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Botulinum toxin in the treatment of refractory constipation associated with anal sphincter hypertonicity: A pilot prospective study in Chinese children (CME paper)




Objective:  Idiopathic constipation in children can be difficult to manage with conventional therapies. The present study aimed to evaluate the efficacy of adjunctive botulinum toxin injection in children attending our regional centre with refractory idiopathic constipation associated with internal anal sphincter hypertonicity.

Methods:  Children suffering refractory constipation after a minimum of 3 months bowel training, dietary and laxative treatments were evaluated by anorectal manometry. Those with idiopathic anal sphincter hypertonicity (resting pressure > 60 mmHg with normal recto-anal reflex) were recruited for botulinum toxin injection. Pretreatment evaluation also included bowel-function score and the degree of megarectum as measured transpubically by ultrasound. Each child received 60 units of Botox® intrasphincterically under general anaesthesia. Follow-up evaluations were carried out at 6 weeks and 6 months.

Results:  Eleven Chinese children, mean age 6.1 years, underwent botulinum toxin treatment. The mean sphincter pressure decreased from 73 mmHg to 55 mmHg and the mean symptom score improved from 2.5 to 6.3 (P = 0.003, Wilcoxon signed rank-sum test). The mean rectal diameter decreased from 3.7 cm to 3.4 cm. Findings were sustained at 6 months with no treatment complications.

Conclusion:  Botulinum toxin intrasphincteric injection is a safe, non-invasive and effective adjunct to conventional therapies in managing children with refractory idiopathic constipation associated with sphincter hypertonicity. Timely definitive therapy to facilitate pain-free habitual defecation plays an important role in these children in their potty training, as demonstrated by the sustained ‘sphincterotomy’ effects outlasting the transient toxin paralysis.