The nature of neurogenic damage to the external anal sphincter in children treated for Hirschsprung's disease

Children with faecal continence problems following surgical pull-through procedures performed for Hirschsprung's disease were investigated by concentric needle electromyographic studies of the external anal sphincter and puborectalis. The results were compared with those from a control group of children incontinent following correction of anorectal anomalies. In the Hirschsprung group the motor unit potentials in the external sphincter, but not in puborectalis, showed florid abnormalities with increased complexity and duration of the waveform, often with blocking and increased jitter, indicative of a continuing process of denervation and reinnervation. In four of the five patients with Hirschsprung's disease who were tested, pudendal nerve terminal latencies were increased, suggesting neurogenic damage to the external sphincter. Where such changes are found in children incontinent following surgery for Hirschsprung's disease, they may indicate a need for modified clinical management.The protocols used in this study were approved by the Standing Committee on Ethical Practice of the Hospital for Sick Children.Offprint requests to: S. G. Boyd