Normal Development

The esophagus develops from the proximal aspect of the embryonic foregut. The tracheoesophageal septum partitions the developing trachea from the esophagus. The epithelium and glands of the esophagus derive from endoderm. Initially, proliferating epithelium obliterates the esophageal lumen; recanalization occurs by the end of the embryonic period. Innervation of the esophagus is by branches of the vagus nerves.

Esophageal Atresia and Tracheoesophageal Fistula

Esophageal atresia and tracheoesophageal fistula comprise a spectrum of congenital abnormalities in which there is failure of normal formation of the tubular esophagus and/or there is an abnormal communication between the esophagus and trachea. This group of anomalies represents the most common congenital malformation of the esophagus. This anomaly occurs in approximately 1:3000 livebirths. Associated anomalies are present in more than 50% of children with esophageal atresia or tracheoesophageal fistula. About one-quarter of these children have an additional GI tract anomaly, such as imperforate anus, pyloric stenosis, duodenal atresia, or annular pancreas. Cardiac, genitourinary, and vertebral anomalies can also occur. Esophageal atresia and tracheoesophageal fistula are important components of the VACTERL complex: vertebral, anal, cardiovascular, tracheoesophageal, renal, radial, and limb malformations.

Although there is an incomplete understanding of the pathophysiology of esophageal atresia and tracheoesophageal fistula, it apparently involves defective formation and separation of the primitive foregut into the trachea and esophagus (Table 34-1). The esophagus and trachea comprise a single tube during early fetal development. There is subsequent division into 2 structures by infolding of the lateral walls of the foregut. A tracheoesophageal fistula is due to incomplete folding of these walls such that the mesodermal surfaces fail to come into contact. Esophageal atresia results if the lateral folds turn dorsally and thereby cut through the esophageal lumen. An alternative mechanism is intrauterine anoxia or stress that causes vascular compromise and focal necrosis of the esophagus.

The traditional classification system for esophageal atresia and tracheoesophageal fistula recognizes 5 types. Type A is pure esophageal atresia without a fistula. Type B is esophageal atresia with a fistula between the proximal pouch and the trachea. Type C is esophageal atresia with a fistula from the distal esophageal segment to the trachea or a main bronchus (Figure 34-1). This is by far the most common type, accounting for approximately 75%. Type D is esophageal atresia with both proximal and distal fistulas (Figure 34-2). Type E is a tracheoesophageal fistula (H-type) without associated atresia.

As with other high GI tract obstructions, an important prenatal manifestation of esophageal atresia is polyhydramnios. The neonate with esophageal atresia is unable to appropriately swallow saliva, and aspiration may occur during attempted feedings. An inability to pass a feeding tube into the stomach confirms the diagnosis. The rare type E tracheoesophageal fistula, in which there is a fistula without atresia, may have a delayed presentation. Common clinical manifestations in these children include recurrent pneumonias and coughing during feedings.¹

The most common manifestations of esophageal atresia on prenatal sonography are polyhydramnios and an absent or small fetal stomach. However, because esophageal atresia is usually accompanied by a tracheoesophageal fistula that allows filling of the stomach, the presence of a normal size stomach does not exclude the diagnosis. Likewise, various conditions other than esophageal atresia can lead to an absent or small fetal stomach. Impaired fetal swallowing due to central nervous system abnormalities, neuromuscular disease, and facial anomalies can cause a small fetal stomach. A more specific diagnosis of esophageal atresia is possible if the ultrasound examination shows transient filling of the distended proximal pouch of the esophagus. Most often, the fluid-filled pouch is located in the fetal neck and extends into the upper portion of the thorax. Coronal images of the neck often provide optimal visualization of the distended pouch. Sagittal images are sometimes more helpful when the pouch is at a lower location. The examination can be supplemented with fetal MR imaging, which is reported to have a sensitivity of 100% and specificity of 80% for the prenatal diagnosis of esophageal atresia.^2,3

Standard radiographs of infants with esophageal atresia typically demonstrate a distended air-filled pouch in the upper mediastinum. This may contain an air–fluid level on upright views. If a feeding tube is introduced, it usually curls within the pouch (Figure 34-3). Atelectasis or consolidation develops in the right upper lobe in many patients. With type A and B lesions, the abdomen is devoid of bowel gas (Figure 34-4). With type C and D lesions, expulsion of air through a distal fistula during respiration typically leads to distention of the bowel with air (Figure 34-5). An esophagram is required for the diagnosis of a type E tracheoesophageal fistula. The fistula courses from its origin in the esophagus anteriorly and superiorly (Figure 34-6). Helical CT can provide supplemental information about the location of the fistula in relationship to adjacent structures.

In some infants with esophageal atresia, there is wide separation between the patent portions of the esophagus. This anatomy is most common in patients who lack a fistula between the atretic esophagus and the trachea (Figure 34-4). Fluoroscopic examination with contrast injected into the distal esophagus via a surgically created gastrostomy and in the upper esophagus via an esophageal tube can be helpful in defining the severity of separation (Figure 34-7).

In addition to the initial characterization of the pathologic anatomy, imaging studies are important for patients with esophageal atresia to diagnose surgical complications, long-term sequelae of the esophageal anomaly, and associated malformations. Tracheomalacia is common in these patients. Defective peristalsis in the distal segment of the esophagus is universal, and can cause dysphagia. Reflux esophagitis is common. A stricture at the site of surgical repair of esophageal atresia can occur (Figure 34-8). A recurrent tracheoesophageal fistula is a rare complication.

Esophageal and duodenal atresias, sometimes occurring concomitantly, are common components of Feingold syndrome (oculo-digito-esophageal syndrome; ODED syndrome). Imperforate anus can also occur. This autosomal dominant disorder is due to a heterozygous mutation in the MYCN gene. There is variable microcephaly in these patients; at least one-third suffer learning disabilities. Common skeletal anomalies in Feingold syndrome include syndactyly of toes, clinodactyly, brachydactyly, hallux valgus, vertebral anomalies, and restricted finger and elbow movement.

Congenital Esophageal Stenosis

Congenital stenosis of the esophagus is a rare lesion; the estimated prevalence is 1 in 25,000 to 50,000 livebirths. This can occur as an isolated lesion, or in association with other upper GI anomalies. In about one-third of patients with congenital esophageal stenosis, the anomaly occurs in conjunction with esophageal atresia and a distal tracheoesophageal fistula or an H-type fistula with a patent esophagus. Obstruction by the distal stricture can cause persistent symptoms in these children after repair of the more superior esophageal lesion. In addition, the elevated intraluminal pressure caused by the stricture increases the risk for an anastomotic leak at the atresia repair site.⁴

Congenital esophageal stenosis can occur due to incomplete embryonic recanalization or lack of development of a normal blood supply to the affected segment. The 2 major forms of congenital esophageal stenosis are webs and annular stenoses. A web is a thin diaphragm-like membrane that partially or completely occludes the esophageal lumen. An annular lesion involves a longer segment of the esophagus. Fibromuscular tissue or tracheobronchial remnants within the esophageal wall, or a membranous diaphragm projecting into the lumen, can cause the stricture. A stricture caused by tracheobronchial remnants usually contains cartilage. Histological examination may also demonstrate respiratory glands. The cartilaginous tissue can form a partial or complete ring within the esophageal wall.

The age at presentation and the nature of clinical manifestations of congenital esophageal stenosis relate to the severity of obstruction and the level of the stricture. Many patients present during infancy with regurgitation after feedings. Patients may have manifestations of failure to thrive or suffer repeated episodes of aspiration. Dilation of the thoracic portion of the esophagus above a stricture can lead to respiratory symptoms (e.g., stridor) due to compression of the trachea. In some infants, the onset of symptoms does not occur until the introduction of solid foods. A mild stenosis may not present until later in childhood when acute symptoms result from failure of passage of poorly chewed solid food.^5,6

A fluoroscopic contrast examination of the esophagus demonstrates congenital stenosis as a persistent area of narrowing. Often, there is smooth tapering of the lumen above and below the stricture. The involved segment of the esophagus does not expand appropriately with the passage of a barium bolus and there is delay in passage of the bolus. Most often, there is transient dilation of the portion of the esophagus immediately above the stricture. The overlying mucosa is normal. Most of these lesions involve a 1 to 2 cm length of the esophagus and are located at the junction of the middle and lower thirds of the esophagus. A congenital esophageal web appears as a thin ring-shaped filling defect (Figure 34-9).^7,8

In addition to congenital stenosis, the differential diagnosis of focal esophageal narrowing includes reflux esophagitis, trauma, scarring due to prior ingestion of a caustic substance, and epidermolysis bullosa congenita. Clinical correlation usually allows a straightforward diagnosis with the latter 3 mechanisms. In many cases, however, the clinical and radiographic findings do not allow accurate differentiation between a congenital and an acquired stenosis. In general, acquired stenosis is much more common than congenital. Strictures from reflux esophagitis are most often located near the gastroesophageal junction. These patients usually become symptomatic later in childhood than do those with a congenital lesion. Although the demonstration of pathological gastroesophageal reflux in a child with an esophageal stricture favors an acquired lesion, reflux is also common in children with a congenital stricture. Esophagoscopy provides additional confirmatory information, as a congenital stricture usually has normal overlying mucosa. Cartilaginous tracheobronchial remnants in congenital stenoses are occasionally demonstrable with transesophageal sonography.^9,10

Attempted balloon or bougie dilator expansion of congenital esophageal strictures due to intramural tracheobronchial remnants is usually ineffective and carries a substantial risk for esophageal perforation. Surgical resection is the standard treatment for these patients. Strictures due to fibromuscular tissue and congenital esophageal webs are sometimes amenable to balloon dilation.⁴

Laryngotracheal Esophageal Cleft

Laryngotracheal esophageal cleft is a rare developmental lesion that results in a persistent communication through the larynx, cricoid cartilages, and part of the upper trachea. There is a spectrum of severity, ranging from a small defect in the posterior aspect of the cricoid cartilage to a large H-type fistula. The most severe form of laryngotracheal esophageal cleft is esophagotrachea, in which there is complete absence of the division between the trachea and esophagus. Most infants with laryngotracheal esophageal cleft have clinically obvious feeding difficulty that includes choking while feeding. Other findings include stridor, drooling, and cyanosis. A concomitant GI anomaly is present in some patients, for example, esophageal atresia.

A definitive diagnosis of laryngotracheal esophageal cleft requires direct inspection by laryngoscopy. Contrast fluoroscopic studies typically demonstrate tracheal aspiration during swallows; however, the defect itself may not be visible. There is the potential for a mistaken diagnosis of aspiration due to functional abnormality of the swallowing mechanism. Therefore, a high index of suspicion for this disorder is appropriate for any infant exhibiting substantial active tracheal aspiration during an esophagram.¹¹

Esophageal Bronchus

Esophageal bronchus is a rare anomaly in which a bronchus arises from the esophagus and extends toward either the right or the left lower lobe. This anomaly is a bronchopulmonary foregut malformation, and results from an ectopic supernumerary lung bud. In some patients, there is a systemic origin of the arterial supply to the portion of the lung involved with the anomaly. The amount of lung tissue supplied by the anomalous bronchus varies considerably between patients. With involvement of only a small portion of the lung, the anomaly may be asymptomatic until infection occurs. Other children present with respiratory distress soon after birth.¹²

Esophagography usually provides a definitive diagnosis of esophageal bronchus. CT also plays an important role in demonstrating the pathological anatomy. Virtual tracheobronchoscopic images from multidetector CT studies allow 3-dimensional depiction of airway anatomy in these children. Contrast-enhanced CT or MR angiography may be useful to define the arterial supply and venous drainage prior to surgical treatment.⁴

Esophageal Diverticulum

Esophageal diverticula are rare in children. A true diverticulum is an outpouching of the esophagus that contains all of the normal layers in the esophageal wall. A pseudodiverticulum, or false diverticulum, is herniation of the inner layers of the esophageal wall through the muscular layer. A walled-off perforation is a type of pseudodiverticulum that lacks a mucosal lining. Esophageal diverticula can be congenital or acquired. Acquired esophageal pseudodiverticula occasionally occur in association with achalasia, Nissen fundoplication, esophageal foreign body, or severe gastroesophageal reflux disease (GERD; Figure 34-10). Some congenital diverticula actually are communicating duplication cysts. Esophageal intramural pseudodiverticulosis is a rare disorder in which dilation of submucosal glands results in multiple small flask-shaped esophageal pseudodiverticula. This disorder can occur in association with reflux esophagitis, candida esophagitis, esophageal dysmotility, and corrosive acid injury.^13–16

Tracheal/Laryngeal Atresia

Laryngeal atresia and tracheal atresia are rare anomalies that are usually lethal. An associated tracheoesophageal or bronchoesophageal fistula is typically present. The trachea is completely absent in the most common form of tracheal atresia, and there is a fistulous connection between the esophagus and the carina (see Figure 30-12 in Chapter 30). The next most common arrangement is a short segment of distal trachea that connects to the anterior wall of the esophagus. Tracheal agenesis without an airway fistula to the GI tract is exceedingly rare.^11,17

Achalasia

Achalasia is a neuromuscular disorder of the esophagus in which there is failure of normal relaxation of the lower esophageal sphincter during deglutition. Abnormally weak motility of the esophagus is an important component of this disorder. The pathophysiology involves failure of distal esophageal inhibitory neurons. Approximately 5% of patients with achalasia present during childhood.¹⁸ Unusual familial cases have been reported. There is sometimes an association with other congenital disorders, such as familial dysautonomia, glucocorticoid insufficiency, and Rozycki syndrome.¹⁹

The typical presenting complaint of individuals with achalasia is dysphagia that is usually worse with solid food. Patients will intermittently regurgitate food from the dilated esophagus. Young children with achalasia are particularly susceptible to pulmonary complications due to chronic aspiration. Some patients report nocturnal cough.

Standard chest radiographs of patients with achalasia often demonstrate a dilated esophagus that is filled with gas, fluid, and/or solid food (Figure 34-11). Parenchymal lung abnormalities due to chronic aspiration are sometimes present. An esophagram shows disordered motility, slow emptying, and an abnormal tapered appearance at the gastroesophageal junction (Figures 34-12 and 34-13). The severity of esophageal dilation roughly correlates with the time course of the disease. In patients with long-standing symptoms, esophageal dilation is marked and there is prolonged retention of food in the distal portion. Scintigraphy with radionuclide-labeled foods allows evaluation of the dynamics of esophageal emptying in patients with achalasia. Manometry shows failure of lower esophageal sphincter relaxation during swallowing and lack of functional peristalsis in the smooth muscle portion of the esophagus.

CT evaluation is useful in selected patients for differentiation between primary achalasia and the rarer secondary form due to a mediastinal tumor at the gastroesophageal junction. In primary achalasia, there is little or no esophageal wall thickening. The distal aspect of the esophagus tapers smoothly and there is no mass. Potential findings in secondary achalasia include asymmetric thickening of the distal esophageal wall, an inferior mediastinal mass, and lymphadenopathy.²⁰

Treatment options for achalasia include the Heller myotomy and balloon dilation. Balloon dilation can be used as the primary therapy or to treat patients with poor results after surgery. This technique is associated with decreased procedure-related morbidity and much shorter hospitalizations than surgery. Azizkhan et al reported a successful resolution of symptoms in 73% of pediatric achalasia patients with pneumatic dilatation as the primary therapy; this is similar to the results for surgical treatment.¹⁸ Upadhyaya et al achieved resolution of symptoms in all 12 of the children who they treated with primary balloon dilation.²¹

A 3 cm balloon is the usual size for treating achalasia in adults and adolescents, whereas a 1.5 to 2 cm size is more appropriate in younger children.^22,23 The balloon is centered at the gastroesophageal junction and slowly inflated under fluoroscopic observation. Inflation is maintained for 30 to 60 seconds. A water-soluble contrast esophagram after the procedure serves to rule out complications such as perforation. The patient experiences chest pain during the dilation, and sometimes for a short time after the procedure. If symptoms of esophageal obstruction persist or recur, additional dilations can be performed, usually with a larger balloon size. The therapeutic effect can be assessed after 7 to 10 days with an esophagram and/or a radionuclide esophageal emptying study.

Reported complications of pneumatic dilation for achalasia include perforation, intramural hematoma, traumatic diverticulum, and prolonged postprocedure chest pain. Complications of a surgical myotomy for achalasia include perforation, recurrence, fibrous stricture, and gastroesophageal reflux. Many surgeons perform a fundoplication procedure in conjunction with the myotomy because of the common occurrence of reflux after surgical therapy.^24,25

Duplication Cyst

An esophageal duplication cyst is a congenital fluid-filled mediastinal lesion. This is the second most common location for an alimentary tract duplication cyst, after those of the ileum. This type accounts for 15% to 20% of duplications. Most esophageal duplication cysts are located adjacent to the inferior aspect of the esophagus, often on the right.¹

The pathophysiologic mechanism for formation of an esophageal duplication cyst apparently involves aberrant luminal recanalization. During the fifth to sixth weeks of gestational age, the foregut is covered by the epithelial cells that grow to obliterate the lumen. Subsequently, secretions from these cells form vacuoles in the intercellular space. These vacuoles line up longitudinally and eventually coalesce to form the esophageal lumen. Failure of some of the vacuoles to coalesce can produce a cyst that migrates laterally into the esophageal wall, where the muscular layers of the esophagus surround it.

An esophageal duplication has a thick wall that contains smooth muscle. The lining consists of alimentary tract mucosa. Uncommonly, there is ectopic gastric mucosa within the lesion, which can result in symptoms due to peptic ulceration. Esophageal duplication cysts are nearly always spherical or oval. Rarely, a tubular duplication occurs, sometimes in association with a gastric duplication cyst. A tubular esophageal duplication may communicate with either the esophagus or the stomach (Figure 34-14). The embryogenesis of a tubular duplication likely differs from that of other foregut malformations, and presumably involves faulty recanalization of the embryonic esophageal lumen.^26,27

Symptoms related to an esophageal duplication cyst vary with the size and location of the lesion. Some are asymptomatic. Mass effect on the adjacent lung or esophagus can produce respiratory symptoms, dysphagia, or vomiting.

Most esophageal duplications are too small to be visualized on standard radiographs; occasionally, there is an appearance of a homogeneous mediastinal mass (Figure 34-15). Extrinsic mass effect is often identifiable on an esophagram. The lesion sometimes has imaging characteristics of an intramural location (Figure 34-16). CT demonstrates a sharply marginated homogeneous mass that has attenuation values similar to those of clear fluid (Figure 34-17). There is no contrast enhancement of the cyst contents. Esophageal duplications typically produce low signal intensity on T1-weighted MR images and high signal intensity on T2-weighted images. Cross-sectional imaging studies allow characterization of the effects of the lesion on adjacent structures. Those esophageal duplication cysts that contain gastric mucosa accumulate ^99mTc pertechnetate.

The radiographic differential diagnosis of a cyst within the esophageal wall or adjacent soft tissues includes bronchogenic cyst, neurenteric cyst, cystic mediastinal neoplasm, and anterior meningocele. A posterior mediastinal bronchogenic cyst can appear identical to an esophageal duplication cyst on imaging studies; however, differentiation is unimportant since surgical resection is carried out in the same manner for both of these lesions. An anterior meningocele communicates with the spinal canal. Cystic mediastinal neoplasms are usually multiloculated and have solid components.

A neurenteric cyst contacts the spinal canal via a fibrous tract or a patent fistula. The tract is associated with anomalous vertebral development. Although some patients are neurologically normal, the intraspinal tract can result in recurrent meningitis, spinal cord compression, or paraplegia. Standard radiographs show a butterfly vertebra or hemivertebra in the region of the defect; the anomalous vertebra is usually superior to the cyst, as the tract follows an oblique superior course to the spine. CT provides optimal demonstration of the bony deformities, whereas MRI is indicated to define the intraspinal pathology. MRI should be performed for any patient with a mediastinal cyst and concomitant vertebral anomalies.

Great Vessel Anomalies

Anomalies of the great vessels frequently cause extrinsic compression of the esophagus (see Chapter 12 for additional discussion). These anomalies range from clinically insignificant developmental variations to severe constrictions of the esophagus and trachea. Detection of these lesions on standard chest radiographs requires careful inspection for intrathoracic tracheal displacement or narrowing. The findings on esophagography frequently allow a specific diagnosis. CT angiography and MRI are usually definitive.

While performing an esophagram of an infant with a possible great vessel anomaly, carefully positioned frontal and lateral views should be obtained with the esophagus well distended with barium. Image quality must be sufficient to evaluate the position and caliber of the intrathoracic segment of the trachea. Great vessel anomalies result in 4 basic patterns on barium esophagography: (1) posterior esophageal impression with normal tracheal caliber, (2) anterior esophageal impression and posterior tracheal impression, (3) posterior esophageal impression and anterior tracheal impression, and (4) normal esophagus and anterior tracheal impression (Table 34-2).

The most common vascular anomaly demonstrated on barium esophagus studies is an aberrant right subclavian artery with a normal left aortic arch (Figure 34-18). The lateral view shows a posterior impression on the esophagus and no concomitant tracheal narrowing. On the frontal view, the impression follows an oblique course, inferior on the left side of the esophagus and superior on the right side (see Figure 12-5 in Chapter 12). There is no narrowing or displacement of the trachea. The degree of esophageal narrowing is minimal. This anomaly does not produce symptoms.