Preliminary experience with intrasphincteric botulinum toxin for persistent constipation after pull-through for Hirschsprung's disease.

Although most children who have Hirschsprung's disease have an excellent result after pull-through surgery, some experience persistent constipation caused by "internal sphincter achalasia." Anal myectomy has been advocated for this problem, but it results in permanent injury to the sphincter and is not universally effective. Botulinum toxin has been safely used to selectively and reversibly weaken a variety of voluntary muscles and sphincters in both adults and children. Injection of botulinum toxin into the internal anal sphincter (IAS) should theoretically produce the same functional result as anal myectomy without permanent sphincter injury. Four children aged 4 to 8 years presented with persistent constipation after a pull-through procedure for Hirschsprung's disease. Two had associated encopresis, both of whom had previous myectomies. The authors performed four-quadrant intrasphincteric botulinum toxin injection (total dose, 15 U). Resting IAS pressure decreased in all children 4 to 8 weeks after injection. Patients have been followed up for 7 to 9 months. One child (with Down's syndrome) remained symptomatically unchanged. The other three families reported significant improvement in bowel function in their children. In two of these, there was a return of symptoms 6 months after injection; one child underwent reinjection with good results. Postinjection incontinence occurred in three children, but resolved after several weeks in the one who did not have encopresis before botulinum toxin injection. These preliminary results suggest that botulinum toxin may represent a less invasive alternative to anal myectomy for children who have severe constipation after surgery for Hirschsprung's disease. If myectomy is contemplated, botulinum toxin may also be useful as a means of predicting which children may benefit.