Glasgow Coma Scale

A patient who opens the eyes to sound, answers with confused speech, and localises pressure has a GCS of E3 V4 M5, or 12. That number is useful only when the components are visible: another patient could also score 12 with a very different pattern and a different clinical concern. The Glasgow Coma Scale is a structured bedside language for describing responsiveness. It scores three independent behaviours—eye opening, verbal response, and best motor response—then records the components separately and, when all are testable, as a total from 3 to 15. It does not identify the cause of reduced consciousness, measure cognition or mood, or establish brain death. A valid score depends on context. Sedation, paralysis, intoxication, hypoxia, hypoglycaemia, language or hearing barriers, and pre-existing neurological deficits can make a response appear worse than the patient's underlying neurological function. The experienced clinician therefore asks two questions before interpreting the number: `What response can I demonstrate?` and `What could be preventing a response?`