Diaphragmatic palsy is a paralytic rise of the diaphragm on one or both sides due to damage to the phrenic nerve and blockage of nerve impulses, resulting in impaired movement. The following are the possible causes of diaphragmatic palsy. 1, malignant tumor invasion or compression Clinically most common, mostly seen in lung cancer mediastinal lymph node metastasis or direct invasion of central lung cancer and mediastinal tumors, but also occasionally seen in malignant tumors of the pericardium, heart and pleura. 2. Traumatic phrenic nerve palsy Surgery involving the mediastinum, including mediastinal tumors, lung cancer, pericardial resection, coronary artery bypass, and intracardiac direct vision surgery, may damage or even sever the phrenic nerve. Various types of chest injuries and excessive cervical stretching of the baby during delivery may also damage the phrenic nerve. 3. Cervical spine diseases The phrenic nerve can be compressed or damaged at the level of the cervical 3-5 vertebrae due to trauma, tumors, cervical spine osteophytes or disc lesions, and cervical spine tuberculosis. 4. Neurological diseases Brainstem diseases involving the respiratory center of the phrenic nerve, infectious polyneuritis, etc., may occasionally cause phrenic nerve paralysis. Infectious diseases such as poliomyelitis, herpes zoster, and diphtheria can involve the phrenic nerve and cause paralysis. 6.Inflammatory diseases involving the mediastinum Giant lymph node tuberculosis of the mediastinum and mediastinitis can damage the phrenic nerve, but they are very rare clinically. 7. Thoracic surgery Occasionally occurs when the nerve is inadvertently injured by thoracic surgery. 8.Other Motor nerve unit diseases, tuberculosis, pericarditis, mediastinitis, pneumonia, lead poisoning, etc. For example, giant aortic aneurysm causes left phrenic nerve palsy. In some patients, no clear cause of phrenic nerve palsy can be found.