3 - Discussion
The diaphragm is the primary muscle used during inspiration. It acts as a barrier between the thoracic and abdominal cavity and is innervated by the phrenic nerve. DE is a condition where there is an abnormal elevation of the diaphragm with maintained continuity and attachments to the costal margin. The diaphragm can be partially or fully replaced with fibroelastic tissue. (1, 2) DE can cause respiratory issues due to reduced lung volume and impaired breathing mechanics. This could lead to atelectasis, pneumonia as well as aspiration and respiratory insufficiency requiring support. (2) Abdominal contents can be displaced into the thoracic cavity, further compromising breathing by compressing the lungs. Complications of eventration can also occur later in life with case reports of volvulus and other issues with malpositioned abdominal contents being the highest risk of morbidity.(3, 4) In infants, DE can be congenital due to abnormal development or acquired due to damage to the phrenic nerve. (5) In congenital diaphragmatic eventration, there is inadequate development of the diaphragmatic muscle or absence of the phrenic nerve. In acquired diaphragmatic eventration, the most common cause is an injury to the phrenic nerve leading to diaphragmatic paralysis. Damage to the phrenic nerve can be caused by either trauma at the time of delivery or thoracic surgery.(5) In our case, there was no history or exam findings suggestive of birth trauma at the time of delivery suggesting a congenital etiology is the more likely cause. Congenital DE constitutes only 5% of all diaphragmatic defects including congenital diaphragmatic hernias (CDH) and is usually unilateral with the left side more commonly affected than the right. (6) It also has a higher male predominance. (7) The incidence and prevalence of congenital DE in infants is unknown due to some lesions being clinically silent. Some reports estimate this to be as low as 1 in 10,000 but the overall incidence is likely higher due to the number of unreported cases. (8) DE can also be associated with many disorders and infections. These include Spondylocostal dysostosis, Kabuki syndrome, Beckwith-Wiedemann syndrome, Poland syndrome, chromosomal abnormalities (trisomy 18), pulmonary hypoplasia, spinal muscular atrophy, malrotation, and congenital heart disease. Infectious associations include fetal rubella and cytomegalovirus infections.(9-12) In our case, the infant appeared non-dysmorphic and there were no associated findings on any investigation to suggest an associated syndrome or disorder.
The diagnosis of DE is usually made postnatally and can be delayed due to the absence of symptoms.(13, 14). Chest X-ray can suggest the diagnosis by showing the elevation of the hemi-diaphragm. Still, it can be challenging to differentiate between DE and CDH due to the similarities in imaging findings. Ultrasound can be used to confirm the findings by demonstrating minimal or paradoxical diaphragmatic movement although this is operator dependent. In our case, the final diagnosis was made using MRI which was able to identify diaphragmatic eventration on both sides of the diaphragm. With regards to management, the choice between conservative management or surgical repair depends on several factors including the presence or absence of symptoms, adequacy of nutritional intake and growth, the need for respiratory support and the presence of complications such as volvulus or recurrent pneumonia. Surgical management is recommended for symptomatic cases, particularly for bilateral eventration although there is no standardized approach regarding the timing of surgical repair. Stabilization on non-invasive ventilation before surgery is suggested, although with limited literature support. Earlier intervention may also improve growth and prevent lung injury (2) In this case, surgery was done closer to term as the infant continued to be symptomatic with ongoing tachypnea and bibasilar atelectasis despite interval growth. Complications after abdominal plication of a diaphragmatic eventration commonly include atelectasis and rarely, abdominal compartment syndrome and splenic injury after mobilization of the left upper quadrant abdominal structures. (15, 16) In our case, he developed findings suggestive of NEC which was managed with bowel rest and antibiotics. Following discharge, he will require routine monitoring and follow-up with a multidisciplinary team including a Pediatrician, Pediatric Pulmonologist and a Pediatric Surgeon as there is a possibility of relapse of eventration. Overall, the prognosis of infants who undergo surgical plication for DE is good. (14) The infant is currently doing well, not requiring any respiratory support and growing appropriately. This case is an excellent example of a multidisciplinary collaboration between Neonatology, Pediatric Pulmonology, Radiology, and Pediatric Surgery teams toward the management of a rare condition.