The diaphragm is the major muscle of respiration and separates the thoracic and abdominal cavities. The phrenic nerve is responsible for the contraction of the diaphragm.
This is a condition in which the diaphragm is placed at a much higher level than it normally is because it is paralyzed and fails to contract. It most commonly is congenital (present at birth) and may result from a phrenic nerve problem or an abnormally thin diaphragm at birth. Rarely it may affects adults or cause symptoms in adults.
In adults this condition is caused by an injury to the phrenic nerve or an infection or a cancer in the chest that causesthe phrenic nerve to function poorly. Often a viral infection that results in an eventration may go unnoticed and the results may become apparent several years later. One half of the diaphragm, commonly the left side, is affected. As the lower half of the lung fails to expand properly as the diaphragm does not contract it does not take part in the breathing process effectively.
This condition is often asymptomatic. The patients may experience respiratory symptoms such as breathlessness, cough or chest pain particularly on exertion. In addition, patients may suffer from recurrent pneumonia, bronchitis, or cardiac arrhythmias. They may also experience gastrointestinal complaints resulting from compression of the stomach.
In the majority of cases, the condition is picked up on a chest x-ray performed for assessment of some other problem demonstrates a raised diaphragm on one side. This is further confirmed by a fluoroscopic examination in which the movement of the diaphragmis observed by continuous x-ray as the patient is asked to breathe in and out deeply. A CT scan may be ordered to rule out a cancer or a tumor inside the chest as a cause for the paralyzed diaphragm. The function of the lungs is assessed by performing pulmonary function tests.