title: Excellent response rate of anismus to botulinum toxin if rectal prolapse misdiagnosed as anismus ('pseudoanismus') is excluded.
abstract: OBJECTIVE
  Anismus causes obstructed defecation as a result of inappropriate contraction of the puborectalis/external sphincter. Proctographic failure to empty after 30 s is used as a simple surrogate for simultaneous electromyography/proctography. Botulinum toxin is theoretically attractive but efficacy is variable. We aimed to evaluate the efficacy of botulinum toxin to treat obstructed defecation caused by anismus.
  
  
  METHODS
  Botulinum toxin was administered, under local anaesthetic, into the puborectalis/external sphincter of patients with proctographic anismus. Responders (resolution followed by recurrence of obstructed defecation over a 1- to 2-month period) underwent repeat injection. Nonresponders underwent rectal examination under anaesthetic (EUA). EUA-diagnosed rectal prolapse was graded using the Oxford Prolapse Grade 1-5.
  
  
  RESULTS
  Fifty-six patients were treated with botulinum toxin. Twenty-two (39%) responded initially and 21/22 (95%) underwent repeat treatment. At a median follow up of 19.2 (range, 7.0-30.4) months, 20/21 (95%) had a sustained response and required no further treatment. Isolated obstructed defecation symptoms (OR = 7.8, P = 0.008), but not proctographic or physiological factors, predicted response on logistic regression analysis. In 33 (97%) of 34 nonresponders, significant abnormalities were demonstrated at EUA: 31 (94%) had a grade 3-5 rectal prolapse, one had internal anal sphincter myopathy and one had a fissure. Exclusion of these alternative diagnoses revised the initial response rate to 96%.
  
  
  CONCLUSIONS
  Simple proctographic criteria overdiagnose anismus and underdiagnose rectal prolapse. This explains the published variable response to botulinum toxin. Failure to respond should prompt EUA seeking undiagnosed rectal prolapse. A response to an initial dose of botulinum toxin might be considered a more reliable diagnosis of anismus than proctography.
authors.affiliation: Oxford Pelvic Floor Centre, Department of Colorectal Surgery, Churchill Hospital, Oxford, UK.
authors.forename: R
authors.initials: R
authors.lastname: Hompes
authors.forename: C
authors.initials: C
authors.lastname: Harmston
authors.forename: N
authors.initials: N
authors.lastname: Wijffels
authors.forename: O M
authors.initials: OM
authors.lastname: Jones
authors.forename: C
authors.initials: C
authors.lastname: Cunningham
authors.forename: I
authors.initials: I
authors.lastname: Lindsey
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000503:physiopathology; D001004:Anus Diseases / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000503:physiopathology; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use*; D003672:Defecation; D019841:Defecography; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008365:Manometry; D008875:Middle Aged; D015999:Multivariate Analysis; D009119:Muscle Contraction; D009465:Neuromuscular Agents / Q000627:therapeutic use*; D016016:Proportional Hazards Models; D012005:Rectal Prolapse / Q000175:diagnosis*; D012008:Recurrence
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A