What is Hemidiaphragmatic Paralysis?

The diaphragm is a dome-shaped sheet of muscle, necessary for normal breathing, which sits under the lungs and keeps the abdomen apart from the chest. In hemidiaphragmatic paralysis, one side of the diaphragm is immobilized. The results can range from no symptoms at all, in someone otherwise fit and healthy, to serious respiratory problems in a person with existing lung disease. Treatment varies accordingly, from nothing at all to a surgical procedure known as diaphragmatic plication. Possible causes of the paralysis include cancer, infection and injury, but often the origin is unknown.

One of the most frequently found causes of hemidiaphragmatic paralysis is a tumor pressing on the nerve that supplies the diaphragm, known as the phrenic nerve. This nerve can also be injured in accidents or surgical procedures involving the chest and neck. An enlarged thyroid gland or the presence of a swelling in a large artery known as the aorta may also affect the phrenic nerve, possibly leading to hemidiaphragmatic paralysis. In many cases, the cause of the paralysis is not discovered.

It is more common for paralysis to affect one side of the diaphragm than it is for both sides to be involved, a condition which is known as bilateral diaphragmatic paralysis. Often, hemidiaphragmatic paralysis does not cause any symptoms, and the patient may be unaware of the condition, which might be discovered on a routine X-ray. Where there are no symptoms, and no existing lung disease, hemidiaphragmatic paralysis normally has a positive outlook and no treatment is required. In some people the condition causes severe breathlessness on exercising, and in those who have existing respiratory problems this shortness of breath may even occur at rest. Surgical treatment may be beneficial for some people whose breathlessness becomes extreme.

Treating hemidiaphragmatic paralysis surgically involves a procedure known as diaphragmatic plication. In a diaphragmatic plication operation, the paralyzed muscle is folded and stitched to make it less mobile, preventing it from moving upward on breathing in. A normally functioning diaphragm would move down on inspiration, increasing the volume of the lungs. The result of the operation is that more air enters the lung on the affected side when breathing in, and symptoms of hemidiaphragmatic paralysis such as breathlessness are reduced.

Complications of hemidiaphragmatic paralysis may occur in people who have existing respiratory disease, due to lung ventilation becoming even worse. Infections such as pneumonia may be more likely to develop. Depending on the cause of the paralysis, medical and surgical treatments may be carried out, and artificial ventilation may be necessary in the case of severe breathing problems.