Glasgow Coma Scale

The Glasgow Coma Scale (GCS) quantifies consciousness by independently scoring three behavioral responses: eye opening (E1-4), verbal response (V1-5), and motor response (M1-6), yielding a composite score of 3-15. Advanced application requires understanding that the motor component carries the greatest prognostic weight and should be reported as component scores (E3V4M5) rather than a single number to avoid losing clinically significant information. The best motor response to central pain stimulation differentiates between upper brain dysfunction (localization, M5) and brainstem dysfunction (flexion withdrawal M4, abnormal flexion/decorticate M3, extension/decerebrate M2, none M1). Pupillary reactivity provides additional prognostic information: bilateral fixed dilated pupils indicate brainstem herniation with extremely poor prognosis, while a unilateral fixed dilated pupil suggests ipsilateral uncal herniation requiring emergent intervention. The GCS-Pupils score (GCS minus pupil reactivity score) improves prognostic accuracy. The nurse performs GCS assessments at standardized intervals, documents component scores individually, applies appropriate stimulation techniques (trapezius squeeze or supraorbital pressure for central stimulus), recognizes confounders (sedation, intubation, orbital trauma), trends scores to detect neurological deterioration, and escalates declining GCS scores immediately.