title: Physiological study of the anorectal reflex in patients with functional anorectal and defecation disorders.
abstract: OBJECTIVE
  Fecal incontinence (FI) and constipation can arise from a variety of alterations of anorectal function. This study aimed to investigate the components of the anorecal reflex in patients with these symptoms and to determine the functional significance of various physiological parameters.
  
  
  METHODS
  Altogether 21 healthy volunteers (controls) and 78 FI-predominant and 74 constipation-predominant patients were recruited and administered Wexner incontinence and constipation questionnaires. All participants underwent standardized anorectal physiology assessments.
  
  
  RESULTS
  Patients with passive FI had lower resting sphincter pressures than controls (38 cmH2O vs 87 cmH2O, P  < 0.05), while those with urge FI had lower squeeze pressures than controls (37 cmH2O vs 119 cmH2O, P  < 0.05). Patients with urge FI had lower maximal tolerable volumes (100 mL vs 166 mL, P  < 0.05). Patients with slow-transit constipation had elevated rectal electrosensitivity thresholds compared with controls (31.4 mA vs 20.2 mA, P  < 0.05), and rectal mucosal blood flow than patients with evacuation difficulty and controls (107 vs 162 flux units (FU) [evacuation difficulty] vs 169 FU [controls], P  < 0.05). Only patients with passive FI were associated with reflex abnormalities (prolonged recovery phase (1.2 ms vs 0.5 ms, P  < 0.05) and total duration of reflex (6.3 ms vs 4.3 ms, P  < 0.05).
  
  
  CONCLUSIONS
  Anorectal motor, sensory and reflex abnormalities are seen in distinct patterns in patients with FI and constipation. This would suggest distinct physiological differences that may predict the potential for different neuromodulation treatment and behavioral modalities in these conditions.
authors.affiliation: Department of Colorectal Surgery, Royal Berkshire Hospital, Reading, UK.|Gastrointestinal Physiology Unit, Department of Gastroenterology, University College Hospital, London, UK.
authors.forename: Kumaran
authors.initials: K
authors.lastname: Thiruppathy
authors.affiliation: Department of Colorectal Surgery, Royal Berkshire Hospital, Reading, UK.
authors.forename: John
authors.identifier: http://orcid.org/0000-0002-4838-8724
authors.initials: J
authors.lastname: Mason
authors.affiliation: Department of Colorectal Surgery, Royal Berkshire Hospital, Reading, UK.
authors.forename: Khalid
authors.initials: K
authors.lastname: Akbari
authors.affiliation: Gastrointestinal Physiology Unit, Department of Gastroenterology, University College Hospital, London, UK.
authors.forename: Amanda
authors.initials: A
authors.lastname: Raeburn
authors.affiliation: Gastrointestinal Physiology Unit, Department of Gastroenterology, University College Hospital, London, UK.
authors.forename: Anton
authors.initials: A
authors.lastname: Emmanuel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001003:Anal Canal / Q000503:physiopathology; D016022:Case-Control Studies; D003248:Constipation / Q000503:physiopathology*; D004558:Electric Stimulation / Q000379:methods; D005242:Fecal Incontinence / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods; D008875:Middle Aged; D011446:Prospective Studies; D012007:Rectum / Q000503:physiopathology*; D012018:Reflex / Q000502:physiology*; D012677:Sensation; D055815:Young Adult
keywords: anorectal physiology; constipation; fecal incontinence; rectoanal inhibitory reflex