Neural electrophysiological studies on the external anal sphincter in children with anorectal malformation

Background/Purpose: Abnormality of innervation of externa I anal sphincter is one of the most important factors affecting postoperative anorectal func tion. The abnormalities of lumbosacral nerves have been reported in many ra diological and histopathologic studies. There are few reports on the neurop hysiological changes in children with anorectal malformation. The aim of th is study was to examine the functional changes of nerves to the external an al sphincter in anorectal malformation. Methods: Forty-five patients with anorectal malformation underwent studies of latencies of pudendo-anal reflex, spinoanal response, and evoked potenti al of cauda equine simultaneously. The conduction time of afferent nerve, e fferent nerve, and sacral spinal center of pudendo-anal reflex are were ana lyzed quantitatively. Results: The latencies of pudendo-anal reflex, spine-anal response, and con duction time of sacral spinal center significantly are prolonged in patient s with anorectal malformation (P < .05). There was significant difference b etween rectourethral fistula group and vestibular fistula group as well as low-type deformity group. The patients with lumbosacral anomalies such as l umbosacral spinal bifida or absence of S4 or S5 had prolonged latencies, es pecially the pudendo-anal reflex latency. There was significant negative co rrelation between the latencies and clinical scores. Although pudendoanal r eflex latency was longer in patients who had posterior sagittal anorectopla sty than those who had abdominoperineal pull-through procedure, the differe nce was not significant. Conclusions: The abnormality of nerves to external anal sphincters is one o f the important causes for clinical outcome. The neural lesions vary in eac h type of anal and lumbosacral deformity. Copyright (C) 2000 by W.B. Saunde rs Company.