Diaphragmatic Eventration- Causes, Symptoms, and Treatment

Introduction

Eventration refers to the protrusion of contents through a defect or weakness. It can be diaphragmatic eventration, herniation, or evisceration. A diaphragmatic eventration is a condition in which a portion or entire hemidiaphragm is elevated. It can be a congenital defect or an acquired condition. It can be present in children and adults.

What Is Diaphragmatic Eventration?

The diaphragm is a dome-shaped respiratory muscle that plays a role in inspiration. It acts as a barrier between the thoracic cavity and the abdomen. The C3, C4, and C5 spinal nerve roots give rise to the phrenic nerves, which innervate the diaphragm muscle. Motor function to each hemidiaphragm is provided by the right and left phrenic nerves. Injury to the phrenic nerve or impaired development results in diaphragmatic paralysis and diminished lung expansion. In diaphragmatic eventration, a portion of the diaphragm becomes weak and thin and causes abnormal elevation of a part or entire hemidiaphragm. It is due to a lack of muscle function or nerve function, but the anatomical attachments are maintained.

What Are the Types of Diaphragmatic Eventration?

Diaphragmatic eventration is divided into congenital and acquired defects. It is divided into complete, partial, or bilateral defects based on the anatomy of eventration. Congenitaleventration is divided into anterior, posterolateral, and medial defects on an embryological basis.

What Are the Causes of Diaphragmatic Eventration?

• Congenital Diaphragmatic Eventration - Congenital eventration occurs due to abnormal diaphragm muscle development. It can also occur in association with congenital disorders like pulmonary hypoplasia, spondylocostal dysostosis, Poland syndrome, Kabuki syndrome, chromosomal defects, Beckwith-Widemann syndrome, congenital heart disease, malrotation, and spinal muscular atrophy. Fetal infections with rubella and cytomegalovirus can cause diaphragmatic dysfunction. Mitochondrial respiratory chain disorder during the neonatal period is associated with diaphragmatic dysfunction.

• Acquired Diaphragmatic Eventration - Acquired eventration is caused by phrenic nerve injury and muscle atrophy. Phrenic nerve injury is caused by blunt or penetrating trauma, birth trauma, or thoracic surgery. Phrenic damage also occurs as a complication of disorders, including multiple sclerosis, Guillain-Barre syndrome, nerve compressions, connective tissue diseases, and radiation therapy. Paralysis or phrenic nerve damage results in muscular atrophy and weakening of the diaphragm, which leads to cephalic displacement.

How Does Diaphragmatic Eventration Occur?

Congenital eventration occurs due to a malformation in the migration of myoblastic cells to the septum transversum. This causes complete or partial replacement of the diaphragmatic muscle with fibroelastic tissue. This results in a weakened and thin hemidiaphragm which causes cephalic displacement of the affected side. Stretched-out and aponeurotic scattered muscle fibers are seen in congenital eventration. This diaphragmatic pattern is described as neurogenic muscular aplasia. These changes are not present in acquired diaphragmatic eventration.

What Are the Symptoms Associated With Diaphragmatic Eventration?

Diaphragmatic eventration does not present any symptoms. It is usually accidentally discovered on a chest X-ray. Individuals may present with respiratory distress or gastrointestinal symptoms. The following symptoms are observed in diaphragmatic eventration:

• Acute respiratory failure and cyanosis (bluish discoloration of the skin) are seen in bilateral congenital diaphragmatic eventration in neonates.

• Respiratory symptoms like dyspnea on exertion, orthopnea, tachypnea, and shallow breathing are present in children and adults.

• Recurrent respiratory infections, lung atelectasis, or chronic productive cough may be present in adults.

• The respiratory symptoms in infants are a result of the shifting of the mediastinal structures to the contralateral side.

• The gastrointestinal involvement presents with symptoms like poor oral intake, poor weight gain, bloating, vomiting, and constipation. Gastric volvulus may be present in severe cases.

• The gastrointestinal symptoms in adults worsen with increased intraabdominal pressure due to ascites, exercise, pregnancy, infection, and fluid sequestration, and the individuals present with symptoms like dyspepsia, dysphagia, gastroesophageal reflux, and/or epigastric pain.

What Are the Complications Associated With Diaphragmatic Eventration?

The following complications are present in diaphragmatic eventration:

• Acute or chronic respiratory failure.

• Nutritional deficiency.

• Pneumonitis.

• Failure to thrive.

• Cardiac arrhythmias are present due to mediastinal shifts.

How Is Diaphragmatic Eventration Diagnosed?

Diaphragmatic eventration is usually an asymptomatic condition. The diagnosis is based on the symptoms, history, and physical examination. The following tests are performed to diagnose diaphragmatic eventration:

• Chest X-Ray - Chest X-ray confirms the presence of an elevation of the affected hemidiaphragm. It also shows the presence of normal cardiomediastinal contours. CT (computed tomography) scan may be required if the diagnosis from the X-ray is unclear. CT scan confirms the rise of the affected portion of the diaphragm and also shows the presence of a sharp edge of the eventration.

• Pulmonary Function tests - Pulmonary function tests detect the presence of a reduction in forced vital capacity and forced expiratory volume that is associated with a restrictive pattern. This pattern is usually seen in bilateral eventration.

• Fluoroscopic Sniff Testing - This test is performed under continuous fluoroscopy to examine diaphragm function. The direction and motion of each hemidiaphragm are assessed when the patient takes hard and fast inspiration. Abnormal movement is seen in a portion of the hemidiaphragm in diaphragmatic eventration. This test is useful in distinguishing diaphragm paralysis and eventration, as paralysis shows paradoxical movement during sniffing.

• Congenital eventration is diagnosed prenatally with ultrasound, CT, or MRI (magnetic resonance imaging) scan.

How Is Diaphragmatic Eventration Treated?

The treatment for diaphragmatic eventration is based on the severity of the disease. It includes the following:

• Oxygen therapy is given if hypoxemia is present. Nasal continuous positive airway pressure (nasal CPAP) is used if oxygen via the nasal cannula is inadequate.

• Gavage feeding or parenteral nutrition is given to maximize nutritional support.

• Mechanical ventilation is required in severe cases.

• Surgical plication is indicated if there is no response to medical treatment. Diaphragmatic plication is the procedure done to treat the weakened diaphragm. It is performed through an open thoracotomy, robotic-assisted surgery, video-assisted thoracoscopic surgery (VATS), or laparoscopic surgery. Surgical treatment is indicated in individuals with severe respiratory distress, recurrent pneumonia, failure to thrive, and inability to remove mechanical ventilation. Surgical plication causes complications like pneumonia, deep vein thrombosis, pleural effusions, and cardiac events.

Conclusion

Diaphragmatic eventration is the elevation of a portion of the hemidiaphragm. It is usually asymptomatic, but it can cause respiratory distress if left untreated. It can be congenital or acquired eventration. Evaluation, early diagnosis, and treatment aid in the management of diaphragmatic eventration.