Botulinum toxin type-A infiltration of the external anal sphincter to treat outlet constipation in motor incomplete spinal cord injury: pilot cohort study.

Background: Outlet constipation is a major problem in spinal cord injury (SCI) patients. We aimed to study the efficacy of external anal sphincter (EAS) infiltration with type-A botulinum toxin (BTX-A) in motor incomplete SCI patients with outlet constipation.

Methods: Double blind, randomized, placebo controlled, comparative study in 16 motor incomplete SCI subjects. Patients were randomly assigned toreceive100 UI of BTX-A ( = 9) or physiologic serum infiltration ( = 7) in the EAS under electromyographic guidance. Outcome measures included a questionnaire for clinical bowel function evaluation, colonic transit time and anorectal manometry. All assessments were done at baseline, 1 and 3 months after treatment.

Results: Fourteen patients completed the study. In the BTX-A group we observed an improvement of subjective perception of bowel function ( = 0.01), constipation ( = 0.02) and neurogenic bowel dysfunction score ( = 0.02). The anorectal manometry revealed are duction of EAS voluntary contraction pressure ( = 0.01). No changes were observed in the placebo group. No significant side effects were observed in none of the groups.

Conclusion: BTX-A infiltration of the EAS is a safe technique that in motor incomplete SCI, decreases the EAS contraction and the anal canal pressure during straining, and improves outlet constipation symptoms. Future studies in larger populations are needed.