A prospective study of botulinum toxin for internal anal sphincter hypertonicity in children with Hirschsprung's disease

Background: Internal anal sphincter hypertonicity with non-relaxation can c ause persistent constipation and obstructive symptoms in children after sur gery for Hirschsprung's disease. Intractable symptoms traditionally have be en treated with anal myectomy, which may be ineffective or complicated by l ong-term incontinence. The authors evaluated prospectively the use of intra sphincteric botulinum toxin for these patients. Methods: Eighteen children were studied (age 1 to 13; median, 4 years). Bot ulinum toxin was injected (total dose 15 to 60 U) into 4 quadrants of the s phincter. Resting sphincter pressure was measured in 14 patients before and after injection. Ten have had 1 to 5 additional injections (total dose, 30 to 60 U per injection). Results: Four patients had no improvement in bowel function, 2 had improvem ent for less than 1 month, 7 had improvement for 1 to 6 months, and 5 had i mprovement more than 6 months. Nine of those with symptomatic improvement l onger than 1 month had pressures measured, with a documented decrease in 8. Five with no significant clinical improvement had pressure measurements, w ith a decrease in 3. There were no adverse effects associated with botulinu m toxin injection. Four children had new encopresis postinjection, which wa s mild and resolved in each case. Conclusions: Intrasphincteric botulinum toxin is a safe and less-invasive a lternative to myectomy for symptomatic internal sphincter hypertonicity. Pe rsistent symptoms, despite a fall in sphincter pressure, suggest a nonsphin cteric etiology. Repeat injections often are necessary for recurrent sympto ms. J Pediatr Surg 35:1733-1736. Copyright (C) 2000 by W.B. Saunders Compan y.