PATTERNS OF ANISMUS AND THE RELATION TO BIOFEEDBACK THERAPY

PURPOSE: A study seas undertaken to assess physiologic characteristics and clinical significance of anismus. Specifically, we sought to asse ss patterns of anismus and the relation of these findings to the succe ss of therapy. METHODS: Sixty-eight patients were found to have anismu s based on history and diagnostic criteria including anismus by defeco graphy and at least one of three additional tests: anorectal manometry , electromyography, or colonic transit time study. Interpretation of d efecography was based on the consensus of at least three of four obser vers. Anal canal hypertonia (n = 32) was defined when mean and maximum resting pressures were at least 1 standard deviation higher than thos e in 63 controls. There were two distinct defecographic patterns of an ismus: Type A (n = 26), a flattened anorectal angle without definitive puborectalis indentation but a closed anal canal; Type B (n = 42), a clear puborectalis indentation, narrow anorectal angle, and closed ana l canal. Outcomes of 57 patients who had electromyography-based biofee dback therapy were reported as either improved or unimproved at a mean follow-up of 23.7 (range, 6-62) months. These two types of anismus we re compared with biofeedback outcome to assess clinical relevance, RES ULTS: Patients with Type A anismus showed greater perineal descent at rest (mean, 5.1 vs. 3.5 cm; P < 0.01), greater dynamic descent between rest and evacuation (mean, 2.7 vs. 1.4 cm; P < 0.01), greater differe nce of anorectal angle between rest and evacuation (mean, 14.6 vs. -3. 1 degrees; P < 0.001), higher mean resting pressure (mean, 77.1 vs. 62 .8 mmHg; P < 0.05), lower mean squeeze pressure (58.8 vs. 80.7 mmHg; P < 0.05), and a higher incidence of anal canal hypertonia (69.2 vs. 33 .3 percent; P < 0.01) than did patients with Type B anismus. Only 25 p ercent of patients who had Type A anismus with anal canal hypertonia w ere improved by biofeedback therapy. Conversely, 86 percent of patient s with Type B anismus without anal canal hypertonia were successfully treated with biofeedback (P < 0.001; Fisher's exact test). CONCLUSIONS : These two distinct physiologic patterns of anismus correlate with th e success of biofeedback treatment. Therefore, knowledge of these patt erns may help direct therapy.