Coma scales

Glasgow Coma Scale

Main reference: Teasdale G, Jennett B. Assessment of coma and impaired consciousness. A practical scale. Lancet ii:81–84, 1974.

Type: Clinician-rated scale.

Main indications: Used to assess level of consciousness. Typically used following traumatic brain injury, cerebrovascular accidents, cerebral infections, and metabolic disorders that have an effect on level of arousal.

Rating performed by: Trained health professional, usually A+E, trauma team, ITU, neurological or neurosurgical staff.

Time period covered by scale: The present; serial measurements are useful in monitoring changes in level of consciousness.

Time required to complete rating: less than 5 minutes.

Remarks: Has a reasonably high degree of interobserver reliability, allowing pragmatic interpretation of clinical state across different units. The speed and ease with which it can be administered sometimes disguises the need for judicious application and interpretation of its findings.

The scale categorises three clinical examination findings:

• Best eye response
• Best verbal response
• Best motor response

Each parameter is scored separately, the worst possible score in each case being 1, the best being 4 (for best eye-opening response), 5 (for best verbal response), or 6 (for best motor response). The three scores are combined to give a total score (range 3–15). The lowest score is 3. Low scores indicate greater impairment of level of consciousness.

The score is most helpfully reported as its component parts and as the total – e.g., E4, V3, M5, total 12/15. This is particularly true in patients whose condition renders one of the three parameters invalid or impossible to assess: for example, an intubated patient, who cannot be assessed for a verbal response, or a patient with severe injuries in the orbital region, who may not be able to be assessed for eye opening.

(cmg)