Clinical trial: effects of botulinum toxin on Levator ani syndrome--a double-blind, placebo-controlled study

Abstract

Background: Levator ani syndrome is characterized by anorectal discomfort/pain, treatment of which is unsatisfactory. We hypothesized that Botulinum toxin relieves spasm and improves symptoms.

Aim: To perform a randomized, placebo-controlled, crossover study to examine the efficacy and safety of botulinum toxin in patients with levator ani syndrome.

Methods: Twelve patients with levator ani syndrome (>or=1 year) received anal intra sphincteric injections of 100 units of botulinum toxin A and placebo at 90-day intervals using EMG guidance. Daily frequency, severity, duration and intensity of pain (VAS) were recorded. Anorectal manometry, balloon expulsion and pudendal nerve latency tests were performed to examine the physiological changes and adverse effects.

Results: Seven patients (male/female = 4/3) completed the study and three had incomplete data, but all 10 underwent in an ITT analysis; two others dropped out. After administration of botulinum toxin, the mean frequency, intensity and duration of pain were unchanged (P = 0.31) compared with baseline. The 90-day mean VAS pain score was 6.79 +/- 0.27 vs. baseline score of 7.08 +/- 0.29 (P = 0.25). Anal sphincter pressures, rectal sensory thresholds, pudendal nerve latency and balloon expulsion times were unchanged after drug or placebo administration.

Conclusions: Injection of botulinum toxin into anal sphincter is safe, but it does not improve anorectal pain in levator ani syndrome.

Figures

Figure 1

This figure describes the set up and methods used for botulinum toxin injection into the anal sphincter. A special EMG needle was attached to a metal needle extender and connected to a syringe containing botulinum toxin via a 3 way stop cock. The needle was also connected via an electrode to a neurophysiology recorder (Cadwell Sierra II Wedge) and the EMG signals were displayed on a monitor.

Figure 2

Weekly total pain scores at baseline and during each 8 week period following injection. (Mean ± SE).

Figure 3

The effects of botulinum toxin or placebo on anorectal pain intensity score (VAS), at baseline, and at 7 and 90 days following each injection. Mean ± SEM.