Experience with type A botulinum toxin for treatment of outlet-type constipation

Puborectalis syndrome remains a therapeutic challenge for today's physicians. Traditional approaches include use of fiber, laxatives, enemas, biofeedback training, and surgery. These often were tried sequentially and had conflicting or even disappointing results. We investigated the efficacy of injections of botulinum toxin in improving rectal emptying in patients with defecatory disorders involving spastic pelvic-floor muscles.

Twenty-four consecutive patients with chronic outlet obstruction constipation resulting from puborectalis syndrome were included in the study. The patients were treated with 60 units of type A botulinum toxin, injected into two sites on either side of the puborectalis muscle under ultrasonographic guidance.

At 2 months, evaluation inspection revealed a symptomatic improvement in 19 patients. Anorectal manometry demonstrated decreased tone during straining from 98 +/- 24 to 56 +/- 20 mmHg at a 1-month evaluation (p < 0.01) and 56 +/- 29 mmHg at a 2-month follow-up (p < 0.01). Pressure during straining was lower than resting anal pressure at the same time in all patients. Defecography after the treatment showed improvement in anorectal angle during straining, which increased from 98 +/- 9 degrees to 121 +/- 15 degrees (p < 0.01).

Botulinum toxin injections should be considered as a simple therapeutic approach in patients with obstructed defecation. The treatment is safe and effective, especially with the use of the ultrasonographic guidance that accounts for a more precise injection and consequently better long-term results. Otherwise, given the limited effect of the toxin, repeated injections may be necessary to maintain the clinical improvement.