MRC sum score in guillian Barre syndrome
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Here is a complete, structured overview of the MRC Sum Score in Guillain-Barre Syndrome:
MRC Sum Score in Guillain-Barre Syndrome (GBS)
What It Is
The MRC sum score was first described by Kleyweg et al. (1988) for use in the Dutch GBS trial. It is the sum of MRC muscle strength scores from 6 muscle groups tested bilaterally (left + right), giving a total that ranges from 0 to 60.
The 6 Muscle Groups Tested (Both Sides)
| Muscle Group | Side | Score (0-5) |
|---|---|---|
| Shoulder abductors | Left / Right | 0-5 each |
| Elbow flexors | Left / Right | 0-5 each |
| Wrist extensors | Left / Right | 0-5 each |
| Hip flexors | Left / Right | 0-5 each |
| Knee extensors | Left / Right | 0-5 each |
| Foot dorsiflexors | Left / Right | 0-5 each |
| TOTAL | 0-60 |
MRC Grading Scale (0-5)
| Grade | Meaning |
|---|---|
| 5 | Normal power - movement against full resistance |
| 4 | Movement against gravity AND resistance (but less than normal) |
| 3 | Movement against gravity over full range (no resistance) |
| 2 | Movement possible but NOT against gravity (gravity eliminated) |
| 1 | Visible contraction, no limb movement |
| 0 | No visible contraction at all |
Note: Scores like 4+/4.5 are rounded DOWN to 4; scores like 4- or 5- are rounded to the lower whole number (4- = 3, 5- = 4).
Score Interpretation
| MRC Sum Score | Clinical Meaning |
|---|---|
| 60 | Normal (no weakness) |
| 51-60 | Mild weakness |
| 41-50 | Moderate weakness |
| ≤40 | Severe weakness - increased risk of respiratory failure |
| 0 | Complete quadriplegia/paralysis |
Role in EGRIS (Erasmus GBS Respiratory Insufficiency Score)
The MRC sum score is one of 3 key factors in the EGRIS, which predicts the probability of respiratory failure within the first 7 days of hospitalization:
| Factor | Categories | Points |
|---|---|---|
| Days from weakness onset to hospitalization | >7 days / 4-7 days / ≤3 days | 0 / 1 / 2 |
| Facial and/or bulbar weakness at admission | Absent / Present | 0 / 1 |
| MRC sum score at admission | >60 / 51-60 / 41-50 / ≤40 | 0 / 1 / 2 / 3 |
EGRIS Total Score Interpretation:
- Score 0-2: Low risk of respiratory failure (~1%)
- Score 3-4: Intermediate risk (~24%)
- Score 5-7: High risk (~65%) - these patients should be admitted to the ICU for close observation and timely intubation if needed
Clinical Significance
- The MRC sum score is one of the most important predictors of respiratory failure in the first week of GBS hospitalization (along with bulbar weakness and time to admission), as demonstrated by a Dutch research group.
- Mechanical ventilation is ultimately required in 20-30% of GBS patients.
- Intubation criteria include: PaCO2 ≥48 mmHg, PaO2 ≤56 mmHg, or vital capacity <15 cc/kg (major criteria); or two of: ineffective cough, impaired swallowing, atelectasis (minor criteria).
- Peripheral muscle strength (MRC sum score) does not directly correlate with respiratory muscle weakness - ventilatory failure correlates specifically with diaphragmatic weakness.
Sources: Fishman's Pulmonary Diseases and Disorders; Kleyweg RP et al., Muscle Nerve 1991; Australian Blood Criteria - Neurological Scales
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