Internal anal sphincter achalasia: Outcome after internal sphincter myectomy

Background: Internal anal sphincter achalasia ([ASA), also referred to as u ltrashort segment Hirschsprung's disease (HD), is a clinical condition with presentation similar to HD, but with the presence of ganglion cells on rec tal biopsy. The diagnosis of IASA is made on anorectal manometry, which sho ws the absence of rectosphincteric reflex on rectal balloon inflation. Alte red intramuscular innervation has been reported in IASA. The purpose of thi s study was to review the outcome after internal sphincter myectomy in pati ents with IASA. Methods: Fifteen consecutive patients (age range, 2 years to 12 years) with IASA underwent posterior internal sphincter myectomy. All patients present ed with severe constipation with or without soiling. The diagnosis of IASA was made by anorectal manometry. HD was excluded in these cases by the pres ence of ganglion cells and normal acetylcholinesterase activity on suction rectal biopsies. Internal sphincter (IS) specimens were examined using immu nohistochemistry for the general neuronal marker PGP 9.5 and synapsin 1 (a presynaptic marker) and using general histochemistry for NADPH-diaphorase. All patients underwent follow-up for periods from 2 years to 6 years. Results: PGP 9.5, synapsin 1 and NADPH-diaphorase positive nerve fibers wer e either absent or markedly reduced in IASA specimens compared with control s, confirming previous reports of defective intramuscular innervation in IA SA. At the time of follow-up, 7 patients have regular bowel motions and are not on any laxatives. Six patients have normal bowel habits but are on sma ll doses of laxatives. One patient is able to stay clean with regular enema regimen. One patient required resection of dilated and redundant sigmoid c olon and now has normal bowel habits with laxatives. Conclusion: The majority of patients with internal anal sphincter achalasia can be treated successfully by internal sphincter myectomy. J Pediatr Surg 36:736-738. Copyright (C) 2001 by W.B. Saunders Company.