Long-term Outcome of Internal Sphincter Myectomy in Patients with Internal Anal Sphincter Achalasia

Background: Internal anal sphincter achalasia (IASA) is a condition with presentation similar to Hirschsprung's disease (HD), but with the presence of ganglion cells on rectal suction biopsy (RSB). The diagnosis is made on anorectal manometry (ARM) by the absence of the rectosphincteric reflex on rectal balloon inflation. Internal sphincter myectomy (ISM) is the treatment of choice for patients with IASA. Recently, botulinum toxin has been used to treat IASA patients. The purpose of this study was to assess the long-term bowel function in patients with IASA following ISM.

Methods: The medical records of 24 patients with IASA managed by ISM during 1993-2005 were examined. There were 18 boys and 6 girls, aged 2-12 years. All patients presented with intractable constipation with or without soiling. The diagnosis was made by the demonstration of the absence of the rectosphincteric reflex on ARM. HD was excluded by the presence of ganglion cells and normal acetylcholinesterase activity in RSB. Patients were followed 4-14 years later.

Results: Fifteen (62.5%) patients at the time of follow-up had regular bowel motions without the use of laxatives. Six (25%) patients had regular bowel motions, but remained on small doses of laxatives. Two (8.3%) patients who suffered from constipation and soiling required twice weekly enemas to remain clean. One (4.2%) patient required resection of dilated rectosigmoid colon 3 years after myectomy, remains on laxatives, but has normal bowel control. No patients had faecal incontinence following ISM.

Conclusion: This long-term follow-up study shows that the vast majority of IASA patients have normal bowel control following ISM.