Outlet type constipation in adult patients treated with type A botulinum toxin: a cohort study.

Purpose: Chronic constipation is a common symptom. Constipation due to pelvic floor disorders remain a therapeutic challenge. Biofeedback therapy is considered as the first-choice treatment for pelvic floor disorders, whenever dedicated expertise is available. Type A botulinum toxin has been used to selectively weaken the external anal sphincter and puborectalis muscle in constipated patients.

Method: Eighty-two patients with chronic outlet obstruction constipation were treated with 100 units type A botulinum toxin, injected into the puborectalis muscle and the external anal sphincter.

Results: At the 2-month evaluation, a symptomatic improvement was noted in 69 patients. Seven (8.5%) patients had mild flatus incontinence. Stool frequency per week increased from 2.4 ± 0.9 to 5.1 ± 1.0 (P = 0.0001). Anorectal manometry demonstrated decreased tone during straining from 91 ± 28 mmHg to 61 ± 27 mmHg (P = 0.0001). Defecography after the treatment showed improvement in anorectal angle during straining, which increased from 96 ± 12° to 124 ± 14° (P = 0.0001).

Conclusion: Type A botulinum toxin relaxes the puborectalis muscle. Pressure values decline after the treatment. Transrectal ultrasonography to guide injections is a safe procedure. Repeated injections were needed to maintain the clinical improvement.