eventration

Eventration is a condition in which a portion of a hollow or muscular structure is abnormally elevated or displaced due to thinning, underdevelopment, or dysfunction of its muscular layer, while the overall continuity of the organ is preserved. The term is most commonly used in reference to the diaphragm, where one half or a portion of the diaphragmatic dome sits higher than normal.

Diaphragmatic eventration can be congenital or acquired. Congenital eventration results from defective muscular development of the diaphragm, leading to a thin, fibroelastic sheet that is elevated but intact. Acquired eventration can follow phrenic nerve palsy, trauma, infection, or surgical injury, in which the muscle is weakened or replaced by nonmuscular tissue. The condition may be asymptomatic or cause respiratory symptoms, particularly in infants or adults with limited pulmonary reserve.

Clinical presentation varies. Some individuals are asymptomatic and the finding is incidental on imaging. Others experience dyspnea, reduced lung volumes on the affected side, chest wall asymmetry, or recurrent respiratory infections, especially in children.

Diagnosis relies on imaging. Upright chest radiographs typically show elevation of the affected diaphragmatic dome with preserved diaphragmatic continuity. Ultrasound can assess diaphragmatic thickness and movement, while CT or MRI delineates anatomy and distinguishes eventration from hernia. Fluoroscopy or dynamic imaging may help evaluate mobility.

Management is typically conservative for asymptomatic cases. Symptomatic or functionally significant eventration is often treated with surgical diaphragmatic plication, performed via open or thoracoscopic approaches, to flatten and stabilize the diaphragm and improve lung expansion. Prognosis after appropriate management is generally favorable.