IS THE AFFERENT PATHWAY FROM THE RECTUM IMPAIRED IN CHILDREN WITH CHRONIC CONSTIPATION AND ENCOPRESIS

Background and Aims: Rectal sensations to balloon distention are impai red in children with chronic constipation and encopresis. The impairme nt of rectal sensation, which is often persistent and is related to no nrecovery, could be caused by a defect in the visceral afferent pathwa ys. The aim of this study was to test whether the afferent pathway fro m the rectum is impaired in children with constipation and encopresis. Methods: Fifteen healthy children and 15 children with constipation a nd encopresis were studied. Cerebral evoked potentials (EPs) were stud ied by averaging results of 100 rectal distentions, which used 10, 20, and 30 mL air. EPs were recorded from Cz' to Fz. Results: Two differe nt types of EPs were recorded in each control subject and each child w ith constipation and encopresis. One EP had an early onset and showed multiple positive and negative peaks. The other EP had a much later on set and was triphasic. Early-onset EPs were recorded with significantl y smaller distention volumes than the late-onset EPs. N1 and P2 latenc ies of the early-onset EPs and NI, PI, and NII latencies of the late-o nset EPs were significantly prolonged in children with constipation an d encopresis compared with controls. Conclusions: The prolonged latenc ies suggest a defect in the afferent pathway from the rectum in childr en with chronic constipation and encopresis.