Overview.
Diaphragmatic paralysis is a paralytic rise of the diaphragm on one side or both sides with impaired movement due to damage of the phrenic nerve and blockage of nerve impulses. It has a wide range of etiologies, most commonly caused by compression or invasion of the phrenic nerve by lymph nodes from lung cancer metastasizing to the mediastinum. Others, such as anterior spinal cord angiitis, motor nerve unit disease, herpes zoster, tuberculosis, diphtheria, pericarditis, mediastinitis, pneumonia, lead poisoning, giant aortic aneurysm, surgery or trauma to the deep neck, excessive pulling of the neck of the infant during delivery, and inadvertent injury to the nerves from thoracic surgery may also involve the phrenic nerve and lead to diaphragmatic paralysis. In some patients, the cause is unknown. Prolonged paralysis of the diaphragm may result in atrophy of the diaphragm to form a membrane.
Causes
1. Invasion or compression by malignant tumor
It is most common in clinic, mostly seen in mediastinal lymph node metastasis of lung cancer or direct invasion of central lung cancer and mediastinal tumor, and also occasionally seen in malignant tumors of pericardium, heart and pleura.
2.Traumatic phrenic nerve paralysis
Surgeries involving mediastinum, including mediastinal tumor, lung cancer, pericardiectomy, coronary artery bypass grafting, direct intracardiac surgery, etc., may damage or even cut the phrenic nerve. Various types of chest injuries and excessive pulling of the baby’s neck during delivery may also damage the phrenic nerve.
3. Cervical spine disease
Trauma, tumor, cervical vertebral osteophytes, intervertebral disc lesions and cervical spine tuberculosis may compress or injure the phrenic nerve at the level of cervical vertebrae 3 to 5.
4. Nervous system diseases
Brainstem diseases involving the respiratory center innervating the phrenic nerve, infectious polyneuritis, etc. may occasionally cause phrenic nerve paralysis.
5.Infectious diseases
Poliomyelitis, herpes zoster, diphtheria and other diseases can involve the phrenic nerve and cause paralysis.
6. Inflammatory diseases involving the mediastinum
Tuberculosis of huge mediastinal lymph nodes, mediastinitis, etc. can damage the phrenic nerve, but it is very rare in clinic.
7. Thoracic surgery
Occasionally occurs when the nerve is inadvertently injured by thoracic surgery.
8. Others
Motor nerve unit diseases, tuberculosis, pericarditis, mediastinitis, pneumonia, lead poisoning, etc. For example, giant aortic aneurysm causes left phrenic nerve palsy. Some patients cannot find a clear cause of phrenic nerve palsy.
Symptoms
Unilateral diaphragmatic paralysis can reduce lung capacity by 37% and ventilation by 20%, but due to the compensatory effect, the patient is often asymptomatic, and the diaphragm is found to be elevated and contradictory movement by chance during chest X-ray examination. Some patients complain of dyspnea during strenuous exercise. Left-sided diaphragmatic paralysis may have gastrointestinal symptoms such as belching, abdominal distension, and abdominal pain due to elevated gastric fundus. In bilateral complete diaphragmatic paralysis, the patient presents with severe dyspnea, paradoxical abdominal breathing (depression of the abdomen during inspiration), labored breathing and assisted respiratory muscle mobilization. There are usually signs of respiratory failure such as cyanosis. In patients treated with mechanical ventilation, most result in ventilator dependence. They are prone to recurrent pneumonia and atelectasis due to limited lung expansion and weak expectoration.
Examination
1. Laboratory examination
Normal or elevated white blood cells in infectious or inflammatory diseases.
2. Chest X-ray
The diaphragm is paralyzed and elevated unilaterally, and the activity is weakened or disappeared. During inhalation, the healthy diaphragm descends while the affected diaphragm rises, and this phenomenon is more obvious during forceful nasal aspiration. The mediastinum may oscillate during respiration, with the heart and mediastinum moving to the healthy side during inhalation and to the affected side during exhalation.
3. Phrenic nerve stimulation
The phrenic nerve can be stimulated by non-invasive electric or magnetic wave at the posterior edge of the sternocleidomastoid muscle 3-4 cm above the sternoclavicular joint in the neck, and the phrenic nerve can also be stimulated by magnetic wave near the spinous process of the cervical spine in the 7th vertebra. Simultaneous recording of evoked action potentials and phrenic nerve conduction time at the 6th to 7th intercostal space of the rib margin; and measurement of evoked transdiaphragmatic muscle pressure by esophageal-gastric cystic tube method can confirm the diagnosis of diaphragmatic paralysis, and also determine whether it is a complete or incomplete paralysis.
Diagnosis
In bilateral complete diaphragmatic paralysis, the clinical manifestations are somewhat characteristic, and a clinical diagnosis can be made on the basis of severe clinical dyspnea and abdominal paradoxical respiration, combined with the underlying diseases that are likely to cause diaphragmatic paralysis. Unilateral diaphragmatic paralysis, especially incomplete paralysis, is usually asymptomatic clinically and needs to be diagnosed through auxiliary tests. Examinations that are useful in confirming the diagnosis of diaphragmatic paralysis include X-ray chest radiography and measurement of action potentials and trans-diaphragmatic muscle pressure induced by electromagnetic wave stimulation of the phrenic nerve.
Treatment
Treatment should first seek to identify the cause of the condition and target it. Most patients with pulling and inflammatory phrenic nerve palsies recover spontaneously within 4 to 7 months. Cutting or invasive (e.g., malignant tumors) phrenic nerve paralysis is permanent damage. Unilateral phrenic paralysis is usually asymptomatic and requires no specific treatment. Most cases of bilateral diaphragmatic paralysis causing severe dyspnea and respiratory failure require mechanical ventilation to assist breathing. Noninvasive positive nasal (face) mask pressure mechanical ventilation or negative chest pressure ventilation should be preferred. When noninvasive mechanical ventilation fails to achieve the desired ventilation effect or when there is obvious lung infection, tracheal intubation or incision should be considered. In patients with permanent bilateral phrenic nerve palsy, diaphragmatic folding may be considered when the underlying disease is stable. By shortening the length of the diaphragm to increase the tension of the diaphragm’s passive upward pull, dyspnea can be alleviated.