Glasgow Coma Scale Calculator

The GCS was published by Graham Teasdale and Bryan Jennett at the University of Glasgow Institute of Neurological Sciences in The Lancet on July 13, 1974 ("Assessment of coma and impaired consciousness. A practical scale."). They built it to replace the vague language of "semi-comatose" and "obtunded" with three reproducible bedside observations: eye opening, verbal response, and motor response. The 3 to 15 total has been the de facto grading system for traumatic brain injury for fifty years and is embedded in the ATLS primary survey, the WHO injury surveillance dataset, and most ICU sedation protocols.

The Advanced Trauma Life Support (ATLS, 10th edition) and Brain Trauma Foundation guidelines call for definitive airway management when GCS falls to 8 or below. The reasoning is mechanical, not magical: at GCS 8, motor responses have dropped to withdrawal or worse and verbal responses to incomprehensible sounds or worse, which together strongly correlate with loss of airway-protective reflexes (gag, cough, ability to clear secretions) and rising risk of aspiration. The cutoff is a heuristic taught as "GCS 8, intubate," not an absolute rule: a rapidly falling GCS, expanding intracranial mass, or impending respiratory failure all warrant earlier intubation, and the final airway call belongs to the treating clinician.

The three TBI severity bands have been the standard CDC, NICE, and Brain Trauma Foundation classification since the 1970s. Severe TBI is GCS 3 to 8 (typically requires intubation, ICU admission, and emergent neurosurgical evaluation; 30-day mortality runs 25 to 40 percent in large registries). Moderate TBI is GCS 9 to 12 (admission for serial neuro checks and CT head; mortality around 5 to 15 percent). Mild TBI is GCS 13 to 15 (the great majority of head injuries; mortality under 1 percent, but post-concussive symptoms are common). The bands are screening categories, not prognoses: pupillary response, age, hypotension, and CT findings all sharpen the prediction.

Eye opening and motor responses are scored identically in adults and children, but the verbal subscale is rewritten because preverbal children cannot follow conversation. The pediatric verbal scale (used in PALS and Pediatric ATLS) scores 5 for cooing, babbling, or age-appropriate words; 4 for an irritable but consolable cry; 3 for inconsolable crying; 2 for moans or grunts to pain; and 1 for no response. The numeric range stays 1 to 5 so the totals remain directly comparable to the adult score and the severity bands and intubation threshold work the same way. Toggle the patient type at the top of the calculator to switch the verbal descriptors.

An intubated patient cannot speak, so the verbal subscale collapses to 1 (often annotated GCS "E_V1T_M_") and the total drops artificially by up to 4 points. Sedation, paralytics, alcohol intoxication, aphasia, profound hearing loss, and orbital trauma all corrupt one or more subscales in the same way. In ICU practice the FOUR score (Full Outline of UnResponsiveness, Wijdicks 2005) is preferred for intubated patients because it adds a brainstem reflex subscale and a respiration pattern subscale and drops the verbal component entirely. For depth of sedation specifically, the Richmond Agitation-Sedation Scale (RASS) or Riker Sedation-Agitation Scale is the standard tool. Treat a GCS in any of these populations as a rough trend marker, not a hard number.