Diaphragm mmt
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diaphragm manual muscle testing MMT technique grading
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The retrieval didn't return specific diaphragm MMT content. Drawing from my clinical knowledge to provide a thorough answer:
Diaphragm Manual Muscle Testing (MMT)
Overview
The diaphragm is the primary muscle of inspiration. Because it is an internal muscle, it cannot be directly palpated or resisted in the conventional MMT sense — standard MMT grading (0–5) is adapted using indirect methods.
Standard MMT Grading Scale (Kendall / MRC)
| Grade | Description |
|---|---|
| 5/5 | Normal strength — full ROM against gravity + full resistance |
| 4/5 | Active movement against gravity + some resistance |
| 3/5 | Active movement against gravity only |
| 2/5 | Active movement with gravity eliminated |
| 1/5 | Visible/palpable contraction, no movement |
| 0/5 | No contraction |
Diaphragm MMT Technique
Patient Position
- Supine (or semi-reclined)
- Knees slightly flexed to relax abdominal muscles
Therapist Position
- Standing at the patient's side
- Hands placed bilaterally over the lower costal margin / subcostal region
Procedure
- Instruct the patient to take a deep diaphragmatic breath (belly breathing, not chest).
- Observe and palpate for:
- Downward descent of the diaphragm → causes abdominal rise (epigastric excursion)
- Lateral costal expansion of the lower rib cage
- Apply resistance at end-inspiration by pressing inward/downward at the lower ribs to resist further expansion.
- Ask the patient to hold the breath at end-inspiration against your resistance.
Key Observation Points
- Symmetry of chest wall excursion (unilateral weakness → hemidiaphragm palsy)
- Paradoxical inward abdominal movement on inspiration = severe weakness or paralysis
- Accessory muscle use (scalenes, SCM) compensating for diaphragm weakness
Grading Interpretation for Diaphragm
| Grade | Clinical Finding |
|---|---|
| 5/5 | Full epigastric rise + normal costal flare; holds against strong resistance |
| 4/5 | Adequate excursion; holds against moderate resistance |
| 3/5 | Visible excursion against gravity (supine); no resistance tolerated |
| 2/5 | Minimal excursion; better in gravity-eliminated position (standing/sitting) |
| 1/5 | Palpable subcostal muscle activity only; no visible movement |
| 0/5 | No activity; paradoxical breathing pattern |
Supplementary Assessment Tools
Because direct MMT of the diaphragm is limited, clinical assessment is often combined with:
| Tool | Finding in Weakness |
|---|---|
| Sniff test (fluoroscopy/ultrasound) | Paradoxical upward movement of affected hemidiaphragm |
| Diaphragm ultrasound | Thickening fraction < 20% indicates weakness; normal ≥ 20–30% |
| MIP (Maximal Inspiratory Pressure) | < −70 cmH₂O normal; < −30 cmH₂O suggests significant weakness |
| Phrenic nerve conduction study / EMG | Confirms neurogenic vs. myopathic etiology |
| Chest X-ray | Elevated hemidiaphragm suggests unilateral paralysis |
Clinical Correlations
Causes of Diaphragm Weakness:
- Cervical SCI (C3–C5 — "C3, 4, 5 keeps the diaphragm alive")
- Phrenic nerve injury (cardiac surgery, neck trauma, tumor)
- ALS / motor neuron disease
- Myasthenia gravis
- Muscular dystrophies (e.g., Duchenne)
- Critical illness myopathy / ICU-acquired weakness
- AIDP/Guillain-Barré syndrome
Red Flags Requiring Urgent Assessment:
- Orthopnea (worsens lying flat — hallmark of bilateral diaphragm weakness)
- SpO₂ drop in supine position
- FVC drop > 25% from sitting to supine
The diaphragm MMT is most clinically useful as a screening tool and is best interpreted alongside respiratory function tests and imaging for definitive assessment.
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