ABNORMALITIES IN VISCERAL EVOKED-POTENTIALS FROM THE ANAL-CANAL IN CHILDREN WITH CHRONIC CONSTIPATION

The integrity of the sensory nervous system in the anal canals of chro nically constipated children was investigated using evoked potential t echniques examining cerebral and spinal evoked potentials from the low er extremities and anal canal. Stimulation of the posterior tibial ner ve produced no significant difference in the parameters of spinal and cerebral evoked potentials between 18 controls and 12 chronically cons tipated children. However, stimulation of the anal canal resulted in e voked potentials related to the age and/or consciousness level of the control children. Reproducible cerebral responses were obtained only f rom nine of these control children, all aged over 4 years, who were ex amined while awake without sedatives, A typical response was character ized by a polyphasic wave occurring with an onset latency of 79.4 +/- 27.7 ms (mean +/- SD). In the 12 chronically constipated children, the 5 sedated patients examined while asleep did not show any reproducibl e potential, as in the controls, However, in the remaining 7 children examined while awake, the occurrence of the anal canal evoked potentia l was significantly reduced, and only two exhibited a cerebral respons e. These findings suggest that rectal mucosal perception of the intral uminal stimuli might be disturbed in some children with chronic consti pation.