title: An increased rectal maximum tolerable volume and long anal canal are associated with poor short-term response to biofeedback therapy for patients with anismus with decreased bowel frequency and normal colonic transit time.
abstract: OBJECTIVE
  Biofeedback is an effective therapy for a majority of patients with anismus. However, a significant proportion of patients still failed to respond to biofeedback, and little has been known about the factors that predict response to biofeedback. We evaluated the factors associated with poor response to biofeedback.
  
  
  METHODS
  Biofeedback therapy was offered to 45 patients with anismus with decreased bowel frequency (less than three times per week) and normal colonic transit time. Any differences in demographics, symptoms, and parameters of anorectal physiologic tests were sought between responders (in whom bowel frequency increased up to three times or more per week after biofeedback) and nonresponders (in whom bowel frequency remained less than three times per week).
  
  
  RESULTS
  Thirty-one patients (68.9 percent) responded to biofeedback and 14 patients (31.1 percent) did not. Anal canal length was longer in nonresponders than in responders (4.53 +/- 0.5 vs. 4.08 +/- 0.56 cm; P = 0.02), and rectal maximum tolerable volume was larger in nonresponders than in responders. (361 +/- 87 vs. 302 +/- 69 ml; P = 0.02). Anal canal length and rectal maximum tolerable volume showed significant differences between responders and nonresponders on multivariate analysis (P = 0.027 and P = 0.034, respectively).
  
  
  CONCLUSIONS
  This study showed that a long anal canal and increased rectal maximum tolerable volume are associated with poor short-term response to biofeedback for patients with anismus with decreased bowel frequency and normal colonic transit time.
authors.affiliation: Division of Gastroenterology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: P L
authors.initials: PL
authors.lastname: Rhee
authors.forename: M S
authors.initials: MS
authors.lastname: Choi
authors.forename: Y H
authors.initials: YH
authors.lastname: Kim
authors.forename: H J
authors.initials: HJ
authors.lastname: Son
authors.forename: J J
authors.initials: JJ
authors.lastname: Kim
authors.forename: K C
authors.initials: KC
authors.lastname: Koh
authors.forename: S W
authors.initials: SW
authors.lastname: Paik
authors.forename: J C
authors.initials: JC
authors.lastname: Rhee
authors.forename: K W
authors.initials: KW
authors.lastname: Choi
mesh_terms: D000328:Adult; D000368:Aged; D001003:Anal Canal / Q000033:anatomy & histology / Q000502:physiology*; D001676:Biofeedback, Psychology; D003248:Constipation / Q000209:etiology / Q000523:psychology / Q000628:therapy*; D003672:Defecation; D005260:Female; D005772:Gastrointestinal Transit / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012007:Rectum / Q000033:anatomy & histology / Q000502:physiology*; D016896:Treatment Outcome