Current approaches to development of the autonomic nervous system: clues to clinical problems

Epidemiology of congenital innervation defects of the distal colon

Congenital colorectal innervation defects were evaluated by studying 3699 colonic mucosal biopsy specimens obtained from 773 patients over a 5-year period (1986-1991). In 358 cases (46.3%) a classifiable defect was present, with aganglionosis in 187 of these patients (52.2%) and hypoganglionosis of the colon in 18 (5.0%). Hypoplastic or aplastic sympathetic innervation (type-A neuronal intestinal dysplasia was found in 2.2% (n = 8) and dysplasia of the parasympathetic submucous plexus (type-B neuronal intestinal dysplasia) in 40.6% (n = 145) of the patients with classifiable defects. Identification of a specific innervation defect was not possible in 229 of the 773 patients (29.6%), 28% of whom exhibited slight dysplasia and 30% immaturity or hypogenesis of the submucous plexus. In 40% of the unclassifiable cases heterotopic nerve cells were found in the muscularis mucosae and/or lamina propria mucosae, while 2% had severe heterotopia with the cells of the myenteric plexus completely displaced into the circular and/or longitudinal muscle layers. These patients generally suffered from severe chronic constipation requiring surgical intervention. Four congenital innervation defects of the colorectum can thus be clearly differentiated at present: aganglionosis (in its various forms), hypoganglionosis, type-A neuronal intestinal dysplasia, and type-B neuronal intestinal dysplasia.