Long-Term Clinical Outcome After Botulinum Toxin Injection in Children With Nonrelaxing Internal Anal Sphincter

OBJECTIVES: Children with surgically repaired Hirschsprung's disease (HD) and those with internal anal sphincter (IAS) achalasia may develop obstructive gastrointestinal symptoms and/or enterocolitis due to a functional obstruction caused by an inability of the IAS to relax. Anal sphincter Clostridium botulinum toxin (BoTox) injections may provide a reversible therapy. However, there is limited information regarding the long-term outcomes of children receiving this therapy. The primary aim of this study was to determine the long-term clinical outcomes of BoTox therapy in children with a nonrelaxing IAS. The secondary aim of this study was to determine prognostic factors predicting a favorable outcome following BoTox IAS injection. METHODS: We conducted a retrospective review of children with nonrelaxing IAS who received anal sphincter BoTox at a tertiary medical center. Children were classified into one of four long-term clinical outcome groups (excellent, good, fair, poor). RESULTS: A total of 73 children (30 HD, 43 IAS achalasia) received anal sphincter BoTox injections and had a mean follow-up of 32.1 +/- 2.9 (s.e.) months. A mean of 2.7 +/- 0.2 injections were given to each child, with 56 (76.7%) children receiving multiple injections. An initial clinical improvement was seen in 65 of 73 (89%) children after the first injection. A total of 39 (53.4%) children had an excellent or good long-term outcome that was maintained for a mean of 17.1 +/- 3.1 months from the time of the last BoTox injection. Hospitalization rates significantly decreased in those previously hospitalized before initial BoTox injection. Seven (9.5%) patients developed transient fecal incontinence, and one (1.3%) developed significant pain after an injection. Factors predicting a favorable long-term clinical outcome were initial short-term improvement after the first BoTox injection and having IAS achalasia rather than HD. CONCLUSIONS: Anal sphincter BoTox may be an effective and safe long-term therapy for children with nonrelaxing IAS.