decisions: GCS ≤ 8 indicates high risk of airway compromise; intubation strongly considered

Prehospital triage and inter-facility transfer decisions

When NOT to Use

Patients under neuromuscular blockade — scale is invalid; do not score

Active deep sedation — score is unreliable; assess before sedating where possible

Isolated spinal cord injury or cauda equina — arousability/awareness are unaffected

Differentiating disorders of consciousness (vegetative vs. minimally conscious state) — GCS was not designed for this; FOUR score or specialist assessment preferred

Note: GCS can still be applied in intoxication, but with caution — impaired consciousness should be attributed to brain injury until excluded

Section 2

Formula & Logic

Scoring Components

Eye Opening (E)	Spontaneous	4
	To sound	3
	To pressure	2
	None	1
	Not testable (NT)	—
Verbal (V)	Oriented	5
	Confused	4
	Inappropriate words	3
	Sounds only	2
	None	1
	Not testable (NT)	—
Motor (M)	Obeys commands	6
	Localizes	5
	Normal flexion	4
	Abnormal flexion	3
	Extension	2
	None	1
	Not testable (NT)	—

Total Score

GCS = E + V + M Range: 3 (lowest) to 15 (normal) Always report components separately — e.g. GCS 10 = E3 V4 M3 Do not report a total score if any component is not testable (NT)

Severity Classification

Mild TBI	13 – 15
Moderate TBI	9 – 12
Severe TBI	3 – 8

GCS-Pupils Score (GCS-P)

GCS-P = GCS − PRS PRS (Pupil Reactivity Score): Both pupils unreactive → PRS = 2 One pupil unreactive → PRS = 1 Both pupils reactive → PRS = 0 GCS-P range: 1 – 15 GCS-P ≤ 8 = severe injury (same threshold as GCS) Validated to outperform GCS alone in predicting mortality after severe TBI (AUC 0.77 vs 0.69)

Verbal Imputation (Intubated Patients)

When verbal component is not testable, estimate V from Eye + Motor (EM) sum: EM 2–6 → add 1 EM 7 → add 2 EM 8–9 → add 4 EM 10 → add 5 For prognostic modelling only — not a substitute for full assessment

Section 3

Pearls/Pitfalls

Assessment Sequence

Check: identify any factors that could interfere — intubation, sedation, orbital trauma, language barrier, pre-existing neurological deficit

Observe: note any spontaneous behaviours before stimulation (eyes open? spontaneous movement?)

Stimulate: start with verbal — normal voice, then loud voice; only escalate to noxious stimulus if no response

Rate: score the best, consistent response on either side of the body

Noxious Stimulus — Recommended Sites

Trapezius	Grip 4–5 cm of muscle at neck–shoulder junction with thumb and two fingers	Clavicle or high spinal fracture
Supraorbital notch	Thumb pressure in supraorbital groove, ~2–3 cm from nasion	Orbital/facial/skull fracture; glaucoma
Retromandibular (TMJ)	Flat thumb pressure on both condyles at jaw angle	Mandibular fracture; raised ICP (may impair venous return)
Lateral digit	Barrel-of-pen pressure to outer aspect of distal index finger	Peripheral neuropathy (unreliable); not for lower limbs

Stimulus Techniques NOT Recommended

Sternal rub — causes skin tears, abrasions, bruising; not endorsed

Nail bed pressure — damages nail matrix; not endorsed

Nipple twisting — not endorsed

Hand squeeze as a command test — unreliable (may be a spinal reflex, not a cortical response; also only a one-part request)

Stimulus Duration

Apply noxious stimulus for no longer than 1–2 seconds. A nociceptive impulse reaches the brain in under 1 second. Observe for response for up to 30 seconds after releasing — do not prolong the stimulus itself. Minimise the number of applications: eye opening and motor response can be assessed simultaneously with a single stimulus.

Differentiating Motor Responses

Obeys commands	M6	Performs a two-part request (e.g. "Lift right arm and wiggle fingers")
Localizes	M5	Hand crosses chin (to supra-orbital stimulus) or crosses midline (to nail-bed stimulus)
Normal flexion	M4	Rapid elbow flexion, forearm supination, abduction — resembles withdrawal from heat
Abnormal flexion	M3	Elbow flexion with adduction, internal shoulder rotation, wrist flexion (decorticate posturing)
Extension	M2	Arm extension, internal shoulder rotation, supination of forearm (decerebrate posturing)
None	M1	No movement to noxious stimulus, no interfering factor

Key Gotchas

Identical total scores can represent very different clinical states — e.g. GCS 8 can be vegetative, minimally conscious, or confusional. Always report components separately.

Alcohol and benzodiazepines can lower GCS by a mean of up to 1.7 points — screen for intoxication; assume brain injury until excluded

Flaccid ocular muscles may leave eyes open passively — score what you see, but document the context

A change of 1 point in the motor component OR 2 points in total GCS is clinically significant and requires immediate escalation

In patients with pre-existing cognitive impairment or dementia, establish and document the baseline GCS as early as possible

Stimulating the feet can provoke a triple flexion response (upper motor neuron sign) — always assess motor response from the upper limbs only

GCS-P distinguishes mortality risk within GCS 3 patients dramatically: GCS-P 1 = 91% mortality vs GCS-P 3 = 36%

Section 4

Next Steps

Score-Guided Actions

≤ 8	Severe TBI — secure airway (intubation strongly indicated), urgent CT head, neurosurgical input, ICU admission
9–12	Moderate TBI — close monitoring, CT head, consider HDU/ICU depending on trajectory
13–15	Mild TBI — neuroimaging based on local criteria (e.g. NICE head injury rules), observe for deterioration

Serial Monitoring

Document each component separately with time-stamp: e.g. "14:30 — GCS 9 = E2 V3 M4"

A drop of 1 motor point or 2 total points = significant deterioration → escalate immediately

Improving GCS may allow reduced frequency of observations — use clinical judgement

Best practice: two clinicians assess together at handover to confirm inter-rater agreement

Add GCS-P When Possible

Incorporate pupil reactivity to calculate GCS-P (GCS − PRS) in any patient with moderate-severe TBI. GCS-P provides superior mortality discrimination (AUC 0.77) versus GCS alone (AUC 0.69) and is particularly valuable for GCS 3 patients where it stratifies three markedly different mortality cohorts.

Disorders of Consciousness Classification (GCS Subscore Decision Tree)

V = 5 (oriented) → Recovered posttraumatic confusional state (rPTCS)

V = 4 (confused) → Posttraumatic confusional state (PTCS)

V = 3 OR M = 6 → Minimally conscious state with language (MCS+)

M = 5 AND V < 3 → Minimally conscious state without language (MCS−)

V = 2 OR E > 1 (none of above) → Vegetative state / unresponsive wakefulness syndrome

None of the above → Coma

Section 5

Evidence Appraisal

Original Publication

Assessment of coma and impaired consciousness: a practical scale

Teasdale G et al. • Lancet. 1974;The original 14-point GCS, revised to 15 points in 1977 to incorporate abnormal flexion into the motor component

GCS-Pupils Score

Simplifying the use of prognostic information in traumatic brain injury. Part 1: The GCS-Pupils score: an extended index of clinical severity

Brennan PM et al. • J Neurosurg. 2018;GCS-P = GCS − PRS. Derived from IMPACT and CRASH databases. GCS-P range 1–15, threshold ≤ 8 for severe injury

External Validation of GCS-P

External validation of the Glasgow Coma Scale-Pupils in patients with severe head injury

Barea-Mendoza JA et al et al. • Emergencias. 2023;n = 1,551 severe TBI patients. GCS-P AUC 0.77 vs GCS AUC 0.69 for hospital mortality (p < 0.0001). GCS-P 1 = 91.1% mortality vs GCS-P 3 = 35.6% — critical differentiation within GCS 3 patients

International Standard for Education & Practice

The Glasgow Coma Scale: an international standard for education and practice with adults

Cook N et al. • British Journal of Neuroscience Nursing. 2025;Consensus standard from European neuroscience specialists covering assessment method, noxious stimulus application, documentation, and education framework

Reliability

The reliability of the Glasgow Coma Scale: a systematic review

Reith FC et al. • Intensive Care Med. 2016;Systematic review of 53 reports: 85% of higher-quality studies showed substantial reliability (kappa > 0.6). Education and training had a beneficial effect on inter-rater reliability

Statistical Validation

Statistical validation of the Glasgow Coma Score

Moore L et al. • Journal of Trauma. 2006;n = 20,494. GCS AUC 0.833 for in-hospital mortality. Eye component adds no predictive information beyond verbal + motor in the general population. GCS modelled as ordered categorical variable performs poorly — continuous or transformed modelling preferred

Section 6

Literature

History

The Glasgow Coma Scale was introduced in 1974 by neurosurgery professors Graham Teasdale and Bryan Jennett at the University of Glasgow. Originally published as a 14-point scale, it was revised in 1977 to 15 points by adding abnormal flexion to the motor component. A further revision was published in 2014, replacing "pain" with "pressure" as stimulus language and formalising the Not Testable (NT) category. Use became widespread in the 1980s after the first ATLS course endorsed it for all trauma patients. In 1988, the World Federation of Neurosurgical Societies adopted it for subarachnoid haemorrhage grading. The scale is now used in over 75 countries, incorporated into ICD-11, and referenced in over 37,000 publications with a 16.7% average annual citation growth rate since 1974.

Key Milestones

1974	Original 14-point GCS published — Teasdale & Jennett, Lancet
1977	Revised to 15 points — abnormal flexion added to motor component
1980s	ATLS first edition endorses GCS for all trauma patients — widespread adoption begins
1988	WFNS incorporates GCS into subarachnoid haemorrhage grading scale
2014	GCS relaunched — "pressure" replaces "pain"; NT category formalised
2018	GCS-Pupils score (GCS-P) published — Brennan, Murray, Teasdale, J Neurosurg
2023	GCS-P externally validated in Spanish multicenter TBI registry (RETRAUCI, n = 1,551)
2025	International consensus standard for GCS education and practice published — BJNN

Last Comprehensive Review: 2026

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