Electrophysiological properties of the aganglionic segment in Hirschsprung's disease.

BACKGROUND: In Hirschsprung's disease, the severity of bowel obstruction varies among those patients who have the affected colon of a similar length, suggesting that there is more than a simple aperistaltic obstruction in the pathophysiology of Hirschsprung's disease.

METHODS: A series of our electrophysiological studies of the aganglionic segments from human specimens and rat models were reviewed to obtain an overview of Hirschsprung's disease.

RESULTS: In human studies, a generation of regular spontaneous activity was recorded in both the dilated ganglionic segment and transitional aganglionic region, while the smooth muscle cells of the narrow aganglionic segment were electrically quiescent. According to a pattern of innervation, in the dilated ganglionic segment inhibitory junction potentials associated with or without excitatory junction potentials were observed in all of the examined cells, and these intrinsic nervous inputs were gradually decreased in the transitional region. In the narrow aganglionic segment, only excitatory junction potentials of the extrinsic nervous origin were found in about 20% of the examined cells In rat models, distally increasing tendency of the excitatory nervous inputs was observed in the narrow aganglionic segment.

CONCLUSION: A bowel obstruction in Hirschsprung's disease might be generated due to complex mechanisms involving myogenic and neurogenic abnormalities.