The Value of Botox for Defecation Dysfunction


In patients who failed to respond to biofeedback therapy alone for anismus, authors in this study reported a beneficial, although temporary, effect of using botulinum toxin type A injection (BTX-A injection) to the puborectalis and external sphincter muscles. Anismus is more commonly referred to as dyssynergic defecation, or an inability to properly lengthen the pelvic floor muscles during emptying of the bowels. 31 patients who had been treated with and failed "simple biofeedback training" were then treated with BTX-A injection followed by biofeedback training. 18 males and 13 females with a mean age of 50 and a mean duration of constipation of 5.6 years were diagnosed with defecation dysfunction, or anismus. Diagnosis of animus was made using anorectal manometry, balloon expulsion test, surface electromyography (EMG) of the pelvic floor, and defecography.

Pelvic floor muscle training included biofeedback therapy consisting of intra-anal surface EMG and electrotherapy (although the way the methods are described make determining if both EMG and electrotherapy were completed with internal sensors difficult). Treatment occurred 1-2 times/day for 30 minutes per session (15 minutes of electrotherapy and 15 minutes of biofeedback). Frequency of the electrotherapy was 10 Mz, 10 seconds of "considerable sensation without…pain" and 10 seconds of rest. During biofeedback sessions, pelvic muscle strengthening and relaxation was also instructed. Therapy occurred for up to one month, and patients were instructed to continue with therapeutic exercises at home. The researchers followed up one month after the injection and therapy, and 6-12 months after intervention by telephone.

The subjects in this study suffered from difficult and incomplete evacuation, use of laxatives, and chronic straining during defecation. The repeated measures for diagnostic criteria that were completed after intervention found improvements in the subjects' resting anal canal pressures and with the balloon expulsion test and constipation scoring system. The authors also reported adverse effects of BTX-A injections including fecal incontinence. Conclusions of the article include that the botox injections were considered a temporary treatment for defecation dysfunction, whereas the botox injection combined with pelvic floor biofeedback training is "a more valid way to treat."

What is missing from this study? Manual therapy, muscle coordination retraining in combination with abdominal wall activation, and functional training related to positioning. While the authors suggest that injections should be used with biofeedback training, the potential negative effects of botox injections cannot be overlooked. Infection, pain, and bleeding are complications that have been highlighted in the literature, and in this study, fecal incontinence (although reported as mild) occurred. The research design appears to fail to recognize the chronic tension and holding pattern of the pelvic floor muscles, and unless the goal of repeated contractions is to elicit a contract/relax effect, the pelvic floor strengthening per se does not align with the ideal therapeutic goal, which should be to correct the dyssynergic pattern of defecation. Relaxing the pelvic floor muscles is not the same as a functional bearing down or lengthening of the pelvic floor involved in defecation. If you are interested in learning more about training defecation patterns and pelvic muscle rehabilitation for bowel dysfunction, check out Pelvic Floor Level 2A (PF2A) which discusses in detail fecal incontinence, constipation, and other colorectal conditions. The next opportunity to take this course is in Wisconsin in March. If you have already taken PF2A, you might find a course focused on Bowel Pathology, Function, Dysfunction & the Pelvic Floor, with the next course taking place in Kansas City in April.

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