The diaphragm is the primary muscle involved in breathing and separates the chest cavity from the abdomen. When one or both sides of the diaphragm become weakened or paralyzed, normal breathing mechanics can be disrupted, causing respiratory symptoms.
At Saint John’s Health Center, patients with diaphragmatic paralysis can receive comprehensive evaluation through our Pulmonary and Thoracic Center of Excellence. Our specialists evaluate diaphragm function, pulmonary health, symptoms, and possible underlying causes to determine whether monitoring, supportive care, or surgical treatment may be appropriate.
Because the effects of diaphragm paralysis vary considerably from person to person, treatment is based on more than the presence of an elevated or weakened diaphragm. Our goal is to understand how the condition is affecting breathing and quality of life and develop an individualized care plan.
What Is a Paralyzed Diaphragm?
Diaphragmatic paralysis occurs when the diaphragm loses some or all of its ability to contract normally. The condition may affect one side of the diaphragm, known as unilateral paralysis, or both sides, known as bilateral paralysis.
The diaphragm normally contracts and moves downward during inhalation, creating additional space for the lungs to expand. When a portion of the diaphragm is paralyzed, it may remain abnormally elevated and can sometimes move upward rather than downward during inspiration—a pattern known as paradoxical movement. This can reduce the space available for the lung to expand and make breathing less efficient.
How the Diaphragm and Phrenic Nerve Support Breathing
Understanding the relationship between the diaphragm and the phrenic nerves helps explain why diaphragm paralysis occurs. The phrenic nerves travel from the neck into the chest and provide the nerve signals that allow the diaphragm to contract.
The Diaphragm
The diaphragm is a large, dome-shaped muscle located beneath the lungs. As it contracts, it moves downward and helps draw air into the lungs; as it relaxes, it rises again during exhalation. When one side does not contract properly, the remaining respiratory muscles may compensate, particularly when a person is otherwise healthy. This helps explain why some people with unilateral diaphragm paralysis have few symptoms while others experience substantial breathing limitations.
The Phrenic Nerve
Each side of the diaphragm is controlled primarily by a phrenic nerve. Injury, compression, inflammation, or another disruption anywhere along the nerve pathway can interfere with the signals responsible for normal diaphragm movement. Identifying a possible phrenic nerve problem can therefore be an important part of evaluating diaphragm weakness or paralysis, although in some patients no definitive cause is found.
Unilateral vs. Bilateral Diaphragm Paralysis
The effect on breathing depends partly on whether one or both sides of the diaphragm are involved. Underlying lung or neuromuscular disease, body position, overall health, and physical activity can also influence the severity of symptoms.
Unilateral Diaphragm Paralysis
When only one side of the diaphragm is affected, the other side may continue functioning normally and compensate for some of the loss of movement. Some patients have few symptoms and discover the condition incidentally during a chest X-ray or other imaging examination. Others may experience shortness of breath during exertion or when lying flat, particularly when another pulmonary condition is also affecting breathing.
Bilateral Diaphragm Paralysis
Bilateral paralysis affects both sides of the diaphragm and can cause more substantial respiratory impairment. Patients may have difficulty breathing while lying flat, disrupted sleep, fatigue, reduced exercise tolerance, or respiratory insufficiency. Evaluation of bilateral disease may require additional investigation for neurologic, neuromuscular, spinal, or other systemic causes, and respiratory support may play a greater role in management depending on severity.
Symptoms of Diaphragmatic Paralysis
Symptoms can range from minimal to significant and often depend on whether one or both sides of the diaphragm are affected. Patients with underlying pulmonary disease may notice greater effects because their existing respiratory reserve is already reduced.
Symptoms may include:
- Shortness of breath, particularly with physical activity
- Difficulty breathing while lying flat (orthopnea)
- Reduced exercise tolerance
- Fatigue
- Sleep disturbance
- Difficulty taking a deep breath
- Shortness of breath when bending forward
- Respiratory difficulties that become more noticeable when another lung condition is present
Some people with unilateral paralysis experience few or no symptoms. For this reason, the severity of a patient’s symptoms and functional limitations is generally more important than the imaging finding alone when considering treatment.
Causes of Diaphragm Paralysis
Diaphragmatic paralysis can result from conditions affecting the diaphragm itself, the phrenic nerve, or the neurologic pathways controlling breathing. Determining the underlying cause can help guide treatment and provide information about the likelihood of recovery.
Phrenic Nerve Injury
Damage to the phrenic nerve is an important cause of acquired diaphragm paralysis. The nerve may be injured, compressed, stretched, or otherwise disrupted anywhere along its path from the neck through the chest. The extent and cause of the nerve injury can influence whether diaphragm function has the potential to recover, although in some cases a clear cause cannot be identified.
Surgery or Trauma
Phrenic nerve injury can occasionally occur following cardiac, thoracic, neck, or other surgical procedures performed near the nerve. Significant trauma involving the neck or chest may also damage the nerve or its associated pathways. The timing of symptoms relative to a previous operation or injury can therefore provide important diagnostic information, and some nerve injuries may recover over time.
Neurologic and Neuromuscular Conditions
Certain neurologic and neuromuscular disorders can interfere with the signals controlling diaphragm movement. These conditions may affect the nerves, spinal cord, neuromuscular junction, or respiratory muscles themselves. When diaphragm dysfunction occurs along with other neurologic symptoms or involves both sides of the diaphragm, additional neurologic or neuromuscular evaluation may be appropriate.
Tumors, Compression and Other Causes
Tumors or other abnormalities in the neck or chest can occasionally compress or involve the phrenic nerve. Imaging may therefore be used not only to evaluate diaphragm position but also to look for structural causes along the course of the nerve. Inflammatory, infectious, metabolic, and other medical conditions may also contribute to diaphragm dysfunction in selected patients; when no identifiable cause is found, the condition may be described as idiopathic diaphragm paralysis.
How Diaphragm Paralysis Is Diagnosed
Diagnosing diaphragmatic paralysis involves determining whether diaphragm movement is abnormal, assessing its effect on breathing, and investigating possible underlying causes. Because an elevated diaphragm seen on an X-ray does not by itself establish paralysis, functional evaluation is often an important part of the diagnostic process.
Pulmonary Function Testing
Pulmonary function tests help measure how effectively the lungs are working and how diaphragm dysfunction may be affecting breathing. Testing may be performed while sitting upright and while lying down because diaphragm weakness can become more apparent in the supine position. Specialists interpret these measurements in the context of symptoms, underlying pulmonary health, and whether one or both sides of the diaphragm are affected.
Chest Imaging
A chest X-ray may initially reveal an abnormally elevated side of the diaphragm. CT or MRI may then be used when additional anatomical information is needed or when physicians need to investigate a possible underlying cause involving the chest, neck, spine, or phrenic nerve pathway. Imaging findings are considered together with symptoms and functional testing because an elevated diaphragm can have causes other than paralysis.
Diaphragm Ultrasound
Ultrasound can provide real-time information about diaphragm movement and function without exposing the patient to ionizing radiation. It may be used to assess diaphragm excursion and changes in muscle thickness during breathing. Depending on the clinical situation and available expertise, ultrasound may complement other diagnostic tests when diaphragm dysfunction is suspected.
Fluoroscopic Sniff Test
During a fluoroscopic sniff test, diaphragm movement is observed while the patient quickly inhales or “sniffs.” A normally functioning diaphragm moves downward during inspiration, while a paralyzed hemidiaphragm may demonstrate abnormal or paradoxical upward movement. The test can help distinguish paralysis from other causes of diaphragm elevation and remains one of several dynamic tools available for evaluating diaphragmatic function.
Additional Testing When Needed
Some patients may benefit from additional evaluation of phrenic nerve or neuromuscular function, particularly when the cause remains uncertain. Testing is selected according to symptoms, medical history, imaging findings, and whether unilateral or bilateral dysfunction is present. This individualized approach is important because diaphragmatic paralysis can arise from several different mechanisms rather than a single disease process.
Treatment for a Paralyzed Diaphragm
Not everyone with diaphragm paralysis requires treatment. Decisions are based on symptoms, respiratory function, underlying health, the cause of paralysis, and the likelihood that diaphragm or phrenic nerve function may recover.
Observation and Treating the Underlying Cause
Patients with mild or no symptoms may initially be monitored, particularly when the condition is unilateral. When a potentially reversible cause is identified, treatment may focus on the underlying condition while diaphragm function is followed over time. Spontaneous improvement can occur in some cases of acquired diaphragm paralysis, including after certain phrenic nerve injuries, so allowing time for possible recovery may be appropriate when respiratory function permits.
Diaphragm Plication
For patients with persistent, function-limiting symptoms, diaphragm plication may be considered. The procedure tightens and repositions the weakened or paralyzed diaphragm so that it remains in a lower, more stable position and interferes less with lung expansion. Plication does not repair the phrenic nerve or cause the paralyzed diaphragm to begin contracting normally again; its purpose is to improve breathing mechanics and reduce paradoxical movement, allowing the lung more room to expand.
Plication may be performed using open or minimally invasive surgical approaches depending on the patient’s anatomy, health, and the recommendation of the thoracic surgeon. Contemporary thoracic surgery increasingly incorporates minimally invasive techniques when they are appropriate for the individual patient.
Other Supportive or Specialized Treatments
Patients with more significant respiratory impairment may require supportive approaches such as noninvasive ventilation, particularly with bilateral diaphragm dysfunction or during sleep. Selected patients may also undergo specialized evaluation for phrenic nerve procedures or diaphragm pacing depending on the underlying cause and integrity of the nerve and diaphragm. These treatments are highly individualized and are not appropriate for every type of diaphragmatic paralysis.
Recovery and Outlook
The outlook for diaphragm paralysis varies according to its cause, whether one or both sides are involved, the presence of underlying pulmonary disease, and the severity of symptoms. Many people with unilateral diaphragm paralysis function well without surgery, while others benefit from intervention when breathing limitations persist.
Can Diaphragm Function Recover?
Recovery is possible when paralysis results from certain temporary or reversible forms of phrenic nerve injury. Improvement may occur gradually over months, which is why observation is sometimes recommended before considering elective surgery when symptoms and respiratory function allow. When nerve function does not recover, treatment can instead focus on improving respiratory mechanics and reducing the functional effects of the paralyzed diaphragm.
Recovery After Diaphragm Plication
Patients undergoing plication are monitored for improvements in breathing, activity tolerance, and pulmonary function. Recovery varies with the surgical approach and the patient’s overall health, but minimally invasive techniques have expanded the options available for appropriately selected patients. The objective is not to restore nerve function but to create more favorable mechanics for lung expansion and improve breathing-related quality of life.
Our program at Saint John’s Health Center brings together pulmonary evaluation, thoracic surgery, advanced imaging, and minimally invasive approaches to diagnose and manage a wide range of conditions affecting the lungs, airways, chest, and respiratory system.Continued advances in minimally invasive procedures, robotic-assisted thoracic surgery, advanced imaging, and image-guided pulmonary technologies are expanding how thoracic and pulmonary conditions can be evaluated and managed.
These capabilities reflect our broader commitment to advancing personalized care for each patient.
If you have questions regarding diaphragm paralysis, or treatment of other thoracic conditions, please call today. Click here to request an appointment.
