OVERVIEW

What is diaphragmatic paralysis?

Diaphragmatic paralysis refers to the weakness and elevation of one or both sides of the diaphragm due to damage to the phrenic nerve caused by various factors, leading to symptoms such as difficulty breathing and gastrointestinal discomfort.

There are many causes of phrenic nerve damage, the most common being lung cancer metastasizing to mediastinal lymph nodes causing compression or direct invasion of the phrenic nerve by malignant tumors. Other causes include surgical trauma or injury, large aortic aneurysms, herpes zoster, tuberculosis, etc. The cause is unclear in some patients.

Is diaphragmatic paralysis common?

No, it is uncommon.

What are the types of diaphragmatic paralysis?

Based on the extent of involvement, diaphragmatic paralysis can be classified into unilateral diaphragmatic paralysis and bilateral diaphragmatic paralysis.

SYMPTOMS

What are the manifestations of diaphragmatic paralysis?

Since the diaphragm is one of the important respiratory muscles, the clinical manifestations of diaphragmatic paralysis mainly include dyspnea. Left-sided diaphragmatic paralysis may also cause gastrointestinal symptoms such as belching, bloating, and abdominal pain due to the elevation of the gastric fundus.

• Unilateral diaphragmatic paralysis often presents with no obvious symptoms due to compensation by the contralateral diaphragm and other accessory respiratory muscles, and is usually detected during physical examination.

• In cases of complete bilateral diaphragmatic paralysis, patients may experience severe dyspnea, which worsens in the supine position, orthopnea, and acute episodes, often accompanied by tachypnea and shallow breathing.
  Additionally, paradoxical inward movement of the abdomen during inspiration (abdominal paradoxical breathing) may be observed, along with the use of other accessory respiratory muscles, leading to supraclavicular and intercostal retractions during inspiration.

What diseases can diaphragmatic paralysis cause? What serious consequences may occur?

Due to insufficient lung expansion caused by diaphragmatic paralysis, recurrent pulmonary infections and atelectasis may occur. In severe cases, respiratory failure may develop, which can be life-threatening, often requiring mechanical ventilation for respiratory support.

What conditions should diaphragmatic paralysis be differentiated from?

Clinically, it should be differentiated from all diseases that cause dyspnea, especially those with similar radiographic findings, such as subpulmonic pleural effusion, diaphragmatic eventration, and diaphragmatic hernia. Left-sided diaphragmatic paralysis should also be distinguished from digestive system disorders that cause belching, bloating, and abdominal pain.

CAUSES

What are the causes of diaphragmatic paralysis?

Diaphragmatic paralysis results from phrenic nerve palsy due to various causes, including the following common etiologies:

• Tumor invasion or compression: This is the most common cause of diaphragmatic paralysis, often due to mediastinal lymph node metastasis from lung cancer compressing the phrenic nerve, or direct invasion by central lung cancer or mediastinal tumors. In rare cases, malignant tumors of the pericardium, heart, or pleura may also directly invade the phrenic nerve.

• Trauma: Surgeries involving the mediastinum, such as mediastinal tumor resection, lung cancer surgery, pericardiectomy, coronary artery bypass grafting, or open-heart surgery, may damage or even sever the phrenic nerve. Thoracic surgeries can also injure the nerve, typically causing unilateral phrenic nerve involvement. Various types of chest trauma or excessive neck traction during childbirth may also damage the phrenic nerve.

• Cervical spine or spinal cord disorders: The phrenic nerve originates from the C3, C4, and C5 nerve roots. Therefore, conditions such as trauma, tumors, cervical spondylosis, intervertebral disc disease, or cervical tuberculosis at the C3–C5 vertebral level may compress or damage the phrenic nerve.

• Neurological diseases: Brainstem disorders affecting the respiratory center that controls the phrenic nerve, or infectious polyradiculoneuritis, may occasionally cause phrenic nerve palsy. Motor neuron disease, systemic myopathy, myasthenia gravis, or Lambert-Eaton syndrome may also present with bilateral diaphragmatic paralysis.

• Infectious diseases: Infections such as herpes zoster, poliomyelitis, or diphtheria may involve the phrenic nerve and lead to paralysis. Rarely, inflammatory diseases affecting the mediastinum (e.g., massive tuberculous lymphadenitis or mediastinitis) may also damage the phrenic nerve.

• Iatrogenic factors: For example, acupuncture in the neck region.

• Others: A large aortic aneurysm may cause left-sided phrenic nerve palsy. Hereditary brachial plexus neuropathy may also lead to phrenic nerve paralysis. In some cases, no clear cause can be identified.

DIAGNOSIS

How is diaphragmatic paralysis diagnosed?

For bilateral complete diaphragmatic paralysis, due to its characteristic manifestations, clinicians can make a clinical judgment based on severe dyspnea and paradoxical abdominal breathing, combined with underlying conditions that may cause diaphragmatic paralysis. The diagnosis is confirmed through auxiliary examinations.

For unilateral diaphragmatic paralysis, especially incomplete paralysis, patients are usually asymptomatic, and auxiliary examinations are required for a definitive diagnosis.

What tests are needed for patients with diaphragmatic paralysis? Why are these tests performed?

• Chest fluoroscopy: Directly observes diaphragmatic movement during respiration. Significant elevation or paradoxical movement of the affected diaphragm confirms diaphragmatic paralysis.

• Chest ultrasound: Evaluates diaphragmatic position, mobility, and paradoxical movement during breathing to determine the presence of paralysis.

• Pulmonary function tests: Measures the extent of impaired lung ventilation.

• Phrenic nerve electromagnetic stimulation and transdiaphragmatic pressure measurement: Uses electromagnetic stimulation of the phrenic nerve while measuring induced transdiaphragmatic pressure via an esophageal-gastric balloon catheter. This confirms diaphragmatic paralysis and helps determine whether it is complete. This test is usually considered for surgical candidates.

• Other tests, such as hematological tests and contrast-enhanced chest CT, may be selected by clinicians based on the patient's history for etiological screening.

TREATMENT

Which department should I visit for diaphragmatic paralysis?

Generally, patients should first visit the Department of Respiratory Medicine or Thoracic Surgery, and further triage will be based on the identified cause.

Can diaphragmatic paralysis heal on its own?

The prognosis varies depending on the cause. Inflammatory phrenic nerve paralysis often resolves on its own within months, while paralysis caused by conditions like tumor invasion is usually permanent.

Does diaphragmatic paralysis require hospitalization?

This depends on the severity of the condition and the underlying cause. Complete bilateral diaphragmatic paralysis typically requires hospitalization.

How is diaphragmatic paralysis treated?

Treatment primarily focuses on identifying and addressing the underlying cause.

• Most patients with unilateral diaphragmatic paralysis are asymptomatic and require no treatment. However, if symptoms like dyspnea affect physical activity, treatment may be considered.

• For patients with permanent bilateral phrenic nerve paralysis, options such as diaphragmatic plication, diaphragmatic pacing, or mechanical ventilation may be considered to alleviate dyspnea, if clinically appropriate.

• Surgical diaphragmatic plication: For carefully selected patients, surgical plication of the affected hemidiaphragm can yield excellent results.

• Diaphragmatic pacing: This may be used for patients with bilateral diaphragmatic paralysis leading to apnea or severe hypoventilation.

• Mechanical ventilation: Most cases of bilateral diaphragmatic paralysis with progressive respiratory failure require mechanical ventilation. Noninvasive positive-pressure ventilation via nasal or oronasal masks is the preferred and most common method. Invasive mechanical ventilation (via endotracheal intubation or tracheostomy) is reserved for patients with life-threatening respiratory failure unresponsive to noninvasive methods or those unable to maintain ventilation otherwise (e.g., high-level quadriplegia).

DIET & LIFESTYLE

What should patients with diaphragmatic paralysis pay attention to in daily life?

• Patients with left diaphragmatic paralysis may experience acid reflux, belching, bloating, and stomach pain. They should consume easily digestible soft foods or liquid diets. Overeating should be avoided to prevent increased abdominal pressure, which may worsen dyspnea. Small, frequent meals are recommended.

• Since diaphragmatic paralysis often leads to breathing difficulties, patients with incomplete paralysis should avoid or reduce strenuous activities, while those with complete paralysis should rest in bed. Elevating the head of the bed may help reduce diaphragm compression.

Does diaphragmatic paralysis require follow-up examinations? How is it rechecked?

Yes, chest X-rays are typically used for follow-up.

Can patients with diaphragmatic paralysis fly, engage in strenuous exercise, or travel to high-altitude areas?

It is not recommended until the underlying cause is identified and the condition is effectively controlled.

PREVENTION

Can Diaphragmatic Paralysis Be Prevented?

Diaphragmatic paralysis has various causes, and preventive measures differ accordingly, such as:

• Careful and standardized surgical procedures may reduce iatrogenic damage;

• Strengthening physical fitness, avoiding cold exposure, and timely vaccination can reduce inflammatory factors;

• Avoiding trauma may minimize traumatic injuries, while regular check-ups and active treatment of detected tumors may reduce tumor compression or invasion of the phrenic nerve.