Glasgow Coma Scale

Introduction and Purpose of the Glasgow Coma Scale

The Glasgow Coma Scale (GCS) is a standardized neurological tool used to evaluate and record the level of consciousness in a patient. Developed in 1974 by neurosurgeons in Glasgow, it provides a simple, objective method for assessing impairment of conscious level in response to defined stimuli. Nursing staff rely on this tool across emergency departments, intensive care units, and general wards to monitor trends in a patient's neurological condition over time. Rapid identification of a declining GCS score allows clinicians to intervene before secondary brain injury occurs.

Components of the Glasgow Coma Scale

The scale evaluates three distinct behavioral domains. Each domain is scored separately, and the final score is the sum of the individual responses.

• Eye Opening (E): Assesses the patient's spontaneous or stimulated visual response.
• Verbal Response (V): Measures orientation, speech coherence, and sound production.
• Motor Response (M): Evaluates voluntary or reflex movement in response to standard commands or painful stimuli.

Eye Opening (E) Response Assessment

The eye opening subscale ranges from 4 to 1. Nurses observe whether the patient opens their eyes spontaneously, to speech, or only to painful stimuli, or not at all.

1. Spontaneous (4): Eyes open voluntarily without any stimulation.
2. To Speech (3): Eyes open when spoken to or commanded to open.
3. To Pain (2): Eyes open only when a noxious stimulus, such as a sternal rub, is applied.
4. None (1): No eye opening occurs even with painful stimulation.

Verbal Response (V) Response Assessment

The verbal subscale evaluates orientation, speech coherence, and appropriateness of answers. The score ranges from 5 down to 1.

• Oriented (5): Patient knows their name, current location, and the date.
• Confused (4): Patient can converse in sentences, but answers are disoriented or disorganised regarding time or place.
• Inappropriate Words (3): Patient speaks understandable words, but conversation lacks coherent context or meaning.
• Incomprehensible Sounds (2): Patient produces moans, groans, or incomprehensible murmurs without forming real words.
• None (1): No vocalization or sound is produced despite stimulation.

Motor Response (M) Response Assessment

The motor subscale is the most reliable predictor of patient outcome and ranges from 6 to 1. Nurses test motor function by asking the patient to obey commands or by applying a central or peripheral pain stimulus.

1. Obeys Commands (6): Patient follows simple multi-step or single commands correctly.
2. Localizes to Pain (5): Patient attempts to remove the source of painful stimulation above the clavicle.
3. Withdraws from Pain (4): Patient pulls a limb away from a painful stimulus.
4. Flexion to Pain (3): Patient adopts a decorticate posture, bringing arms towards the core with flexion at the elbow.
5. Extension to Pain (2): Patient adopts a decerebrate posture, extending arms and rigidly pointing toes.
6. None (1): Flaccid paralysis with no movement to painful stimuli.

Scoring and Interpreting GCS Results

The total GCS score is calculated by adding the individual scores together: $E + V + M$. Scores range from a maximum of 15 for a fully alert person to a minimum of 3 for an unresponsive patient. Rather than relying on a single total number, nurses document the breakdown, such as E4V5M6, to give a clearer clinical picture. A total score of 13 to 15 indicates mild brain injury, 9 to 12 indicates moderate injury, and 8 or below typically signals severe impairment requiring urgent airway management.

Special Considerations and Limitations in Nursing Practice

Several clinical factors can falsely lower or alter a patient's GCS score, leading to misinterpretation. Intubation or a tracheostomy prevents verbal assessment, requiring the nurse to document the score with a modifier like 'T'. Severe facial trauma, periorbital edema, or pre-existing eye conditions prevent accurate eye opening assessment. Factors like alcohol intoxication, drug overdose, severe shock, or hypothermia also depress neurological function without necessarily indicating structural brain damage. Nurses must document these confounding barriers alongside the score to provide safe context.