What Is Diaphragmatic Paralysis? Symptoms And Treatment

Diaphragmatic paralysis is the loss of muscle function in the diaphragm, the large dome-shaped muscle that powers breathing. When the diaphragm cannot contract properly, the lungs do not expand fully, which makes it harder to take a deep breath. Treatment depends on the cause and severity, ranging from monitoring and breathing exercises to surgery for severe cases.

What Does the Diaphragm Actually Do?

The diaphragm sits just below the lungs and separates the chest cavity from the abdomen. It is the primary muscle used for breathing. When you inhale, the diaphragm contracts and flattens downward. This creates more space in the chest cavity, allowing the lungs to expand and pull in air.

When you exhale, the diaphragm relaxes and returns to its dome shape. This process happens automatically about 12 to 20 times per minute in a resting adult. The diaphragm also plays a role in other functions, including coughing, sneezing, and pressure within the abdomen.

Breathing is a complex process. The diaphragm does most of the work during quiet breathing. The muscles between the ribs, called intercostal muscles, help expand the ribcage. The neck and chest muscles only become active during deep or labored breathing. When the diaphragm fails, these accessory muscles must work harder to keep air moving.

What Causes Diaphragmatic Paralysis?

The phrenic nerve controls the diaphragm. This nerve originates in the neck at the C3, C4, and C5 spinal levels. It travels down through the chest to reach the diaphragm. Damage anywhere along this path can cause paralysis.

The most common causes include:

• Trauma — Injury to the neck, chest, or spine can damage the phrenic nerve. Car accidents, falls, and surgical complications are frequent causes.
• Cardiac surgery — Open-heart surgery, especially coronary artery bypass grafting, can injure the phrenic nerve. The nerve runs close to the heart and can be damaged during the procedure.
• Spinal cord injury — Damage at the C3 to C5 level affects the nerve supply to the diaphragm.
• Tumors — Growths in the chest or neck can press on the phrenic nerve.
• Neuromuscular diseases — Conditions like amyotrophic lateral sclerosis (ALS), muscular dystrophy, and myasthenia gravis can weaken the diaphragm.
• Infections — Viral infections such as herpes zoster (shingles) or Lyme disease can inflame the phrenic nerve.
• Idiopathic — In many cases, no clear cause is found. Doctors call this idiopathic diaphragmatic paralysis.

Some cases are congenital, meaning present from birth. This is rare and often related to abnormal development of the phrenic nerve or diaphragm muscle itself.

What Are the Symptoms of Diaphragmatic Paralysis?

Symptoms vary widely. Some people have no symptoms at all and only discover the condition through imaging done for another reason. Others experience significant breathing difficulty.

Common symptoms include:

• Shortness of breath — This is most noticeable when lying flat, exercising, or bending forward.
• Difficulty breathing when lying down — Called orthopnea, this occurs because gravity no longer helps the diaphragm descend.
• Fatigue — Breathing takes more effort, which can cause general tiredness.
• Morning headaches — These can result from reduced oxygen levels during sleep.
• Poor sleep quality — Waking up frequently or feeling unrefreshed after sleep.
• Reduced exercise tolerance — Getting winded with activities that used to be easy.
• Anxiety — Feeling like you cannot catch your breath can cause distress.

Unilateral paralysis, where one side of the diaphragm is affected, often causes milder symptoms than bilateral paralysis, where both sides are affected. Many people with unilateral paralysis are asymptomatic at rest. Bilateral paralysis is much more serious and usually causes significant breathing problems even at rest.

Some people develop paradoxical breathing. This means the diaphragm moves upward instead of downward during inhalation. The abdomen pulls in instead of pushing out with each breath. This is a sign of significant dysfunction.

How Is Diaphragmatic Paralysis Diagnosed?

Diagnosis begins with a physical exam and medical history. Your doctor will listen to your lungs and observe your breathing pattern. They may notice reduced breath sounds on one side or see the abdomen move paradoxically.

Several tests help confirm the diagnosis:

• Chest X-ray — This can show an elevated diaphragm on the affected side. In unilateral paralysis, one side of the diaphragm sits higher than the other.
• Fluoroscopy — Also called a sniff test, this uses live X-ray imaging while you breathe in sharply. A paralyzed diaphragm will move upward instead of downward during the sniff.
• Pulmonary function tests — These measure how much air your lungs can hold and how forcefully you can exhale. Results often show a restrictive pattern, meaning reduced lung volumes.
• Nerve conduction studies — These test how well the phrenic nerve conducts electrical signals. A delayed or absent signal indicates nerve damage.
• Electromyography (EMG) — This measures the electrical activity of the diaphragm muscle itself. It can help determine if the problem is in the nerve or the muscle.
• Ultrasound — This can assess diaphragm movement and thickness in real time.
• CT or MRI scans — These help identify structural causes like tumors or spinal cord issues.

A diagnosis of bilateral paralysis is usually obvious from symptoms alone because breathing is visibly difficult. Unilateral paralysis requires imaging to confirm which side is affected.

What Are the Treatment Options?

Treatment depends on the cause, severity, and whether one or both sides of the diaphragm are affected. There is no single standard approach for every patient.

Observation and Monitoring

For people with mild unilateral paralysis and no symptoms, doctors often recommend observation. The condition may improve on its own, especially if caused by a temporary injury to the phrenic nerve. Regular follow-up with pulmonary function tests helps track any changes.

Breathing Exercises and Pulmonary Rehabilitation

Pulmonary rehabilitation can help strengthen the accessory breathing muscles. Techniques like pursed-lip breathing and diaphragmatic breathing exercises may improve symptoms, though evidence for their effectiveness in paralysis specifically is limited. Some clinicians recommend them as part of a broader treatment plan.

Treating the Underlying Cause

If a specific cause is identified, treating it may resolve the paralysis. For example, surgery to remove a tumor pressing on the phrenic nerve may restore function. Treating an infection with appropriate medication can allow the nerve to recover. In cases related to neuromuscular disease, managing the underlying condition is the priority.

Surgical Options

Surgery is reserved for severe cases that do not improve with conservative management. Options include:

• Diaphragm plication — This procedure flattens and tightens the paralyzed diaphragm. It reduces the space the diaphragm takes up in the chest, allowing the lungs to expand more easily. It is most commonly performed for unilateral paralysis.
• Phrenic nerve pacing — This involves implanting a device that sends electrical impulses to the phrenic nerve, stimulating the diaphragm to contract. It is used for bilateral paralysis, particularly in people with spinal cord injuries. Not everyone is a candidate for pacing, and the nerve must be intact for it to work.

Both procedures have risks and benefits. A specialist in thoracic surgery or pulmonary medicine can help determine if surgery is appropriate.

Breathing Support

Severe bilateral paralysis may require mechanical ventilation. Some people need non-invasive ventilation at night, using a mask that delivers pressurized air. This supports breathing during sleep and gives the accessory muscles a rest. In the most severe cases, a tracheostomy with long-term ventilation may be necessary.

What Is the Outlook for People with Diaphragmatic Paralysis?

The prognosis depends heavily on the cause. When the phrenic nerve is injured but not severed, recovery is possible. Nerve recovery is slow, often taking 6 to 12 months or longer. Some people regain full function; others improve partially.

Idiopathic cases have a variable outlook. Some improve spontaneously, while others remain stable with symptoms managed through treatment. Cases caused by progressive neuromuscular diseases tend to worsen over time as the underlying condition progresses.

Unilateral paralysis generally carries a better prognosis than bilateral paralysis. Most people with unilateral paralysis live normal lives with manageable symptoms. Bilateral paralysis is more serious and often requires ongoing respiratory support.

When Should You See a Doctor?

Shortness of breath that is new, worsening, or occurring with minimal exertion warrants medical evaluation. Difficulty breathing when lying flat is another reason to seek care. If you have had cardiac surgery or a neck injury and notice breathing changes, mention this to your doctor.

Sudden severe shortness of breath, chest pain, or bluish lips or fingers are emergency signs. These require immediate medical attention.

Frequently Asked Questions