Efficacy of anal botulinum toxin injection in children with functional constipation

Functional constipation (FC) is a common diagnosis in the pediatric age group. In addition to laxative regimens and behavioral interventions, some have reported the use of anal botulinum toxin (BTX) injections to treat FC, with limited data regarding its efficacy.

This is a retrospective, multicenter study including patients who received BTX for FC refractory to medical therapy. Demographic data, results of anorectal manometry, and BTX data (number of sessions, dose, and side effects) were collected. Patients were divided into three groups based on the indication for BTX: group 1 (FC with FI [fecal incontinence]), group 2 (FC without FI), and group 3 (FI alone). Response to therapy was assessed for whole cohort and for each group based on improvement in weekly frequency of BM (bowel movements) to 3 or more per week and/or resolution of FI. We also compared the response to therapy to the parental and provider report.

A total of 63 patients were included in the study. Median age was 6.4 years and 32 (51%) were female. The median dose of BTX was 100 units, and most patients (55/63) received a single BTX injection. Medical therapy was continued after BTX injections in most patients (60/63 or 95%). After BTX, the frequency of BM increased to >3/week in 29/56 (52%) and FI improved in 8/47 (17%) for the whole cohort. We observed a response rate of 10% in group 1, 50% in group 2 and 14% in group 3. No factors (age, gender, anal resting pressure) were associated with BTX response except for prolonged time of therapy before BTX and shorter median follow up after BTX. Parents/primary provider reported improvement in 44/63 (70%) after BTX, which was significantly higher than the actual observed response to therapy (70% vs. 21%, p = 0.003, kappa = 0.202). We found no association between response to BTX and presence of developmental delay and/or behavioral disorders (p = 0.531). Side effects were minimal and noted in seven (11%) patients, mainly FI. No factors were associated with the development of side effects.

Anal BTX injections improved BM frequency with minimal effect on FI with an overall symptom resolution in 21% of patients. BTX does not seem to have a notable effect in patients with FC and developmental delay and/or behavioral disorders. Provider and parental reported success were significantly higher than the actual observed response.