Poor Outcome of Biofeedback Therapy in Anismus Patients with Increased Rectal Maximum Tolerable Volume

Choi, Moon Seok; Rhee, Poong Lyul; Son, Hee Jung; Kim, Jae Jun; Koh, Kwang Cheol; Paik, Seung Woon; Rhee, Jong Chul; Choi, Kyoo Wan; Chun, Ho Kyung

Abstract

BACKGROUND/AIMS: Biofeedback is the only successful treatment method for anismus, but little is known about factors to predict its effect. Rectal maximum tolerable volume (MTV) is increased in some patients with anismus, which reflects sustained rectal retention and subsequent reduction of rectal elasticity. We performed this study to investigate the difference in success rate of biofeedback according to rectal MTV status among the patients with anismus.
METHODS
Thirty patients with anismus were enrolled and classified into two groups according to rectal MTV status which was measured by rectal barostat. The group 1 revealed increased rectal MTV (>322 ml, n=16) and group 2 showed normal rectal MTV (< or =322, n=14). Electromyogram-based biofeedback was performed for 2 weeks, and stool frequency before and after therapy was compared.
RESULTS
Stool frequency (defecation episodes/week) was significantly increased after therapy from 1.81 +/-0.94 to 4.38 +/-2.72 in group1 (p<0.05) and from 1.74 +/-0.74 to 5.18 +/-1.95 in group 2 (p<0.05). Stool frequency was increased by 3 times/week after therapy (regarded as success) in 21 among 30 patients. Success rate of group 1 (50%) was significantly lower than that of group 2 (93%) (p<0.01).
CONCLUSIONS
The therapeutic efficacy of biofeedback was significantly lower in anismus patients with increased rectal MTV than in those with normal rectal MTV. Rectal MTV seems to be an important factor to predict the effec of biofeedback in patients with anismus.