title: Rectoanal reflexes and sensorimotor response in rectal hyposensitivity.
abstract: OBJECTIVE
  Rectal hyposensitivity commonly causes anorectal disorders, but its underlying mechanism is unknown. We hypothesized that subjects with rectal hyposensitivity have altered rectoanal reflexes and/or sensorimotor response.
  
  
  METHODS
  We performed stepwise graded balloon distensions of the rectum in 30 subjects with constipation and rectal hyposensitivity and in 23 healthy controls. Thresholds for first sensation, desire, and urgency to defecate were assessed. The lowest balloon volume that evoked rectoanal inhibitory reflex, rectoanal contractile reflex, and sensorimotor response and manometric characteristics and rectal compliance were examined.
  
  
  RESULTS
  Reflex responses were present in all subjects. The balloon volumes were higher in subjects with rectal hyposensitivity for inducing rectoanal inhibitory reflex (P = .008) and contractile reflex (P = .001) compared with controls. All controls showed a sensorimotor response, but in 13 hyposensitive subjects (43%) the onset of sensorimotor response was associated with absent sensation and in 17 (57%), with a transient rectal sensation. Thresholds for eliciting sensorimotor response were similar between patients and controls, but the amplitude, duration, and magnitude of response were higher (P < .05) in patients. Rectal compliance was similar between controls and hyposensitive subjects with transient sensation but higher (P = .001) in subjects with absent sensation.
  
  
  CONCLUSIONS
  Constipated subjects with rectal hyposensitivity demonstrate higher thresholds for inducing rectoanal reflexes and abnormal characteristics of sensorimotor response. These findings suggest either disruption of afferent gut-brain pathways or rectal wall dysfunction. These altered features may play a role in the pathogenesis of bowel dysfunction in rectal hyposensitivity.
authors.affiliation: Digestive Physiology and Motility Department, Medical-Biological Research Institute, Universidad Veracruzana, Veracruz, Mexico.
authors.forename: Jose M
authors.initials: JM
authors.lastname: Remes-Troche
authors.forename: Sherrie
authors.initials: S
authors.lastname: De-Ocampo
authors.forename: Jessica
authors.initials: J
authors.lastname: Valestin
authors.forename: Satish S C
authors.initials: SS
authors.lastname: Rao
mesh_terms: D000344:Afferent Pathways / Q000503:physiopathology*; D001003:Anal Canal / Q000294:innervation* / Q000503:physiopathology; D002404:Catheterization; D003187:Compliance; D003248:Constipation / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008365:Manometry; D008875:Middle Aged; D012002:Rectal Diseases / Q000503:physiopathology*; D012007:Rectum / Q000294:innervation* / Q000503:physiopathology; D012021:Reflex, Abnormal; D012677:Sensation / Q000502:physiology; D020886:Somatosensory Disorders / Q000175:diagnosis / Q000503:physiopathology*