Initial North American experience with botulinum toxin type A for treatment of anismus

Botulinum toxin type A (BTX-A), produced by Clostridium botulinum, is a potent neurotoxin. The purpose of this study was to evaluate the efficacy of BTX-A for treatment of anismus.

All patients treated with BTX-A for anismus were evaluated. Eligibility criteria included a history of chronic assisted evacuation (laxatives, enemas, or suppositories), demonstration of anismus by cinedefecogram and electromyography, and failure of a minimum of three sessions of supervised biofeedback therapy (BF). Contingent on body mass, 6 to 15 units of BTX-A was injected bilaterally under electromyography guidance into the external sphincter or the puborectalis muscle. Treatment was repeated as necessary for a maximum of three sessions during a three-month period. Success was considered as discontinuation of evacuatory assistance and was evaluated between one and three months and again at up to one year.

Between July 1994 and May 1995, four patients ranging from 29 to 82 years in age (2 females, 2 males) had anismus that failed to respond to between 3 and 15 biofeedback sessions. All patients improved between one and three months after BTX-A injection, and two had sustained improvement for a range of three months to one year. There was no morbidity or mortality associated with BTX-A injection.

BTX-A is extremely successful for temporary treatment of anismus that is refractory to BF management. However, because the mechanism of action is short, longer term results are only 50 percent successful. Hopefully, modifications in the strain of BTX-A and dose administered will allow longer periods of success or a repeat trial of BF. Nonetheless, this preliminary report is very encouraging in offering a method of managing this recalcitrant condition.