Significance of abnormalities in systems proximal and distal to the obstructed site of duodenal atresia

BACKGROUND:: Duodenal atresia (DA) is a well-known neonatal intestinal disease. Even after surgery, the proximal segment can continue to be severely dilated with hypoperistalsis, resulting in intestinal dysmotility problems in later life. No data have been published regarding the morphologic differences between the proximal and distal regions of obstructed sites of the intramural components in DA. METHODS:: Operative duodenal samples (N=12) from cases with DA (age 1-3 days) were used. Age-matched controls (N=2) were used. All of the specimens were immunohistochemically stained with antibodies to S-100 protein, α-smooth muscle actin, and c-kit protein. RESULTS:: At the proximal segments of the obstructed site in DA, the number of neuronal cells decreased in size and number. The circular musculature was moderately to severely hypertrophic. Unusual ectopic smooth muscle bundles were also identified. The innermost layer of the circular musculature was thinner. Interstitial cells of Cajal are decreased, even around the myenteric plexus. All of the staining in the distal segments in DA was similar to the control tissues. CONCLUSIONS:: Proximal and distal segments in DA differ in the neural cells, musculature, and distributions of the interstitial cells of Cajal. Based on the present study, these morphologic changes may contribute to the onset of postoperative duodenal dysmotility.