Diaphragmatic eventration (DE) is a medical condition affecting the diaphragm, the large, dome-shaped muscle situated beneath the lungs that separates the chest cavity from the abdomen. As the primary muscle of respiration, the diaphragm allows the lungs to expand and contract during breathing. DE is relatively rare in both pediatric and adult populations, often being discovered incidentally during imaging for other reasons. The condition involves an abnormality of the diaphragm muscle itself, which compromises its ability to function correctly.
Understanding Diaphragmatic Eventration
Diaphragmatic eventration is characterized by the permanent, abnormal elevation of a portion or the entire half of the diaphragm (hemidiaphragm). This elevation occurs because the muscular tissue has become thin, weak, or partially replaced by non-contractile fibroelastic tissue. Although the diaphragm remains structurally complete, the affected segment loses its normal tone and capacity for effective contraction. This loss of function causes the affected side to move upward into the chest cavity, reducing the space available for the lung to expand fully.
During inhalation, a healthy diaphragm moves downward to create negative pressure, pulling air into the lungs. In eventration, the weakened segment moves paradoxically, pushed upward by abdominal pressure instead of moving down. This paradoxical movement impairs lung expansion and leads to inefficient breathing mechanics. Eventration is not a diaphragmatic hernia, which involves a tear or hole allowing abdominal organs to pass into the chest. In eventration, the diaphragm is intact but too weak to resist the pressure from the abdominal contents below.
Causes and Clinical Presentation
The underlying cause of diaphragmatic eventration is categorized as either congenital or acquired. Congenital eventration is present from birth, stemming from incomplete muscular development during fetal growth. This results in the diaphragm muscle being inherently thin and underdeveloped, with muscle fibers replaced by non-functional tissue. Acquired eventration, which is often more common, usually results from damage to the phrenic nerve, which provides motor control to the diaphragm.
Phrenic nerve injury can be caused by various events, including birth trauma, thoracic surgery (especially those involving the heart), or external trauma. The resulting nerve damage leads to paralysis and subsequent atrophy of the diaphragm muscle, causing it to thin and elevate. Other acquired causes include neuromuscular disorders or infections that compromise nerve function.
The symptoms of diaphragmatic eventration depend on the severity of the muscle weakness and the patient’s age. Many adults and older children with mild eventration remain asymptomatic, often discovered incidentally on a chest X-ray. When symptoms occur, they are primarily respiratory, resulting from the compressed lung and inefficient breathing. Patients may experience dyspnea (difficulty breathing), particularly during physical exertion or when lying flat.
In infants and young children, the presentation can be more severe, including rapid breathing (tachypnea), poor weight gain, and significant respiratory distress. The elevated diaphragm can allow abdominal organs, such as the stomach or spleen, to protrude into the chest cavity, potentially causing digestive issues. Recurrent lung infections, like pneumonia, are a common complication due to the reduced ability of the affected lung to clear secretions effectively.
Diagnosis and Management Approaches
Suspicion of diaphragmatic eventration often arises from a standard chest X-ray, which shows the abnormal elevation of the diaphragm dome on one side. While the X-ray suggests the diagnosis, functional imaging is required to confirm the lack of proper movement and distinguish it from other conditions. Fluoroscopy, often called a “sniff test,” is a dynamic X-ray examination where the patient inhales sharply. A healthy diaphragm descends, but an eventrated or paralyzed one moves paradoxically upward due to the pressure change.
Ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI) scans can evaluate the diaphragm’s structure and its relationship with surrounding organs. These scans help visualize the extent of the thinning and confirm that the diaphragm is intact, which is essential for differential diagnosis. The management strategy is determined by the severity of the symptoms rather than the mere presence of the condition.
For patients who are asymptomatic or have only mild symptoms, the approach is typically observation with periodic clinical surveillance. No surgical intervention is necessary in these cases, as the condition may not progress or cause significant issues. Surgical intervention, usually diaphragmatic plication, is reserved for symptomatic patients with severe respiratory distress, recurrent infections, or dependence on mechanical ventilation. Plication involves surgically flattening and tightening the weakened diaphragm by folding and stitching the flaccid tissue. This restores the volume of the chest cavity, allowing the lung to re-expand and function more efficiently.