Muscle Strength Grading in Post-Stroke Patients
Use the 0-5 manual muscle testing (MMT) scale for routine clinical assessment of muscle strength in post-stroke patients, supplemented by the Motricity Index for standardized documentation of upper and lower extremity strength. 1
Primary Grading Method: Manual Muscle Testing (0-5 Scale)
The standard approach for grading muscle strength after stroke uses the 0-5 ordinal scale via manual muscle testing, which provides reliable assessment particularly for weaker muscles (grades 0-3). 1, 2
The 0-5 Grading Scale:
- Grade 0: No visible or palpable muscle contraction 1
- Grade 1: Visible or palpable contraction without joint movement 1
- Grade 2: Movement with gravity eliminated 1
- Grade 3: Movement against gravity through full range 1
- Grade 4: Movement against gravity with some resistance 1
- Grade 5: Normal strength against full resistance 1
Important caveat: The 0-5 MMT scale is most reliable and accurate for weak muscles (grades 0-3), but becomes less precise for stronger muscles (grades 4-5). 2 For bulky muscles operating at 50% or more of normal power, consider supplementing with objective measures like handheld dynamometry. 2
Recommended Standardized Tool: Motricity Index
The Motricity Index is the guideline-recommended instrument for quantifying post-stroke strength because it provides a weighted scoring system specifically designed for stroke assessment. 1
Motricity Index Structure:
- Upper extremity subscale: 0-66 points testing 3 key segments 1
- Lower extremity subscale: 0-34 points testing 3 key segments 1
- Administration time: Less than 5 minutes per limb 1
- Reliability: High test-retest reliability (ICC=0.93) for lower extremity assessment 3
The Motricity Index uses manual muscle testing at three key segments per limb and converts these to a weighted score from 0-100, indicating overall limb strength. 1 This provides more granular documentation than simple MMT grades alone.
Supplementary Objective Measures
When more precise quantification is needed, particularly for research or tracking subtle changes:
Grip and Pinch Dynamometry
- Available in most rehabilitation settings 1
- Provides objective force measurements 1
- Normative data available for comparison 1
- Administration time: Less than 5 minutes 1
Handheld Dynamometry
- More accurate than MMT for stronger muscles (grades 4-5) 1, 2
- Particularly useful for bulky muscle groups 2
- Provides quantitative torque measurements 1
Clinical Application Algorithm
For initial assessment and routine monitoring:
- Perform manual muscle testing (0-5 scale) on key muscle groups bilaterally 1
- Document using Motricity Index format for standardized scoring 1
- Test 3 key upper extremity segments: shoulder, elbow, wrist/hand 1
- Test 3 key lower extremity segments: hip, knee, ankle 1
For patients with grades 4-5 strength or when tracking subtle improvements:
- Add grip/pinch dynamometry for hand function 1
- Consider handheld dynamometry for major muscle groups 1, 2
For comprehensive impairment assessment:
- Integrate strength testing into the Fugl-Meyer Assessment, which quantifies sensorimotor impairment including ability to move out of abnormal synergies (UE: 0-66 points, LE: 0-34 points, administration time: 25 minutes) 1
Common Pitfalls to Avoid
Do not rely solely on MMT grades 4-5 for precise assessment - the distinction between these grades is subjective and less reliable than for weaker muscles. 2 Use objective dynamometry when precision matters for stronger muscles.
Do not assess strength in isolation - strength correlates highly with functional outcomes like locomotion (particularly knee strength and balance), so integrate strength assessment with functional mobility testing. 4
Do not forget bilateral comparison - always test the non-paretic side for comparison, as the difference between sides provides important prognostic information. 4