Botulinum toxin injection for childhood constipation is safe and can be effective regardless of anal sphincter dynamics.

[BACKGROUND] Childhood constipation is common. Previously, internal anal sphincterotomy has been used for hypertensive/non-relaxing sphincters; however, recent benefit has been shown with Botulinum Toxin (BT) injections. The aim is to investigate BT, including response duration, symptom association and effectiveness in relation to sphincter dynamics.

[METHODS] Retrospective study of 164 children receiving sphincter BT for severe constipation unresponsive to medication management. Charts reviewed for symptoms, anorectal manometry (ARM) findings and response defined by decreased pain or increased defecation. Patients were grouped: normal sphincter pressure (≤50 mmHg), elevated (>50 mmHg), normal and abnormal rectoanal inhibitory reflex (RAIR).

[RESULTS] There were 142 analyzed and 124 completed ARMs; 98 (70%) had positive response with 57% lasting greater than 6 months. 36 had normal sphincter pressure with 24 (69%) responding. 88 had elevated pressure with 60 (68%) responding (p=0.87). 90 normal RAIRs with 64 (71%) responding. 34 abnormal RAIRs with 22 (64%) responding (p=0.41). With logistic regression, fecal incontinence prior to BT was a predictor of poor response (p= 0.02). The most common side effect was fecal incontinence typically resolving within week with equal frequency regardless of sphincter dynamics.

[CONCLUSIONS] BT is effective for children with chronic constipation. Patients with fecal incontinence are less likely to respond. More than half had prolonged beneficial response. Those with normal and abnormal sphincter dynamics had similar responses and without differences in side effects. Therefore, injection may be considered in patients with intractable constipation unresponsive to medication, regardless of anal sphincter dynamics.

[LEVEL OF EVIDENCE] Level III (Treatment Study: Retrospective comparative study).