Diaphragmatic eventration is a medical condition involving the diaphragm, the primary muscle responsible for breathing. It is characterized by an abnormal elevation of a portion or the entire diaphragm into the chest cavity. This occurs due to weakness or thinning of the diaphragm muscle, rather than a true opening or defect. Understanding this condition involves its causes, effects, and management.
Understanding the Diaphragm and Eventration
The diaphragm is a dome-shaped muscle positioned just below the lungs and heart, separating the chest cavity from the abdomen. It serves as the primary muscle for respiration, contracting and flattening during inhalation to create a vacuum that pulls air into the lungs. Conversely, when it relaxes, it curves upward, pushing air out of the lungs during exhalation. The phrenic nerves, originating from the neck, control the diaphragm’s movement.
Diaphragmatic eventration involves the diaphragm. This elevation occurs because the muscle fibers in the affected area are thin and weak, or even absent, rather than being a tear or hole. This differs from a diaphragmatic hernia, where there is a distinct opening in the diaphragm through which abdominal organs can protrude into the chest. In eventration, the diaphragm maintains continuity, but its weakened structure leads to upward displacement and impaired function.
How Eventration Develops
Diaphragmatic eventration can develop either congenitally, meaning it is present at birth, or it can be acquired later in life. Congenital eventration typically results from incomplete muscle development during fetal growth, where normal muscle tissue is replaced by a thin, fibrous membrane. This can occur due to abnormal migration of myoblasts, cells that form muscle tissue, to the diaphragm during embryonic development. Congenital eventration has an incidence of about 1 in 10,000 live births and is sometimes associated with genetic conditions like Beckwith-Wiedemann syndrome or certain trisomies.
Acquired forms of eventration often stem from injury or damage to the phrenic nerve, which controls the diaphragm’s movement. Such injuries can result from trauma, including birth trauma, or surgical procedures, particularly those involving the chest or neck. Neuromuscular disorders, infections, or tumor infiltration can also weaken the phrenic nerve, leading to diaphragmatic dysfunction and subsequent eventration. In some instances, the precise cause remains unknown, classified as idiopathic.
Recognizing Signs and Diagnosis
The signs and symptoms of diaphragmatic eventration can vary widely, depending on the severity of the condition and the patient’s age. Many individuals, especially adults, may experience no symptoms, with the condition discovered incidentally during imaging for other reasons. When symptoms occur, they are often related to respiratory compromise or gastrointestinal issues.
Common respiratory symptoms include shortness of breath, particularly during exertion or when lying flat, rapid breathing, and recurrent respiratory infections. Infants with severe eventration may exhibit respiratory distress, poor weight gain, or a bluish discoloration of the skin due to inadequate oxygenation. Gastrointestinal symptoms such as abdominal discomfort, bloating, or difficulty swallowing can also arise if abdominal organs are pushed upward, compressing other structures.
Diagnosis typically begins with imaging studies. A chest X-ray is the initial tool, revealing an elevated diaphragm. To further assess diaphragm movement and differentiate eventration from other conditions like diaphragmatic paralysis or hernia, dynamic imaging techniques such as fluoroscopy or ultrasound may be employed. Computed tomography (CT) and magnetic resonance imaging (MRI) provide more detailed views of the diaphragm and surrounding structures, helping to rule out other causes of diaphragm elevation. Pulmonary function tests can also assess the degree of lung impairment caused by the elevated diaphragm.
Approaches to Management
The management of diaphragmatic eventration depends on the presence and severity of symptoms. For individuals who are asymptomatic or experience mild symptoms, a conservative approach of watchful waiting is often recommended. Regular monitoring may be advised to observe for any progression of the condition or development of new symptoms.
When symptoms are significant and impact breathing or quality of life, surgical intervention is considered. The most common surgical procedure is diaphragmatic plication, where the thinned or weakened portion of the diaphragm is folded and stitched to flatten and strengthen it. This procedure helps to lower the diaphragm to a more normal position, allowing the lungs to expand more effectively and improving respiratory function. Plication can be performed using traditional open surgery or minimally invasive techniques like video-assisted thoracoscopic surgery (VATS). The goal of treatment is to alleviate symptoms, enhance lung function, and prevent complications.