Esophageal atresia, choanal atresia, and dysautonomia

Asymmetric sweating and flushing in infants with esophageal atresia

Of 136 infants with repaired esophageal atresia, one presented an unilateral facial flushing and 2 presented a flushing and sweating of one half of the body. The topography of these disorders and/or the associated clinical manifestations suggest that the asymmetry may be related to an instability of unilateral autonomic centers more than to a surgical injury of upper thoracic sympathetic chain during esophageal repair.

Pathogenesis of apparent life-threatening events in infants with esophageal atresia

Many infants with a repaired esophageal atresia (EA) undergo fundoplication, aortopexy, or glossopexy because the mechanisms most responsible for airway obstruction and/or apparent life-threatening event (AO/ALTE) syndrome are considered to be gastroesophageal reflux (GER), tracheal compression (TC), or obstructive apnea, respectively. In the present study, we investigated whether these mechanisms are independent or interrelated. We developed a database of 120 consecutive patients with EA treated by the senior author between 1967-2002. We studied the clinical manifestations of patients with a cervical esophagostomy and/or blind lower esophageal stump, which ruled out TC and/or proximal esophageal GER as a mechanism for AO/ALTE. Of 25 neonates who underwent section/ligation of lower tracheo-esophageal fistula and/or feeding gastrostomy, 10 critically ill neonates died. Of 15 survivors, 9 infants had a feeding gastrostomy without an esophagostomy. Of these, 6 infants presented one or more episodes of AO, and 8 presented ALTE with or without AO. Subsequently, 5 of the 9 infants underwent an esophagostomy. Eventually, 11 infants had a feeding gastrostomy with an esophagostomy. Of the latter, 5 infants presented one or more episodes of AO, and 6 presented ALTE without AO. In conclusion, oral feeding, proximal esophageal GER, and TC are not essential for AO/ALTE syndrome to occur. They are probably factors which offer evidence of an underlying problem with control of upper airway patency.

Decrease of parafollicular thyroid C-cells in experimental esophageal atresia: further evidence of a neural crest pathogenic pathway

Adriamycin-induced experimental esophageal atresia (EA) is often associated with malformations of neural crest (NC) origin, such as abnormal pharyngeal pouch derivatives like the thymus and the parathyroids. The aim of the present study was to examine whether NC-derived thyroid C-cells were abnormal in a rat model. Pregnant rats received intraperitoneally either 2 mg/kg Adriamycin (EA) or vehicle (controls) on days 8 and 9 of gestation. Fetuses were recovered on day 21, and blocks including the trachea and thyroid were fixed in formalin, coronally sectioned at 3-mum widths, and stained with standard hematoxylin and eosin until the largest area of thyroid was reached. From this point on, the 1st, 10th, and 20th slices were immunohistochemically stained with anti-calcitonin antibody. Positively-stained cells in each section of the gland were counted using a computer-assisted image analysis method, and the results were averaged. The distribution of the cells within the gland was assessed as well. Comparisons between EA and control rats were made by nonparametric tests with a significance threshold of p<0.05. The number of C-cells was dramatically reduced in EA animals compared with controls (32.4+/-36 vs. 92.3+/-60.5, p<0.001). Histology of the thyroid was similar in both groups, but the distribution of positive C-cells within the gland followed an abnormal pattern in EA rats. Adriamycin causes a pattern of NC-derived malformations, including a severe decrease in thyroid C-cells accompanied by abnormal distribution or migration patterns. These results represent further evidence of the involvement of NC organogenic control dysregulation in the pathogenesis of EA and its associated malformations. The similarities between the rat model and the clinical picture strongly support investigating other subclinical NC-derived anomalies in patients with EA.

Glossopexy as an alternative to aortopexy in infants with repaired esophageal atresia and upper airway obstruction

BACKGROUND/PURPOSE

Clinical manifestations of airway obstruction in infants with repaired esophageal atresia or tracheoesophageal fistula (EA/TEF) are attributed conventionally to tracheomalacia. In the current study, the authors tested the hypothesis that a retrodisplacement of the tongue (glossoptosis), by causing a functional upper airway obstruction (obstructive apnea/hypopnea), may play a role in the pathogenesis of the respiratory problems.

METHODS

The records of 5 infants with repaired EA/TEF and respiratory symptoms treated by glossopexy, which serves to anchor the tongue forward, were reviewed. Prompt improvement after glossopexy in clinical manifestations, in blood gas exchange, and in weight velocity was used to establish a primary cause-effect relationship between glossoptosis and respiratory problems.

RESULTS

Before glossopexy, all infants presented with severe respiratory distress. Three infants had life-threatening events requiring recurrent or chronic airway intubation. Four infants had severe tracheomalacia, diagnosed at bronchoscopy. All infants presented obstructive apnea/hypopnea with desaturation. Body weight was below the third percentile in all infants. After glossopexy, 3 presented a marked clinical improvement associated with significant increase in mean oxygen saturation (88% +/- 0.4 SE v 95% +/- 0.3 SE; P <.001). In another infant, glossopexy allowed permanent decannulation but did not relieve the problem during crying or excitement when obstructive hypopnea with desaturation required supplemental oxygen. After glossopexy and despite subsequent aortopexy, the last infant could not be extubated and died later of mycotic sepsis. Autopsy results showed a vascular ring. In the 4 surviving infants, glossopexy was followed promptly by significant catch-up growth and subsequent normal growth velocity (P =.03).

CONCLUSIONS

Present findings support the concept that, in some infants with EA/TEF, respiratory problems are mainly caused by recurrent obstructive apnea/hypopnea, which may be treated successfully by lip-tongue adhesion procedures. Severe airway obstruction, not relieved by glossopexy, requires aortopexy to reduce the respiratory load imposed by tracheomalacia.

Pattern of cardiovascular anomalies associated with esophageal atresia: support for a caudal pharyngeal arch neurocristopathy

Patients with cephalic neurocristopathy (an abnormality of neural crest differentiation) present a striking pattern of associated cardiovascular anomalies (CVA). Therefore, to support the hypothesis that esophageal atresia (EA) may be related to a defective contribution from the cephalic neural crest, we studied the pattern of CVA associated with EA. Medical records of 99 patients with isolated EA, 101 with isolated anorectal malformations (ARM) and 15 with both EA and ARM, consecutively admitted to our unit, were reviewed. The prevalence and pattern of CVA associated with isolated EA or isolated ARM were compared on the assumption that the cranial or caudal location of a major malformation is related to a different regional patterning of associated anomalies. The prevalence of CVA was 39% in patients with isolated EA and 7% in those with isolated ARM (p < 0.01). Neural crest-related CVA (aortic arch anomalies, conotruncal defects, and superior vena cava malformations) accounted for 72% of all CVA in patients with isolated EA versus 14% in those with isolated ARM (p < 0.02). In patients with isolated EA, anomalies of the fourth and sixth aortic arch derivatives accounted for 75% of all neural crest related CVA. The present pattern of CVA in infants with EA supports the concept that EA may be related to an abnormal contribution from caudal portion of cephalic neural crest.

Neural crest-derived defects in experimental esophageal atresia

Esophageal atresia (EA) is often associated with cardiovascular and other malformations that are likely neural crest derived. The present study tests the hypothesis that the heart and great vessels and the thymus and parathyroids may be abnormal in the rat model of EA as a result of disturbed neural crest development. Time-mated pregnant rats received intraperitoneally on d 8 and 9 of gestation either 2 mg/kg adriamycin or vehicle. Esophageal, heart, and thymic malformations were sought under the microscope in term fetuses. The parathyroids were histologically investigated. Control fetuses had no malformations, whereas 69 of 109 fetuses exposed to adriamycin had EA and 45 of 69 had 15 right aortic arches, nine aberrant right subclavia, eight ventricular septal defects, six narrow pulmonary outflow tracts, five tetralogies of Fallot, three double outflow right ventricles, three double aortic arches, three atrial septal defects, three right ductus arteriosus, and two truncus. The thymus was absent in 19, hypoplastic in 12, and ectopic in five out of 36 fetuses with EA in which it was studied, whereas the parathyroid glands were absent in 16, single in four, and ectopic in one of the 23 fetuses with EA in which they were studied. In conclusion, the nature of the cardiovascular, thymic, and parathyroid malformations associated with EA in rats is consistent with the hypothesis of neural crest participation in their pathogenesis. Mechanisms simultaneously disturbing foregut septation, somitic segmentation, and neural crest development should be sought to explain the combined occurrence of malformations in EA.

Recurrent apparent life-threatening event relieved by glossopexy

An infant with repaired esophageal atresia presented with several apparent life-threatening events (ALTEs). He had upper airway instability, gastroesophageal reflux (GER), and tracheomalacia. Oxygen breathing test results showed a modest increase in arterial Po2 consistent with the development of an intrapulmonary shunt from absorption collapse of some hypoventilated areas of the lung. Glossopexy was followed by improvement in upper airway stability, normal oxygen test, and disappearance of ALTE. These findings support the concept that upper airway instability, obstructive apnea, lower airway instability, absorption collapse, massive intrapulmonary shunt, and ALTE are the result of a cascade reaction. The authors conclude that infants with ALTE associated with obstructive apnea and O2 shunting require glossopexy to reduce the risk of sudden death.

Assessment of pulmonary mechanics and breathing patterns during posturally induced glossoptosis in infants

Respiratory mechanics were studied in nine infants with glossoptosis-apnoea syndrome to determine whether glossoptosis may account for signs of both inspiratory and expiratory airway obstruction. Airflow, oesophageal pressure, inspiratory and expiratory time (Ti and Te), and inspiratory and expiratory resistance (Ri and Re) were measured before and during ventilatory phases characterised by glossoptotic pharyngeal obstruction, induced by turning the infants onto their backs. In addition, an attempt was made to correlate the abnormalities in pulmonary mechanics with the clinical features. During partial glossoptotic pharyngeal obstruction, a significant increase was observed in Te and Re and variable changes in Ti and Ri. During severe obstruction, the infants displayed obstructed inspiratory efforts often associated with stridor, as well as obstructed expiratory efforts often associated with audible grunting and retarded expiratory flow pattern. The expiratory grunt was loudest over the neck and mimicked bronchospasm over the chest. These findings indicate that glossoptotic pharyngeal obstruction induces functional airway obstruction which may affect both inspiration and expiration. Expiratory airway obstruction seems, at least in part, to be due to active braking of expiratory flow.

Airway obstruction and gastroesophageal reflux: an experimental study on the pathogenesis of this association

Gastroesophageal reflux (GER) frequently complicates the clinical course of children suffering from conditions leading to upper airway obstruction (UAO) (choanal atresia, tracheomalacia, esophageal atresia, vascular rings, etc). In an attempt to explore whether partial airway obstruction causes changes in the normal thoracoabdominal pressure gradients, we measured end-inspiratory intrathoracic and intraabdominal pressures in anesthetized rats under spontaneous breathing conditions, after tracheostomy, and under upper airway obstruction induced by tracheal intubation with three progressively narrower cannulae (inner diameters 1.0 mm, 0.5 mm, and 0.2 mm). We also measured the lower esophageal sphincter pressure (LESP) and length (LESL) and calculated the thoracoabdominal end-inspiratory pressure gradient (TAEIPG). Neither LESP nor LESL changed significantly before or after maximal tracheal obstruction (14.3 +/- 6.2 v 18 +/- 7.6 cm H2O [P > .05] and 0.34 +/- 0.09 v 0.41 +/- 0.1 cm H2O [P > .05] respectively) but TAEIPG significantly increased from 5.58 +/- 1.34 cm H2O to 17.62 +/- 4.27 cm H2O (P < .01) under the same conditions, mainly as a result of progressively increasing negative intrathoracic pressures during inspiration. These experiments prove that the powerful thoracoabdominal pressure gradients developed after partial UAO may contribute to the pathogenesis of GER by overcoming the antireflux barrier function. This study points out the convenience of routinely screening for GER all children with airway obstructive conditions, bearing in mind that the reestablishment of normal respiratory conditions should be the primary goal of treatment.

Maturational dysautonomia and facial anomalies associated with esophageal atresia: support for neural crest involvement

Patients with esophageal atresia (EA) or choanal atresia/stenosis (CA) present with many clinical features of maturational dysautonomia (DY). Since CA and DY are considered manifestations of cephalic neurocristopathy, we tested the hypothesis that EA may also be related to faulty development of cephalic neural crest. Forty-eight patients with EA and 53 with CA were followed up to study the frequency of the facial anomalies which are regarded as the phenotypic expression of an abnormal cephalic neural crest contribution to facial embryogenesis. Forty-eight patients with EA and 51 with CA had clinical manifestations of DY. Forty-four patients with EA (91%) and 49 with CA (92%) had one or more facial anomalies. Comparing the groups, patients with EA had an increased frequency of unilateral facial anomalies of branchial arch derivatives (P < .01); those with CA had an increased frequency of anomalies of frontonasal process derivatives (P < .01). These findings support the hypothesis that EA may be related to an abnormal contribution from the cephalic neural crest. The presence of facial anomalies may facilitate the diagnosis of subclinical DY.