title: Central sensitization in patients with non-cardiac chest pain: a clinical experimental study.
abstract: OBJECTIVE
  Patients with non-cardiac chest pain (NNCP) suffer from unexplained and often intractable pain which can pose a major clinical problem. The aim of this study was to investigate nociceptive processing in NNCP patients and their response to experimentally acid-induced oesophageal hyperalgesia using a multimodal stimulation protocol.
  
  
  METHODS
  Ten highly selected patients with NCCP (mean age 43 years, 1 M) were compared with an age- and gender-matched group of 20 healthy subjects. After preconditioning, the distal oesophagus was painfully distended with a balloon using "impedance planimetry". This method assesses the luminal cross-sectional area of the oesophagus based on the electrical impedance of the fluid inside the balloon. The baseline distensions were done before and after pharmacological relaxation of the smooth muscle with 20 mg butylscopolamine. After baseline distensions, a series of up to 10 mechanical stimuli was performed (temporal summation). The stimulations were repeated after sensitization of the oesophagus induced by acid perfusion. The sensory intensities were assessed during the stimulations and the referred pain area was mapped.
  
  
  RESULTS
  At baseline distensions, no differences were seen between patients and controls before and after relaxation of the smooth muscles. The patients tolerated fewer repeated distensions than controls (4.8+/-0.5 versus 9.1+/-0.9; p=0.04) and had an increased size of the referred pain areas to the mechanical stimulations (32.9+/-6.2 versus 64.9+/-18.3 cm2; p=0.01). After sensitization with acid, the patients developed hyperalgesia (p<0.001), whereas no significant changes were seen in controls.
  
  
  CONCLUSIONS
  NCCP patients showed facilitated central pain mechanisms (temporal summation and visceral hyperalgesia after sensitization). This could be used in the diagnosis and understanding of the symptoms in these patients.
authors.affiliation: Centre for Visceral Biomechanics and Pain, Department of Gastroenterology, Aalborg Hospital, Aalborg, Denmark. drewes@smi.auc.dk
authors.forename: Asbjørn Mohr
authors.initials: AM
authors.lastname: Drewes
authors.forename: Jan
authors.initials: J
authors.lastname: Pedersen
authors.forename: Hariprasad
authors.initials: H
authors.lastname: Reddy
authors.forename: Klaus
authors.initials: K
authors.lastname: Rasmussen
authors.forename: Peter
authors.initials: P
authors.lastname: Funch-Jensen
authors.forename: Lars
authors.initials: L
authors.lastname: Arendt-Nielsen
authors.forename: Hans
authors.initials: H
authors.lastname: Gregersen
mesh_terms: D000143:Acids; D000328:Adult; D035843:Biomedical Research; D002086:Butylscopolammonium Bromide / Q000494:pharmacology; D016022:Case-Control Studies; D002404:Catheterization; D002490:Central Nervous System / Q000502:physiology*; D002637:Chest Pain / Q000139:chemically induced / Q000503:physiopathology*; D004947:Esophagus / Q000503:physiopathology; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D008954:Models, Biological; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009619:Nociceptors / Q000502:physiology; D010276:Parasympatholytics / Q000494:pharmacology; D010812:Physical Stimulation; D013268:Stimulation, Chemical
chemical_list: D000143:Acids; D010276:Parasympatholytics; D002086:Butylscopolammonium Bromide