Congenital Diaphragmatic Hernia



Congenital Diaphragmatic Hernia

Practice Essentials

The diaphragm is the major muscle of respiration and the second most important muscle within the body after the heart. Because the body relies so much on the diaphragm for respiratory function, understanding how many different diseases processes ultimately result in dysfunction of the diaphragm is vitally important.
When a decrease in diaphragmatic function occurs, a concomitant respiratory dysfunction occurs. The body has many mechanisms in place to compensate for decreased diaphragmatic function. However, no compensatory mechanisms are in place to prevent respiratory compromise in the setting of decreased diaphragmatic excursion.
Diaphragmatic hernias can be divided into two broad categories: congenital and acquired. [1 A congenital diaphragmatic hernia (CDH) occurs through embryologic defects in the diaphragm, and most patients present early in life rather than later. However, a subset of adults may present with a smaller CDH that was undetected during childhood. [2]
CDH was first described in 1679 by Riverius, who incidentally noted a CDH during a postmortem examination of a 24-year-old person. [3 In 1701, Holt described the classical clinical and postmortem findings of an infant with CDHIn 1761, Morgagni described the classical anterior diaphragmatic hernia, which today bears his name—Morgagni hernia. In 1848, Bochdalek described both right and left posterolateral CDH. To this day, these CDHs are commonly referred to as Bochdalek hernias.
In 1828, Laënnec described the numerous causes of diaphragmatic hernias, as well as an auscultatory mechanism by which to diagnose them; he also discussed the potential for surgical repair of a diaphragmatic hernia. In 1888, Nauman proposed a two-cavity approach to repair diaphragmatic hernias. In 1889, O'Dwyer attempted the first reported repair of a CDH in an infant. At that time, O'Dwyer discovered the loss of "right of domain" commonly encountered during attempts to repair CDH. In 1929, the first successful CDH repair was performed in an infant, a 3.5-month-old girl.
In 1977, extracorporeal membrane oxygenation (ECMO) was introduced as a treatment for neonates with respiratory failure refractory to conventional care, [4 and its application to CDH increased the survival rate of infants born with CDH from around 20% to 55-75%. ECMO provides a modality by which blood can be withdrawn, oxygenated, and finally returned to the body for circulation. With ECMO, infants are medically stabilized before surgery; surgical intervention after stabilization produces better outcomes.
Since the time of the first successful repair, great strides have been made in the field of CDH. However, until 1982, when ECMO was first used in the treatment of CDH, mortality remained extremely high for infants born with CDH and severe pulmonary hypoplasia. The field of CDH continues to grow as knowledge of the disease entity increases and progress is made with newer treatment modalities.


Anatomy

The diaphragm is a modified half-dome of musculofibrous tissue that separates the thorax from the abdomen. Four embryologic components make up the formation of the diaphragm, as follows:
·        Septum transversum
·        Two pleuroperitoneal folds
·        Cervical myotomes
·        Dorsal mesentery
Development begins during week 3 of gestation and is completed by week 8. Failure of the development of the pleuroperitoneal folds and subsequent muscle migration results in congenital defects.
The muscular origin of the diaphragm is from the lower six ribs bilaterally, the posterior xiphoid process, and from the external and internal arcuate ligaments. A number of different structures traverse the diaphragm, including three distinct apertures that allow the passage of the aorta, the esophagus, and the vena cava.
The aortic aperture is the lowest and most posterior of the openings, lying at the level of T12. The aortic opening also transmits the thoracic duct and sometimes the azygos and hemiazygos veins. The esophageal aperture is surrounded by diaphragmatic muscle and lies at the level of T10. The vena caval aperture is the highest of the three openings and lies level with the disc space between T8 and T9.
Arterial supply to the diaphragm comes from the right and left phrenic arteries, the intercostal arteries, and the musculophrenic branches of the internal thoracic arteries. Some arterial blood is provided from small branches of the pericardiophrenic arteries that run with the phrenic nerve mainly where the nerves penetrate the diaphragm. Venous drainage is via the inferior vena cava and azygos vein on the right and the adrenal/renal and hemiazygos veins on the left.
The diaphragm receives its sole muscular neurologic impulse from the phrenic nerve, which originates primarily from the fourth cervical ramus but also has contributions from the third and fifth rami. [5Originating around the level of the scalenus anterior, the phrenic nerve courses inferiorly through the neck and thorax before reaching its terminus, the diaphragm. Because the phrenic nerve has such a long course before reaching its final destination, any processes that disrupt the transmission of neurologic impulse through it directly affect the diaphragm.


Etiology

CDH occurs when the muscular entities of the diaphragm fail to develop normally, resulting in displacement of abdominal components into the thorax.

Bochdalek hernia

Bochdalek hernias [6make up the majority of cases of CDH. The major problem in these hernias is posterolateral defects of the diaphragm, which results in either failure in the development of the pleuroperitoneal folds or improper or absent migration of the diaphragmatic musculature.
As many as 90% of patients with CDH present in the neonatal period or within the first year of life. These cases have a mortality of 45-50%. Most of the morbidity and mortality of CDH relates to hypoplasia of the lung and pulmonary hypertension on the affected side. Thus, timely diagnosis and proper management remain the keys to survival.

Morgagni hernia

Morgagni hernia [789is a less common CDH, accounting for only 5-10% of CDH cases. The foramen of a Morgagni hernia occurs in the anterior midline through the sternocostal hiatus of the diaphragm, with 90% of cases occurring on the right side.


Epidemiology

CDH occurs in 1 in 3000 newborns. Mortality and morbidity are due to the amount of pulmonary hypoplasia (PH), the response on artificial ventilation, and the presence of therapy-resistant pulmonary hypertension. The survival rate is 55-65%. [10]
International data are available from the registry maintained by the Congenital Diaphragmatic Hernia Study Group (CDHSG), a consortium that includes 66 centers from 13 countries and that has amassed data on more than 8000 children with CDH to date.

Prognosis

With the development of newer treatment techniques (see Treatment), including high-frequency oscillatory ventilation (HFOV) and more sophisticated extracorporeal oxygenation equipment, the mortality associated with CDH has continually decreased. [12131415However, long-term morbidity includes such entities as gastroesophageal reflux disease (GERD), [16neurologic and developmental disorders, [17and musculoskeletal disorders. [18]
Partridge et al analyzed outcomes in right-side CDH as compared with left-side CDH and found that whereas the former did not have a higher mortality, it was associated with increased need for pulmonary vasodilatory therapy and need for tracheostomy. [19]
Collin et al found that patients with right-side CDH required patch repair more often than those with left-side CDH did. [20The only morbidity that was signnificantly more frequent in the former was the rate of recurrent herniation. There were no significant differences in neurodevelopmental outcome between the two groups: Both groups exhibited normal median Griffiths general quotient scores at the age of 1 year.


Congenital Diaphragmatic Hernia Clinical Presentation

History and Physical Examination

Clinical manifestations of congenital diaphragmatic hernia (CDH) include the following:
·        Early diagnosis - Right-side heart; decreased breath sounds on the affected side; scaphoid abdomen; bowel sounds in the thorax, respiratory distress, and/or cyanosis on auscultation; CDH can often be diagnosed in utero with ultrasonography (US), magnetic resonance imaging (MRI), or both
·        Late diagnosis - Chest mass on chest radiography, gastric volvulus, splenic volvulus, or large-bowel obstruction
·        Congenital hernias (neonatal onset) - Respiratory distress and/or cyanosis occurs within the first 24 hours of life; CDH may not be diagnosed for several years if the defect is small enough that it does not cause significant pulmonary dysfunction
·        Congenital hernias (childhood or adult onset) - Obstructive symptoms from protrusion of the colon, chest pain, tightness or fullness the in chest, sepsis following strangulation or perforation, and many respiratory symptoms occur


Congenital Diaphragmatic Hernia Workup


Laboratory Studies

Low levels of maternal serum alpha-fetoprotein (AFP) have been associated with congenital diaphragmatic hernia (CDH). However, decreased AFP also is observed with trisomy 18 and trisomy 21; thus, a low AFP level, by itself, is not diagnostic of CDH.

Imaging Studies

On chest radiography, [21CDH may be signaled at an early stage by a finding of bowel and stomach in the chest cavity and shifting of the mediastinum (usually to the right). (See the image below.) At a later stage, CDH may be signaled by a suspicious mass incidentally found on a chest radiograph.
Anteroposterior view of chest in patient with congenital diaphragmatic hernia shows herniation of bowel loops into left hemithorax, with right shift of heart and mediastinum.
For reaching a diagnosis of CDH in utero, a level 3 ultrasound examination is the criterion standard. Features indicative of CDH are as follows:
·        Polyhydramnios
·        Absent or intrathoracic stomach bubble
·        Mediastinal and cardiac shift away from the side of herniation
·        Fetal hydrops (rare)
Magnetic resonance imaging (MRI) can be utilized to show a fetal lung volume and, in some instances, to help determine postnatal mortality. [


Congenital Diaphragmatic Hernia Treatment & Management

Approach Considerations

The diaphragm is the major muscle of respiration and the second most important muscle after the heart. When a decrease in diaphragmatic function occurs, a concomitant respiratory dysfunction generally always accompanies the functional decrease. Although the body has many compensatory mechanisms in the setting of decreased diaphragmatic function, little can be done to prevent respiratory compromise if excursion of the diaphragm is moderately diminished or simply absent. Appropriate treatment is essential in cases of congenital diaphragmatic hernia (CDH).
Some reports exist of increases in mortality with early surgical intervention for CDH in infants. Many authors suggest that the patient be stabilized (often with the use of extracorporeal membrane oxygenation [ECMO]) and that repair be delayed until the infant is better prepared to survive the operation.
Research is under way into the use of inhaled nitric oxide (iNO) or partial liquid ventilation and the possibility of lung transplantation for infants born with severe hypoplasia. [18 Minimally invasive repair techniques for latent CDH are being explored at a number of institutions.
Guidelines for the management of CDH have been published. 

Medical Therapy

Resuscitation with ventilatory support is of prime importance in patients born with a CDH. There has been a trend toward switching from conventional mechanical ventilation to high-frequency oscillatory ventilation (HFOV). HFOV serves to minimize airway pressure and, in conjunction with permissive hypercapnia, helps those with CDH suffer less traumatic lung injury and fewer long-term complications. Mortality has been shown to decrease from 49% to 20% when HFOV is used early in the treatment course. [24]
ECMO has been shown to decrease the mortality of CDH significantly but is currently reserved for individuals whose condition fails to improve with both HFOV and conventional mechanical ventilation. The decision to utilize ECMO is made early in the disease process, usually within 24 hours of birth.
With the addition of HFOV, more reports exist of decreased morbidity and mortality with early surgical intervention. However, there remains some controversy regarding this practice. The classical teaching is that patients need to be stabilized (often with the use of ECMO) and that repair should be delayed until the infant is better prepared to survive the operation. [25]
Maternal antenatal corticosteroid administration has also been employed in an effort to improve fetal lung growrth and maturity, but the available evidence is insufficient to support its routine use. [26]
Prostaglandin E1 (PGE1) has been used to treat severe pulmonary hypertension in patients with CDH; a study by Lawrence et al found it to be well tolerated in this setting and to be associated with improvements in B-type natriuretic peptide (BNP) and echocardiographic indices of pulmonary hypertension.

Surgical Therapy

With regard to treatment of CDH in the perinatal period, significant issues remain, and many questions are yet to be answered. However, the possibility of maternal-fetal surgical treatment of CDH is on the horizon. [2829]
For treatment of CDH in the neonatal period, a subcostal incision is used. An attempt should be made to carry out a primary repair of the hernia. The abdominal contents are reduced, and the edges of the diaphragm are then approximated with nonabsorbable suture. In some cases, such as when the defect is large or the repair is being made while the patient is on ECMO, a prosthetic material such as expanded polytetrafluoroethylene (ePTFE) or polypropylene is used.
For treatment of latent CDH, the typical surgical approach has been through a thoracotomy or laparotomy. Most surgeons approach via a laparotomy so that abdominal contents can be inspected adequately. In children, prosthetic mesh is typically used; in adults, direct suture technique using nonabsorbable suture material is commonly employed.
For CDH related to traumatic rupture, [303132 the surgical approach depends on the timing of the diagnosis with the surgical intervention. [29]
Minimally invasive approaches (eg, involving video-assisted thoracoscopy
[33]
or laparoscopy
[34]
) are being explored. Putnam et al found that a minimally invasive approach was associated with a shorter hospital stay and reduced small-bowel obstruction but with higher recurrence rates.
[35]
Criss et al found that in low-risk patients born with small or moderate-sized defects, a thoracoscopic approach was associated with a shorter hospital stay, reduced mechanical ventilation days, and decreased time to feeding but also with a trend toward higher recurrence rates.
[36]
 Robotic approaches are being explored as well.
[37]
Fetoscopy
Some centers use intrauterine fetal surgery (fetoscopy) to repair diaphragmatic defects in an attempt to prevent the hypoplastic lung problems encountered with large hernias. [18 (See Fetal Surgery for Congenital Diaphragmatic Hernia.)
Because the number of cases performed is still relatively small and very few centers are capable of performing intrauterine surgery, this practice has been controversial. A 2015 Cochrane review concluded that there was not sufficient evidence to recommend in-utero intervention for fetuses with CDH (including both maternal antenatal corticosteroid administration and fetoscopic tracheal occlusion) as a part of routine clinical practice. [26 
Preterm rupture of membranes remains the weak link of fetoscopy. Refinement of the technique of fetoscopy and technologic advances such as partial amniotic carbon dioxide insufflation will help correct this problem and may allow the application of fetoscopy to other pathologies in the future.


Long-Term Monitoring

Once an anatomic defect has been corrected, periodically assessing pulmonary function and obtaining chest radiographs is important. Although spontaneous recurrence of a repaired diaphragmatic hernia is low, small defects in the repair site have been reported; accordingly, surveillance is essential.



Esophageal Cysts

Practice Essentials

In 1711, Blasius initially described esophageal cysts as duplications. In 1881, Roth also described these cysts, which can be divided into the following two categories:
·        Simple epithelial-lined cysts
·        Esophageal duplication, which is an embryologic duplication of a portion of the muscle and submucosa of the esophagus without epithelial duplication
The term esophageal cysts applies to both categories. [1]
The diagnosis and treatment of esophageal cysts are still evolving. Diagnosis is aided by the use of computed tomography (CT) and endoscopic ultrasonography (EUS). Treatment is currently moving from thoracotomy to less invasive procedures, including video-assisted thoracoscopic surgery (VATS) and endoscopic techniques.


Anatomy

Embryologically, the upper gastrointestinal (GI) tract develops from the posterior division of the primitive foregut. During week 4 of gestation, the primitive foregut develops an anterior diverticulum, which becomes the respiratory bud. Meanwhile, the posterior division develops into the esophagus and upper GI tract. The tracheoesophageal septum separates the primitive esophagus from the primitive trachea. As the esophagus continues to develop, the epithelium eventually obliterates the lumen and later recannulizes.
As would be expected from the common embryologic origin, bronchogenic and esophageal cysts can occur together. Esophageal cysts develop from aberrant elements of the esophageal wall. Simple cysts are duplication of the epithelium, whereas true esophageal duplications are duplications of the submucosa and the muscle wall without duplication of the epithelium.
Esophageal cysts and duplications do not usually communicate with the lumen of the esophagus. Esophageal cysts usually occur in the neck, chest, and abdomen.

Pathophysiology

Esophageal cysts develop from aberrant elements of the esophageal wall. Simple cysts are duplication of the epithelium, whereas true esophageal duplications are duplications of the submucosa and the muscle wall without duplication of the epithelium. Maldevelopment of the posterior division of the primitive foregut is the embryologic defect responsible for esophageal cysts.
The lining of the cyst can vary and can include squamous columnar, cuboidal, pseudostratified, ciliated, and gastric mucosae. Hemorrhage can be the presenting symptom if gastric mucosa is present in the cyst. The other types of mucosa are not specifically associated with particular symptoms.
Symptoms are caused by compression of surrounding structures. Approximately 60% of esophageal cysts occur in the lower third of the esophagus, where difficulty with swallowing from compression is the most common symptom; 20% occur in the upper third of the esophagus, where respiratory difficulty from compression of the tracheobronchial tree is the most common symptom; and 20% occur in the middle third of the esophagus, where retrosternal chest pain and difficulty with swallowing are the most common symptoms.
Posterior cysts in the lower third of the esophagus can cause cardiac arrhythmias. The larger the cyst, the greater the chance of it causing symptoms.


Epidemiology

Esophageal cysts are rare, [43 but their true incidence is unknown. No large study has defined the true frequency of esophageal cysts in the United States or internationally. Cysts are usually grouped with other benign lesions of the esophagus, and they account for as many as 20% of such lesions.
Many patients with esophageal cysts are asymptomatic and are never diagnosed. As many as 80% of these cysts are diagnosed in childhood.

Prognosis

If the entire cyst is excised, recurrence is rare. Morbidity is low. Overall, most patients do well, both in the short term and in the long term.


Esophageal Cysts Clinical Presentation

History and Physical Examination

Most esophageal cysts are diagnosed during childhood. [3 Many children with these cysts are asymptomatic.
Most adults (67%) with esophageal cysts are symptomatic. Chest pain (tightness or fullness) is the most common presentation. [2 Dysphagia may also occur. [25 Hematemesis can occur if gastric epithelium is present in the cyst.
Most esophageal cysts develop in the right posteroinferior mediastinum.
Malignant degeneration can occur, albeit rarely. 


Esophageal Cysts Workup

Laboratory Studies

Laboratory studies do not specifically aid in the diagnosis of esophageal cysts. Laboratory evaluation should be guided by the patient's other medical problems.

Imaging Studies

Radiography guided by history and physical examination findings usually confirms the diagnosis. Plain chest radiographs can reveal a cyst within the mediastinum. Barium swallow studies reveal compression of the esophagus without ulceration.
Computed tomography (CT) reveals a fluid-filled cystic structure originating from the esophagus. CT is the radiologic modality of choice to aid in diagnosis and operative preparation (see the image below). Chest radiographic findings that suggest a mass in the mediastinum should be followed by a CT scan. Magnetic resonance imaging (MRI) can also help diagnose esophageal cysts.
CT scan of esophageal cyst demonstrated by the white line

Procedures

Endoscopy demonstrates extrinsic compression with intact mucosa. Esophagoscopy should be performed to rule out an intrinsic component, which should be biopsied to exclude malignancy. Endoscopic ultrasonography (EUS) reveals a cystic filled structure in connection with the esophagus. If EUS is available, then esophagoscopy should be performed to further delineate the extent of the cyst.

Esophageal Cysts Treatment & Management

Approach Considerations

Medical therapy has no role in the management of esophageal cysts. All esophageal cysts should be evaluated and, eventually, resected, except in those situations where the patient's other medical ailments prohibit operation. Given that nearly 75% of patients with esophageal cysts eventually become symptomatic, cysts should be resected when they are diagnosed.
The future of the treatment of esophageal cysts lies in the advancement of minimally invasive operative techniques, which will lessen morbidity and mortality. Endoscopic treatment has been reported as a feasible and reasonable alternative. [78Robotic-assisted thoracic surgery has also been used for resection of an esophageal cyst.

Surgical Therapy

Simple cysts are enucleated, whereas duplications are excised. [10 Previously, a posterolateral thoracotomy was required to remove the cyst or the duplication; however, video-assisted thoracoscopic surgery (VATS) is currently used to enucleate cysts and resect duplications, and it is the procedure of choice. [1121213]
Also described in the literature is endoscopic treatment of esophageal duplications, which, essentially, creates a lumen from the cyst into the esophageal lumen. [37 Laparoscopic excision of intra-abdominal esophageal cysts has been described as well. [14151617]

Preparation for surgery

Preoperative workup is based on the following two points:
·        A thorough history and a careful physical examination are important for elucidating comorbid conditions that can be addressed before the operation, thus decreasing morbidity
·        A thorough radiologic workup demonstrates the anatomy of the cyst and assists in the planning of the operation

Operative details

Before induction of anesthesia, an epidural catheter is placed for pain control. Alternatively, an ON-Q pain pump (VQ OrthoCare, Irvine, CA) can be placed at the time of operative intervention. Anesthesia is administered, and a double-lumen endotracheal tube is placed. The patient is then placed in the full lateral position.
A non-rib-spreading thoracotomy is performed (3-6 cm), with an additional Thoracoport (Tyco Healthcare, Mansfield, MA) used for visualization. Esophageal muscle fibers are carefully separated to expose the cyst. Blunt dissection is then performed to enucleate the cyst. If a duplication is present, it is excised in a similar manner. During dissection, it is important to preserve both vagus nerves and the phrenic nerves.
After the lesion is removed, the muscle layers are reapproximated, thus preventing pseudodiverticula formation. Simultaneous esophagoscopy to illuminate the esophagus assists in visualization of the mucosa. Placement of a chest tube (or tubes) follows, and the incisions are closed in standard fashion.
Alternatives to VATS include robotic-assisted thoracoscopic surgery [9and posterolateral thoracotomy.

Postoperative Care

Most patients do well after surgical therapy, with minimal morbidity. Aggressive pulmonary toilet and early mobilization prevent pulmonary complications. Adequate analgesia is essential to patient cooperation with pulmonary toilet.
If the mucosa was not violated, the patient can be started on liquids within 1-2 days of the operation. If the mucosa was violated, then placement of a drain assists in determining the presence of a leak. Esophagography can be performed to assess esophageal integrity.

Complications

The overall complication rate is very low. Most complications are inherent to the thoracotomy or to VATS. Complications that may develop include the following [18:
·        Pneumonia
·        Persistent air leak
·        Deep venous thrombosis
·        Esophageal leak or pseudodiverticulum
·        Vagus nerve paralysis
·        Wound infection
A small study by Benedict et al suggested that after resection of an esophageal duplication cyst, closing the esophageal muscle layer rather than leaving it open may reduce complications and the need for repeat operations. [