Assessment of the Level of Consciousness Using the Glasgow Coma Scale

Quantitative Disorders of Consciousness

Before proceeding to the scoring, it is necessary to understand the classical gradation of impaired consciousness. This is a sequential process of fading responses to external stimuli:

• Obnubilation (Mild Lethargy) — perception threshold is elevated, mental processes are slowed, orientation is incomplete.
• Somnolence (pathological drowsiness) — a mild degree of depression. The patient is asleep but wakes up upon external stimulation and answers questions. Falls back asleep immediately without stimulation.
• Sopor (Stupor) — deep pathological sleep. Verbal contact is completely lost, but the defensive reaction to strong pain is preserved.
• Coma — the extreme degree of impairment. Complete loss of consciousness and responses to any stimuli, accompanied by a failure of vital functions.

Structure of the Glasgow Coma Scale

The assessment consists of the sum of points from the classical triad of independent parameters. The minimum possible score is 3, and the maximum is 15.

1. Eye response (1–4 points)

• 4 — spontaneous.
• 3 — to speech.
• 2 — to pain.
• 1 — no response.

2. Verbal response (1–5 points)

• 5 — oriented (coherent speech).
• 4 — confused speech (disintegration).
• 3 — inappropriate words.
• 2 — incomprehensible sounds.
• 1 — no response.

3. Motor response (1–6 points)

• 6 — obeys commands.
• 5 — purposeful movement to pain (localizes pain).
• 4 — withdrawal from pain (non-purposeful).
• 3 — abnormal flexion.
• 2 — extensor response.
• 1 — no movement (flaccid / complete atonia).

Clinical Significance of the Motor Response

The motor component of the scale is of particular diagnostic value, as it reflects the integrity of motor pathways from the cerebral cortex to the brainstem.

• A score of 3 points corresponds to decorticate rigidity (abnormal flexion and adduction of the arms with extension of the legs). This is a sign of damage to structures above the brainstem level.
• A score of 2 points corresponds to decerebrate rigidity (abnormal extension, internal rotation of the arms, and extension of the legs). This is a marker of deep brainstem injury.

Interpretation of results

The total score allows for risk stratification, prognosis determination, and the translation of quantitative assessment into qualitative clinical terms.

Clinical Rule: a score of less than 9 points indicates severe central nervous system damage. A score of 8 points and below is interpreted as a coma — this is a critical condition that poses an immediate threat to life and requires neuro-intensive care.

Algorithm for Managing Impaired Consciousness

Examination of an unconscious patient is carried out as quickly as possible, as life-saving therapy depends on it.

1. ABC Rule: Before taking an anamnesis, it is critically important to secure the airway and stabilize hemodynamics.
2. Anamnesis: Information is obtained from witnesses. Sudden onset of coma is typical for acute cerebrovascular accident (stroke) or epilepsy. Gradual onset points to infections or metabolic disorders (e.g., diabetic ketoacidosis coma).
3. Assessment of Premorbid Status: The presence of chronic pathologies is checked. Renal or hepatic failure can lead to uremic or hepatic encephalopathy.
4. Pharmacological Anamnesis: Toxic CNS depression must be ruled out (overdose of neuroleptics, hypnotics).

Class and exam questions

What else to study on this topic

• Clinical classification of coma by severity (stages I, II, III) and reflex assessment.
• Differential diagnosis of metabolic and toxic causes of depressed mental status.
• Assessment of the patient's posture (active, passive, forced) as a marker of severity.
• Diagnostic significance of facial expression (facies Hippocratica, facies mitralis, etc.).
• Qualitative disorders of consciousness (mental disturbances with preserved wakefulness).

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.