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

Harlequin Syndrome after Thoracoscopic Repair of a Child with Tracheoesophageal Fistula (TEF)

Harlequin syndrome (HS) is a rare dysautonomia of the sympathetic nervous system leading to asymmetric facial flushing and sweating. In the literature, only a few cases of HS after thoracoscopic tracheoesophageal fistula (TEF) repair are reported. We report on a newborn with TEF who developed HS after thoracoscopic repair. On the first day of life, the girl (3,480 g, gestation age: 41 week) underwent thoracoscopic repair of a type C esophageal atresia (TEF; OR time 105 minute) without complications. The postoperative course was uneventful, the patient swallowed and thrived well and did not require esophageal dilatations. At 2 years of age, missing facial flushing, transpiration, and warming on the right side of her face during agitation were noticed. As no further intervention was required, the girl and her parents adapted well to the symptoms. Our report shows that the late onset of HS after the surgical procedure is unlikely a direct causal relation to the thoracoscopic operation but rather a shared embryological pathogenesis, like a neurocristopathy.

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.

Not all symptoms disappear after vascular ring division: a pathophysiological interpretation

Vascular rings are a group of cardiovascular lesions due to faulty embryological development derived from an abnormality of neural crest cells (cephalic neurocristopathy). In addition to peculiar symptoms due to compression on the trachea and/or the esophagus, patients with vascular rings might present further features of neural crest-related defects. We report on a case of a child with complete vascular ring, affected both by compressive symptoms and by autonomic disturbances and minor facial anomalies. The autonomic disturbances are clinical features of maturational dysautonomia and tend to disappear with aging, whereas major compressive symptoms are solved by surgery.

Stephen L. Gans Distinguished Overseas Lecture. The neural crest in pediatric surgery

AIM

This review highlights the relevance of the neural crest (NC) as a developmental control mechanism involved in several pediatric surgical conditions and the investigative interest of following some of its known signaling pathways.

METHODS

The participation of the NC in facial clefts, ear defects, branchial fistulae and cysts, heart outflow tract and aortic arch anomalies, pigmentary disorders, abnormal enteric innervation, neural tumors, hemangiomas, and vascular anomalies is briefly reviewed. Then, the literature on clinical and experimental esophageal atresia-tracheoesophageal fistula (EA-TEF) and congenital diaphragmatic hernia (CDH) is reviewed for the presence of associated NC defects. Finally, some of the molecular signaling pathways involved in both conditions (sonic hedgehog, Hox genes, and retinoids) are summarized.

RESULTS

The association of facial, cardiovascular, thymic, parathyroid, and C-cell defects together with anomalies of extrinsic and intrinsic esophageal innervation in babies and/or animals with both EA-TEF and CDH strongly supports the hypothesis that NC is involved in the pathogenesis of these malformative clusters. On the other hand, both EA-TEF and CDH are observed in mice mutant for genes involved in the previously mentioned signaling pathways.

CONCLUSIONS

The investigation of NC-related molecular pathogenic pathways involved in malformative associations like EA-TEF and CDH that are induced by chromosomal anomalies, chemical teratogens, and engineered mutations is a promising way of clarifying why and how some pediatric surgical conditions occur. Pediatric surgeons should be actively involved in these investigations.

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.

Speculations on the pathogenesis of CHARGE syndrome

To be seriously considered, a theory about the pathogenesis of a multiple congenital anomaly syndrome should meet three criteria: (1) it should explain all of the anomalies associated with the syndrome; (2) it should explain why certain anomalies are not associated with the syndrome; and (3) it should predict anomalies that could be associated with the syndrome, but have not yet been described. The theory must eventually pass the ultimate test, that is, molecular confirmation of the proposed mechanism. Several theories about the pathogenesis of CHARGE syndrome have been proposed, but none of these meet the three criteria stated above. In this study, the author proposes that CHARGE syndrome is due to a disruption of mesenchymal-epithelial interaction (epithelial includes ectoderm and endoderm). The theory is tested against the major, minor, and occasional anomalies that are used to make the clinical diagnosis of CHARGE syndrome. Review of the known embryology of the organs and tissues involved in CHARGE syndrome confirms that mesenchymal-epithelial interactions are necessary for proper formation of these organs and tissues. The presence of limb anomalies in approximately one-third of CHARGE syndrome patients fulfills criteria #3 above, in that limb anomalies were not felt to be a part of CHARGE syndrome until relatively recently. It is known that some patients with chromosomal abnormalities have a phenotype that overlaps with CHARGE syndrome. Given that critical developmental pathways must be robust and redundant in order to minimize errors, it may be that disruption of more than one gene is necessary to generate the CHARGE phenotype, as has been proposed for the holoprosencephaly sequence. Mutations and deletions of CHD7 have recently been identified as causing CHARGE syndrome in more than 50% of tested patients. Given this gene classes' putative role as a general controller of developmental gene expression as well as mesodermal patterning, it would fit the hypothesized mechanisms discussed in the study.

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.

Oesophageal atresia, related malformations, and medical problems: a family study

Oesophageal atresia (OA) and tracheo-oesophageal fistula (TOF) are life-threatening malformations of generally undefined cause. Previous reports of familial cases suggest a genetic contribution. The pattern of inheritance appears non-Mendelian, i.e., multifactorial. Individuals with OA/TOF often have other malformations and medical problems. The aim of this study was to determine the association in OA/TOF cases and healthy control subjects of associated malformations, midline defects, and medical conditions. We also investigate the relationships of these conditions in the relatives of the cases and controls. The results show that infants with OA/TOF frequently have VACTERL anomalies (vertebral, 17%; anal, 12%; cardiac, 20%; renal, 16%; limb, 10%) and other midline defects (cleft lip and palate, 2%; sacral dysgenesis, 2%; urogenital anomalies, 5%). The following medical problems were also reported: oesophageal dysmotility, 21%; gastro-oesophageal reflux, 22%; chest infections, 6%; and autonomic dysfunction, 0.5%. The first-degree relatives of children with OA are much more likely to have one of the aforementioned malformations or medical conditions when compared with the control group: one or more VACTERL anomalies (P < 0.01), gastro-oesophageal reflux (P < 0.05), recurrent respiratory infections (P < 0.05), and autonomic dysfunction (P < 0.001). The more distant relatives also show an increased incidence of such problems although in this case the data must be viewed with caution. The results confirm that the associated malformations and related medical problems occur significantly more frequently in the relatives of individuals with OA/TOF. These families may prove valuable for linkage analysis in an attempt to determine the genetics of OA/TOF.

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.

Anatomy of the extrinsic nerve supply of the oesophagus in oesophageal atresia of the common type

Cadaver dissections of the oesophagus were carried out to evaluate its extrinsic nerve supply in oesophageal atresia (OA) with distal tracheo-oesophageal fistula. In OA the atresia occurs at an anatomic watershed in the oesophagus. Proximal to the atresia, the oesophageal wall contains striated muscle. There is a known change in the type of muscle that forms the oesophagus as it descends through the chest. As a continuation of the pharynx, its wall is made up entirely of striated muscle, which is gradually replaced by smooth muscle. What percentage of the wall proximal to an atresia is normally striated is not known. Distal to the atresia the oesophagus is a smooth-muscle tube that receives its extrinsic motor nerve supply from the vagal nerves. These specific nerve fibres have their central origin in the dorsal nucleus of the vagus and are part of the autonomic nervous system. They appear to reach the oesophagus with its blood supply in an ordered but random manner. As the autonomic nervous system does not supply striated muscles, fibres of the vagal nerves that supply the proximal pouch must be somatic nerves. This is confirmed, as this portion of the oesophagus is shown to be supplied by the recurrent laryngeal nerves, which contain fibres that have their origin in the nucleus ambiguous. These nerves are bilateral and reach the oesophageal wall in a segmental fashion; this supply is continuous with that of the pharynx. As the oesophagus proximal to an atresia anatomically belongs to the pharynx, it is called the pharyngeal oesophagus. For a similar reason, the distal segment is named the gastric oesophagus. This anatomy is of practical importance to the surgeon.

Decreased incorporation of D-glucosamine into glycosphingolipids of intact Familial Dysautonomia lymphoblasts

Familial Dysautonomia (FD) is an autosomal recessive Ashkenazi Jewish genetic disease, of unknown etiology, involving deficits in both autonomic and sensory functions. Previously, we found statistically significant increases in globotriaosylceramide (Gb3) in FD fibroblasts and lymphoblasts, and a decrease in ganglioside levels. FD fibroblasts exhibited pleiomorphic changes at the light microscopy level, suggestive of changes in the plasma membrane. We described an increase in Gb3 on the surface of synchronized cells at the G1/S boundary of the cell cycle, based on Gb3-verotoxin (derived from E. coli) interactions. Using D-glucosamine-1-14C as an in vitro precursor, we herein report a marked decrease in the rate of incorporation of D-glucosamine into the sialic acid and the N-acetylgalacto/glucosamine moieties of gangliosides and neutral glycosphingolipids in intact FD compared to control lymphoblasts. The total ganglioside content of FD cells (primarily GM3, measured as incorporation of 3H from NaB3H4) was also decreased. These data indicate differences in the turnover of sialic acid and N-acetylated sugar constituents in FD vs normal cells.

A cluster of choanal atresia

During a 5-month period in 1991 four infants with choanal atresia or stenosis were born at one hospital. We therefore reviewed our experience of this condition during the past 6 years and compared the patients who presented before with the four clustered cases. No definite explanation has been ascertained for this cluster of cases of choanal obstruction but a viral or other environmental teratogen could not be excluded.