Diaphragmatic Weakness & Paralysis

A weak or paralyzed diaphragm often goes misdiagnosed and left untreated, causing breathing issues that can worsen over time. While there are several medical treatments options, surgery remains the most effective way to treat a paralyzed or weakened diaphragm.

What is the Diaphragm?

The diaphragm is a large muscle that sits below the lungs and heart. The diaphragm is important as it is the primary muscle that facilitates breathing. When the diaphragm contracts, it becomes smaller, causing the lungs to expand in the chest cavity and allowing air to move into the lungs (inhaling). When it relaxes, it enlarges, causing a decrease in lung size thus forcing air out (exhaling).

The diaphragm is controlled by the phrenic nerve, a nerve that is attached to the cervical spine, the area of the spinal cord found in your neck. A paralyzed diaphragm is rarely caused by an injury to the diaphragm itself, but rather by an injury to the phrenic nerve or cervical spine.

What is Diaphragm Weakness or Paralysis?

Patients with a paralyzed diaphragm experience weakness of the diaphragm and have reduced breathing capabilities or are unable to control their voluntary breathing. They also have difficulty maintaining adequate gas exchange, as the lungs are not able to inhale and exhale outside air as efficiently. This is because the phrenic nerve is sending weak signals to the diaphragm to relax or contract, or is unable to send any signal part of or the entire diaphragm.

Diaphragm paralysis can be unilateral or bilateral.

Unilateral paralysis involves one side of the diaphragm. This means that the diaphragm is partially functioning, and the part that is paralyzed will move higher into the chest cavity, taking up space meant for the lungs and interfering with breathing.

Bilateral paralysis occurs when the entire diaphragm is paralyzed. This means that the diaphragm is unable to function in inhalation and exhalation and often requires a machine to assist with breathing.

What Causes Diaphragm Paralysis and Weakness?

Diaphragmatic weakness or paralysis is caused by damage or pressure on the phrenic nerve. There are several known causes that can lead to diaphragm paralysis:

• Birth defects such as congenital central hypoventilation syndrome
• Diseases of the nervous system, such as amyotrophic lateral sclerosis (ALS) or multiple sclerosis
• Injury, such as an upper cervical spinal cord injury that has spared the phrenic nerve
• Phrenic nerve fraying or damaging following cardiothoracic or pulmonary surgery
• Cervical spine arthritis
• Cancer that has spread and compresses the phrenic nerve.

While the cause can be identified in some cases, as many as 40 to 50% of paralyzed diaphragms are idiopathic, meaning the cause is unknown.

What are the symptoms of diaphragmatic weakness and paralysis?

Because the diaphragm plays a central role in breathing, the symptoms are more apparent when both sides of the diaphragm are affected. Symptoms of bilateral diaphragmatic weakness and paralysis include:

• Difficulty breathing, both at rest and when active
• Difficulty sleeping
• Fatigue
• Recurrent pneumonia

In unilateral diaphragmatic paralysis, which affects only one side of the diaphragm, dyspnea – or difficulty breathing – on exertion or when lying down is the most typical symptom.

How are diaphragmatic weakness and paralysis diagnosed?

Sometimes diaphragmatic weakness and paralysis is an incidental finding with imaging such as x-rays, MRIs, or ultrasounds. Other times, the diagnosis can be made with blood tests, such as arterial blood gas analysis, that can reveal a lack of needed oxygen in the bloodstream. Pulmonary function tests may also be performed to help confirm diaphragm issues. 

What is the treatment for diaphragmatic weakness?

Depending on the severity of injury to the diaphragm, some doctors recommend non-surgical options to treat the breathing issues associated with diaphragm weakness and paralysis. Surgical treatment is an option for more advanced cases or if breathing becomes so impacted daily life is affected. 

• Diaphragmatic Pacing: If the phrenic nerve is intact, diaphragmatic pacing is an option. Diaphragmatic pacing is a minimally-invasive surgical option that involves placing a pacemaker to regulate breathing by electrically stimulating the phrenic nerve. 
• Diaphragm Plication: Plication is another surgical option for treating a paralyzed diaphragm. Plication involves tying the affected side of the diaphragm to the side that is still functioning normally. This prevents the weakened diaphragm from becoming elevated in the chest cavity and allows the lungs to expand more efficiently and making breathing easier.

Mechanical ventilation with a breathing machine might be required in some more advanced cases.