Quick answer: Score Eye opening (E, max 4), Verbal response (V, max 5), and Motor response (M, max 6). Add all three for a total GCS of 3–15. A GCS of 8 or below indicates severe TBI and the threshold for intubation consideration. Express as total and components: e.g., GCS 11 = E3V3M5. Use our free GCS calculator for instant scoring and EMR documentation.
What Is the Glasgow Coma Scale?
The Glasgow Coma Scale (GCS) is a standardised neurological assessment tool that quantifies a patient’s level of consciousness by evaluating three components: eye opening, verbal response, and motor response. Developed by Graham Teasdale and Bryan Jennett at the University of Glasgow in 1974 and published in The Lancet, the GCS has become the most widely used and cited consciousness assessment tool in clinical medicine, with over 37,000 citations in the global literature.
The GCS was originally developed to standardise the description of coma and impaired consciousness after traumatic brain injury (TBI), but its application has expanded to any condition causing altered consciousness — including stroke, metabolic encephalopathy, drug intoxication, hypoxic brain injury, and sepsis-related encephalopathy.
Why Express GCS as Components, Not Just a Total
A total GCS of 8 can arise from many different combinations: E2V2M4, E1V2M5, E1V1M6. Each combination has different clinical significance. Reporting only the total loses critical diagnostic information. Always document individual component scores alongside the total: GCS 8 = E2V2M4.
Complete GCS Scoring — All Three Components
Component 1: Eye Opening (E) — Maximum 4 points
| Score | Response | How to assess |
|---|---|---|
| E4 | Spontaneous | Eyes open without any stimulation. Patient is aware of their environment. |
| E3 | To voice | Eyes open in response to your verbal instruction or normal speech. Do not shout — use normal voice first. |
| E2 | To pain | Eyes open in response to painful stimulus only. Apply central pain (trapezius squeeze or sternal rub) after verbal fails. |
| E1 | None | No eye opening despite voice and pain stimulation. |
| EC (modifier) | Closed — untestable | Eyes cannot be assessed due to periorbital oedema, dressings, or facial trauma. Document as EC and note reason. Do not score as E1. |
Stimulus application rules: Always apply the least invasive stimulus first. Verbal → light touch → central pain (trapezius) → peripheral pain (nail bed pressure). Central pain is preferable for eye and verbal assessment; peripheral pain is better for assessing motor response localisation.
Component 2: Verbal Response (V) — Maximum 5 points
| Score | Response | How to assess |
|---|---|---|
| V5 | Oriented | Patient correctly states their name, where they are, and the approximate date/year. All three must be correct for V5. |
| V4 | Confused | Patient speaks in coherent sentences but is disoriented — may not know date, location, or what happened. Engaged in conversation but incorrect. |
| V3 | Words | Patient produces recognisable single words — may be random, inappropriate, or out of context. Not full sentences. “Help”, “No”, “Pain” — single intelligible words. |
| V2 | Sounds | Produces vocal sounds that are not recognisable as words — moaning, groaning, incomprehensible vocalisations. |
| V1 | None | No vocal response despite stimulation. |
| VT (modifier) | Intubated/Tube | Patient is intubated or has a tracheostomy and cannot produce verbal sounds. Document as VT. Do not score V1 for an intubated patient. Maximum GCS in intubated patient = 10T (E4M6T). |
Common errors in verbal scoring:
- Scoring V4 (confused) when the patient is just slow to respond — slowness alone does not indicate confusion. Test orientation: name, place, year.
- Scoring V3 (words) when the patient produces sounds that aren’t intelligible words — these are V2 (sounds).
- Scoring V1 for an intubated patient — this is VT (tube), not V1 (none). This distinction matters for mortality predictions and treatment decisions.
Component 3: Motor Response (M) — Maximum 6 points
| Score | Response | Clinical description | How to assess |
|---|---|---|---|
| M6 | Obeys commands | Patient follows a two-step motor command reliably | “Hold up two fingers.” “Stick out your tongue.” Use two different commands to confirm compliance vs reflexive movement. |
| M5 | Localising | Patient moves limb purposefully toward a painful stimulus to remove it | Apply supraorbital pressure or trapezius squeeze. Patient’s hand must cross the midline toward the stimulus. Movement toward the stimulus = M5. |
| M4 | Withdrawal | Patient pulls limb away from peripheral painful stimulus — not toward it | Apply nail bed pressure. Patient withdraws (pulls away from pain) but does not localise. Flexion at elbow without localising = M4. |
| M3 | Abnormal flexion (Decorticate) | Stereotyped flexion of arm at elbow, wrist, fingers; internal rotation of shoulder; leg extension | Central pain stimulus. Flexion is slow, stereotyped, and sustained. Arm flexes, wrist flexes, fingers flex. Indicates damage above midbrain. |
| M2 | Extension (Decerebrate) | Extension of arm at elbow, pronation of forearm; leg extension, plantar flexion | Central pain. Extension and internal rotation of arm, pronation. Indicates brainstem damage at midbrain level or below. |
| M1 | None | No motor response to any stimulus | No movement despite central and peripheral pain stimulation. |
Decorticate vs Decerebrate — the critical distinction:
- Decorticate (M3): Think “decorticates — curls toward the core.” Arms flex toward the body. Lesion above the midbrain (cortical or internal capsule).
- Decerebrate (M2): Think “decerebrate — extends away.” Arms extend and pronate. Lesion at or below the midbrain (brainstem). Worse prognosis than decorticate.
GCS Score Interpretation — TBI Severity Classification
| Total GCS | TBI Severity | Clinical significance | 30-day mortality (est.) |
|---|---|---|---|
| 13–15 | Mild TBI | Alert, oriented, minor neurological deficit possible. Most patients managed without ICU admission. | <2% |
| 9–12 | Moderate TBI | Confused, may obey commands. CT scan mandatory. Neurological monitoring required. Many admitted to HDU/ICU. | 5–15% |
| 3–8 | Severe TBI | Unable to follow commands. GCS ≤8 = accepted threshold for intubation consideration to protect airway. | 25–50%+ |
| 3 | Deepest coma | No eye opening, no verbal, no motor response. Worst possible score. Poor prognosis — context-dependent. | >70% |
The GCS 8 Intubation Threshold
A GCS of 8 or below is the widely accepted clinical threshold for considering endotracheal intubation to protect the airway. The rationale: a GCS below 9 suggests inability to maintain and protect the airway due to loss of laryngeal reflexes and reduced consciousness.
Important caveat: GCS 8 is a threshold for consideration, not an automatic mandate. Clinical context matters — a patient with GCS 8 due to opiate overdose who responds rapidly to naloxone does not require intubation. Always interpret the GCS alongside the clinical trajectory and cause.
GCS-P: Adding Pupil Reactivity to the Score
The GCS-Pupils (GCS-P) score was developed by Brennan et al. (2018) to improve mortality prediction by incorporating pupil reactivity into the standard GCS. It is increasingly used in TBI research and specialist neurocritical care settings.
Formula: GCS-P = GCS Total − Pupil Reactivity Score (PRS)
| Pupil Reactivity Score (PRS) | Pupil findings |
|---|---|
| 0 | Both pupils reactive |
| 1 | One pupil unreactive |
| 2 | Both pupils unreactive |
Example: GCS 10, one pupil unreactive → GCS-P = 10 − 1 = 9. A GCS-P of 9 or below carries significantly higher mortality than a GCS of 10 alone would suggest.
GCS in Intubated and Sedated Patients
This is the most common source of GCS error in ICU practice. Two specific situations require modified documentation:
Intubated patients
Use the modifier T (tube) for the verbal component. The maximum achievable GCS in an intubated patient is 10T (E4 + VT + M6 = 10T). Do not write this as GCS 10 — write GCS 10T or E4VTM6 to make the intubation status explicit.
Sedated patients
Sedation artificially suppresses the GCS — particularly the motor and verbal components. Document the sedation agent and dose alongside the GCS. A patient with GCS 6T on propofol 4 mg/kg/h cannot be interpreted the same way as a GCS 6T in an unsedated patient. The GCS is most meaningful when obtained during sedation holds or in patients receiving minimal or no sedation.
Mnemonics for Remembering GCS Components
The most reliable mnemonic for the scoring maximum is 4-5-6:
- Eyes: max 4 (4 letters in “eyes”)
- Verbal: max 5 (5 letters in “speak”)
- Motor: max 6 (6 letters in “moving”)
For the order of verbal scores from highest to lowest, use O-C-W-S-N: Oriented, Confused, Words, Sounds, None.
For motor scores from highest to lowest: O-L-W-F-E-N: Obeys, Localises, Withdrawal, Flexion (abnormal), Extension, None.
Worked Clinical Example
Patient: 34-year-old male brought to ED following motorcycle accident. Not intubated. Spontaneous eye opening. Answers questions but is confused about date and location. Withdraws right arm from nail bed pressure.
- Eye: Opens spontaneously = E4
- Verbal: Speaks in sentences but is confused/disoriented = V4
- Motor: Withdraws from pain (pulls away, does not localise) = M4
- Total GCS = 12 → E4V4M4 → Moderate TBI
This patient requires CT head, neurosurgery review, and close neurological monitoring. The component breakdown (M4 rather than M5 or M6) indicates the patient is not following commands or localising, which is more concerning than the total GCS alone might suggest.
Free GCS Calculator
Our free Glasgow Coma Scale calculator scores all three components interactively, calculates the total and GCS-P, classifies TBI severity, applies intubation modifier for VT, and generates EMR-ready documentation. No login required.
→ Open the free GCS Calculator
Related ICU Calculators
- SOFA Score — GCS is the neurological component of the full SOFA score
- APACHE II — GCS contributes to ICU admission severity scoring
- MAP Calculator — cardiovascular assessment alongside neurological scoring
Frequently Asked Questions
What does a GCS of 15 mean?
GCS 15 (E4V5M6) is the highest possible score, indicating the patient opens eyes spontaneously, is fully oriented to person, place, and time, and follows all motor commands accurately. It represents normal consciousness.
What is the minimum GCS score?
The minimum GCS is 3 (E1V1M1) — no eye opening, no verbal response, and no motor response to any stimulus. This represents the deepest measurable level of unresponsiveness and carries the poorest prognosis.
At what GCS do you intubate?
A GCS of 8 or below is the accepted clinical threshold for considering intubation to protect the airway. This is a threshold for consideration, not an absolute rule — clinical context, trajectory, and the cause of impaired consciousness all inform the decision.
How do you score GCS in an intubated patient?
Use the VT modifier for the verbal component. The maximum achievable score is GCS 10T (E4 + VT + M6). Always document the T suffix and express the score as individual components (E4VTM6), not just the total.
What is GCS-P?
GCS-P is the Glasgow Coma Scale with Pupils score, calculated as GCS minus the Pupil Reactivity Score (0 for both reactive, 1 for one unreactive, 2 for both unreactive). It provides better mortality prediction in TBI than GCS alone by incorporating pupil reactivity.
References
- Teasdale G, Jennett B. Assessment of coma and impaired consciousness. A practical scale. Lancet. 1974;2(7872):81-84. PMID: 4136544.
- Teasdale GM, Maas A, Lecky F, Manley G, Stocchetti N, Murray G. The Glasgow Coma Scale at 40 years: standing the test of time. Lancet Neurol. 2014;13(8):844-854. PMID: 25030515.
- Brennan PM, Murray GD, Teasdale GM. Simplifying the use of prognostic information in traumatic brain injury. Part 1: The GCS-Pupils score: an extended index of clinical severity. J Neurosurg. 2018;128(6):1612-1620. PMID: 28960154.
- Reith FCM, Van den Brande R, Synnot A, et al. The reliability of the Glasgow Coma Scale: a systematic review. Intensive Care Med. 2016;42(1):3-15. PMID: 26564211.
- Green SM. Cheerio, Laddie! Bidding Farewell to the Glasgow Coma Scale. Ann Emerg Med. 2011;58(5):427-430. PMID: 21803447.
Written by Nikhil Mahajan, PT, MPT | Last reviewed: June 2026 | Free GCS Calculator →