mrc sum score calculator

Score each muscle group from 0 to 5 on both sides. The total ranges from 0 to 60.

Right Shoulder Abduction

Left Shoulder Abduction

Right Elbow Flexion

Left Elbow Flexion

Right Wrist Extension

Left Wrist Extension

Right Hip Flexion

Left Hip Flexion

Right Knee Extension

Left Knee Extension

Right Ankle Dorsiflexion

Left Ankle Dorsiflexion

MRC Muscle Strength Scale (0-5):

0 = No visible or palpable contraction
1 = Flicker or trace of contraction
2 = Active movement with gravity eliminated
3 = Active movement against gravity
4 = Active movement against gravity and resistance
5 = Normal power

What Is the MRC Sum Score?

The Medical Research Council (MRC) Sum Score is a bedside tool used to quantify global muscle strength. It is commonly used in rehabilitation and critical care settings, especially when evaluating possible ICU-acquired weakness. The score is based on manual muscle testing of six bilateral muscle groups, producing a total score from 0 to 60.

How the Calculator Works

This calculator asks for a score (0 to 5) for each of the following muscle groups on both the right and left sides:

Shoulder abduction
Elbow flexion
Wrist extension
Hip flexion
Knee extension
Ankle dorsiflexion

The total is calculated as: Sum of all 12 muscle scores = MRC Sum Score (0-60).

Interpretation Guide

Typical Clinical Thresholds

< 48/60: Often used as a cutoff suggesting clinically significant weakness (including possible ICU-acquired weakness).
< 36/60: Often interpreted as severe weakness.
48-60: Above common weakness cutoff, though clinical context still matters.

Thresholds may vary slightly by institution, patient population, and examiner practice. Always combine the score with the full clinical exam.

Best Practices for Scoring

Before You Start

Ensure the patient is alert enough to follow commands.
Use a consistent testing position and method.
Document pain, sedation level, and any movement limitations.

During Manual Muscle Testing

Give clear, simple instructions.
Stabilize proximal joints appropriately.
Apply resistance consistently and safely.
Compare both sides and note asymmetry.

Why the MRC Sum Score Matters

In many clinical settings, a structured strength measure helps teams track change over time. A declining score may prompt further evaluation, while improving scores can support rehabilitation planning and discharge decisions.

The MRC sum score is especially useful because it is:

Simple and quick to perform at bedside
Low-cost and equipment-free
Easy to repeat for trend monitoring

Limitations to Keep in Mind

The exam depends on patient cooperation and cognition.
Inter-rater variability can occur without standardized technique.
It does not replace neurological localization or electrophysiologic testing when needed.
Pain, orthopedic injury, and fatigue can reduce apparent strength independent of neuromuscular disease.

Quick Example

If a patient scores mostly 4s with a few 3s, the total may land around 44-50. A score of 44 would be below the common 48 threshold and should prompt closer clinical review.

Clinical Use Disclaimer

This tool is intended for educational and workflow support purposes. It does not diagnose disease on its own and should not replace professional clinical judgment. For diagnosis and treatment decisions, use this score alongside complete history, exam findings, and other investigations.