30/07/2026
🫁 Dyspnea with an Elevated Hemidiaphragm? Don't Miss Phrenic Nerve Palsy
Shortness of breath is commonly attributed to pulmonary or cardiac disease. However, diaphragmatic dysfunction due to phrenic nerve injury is an important—and frequently overlooked—neurological cause of respiratory compromise.
For physiotherapists, pulmonologists, neurologists, and rehabilitation professionals, recognizing phrenic nerve dysfunction is essential for timely diagnosis and management.
🧠 What Is the Phrenic Nerve?
The phrenic nerve arises primarily from the C3–C5 cervical nerve roots, with C4 providing the major contribution.
> "C3, 4, 5 keep the diaphragm alive."
It provides:
✅ Motor innervation to the diaphragm
✅ Sensory innervation to the central diaphragm, mediastinal pleura, pericardium, and central diaphragmatic peritoneum.
Because the diaphragm is the principal muscle of inspiration, phrenic nerve dysfunction can significantly impair ventilation.
⚙️ Common Causes
• Cardiac surgery (especially CABG)
• Cervical spine surgery or trauma
• Brachial plexus injury
• Neck tumors or mediastinal masses
• Radiation therapy
• Viral neuropathies (e.g., Neuralgic Amyotrophy/Parsonage-Turner Syndrome)
• Regional anesthesia (interscalene block)
• Idiopathic phrenic neuropathy
🚩 Clinical Presentation
Unilateral Palsy
✔ Dyspnea during exertion
✔ Orthopnea
✔ Reduced exercise tolerance
✔ Elevated hemidiaphragm on chest radiograph
Many patients remain asymptomatic at rest.
Bilateral Palsy
✔ Severe dyspnea
✔ Orthopnea
✔ Sleep-disordered breathing
✔ Morning headaches
✔ Hypercapnia
✔ Respiratory insufficiency
🩺 Clinical Examination
Observe
• Paradoxical abdominal movement during inspiration
• Use of accessory respiratory muscles
Imaging
✅ Chest X-ray
May reveal an elevated hemidiaphragm.
Dynamic Ultrasound
First-line imaging to assess diaphragmatic excursion and thickness during respiration.
Fluoroscopic "Sniff Test"
Demonstrates paradoxical elevation of the affected hemidiaphragm during a forceful sniff.
Pulmonary Function Tests
Typically show a restrictive ventilatory pattern with greater reduction in supine vital capacity.
Electrophysiological Studies
Phrenic nerve conduction studies and diaphragmatic EMG may help confirm the diagnosis.
⚠️ Commonly Misdiagnosed As
❌ Asthma
❌ COPD
❌ Heart Failure
❌ Deconditioning
❌ Anxiety-related Dyspnea
❌ Pulmonary Fibrosis
💡 Evidence-Based Management
Conservative Management
✔ Treat the underlying cause
✔ Inspiratory muscle training (selected patients)
✔ Pulmonary rehabilitation
✔ Breathing retraining
✔ Optimize posture and thoracic mobility
Advanced Management
Patients with persistent respiratory compromise may require:
• Non-invasive ventilation (particularly bilateral palsy)
• Surgical diaphragmatic plication (selected unilateral cases)
• Phrenic nerve reconstruction or pacing in carefully selected patients
📈 Prognosis
Recovery depends on the underlying etiology.
Neuropraxic injuries may recover over several months.
Post-surgical injuries may recover spontaneously, although some remain permanent.
Bilateral palsy generally carries a poorer prognosis and often requires long-term respiratory support.
📌 Clinical Pearl
A patient with:
🫁 Unexplained exertional dyspnea
⬆️ Elevated hemidiaphragm
😴 Orthopnea with otherwise normal cardiac evaluation
…may have phrenic nerve dysfunction rather than primary lung disease.
Dynamic diaphragm ultrasound has become an invaluable, non-invasive tool for confirming the diagnosis and monitoring recovery.
📚 References
1. StatPearls. Phrenic Nerve Injury.
2. American Thoracic Society (ATS). Clinical guidance on diaphragmatic dysfunction.
3. Boon AJ, Harper CJ, Ghahfarokhi LS, et al. Ultrasound Assessment of Diaphragm Function. Muscle & Nerve.
4. Versteegh MI, et al. Diaphragm Plication in Adults with Unilateral Diaphragm Paralysis.
5. European Respiratory Society (ERS). Recommendations on respiratory muscle assessment.
💬 In your clinical practice, have you encountered a patient with an elevated hemidiaphragm that was ultimately diagnosed as phrenic nerve palsy? Share your experience below.
