GCS Calculator (Glasgow Coma Scale)

What the GCS measures

The Glasgow Coma Scale (GCS) was described by Graham Teasdale and Bryan Jennett in The Lancet in 1974 as a practical way to communicate the level of consciousness of patients with an acute brain injury. It is now used to record impaired consciousness from many causes, not only trauma.

The scale has three components: eye opening (E), verbal response (V) and motor response (M). The original version did not separate normal from abnormal flexion, so its maximum was 14. When the summed score was set out in 1979, the motor component gained a sixth level, giving the 3-15 range used today.

How to use this calculator

The official assessment aid describes four steps. Enter the result of the last one.

1. Check for factors that interfere with communication or the ability to respond, such as a language barrier, hearing loss, intubation, sedation, swelling around the eyes or spinal cord injury.
2. Observe eye opening, the content of speech and movements of the right and left sides before giving any stimulus.
3. Stimulate with a spoken or shouted request, then with physical pressure if there is still no response.
4. Rate by the highest response observed.

Physical stimuli are fingertip pressure, trapezius pinch and supraorbital notch pressure. The official site strongly discourages rubbing the knuckles on the sternum, because it can bruise and the responses are hard to interpret.

Criteria for each response

Normal and abnormal flexion are easy to confuse. The official aid lists these features.

Formula

Total = eye (E) + verbal (V) + motor (M)

Eye scores 1-4, verbal 1-5 and motor 1-6, so the total runs from 3 to 15. Record it with the components, as in "E2V4M6 = 12". The official guidance asks for the full description of each response alongside the numbers: a total of 8 could be E2V2M4 or E1V1M6, with very different implications.

Handling a component that is not testable (NT)

• When a factor prevents assessment, record that component as NT (not testable). Examples are eyes closed by swelling, an endotracheal tube or tracheostomy, or paralysis.
• Never record NT as 1. It would make the patient look more unwell than they are.
• When a component is NT, do not report a total. Follow the trend in the components you can assess. This calculator shows no total or severity band when NT is chosen.
• Some units chart an intubated verbal response as VT, or add a T to the eye plus motor sum (for example 8T). That notation is not part of the official method, so check local policy.
• For sedation or paralysis, the official FAQ suggests a temporary wake-up test where appropriate.

Reading the total

Head injury research commonly groups the total into three bands.

Teasdale et al. (2014) explain that the bands grew out of research practice, starting when the Traumatic Coma Data Bank used a score of 8 to signify severe injury, and call the classification ad hoc rather than scientifically grounded. It is useful for summarising groups of patients; individual patients are best described by the three components.

GCS-Pupils score (GCS-P)

The GCS-P was described by Brennan, Murray and Teasdale (2018) from data on 15,900 patients with head injury in the CRASH trial and the IMPACT database. It adds pupil reactivity, a sign of brainstem function, to the GCS total.

GCS-P = GCS total − pupil reactivity score

The range is 1-15, extending the scale below a GCS of 3. The official site notes that the GCS-P does not replace separate recording of each component and the pupils. With no GCS total (an NT component), there is no GCS-P either.

Worked example

"Load example" enters the case used on the official GCS-P page.

• No eye, verbal or motor response, spontaneously or to spoken requests. With fingertip pressure the eyes do not open and there are no sounds, but the arms flex normally.
• E1 (none) + V1 (none) + M4 (normal flexion) = 6, in the severe band.
• Neither pupil reacts to light, so the pupil reactivity score is 2. GCS-P = 6 − 2 = 4.

An intubated patient who opens the eyes to sound (E3) and localises (M5) is recorded as E3 VNT M5, with no total.

Nursing notes

• Plot serial findings on a GCS observation chart so trends stand out, and escalate any deterioration promptly.
• The NICE head injury guideline quoted in the official FAQ (CG176, 2014) calls for urgent reappraisal after a sustained (30 minutes or more) drop of one GCS point, a drop of 3 or more in eye or verbal, or 2 or more in motor. A one-point drop in motor carries more weight.
• According to the official FAQ, the scale applies without change to children over 5. Younger children need the paediatric (Adelaide) version, which this calculator does not cover.

Sources

• Teasdale G, Jennett B. Assessment of coma and impaired consciousness. A practical scale. Lancet. 1974;2(7872):81-84.
• Sir Graham Teasdale. Glasgow Coma Scale: Do it this way (GCS Assessment Aid), Institute of Neurological Sciences NHS Greater Glasgow and Clyde, 2015. Check, observe, stimulate, rate; criteria; NT.
• glasgowcomascale.org FAQ: NT handling, scale versus score, children, observation frequency.
• Teasdale G, Murray G, Parker L, Jennett B. Adding up the Glasgow Coma Score. Acta Neurochir Suppl. 1979;28:13-16.
• Teasdale G, 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. Table 1: severe 3-8, moderate 9-12, mild 13-15.
• Brennan PM, Murray GD, Teasdale GM. Simplifying the use of prognostic information in traumatic brain injury. Part 1: The GCS-Pupils score. J Neurosurg. 2018;128(6):1612-1620. Official GCS-P page

Frequently asked questions