APA Dictionary of Psychology

a standardized observational tool widely used to assess level of consciousness following a head injury. Scores range from 3 to 15 and represent the sum of clinician ratings of three aspects of patient functioning: eye-opening response (graded 1–4), motor response (1–6), and verbal response (1–5). Scores of 8 or below are indicative of severe brain injury and coma, scores of 9 to 12 are indicative of moderate injury, and scores of 13 or higher are indicative of mild injury. Although the GCS is the most popular method of evaluating impairment severity, monitoring neurological status, and evaluating prognosis in traumatic brain injury—having been widely validated and shown to have good reliability—it is not without limitations. Shortcomings, such as the inability of the GCS to test brainstem reflexes or to obtain a verbal subscore in intubated patients, have prompted the development of other instruments to assess neurological alterations associated with trauma, notably the Grady Coma Scale, the Full Outline of Unresponsiveness Score, and the Wessex Head Injury Matrix (see vegetative state). [introduced in 1974 by British neurologists Graham Michael Teasdale (1940–  ) and William Bryan Jennett (1926–2008) while at the University of Glasgow, Scotland]