Diaphragm Paralysis

The diaphragm is a thin muscle (smaller than the width of a finger), which separates the chest and abdomen. Its function is to serve as bellows for breathing. Since it is a muscle, the diaphragm pulls air in during contraction. When the diaphragm relaxes, air pushes out.

Originating in the brain, phrenic nerves control diaphragm function. These nerves run along each side of the neck and along the right and left sides of the heart to reach the diaphragm. Damage to one of these nerves paralyzes the diaphragm. A paralyzed diaphragm becomes stretched out and floppy. Instead of opening up the lung when you breathe in, it collapses the lung.


Diaphragm paralysis is caused by direct damage to the nerve (trauma, damage during surgery) or compression by adjacent structures (tumors, bony protrusions). Some viral infections or other diseases, such as diabetes, can affect nerves. In all cases, injury to the nerve leads to a paralyzed diaphragm.
Almost half of people will not have a clearly identified cause. It is encouraging, however, that a large number will have minimal to no symptoms. 

  • Procedures
    • Neck (e.g., spinal fusion) or chest (e.g., heart) surgery
    • Injections in the neck area (such as pain blocks)
  • Trauma to the neck 
  • Cancer
    • Chest tumors (lung cancer or other metastatic cancers)
    • Neck tumors
    • Lymphoma
  • Infection
    • Shingles
    • Other viral infections
  • Radiculopathy (nerve compression) in the neck


When the diaphragm does not work properly, it interferes with breathing and the following symptoms may occur. 

  • Inability to take a full or deep breath (usually worse when lying down)
  • Shortness of breath during activities
  • Sensation of heaviness or breathlessness when leaning or bending down
  • Asymptomatic (showing no signs) symptoms

Most of the time one side of the diaphragm is affected. When the entire diaphragm (right and left) is involved, symptoms are severe.

Diagnosing Diaphragm Paralysis

Many people have minimal symptoms and diagnosis results from a chest X-ray, which shows that part of the diaphragm is higher than expected. The following tests can help determine if the diaphragm is working properly.  

  • Chest X-ray: typically the first test to detect this condition
  • Pulmonary function test: shows evidence of lung not being fully inflated
  • “Sniff” test: uses a type of X-ray or ultrasound to capture images of a person sniffing, which reveals if the diaphragm is moving as expected. 
  • Chest CT scan: provides a detailed picture of the chest, evaluates the presence of tumors that can cause this condition, shows how severely lungs are compressed


No treatment is required for people who are asymptomatic. If cancer was excluded, it is reasonable to wait several months before treating, as there is a chance diaphragm function may return. People with life-altering symptoms should consider surgery. 

Surgery consists of plication, which involves creating fixed pleats along the stretched out parts of the diaphragm. While this procedure does not restore normal function, it decreases or neutralizes the negative effect on the function of the normal side diaphragm. As a result, breathing improves. Two surgical approaches include minimally invasive thoracoscopy/VATS (video-assisted thoracoscopic surgery) or thoracotomy, depending on medical history and other conditions.