The Glasgow Coma Scale
Consciousness reduced to a number between three and fifteen.
Origin
Published by Graham Teasdale and Bryan Jennett at the University of Glasgow’s Institute of Neurological Sciences in 1974, and now used in hospitals worldwide.
The catch
The scale cannot reach zero. The minimum is three, because each of the three components starts at one, and a patient who scores three is deeply unresponsive rather than absent. It is a reminder that the scale measures response, not existence.
No eye opening, no verbal response, no motor response. The lowest possible score.
Minimal response to painful stimulus only.
The conventional threshold below which a patient is considered comatose.
Confused or inappropriate responses, localised movement to pain.
Some disorientation or delayed response, but substantially responsive.
Spontaneous eye opening, oriented speech, obeys commands. The maximum.
The scale sums three separate observations: eye opening out of four, verbal response out of five, and motor response out of six. Its achievement was not the arithmetic but the standardisation, since before it clinicians described consciousness in words like stuporous and semi-comatose that meant different things to different people. Reducing it to a reproducible number let one shift hand over to the next without ambiguity, and let outcomes be compared between hospitals and between countries. It remains among the most widely used clinical scales in the world, half a century after a Glasgow neurosurgical unit devised it.