What are the criteria for the Glasgow Coma Scale (GCS)?

Glasgow Coma Scale Assessment Criteria

The Glasgow Coma Scale (GCS) evaluates consciousness through three independent components—eye opening (E, scored 1-4), verbal response (V, scored 1-5), and motor response (M, scored 1-6)—with each component documented separately rather than just as a sum, because patients with identical total scores but different component profiles have vastly different outcomes and prognoses. 1

Eye Opening Component (E: 1-4 points)

• E4: Eyes open spontaneously without any stimulation 1
• E3: Eyes open to verbal command or speech 1
• E2: Eyes open only to painful stimulus 1
• E1: No eye opening response 1

Verbal Response Component (V: 1-5 points)

• V5: Oriented and conversing appropriately, knows who they are, where they are, and the date 1
• V4: Confused conversation, responds to questions but answers are disoriented or inappropriate 1
• V3: Inappropriate words, random or exclamatory speech without conversational exchange 1
• V2: Incomprehensible sounds, moaning or groaning without recognizable words 1
• V1: No verbal response 1

Motor Response Component (M: 1-6 points)

The motor component is the most difficult to assess but has the highest predictive value for outcomes. 2, 1 Use central stimuli (supraorbital pressure or trapezius squeeze) rather than peripheral stimuli to avoid spinal reflexes that can falsely suggest higher cortical function. 1

• M6: Obeys commands, follows simple instructions like "squeeze my hand" or "wiggle your toes" 1
• M5: Localizes to pain, reaches toward and attempts to remove the source of central painful stimulus with purposeful, coordinated movement that crosses the midline 1
• M4: Withdraws from pain, pulls limb away from painful stimulus but does not localize 1
• M3: Abnormal flexion to pain (decorticate posturing), flexion of arms with adduction and internal rotation 1
• M2: Abnormal extension to pain (decerebrate posturing), extension and internal rotation of arms 1
• M1: No motor response to painful stimulation 1

Critical Documentation Principles

Always record individual E, V, and M scores (e.g., E3V4M5 = 12) rather than just the sum score. 1 This component-based documentation is essential because:

• Patients with identical total scores but different component profiles have different outcomes and require different management approaches 1
• The motor component alone has prognostic value—a motor score >3 on day 4 after cardiac arrest predicts favorable outcome at 6 months with 84% specificity and 77% sensitivity 1
• Serial assessments showing declining component scores provide substantially more valuable clinical information than single determinations 1

Simultaneous Pupillary Assessment

Assess pupils simultaneously with GCS at every evaluation, documenting pupillary size and reactivity as key prognostic indicators. 1 Pupillary responses maintain prognostic value even when other components cannot be assessed due to sedation or paralysis. 1

Common Pitfalls to Avoid

• Confounding factors: Document explicitly when sedation, neuromuscular blockade, intubation (preventing verbal assessment), facial trauma, intoxication, hypothermia, severe hypotension, or hypoglycemia interfere with accurate assessment 1, 3
• Peripheral vs. central stimuli: Using peripheral painful stimuli can elicit spinal reflex withdrawal without cortical involvement, falsely elevating the motor score 1
• Single assessments: One-time GCS measurements have limited value; serial assessments detect deterioration and guide management 1, 3
• Sum score only: Recording only the total (e.g., "GCS 12") without components loses critical prognostic and management information 1

Clinical Significance Thresholds

• GCS <14: Represents significant injury with mortality rates of 24.7%, warranting highest level trauma activation and intensive monitoring 4, 1, 5
• GCS 13-15: Mild traumatic brain injury 1
• GCS 9-12: Moderate traumatic brain injury, requiring GCS assessment every 15 minutes for first 2 hours, then hourly 1, 3
• GCS 3-8: Severe traumatic brain injury, requiring immediate neurosurgical consultation 1, 5