Diaphragmatic Eventration (Eventration of the Diaphragm)

Definition:
An abnormally high or elevated position of one leaf of the intact diaphragm as a result of paralysis, aplasia, or atrophy of varying degree of muscle fibers.

History:
Eventration was first described in 1774. The first successful repair in an adult was done in 1923 by Jean Louis Petit. The first successful repair in an infant was in 1946 by Bisgard

Description:
Congenital diaphragmatic eventration may result from congenital phrenic nerve problem or a thin, abnormal diaphragm at birth.  Newborns may present with dyspnea, cyanosis, tachypnea, or vomiting secondary to gastric volvulus. Asymptomatic noniatrogenic diaphragmatic eventrations occur in 7 to 35 per 100,000 persons and was noted in 1 per 10,000 healthy military recruits in one study. Assoicated findings include Horner’s syndrome, contralateral ptosis, and chest wall deformities with and without missing ribs, hypoplastic lung, gastric volvulus, hypoplastic ribs, coarctation of the aorta, cleft palate, hemivertebrae, congenital heart disease, renal ectopia, hypoplastic aorta, situs inversus, and club foot.

Acquired diaphragmatic eventration:
Is usually the result of phrenic nerve injury. Common causes include :  birth trauma, thoracic surgery, and rare tumors of the chest.

Pathophysiology:
Eventration of the diaphragm causes problems in 4 ways:

• Inability to ventilate the ipsilateral lung
• Direct Compression of the ipsilateral lung
• Pneumonia due to chronic atelectasis
• Paradoxical motion of the diaphragm making ventilation of the contralateral lung inefficient. In the infant, the mediastinum is very mobile and paradoxical movement of the effected diaphgram causes a shift of the heart and mediastinum toward the contralateral thorax. This limits effective ventilation of the opposite lung and also impedes venous return to the heart.

Segmental diaphragmatic:
Eventrations rarely cause symptoms because the majority of the diaphragm remains stabilized. Rarely, eventrations posterior to the heart may require repair to improve venous return to the heart in neonates.

Indications for surgery:

• Two or more recurrent ipsilateral pneumonias
• One life-threatening pneumonia
• Inability to wean from mechanical ventilation
• Respiratory distress related to paradoxical motion of the diaphragm

Operative treatment: Diaphgramatic plication.

Thoracocsopic approach:
Using unpledgeted or Teflon pledgeted non-absorbable suture to pleating the diaphragm. Care should be taken to avoidance the phrenic nerve branches if there is a change of phrenic nerve recovery. The pleated diaphragm is repeatedly pleated in a radial direction until flat. The Ti-knot device can facilitate the plication greatly over intracorporal knot tying. Stablizing the eventrated diaphragm allows the working diaphram to effectively ventilate both sides. One working diaphragm still generates negative intra-thoracic pressure drawing air into both lungs.

Alternatives:

• Diaphragmatic pacemakers
• Intercostal nerve to phrenic nerve transfers
• Tracheostomy
• Positive pressure assistance (NCAP, etc)

Results:
In one unpublished study at Emory, 35 cases of diaphragmatic eventration treated with plication. Congenital (n = 6), Non-cardiac acquired (n = 2,) Cardiac (n = 27). No recurrent pneumonias in patients done for pneumonia. Among cardiac patients, 20 of 27 were extubated and discharged. Definitive extubation in the survivors was achieved an average of 6.0 ± 3.0 days following plication with a median of 4 days. Mortality among cardiac patients requiring plication was 19%. The study was done from 1992 to 1997.

Conclusions:
Diaphragmatic plication appears to be safe and effective treatment for the patient with recurrent ipsilateral pneumonia. Plication appears to facilitate extubation in infants with eventration who have failed weaning from mechanical ventilation. Other options are available, but not in common use.