Diagnosis of innervation-related motility disorders of the gut and basic aspects of enteric nervous system development.

Abstract

Motility disorders of the gut in children have become a matter of increasing concern for the pediatric surgeon. Infantile hypertrophic pyloric stenosis is the most common disease requiring surgery in early infancy. While this entity was first described as early as 1888 by Hirschsprung, its etiology and pathogenesis are still an enigma. Fortunately, its surgical treatment is simple and safe, which cannot be said of all other motility disorders of the infantile gut. Dysmotility in small bowel atresia and in gastroschisis is related to damaged smooth muscle cells caused by concomitant ischemia of the bowel wall. In contrast, the temporarily adynamic bowel of the prematurely born child, as well as Hirschsprung's disease and related disorders, is the result of anomalies of the intestinal innervation. The pathogenesis of congenital malformations of the enteric nervous system is still a mystery to surgeons and physicians alike. With his pressure studies of the colon, Swenson first recognized Hirschsprung's disease for what it was. This led to the resection of the manometrically diagnosed abnormal colon, which was found to be aganglionic. Histological investigation of the bowel wall became the decisive tool, replacing manometry, in the diagnosis of Hirschsprung's disease. Histochemical investigation of the bowel wall is not conclusive in other malformations of the enteric nervous system, since the presence or absence of enteric neurons is not the definitive factor discriminating between normally and abnormally functioning bowel. Monoclonal antibodies raised against neuron-specific markers may become important tools for differentiation within the spectrum of congenital malformations of the enteric nervous system. The immunocytochemical technique, however, does not provide sufficient information to explain the cause of innervation disorders of the gut in infancy and childhood. Primary migration disturbances or selective disappearance of enteric neurons following ischemia are highly unlikely to cause aganglionosis of the gut. With respect to the pathogenesis and etiology of Hirschsprung's disease, current research is focused on the embryonic bowel (target organ) in plexus formation. The enteric nervous system is still an enigma, although its origin is known, at least in birds. Why neural crest cells travel, along what paths, how they reach their destination, and what may go wrong during the migratory process, are questions that must be answered. There is increasing knowledge concerning the way in which neural crest cells aggregate and form plexuses in the gut. It is largely unknown why neural crest cells settle, in the bowel, at the sites of the myenteric and submucous plexus.(ABSTRACT TRUNCATED AT 400 WORDS)