title: Alteration of the spinal modulation of nociceptive processing in patients with irritable bowel syndrome.
abstract: BACKGROUND
  Visceral hypersensitivity has been evidenced in patients with irritable bowel syndrome (IBS) but its mechanisms remain poorly elucidated. We investigated the spinal transmission of nociceptive signals in IBS patients by analysing the effects of rectal distensions on electromyographic recordings of the somatic nociceptive flexion (RIII) reflex, an objective index of spinal nociceptive processes.
  
  
  METHODS
  Fourteen IBS and 10 healthy volunteers were included in the study. Slow ramp (40 ml/min) and rapid phasic (900 ml/min, 10, 20, 30, and 40 mm Hg) rectal distensions were randomly performed while the RIII reflex evoked by electrical stimulation of the sural nerve at the ankle was continuously recorded from the ipsilateral biceps femoris.
  
  
  RESULTS
  In healthy volunteers, significant progressive inhibition of the RIII reflex was observed during slow ramp distension (61 (13)% of control values) while biphasic effects (facilitation and inhibition) were observed during rapid distensions. In contrast, in IBS patients, the RIII reflex was significantly facilitated during slow ramp distension (139 (15)% of control values) and inhibitions induced by rapid distensions were significantly reduced. Volumes of distension and rectal compliance were similar in both groups.
  
  
  CONCLUSIONS
  Our results provide direct evidence that a hyperexcitability of spinal nociceptive processes is present in a large subgroup of IBS patients.
authors.affiliation: Service d'Hépato-Gastroentérologie, Hôpital Louis Mourier, 178 rue des Renouillers, 92701 Colombes Cedex, France. benoit.coffin@lmr.ap-hop-paris.fr
authors.forename: B
authors.initials: B
authors.lastname: Coffin
authors.forename: D
authors.initials: D
authors.lastname: Bouhassira
authors.forename: J-M
authors.initials: JM
authors.lastname: Sabaté
authors.forename: L
authors.initials: L
authors.lastname: Barbe
authors.forename: R
authors.initials: R
authors.lastname: Jian
mesh_terms: D000328:Adult; D000368:Aged; D004106:Dilatation; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009619:Nociceptors / Q000502:physiology*; D010147:Pain Measurement; D012007:Rectum / Q000294:innervation*; D012018:Reflex; D012677:Sensation; D013116:Spinal Cord / Q000503:physiopathology*; D013497:Sural Nerve / Q000503:physiopathology