Level of Consciousness & Glasgow Coma Scale

Level of consciousness (LOC) is the most sensitive indicator of neurological status change. LOC exists on a continuum: alert → confused → lethargic (drowsy but arousable with verbal stimuli) → obtunded (arousable only with vigorous stimulation) → stuporous (responds only to painful stimuli) → comatose (unarousable). The Glasgow Coma Scale quantifies LOC across three domains: Eye opening (1–4), Verbal response (1–5), and Motor response (1–6). Scores range from 3 (deep coma) to 15 (fully alert). A GCS of 8 or below indicates coma and inability to protect the airway — this is the classic intubation threshold. When scoring motor response, always document the best response from the best-performing limb, not the worst. A decline of 2 or more points from baseline is clinically significant and demands immediate provider notification. Painful stimuli should be central (trapezius squeeze, sternal rub) to distinguish purposeful localization from spinal reflex withdrawal; nail bed pressure is a peripheral stimulus and may elicit only spinal-level reflexes. Document trends, not just single scores — the trajectory tells the clinical story.