GCS — Motor Response Score Calculator

The motor component scores 1–6: 6=obeys commands, 5=localizes pain, 4=withdrawal, 3=abnormal flexion, 2=extension, 1=none. It is the most clinically important GCS component for prognosis.

The motor score has the strongest correlation with outcome after TBI. In many prognostic models (IMPACT, CRASH), the motor score replaces total GCS for predictive accuracy.

Decorticate (flexion of arms, extension of legs) suggests injury above the midbrain, while decerebrate (extension of all limbs) indicates injury at or below the midbrain. Decerebrate is typically worse.

M6 indicates the patient can follow verbal commands (e.g., "hold up two fingers," "squeeze my hand"). It requires intact language comprehension and motor pathways.

M5 means the patient reaches toward the painful stimulus. This requires cortical processing and represents a higher level of function than simple withdrawal (M4).

Withdrawal (M4) is a reflexive, non-purposeful pulling away. Localization (M5) is a purposeful movement toward the stimulus, indicating cortical involvement.

The minimum motor score is 1 (no response). Combined with minimum eye (1) and verbal (1), it gives total GCS 3, the lowest possible.

Yes, spinal cord injury may prevent motor responses despite intact consciousness. The motor score should be scored as "not testable" (NT) in such cases.

Yes, the motor score is the single strongest GCS predictor of mortality. Mortality ranges from <1% for M6 to >50% for M1 in severe TBI.

Vegetative state typically shows spontaneous eye opening (E4) with no meaningful motor response (M1–3) and no verbal response (V1–2).

Neuromuscular blocking agents prevent motor assessment. The motor component is scored as NT (not testable) and the GCS should be documented as untestable.

The best motor score is 6 (obeys commands). Combined with best eye (4) and verbal (5), total GCS is 15.

Abnormal flexion (decorticate posturing) involves adduction and flexion of arms with extension of legs. It indicates severe brain injury above the midbrain level.

Extension (decerebrate posturing) involves extension, adduction, and internal rotation of all limbs. It indicates injury at or below the midbrain and is a poor prognostic sign.

Yes, motor response can change rapidly due to sedation, seizures, cerebral edema progression, or improving neurological status. Serial assessments are critical.

The motor score alone has AUC 0.70–0.80 for predicting unfavorable outcome after TBI. Combined with age, pupils, and CT findings, it reaches AUC 0.84–0.90.

The IMPACT prognostic model uses the motor score as one of three core predictors (along with age and pupillary reactivity) to predict 6-month outcome.

The CRASH model includes motor score categories (M1, M2–4, M5–6) as strong predictors of 14-day mortality and 6-month disability.

The FOUR score motor component scores 0–4: 4=thumbs up/fist, 3=localizes, 2=flexion, 1=extension, 0=no response. It adds myoclonus status epilepticus (0).

The pediatric GCS uses the same motor criteria as the adult GCS. Children aged >2 years should be scored using the standard adult motor descriptors.

Sedation depresses motor responses and can mimic brainstem injury patterns. The motor score should ideally be assessed during a sedation holiday or off-sedation window.

A motor score of 1 (no response) with absent brainstem reflexes in the appropriate clinical context may indicate brain death, which is prerequisite for organ donation.

Yes, ongoing seizure activity or post-ictal state can alter motor responses. The best motor response should be assessed after seizure activity has resolved.

TBI is brain dysfunction caused by an external force. Ranges from mild (concussion) to severe (coma). GCS is the standard tool for classifying TBI severity.

The GOS is a 5-point functional outcome scale: 1=death, 2=vegetative, 3=severe disability, 4=moderate disability, 5=good recovery. Used in TBI research.

NIHSS is a 15-item, 42-point scale for stroke-related neurological deficits. It quantifies consciousness, language, motor, sensory, neglect, and cerebellar function.

APGAR scores newborn health at 1 and 5 minutes: Appearance, Pulse, Grimace, Activity, Respiration. Total 0–10. It is unrelated to GCS.

Child-Pugh assesses liver disease severity using bilirubin, albumin, INR, ascites, and encephalopathy. Class A (5–6), B (7–9), C (10–15).

Structured training with video examples, standardized scenarios, and inter-rater reliability checks improve scoring accuracy. Refresher training is recommended annually.

In acute TBI, hourly for the first 24–48 hours, then every 2–4 hours. Any deterioration in motor score warrants immediate CT and neurosurgical evaluation.

Unilateral motor deficits suggest a focal brain lesion (e.g., subdural hematoma, contusion) rather than diffuse brain injury. This may require urgent surgical intervention.

Yes, hemiparesis from prior stroke, Parkinson disease, cerebral palsy, or other neuromuscular conditions can alter baseline motor responses. The best achievable score should be documented.