Diaphragmatic Paralysis: Diaphragmatic Eventration

GENESIS

Eventration of the diaphragm is defined as abnormal elevation of the diaphragm. It may originate from a congenital defect or be acquired. Congenital eventration is a rare developmental abnormality characterized by muscular aplasia or hypoplasia of the diaphragm. The diaphragm is the main inspiratory muscle of the respiratory system, and it is innervated by the left and right phrenic nerves, which are branches of the cervical plexus arising at C3–C5. Acquired eventration is caused by injury to the phrenic nerve with resultant paralysis and elevation of the entire diaphragm. The paralysis may be secondary to an injury sustained during cardiothoracic surgery (1.2–5.5%), or due to birth trauma (1 per 15,000–30,000 live births). Because the cervical plexus arises near the brachial plexus (C5–T1), in a study by Rizeq et al., 2% of 5832 newborns with birth-related brachial plexus palsies also had diaphragmatic paralysis, which was usually ipsilateral. Of these 122 infants, 32% were born to diabetic mothers, 65% required mechanical ventilation, and 27% required surgical diaphragmatic plication at a median age of 36 days. Traction to the phrenic nerve during difficult deliveries or vaginal breech deliveries has been reported, and brachial plexus palsy is the most common comorbidity with phrenic nerve injury, although 66%–92% of these brachial plexus palsies resolve by 2 months of age. Thoracic surgery for cardiovascular or tracheoesophageal fistula repair may also injure the phrenic nerve and result in diaphragmatic paralysis. Tetralogy of Fallot correction was the most associated cardiothoracic surgery, followed by arterial switch operation, Fontan procedure, and Blalock-Tausig shunt surgery.