title: The esophageal multimodal pain model: normal values and degree of sensitization in healthy young male volunteers.
abstract: BACKGROUND
  Sensory changes are thought to be involved in gastro-esophageal reflux disease (GERD). The esophageal multimodal pain model can be used to investigate sensations in response to distension, heat, electric current and acid.
  
  
  OBJECTIVE
  The aim of this study was to provide normal values for this model in the normal state and in the acid induced sensitized state.
  
  
  METHODS
  Fifty-three healthy men (20-38 years old) underwent esophageal stimulation with distension, heat and electrical current before and after sensitization with 0.1 N HCl acid. Stimulus intensities at painful and non-painful thresholds and referred pain areas were measured. The percentage of individual participants sensitized to each modality was calculated. In 22 subjects the pre-acid tests were repeated on three subsequent visits.
  
  
  RESULTS
  To reach moderate pain, subjects tolerated mean distension of 29.1 ± 11 mL, heat stimulation time of 141 ± 33 s, and mean current of 17.6 ± 6.4 mA. After acid exposure, significantly reduced thresholds were observed for mechanical (24%), heat (11%) and electrical (14%) stimulation (P values < 0.05). The percentage of subjects sensitized, defined as reductions in thresholds of ≥10% or ≥20% after acid perfusion, was as follows: for distension 77%/62%, for heat 48%/28%, and for current 58%/44%. The model showed good reliability (intra-class correlations >0.6).
  
  
  CONCLUSIONS
  Normal values for healthy young men are now provided for the normal and the sensitized state. The percentage of subjects sensitized after acid stimulation are thoroughly documented, and depends on stimulation type and the cut-off value chosen.
authors.affiliation: Department of Gastroenterology, Aalborg Hospital, Aarhus University Hospital, Mølleparkvej 4, 9000, Aalborg, Denmark. annelundkrarup@gmail.com
authors.forename: Anne L
authors.initials: AL
authors.lastname: Krarup
authors.forename: Magnus
authors.initials: M
authors.lastname: Simrén
authors.forename: Peter
authors.initials: P
authors.lastname: Funch-Jensen
authors.forename: Mark B
authors.initials: MB
authors.lastname: Hansen
authors.forename: Frederik
authors.initials: F
authors.lastname: Hvid-Jensen
authors.forename: Jan
authors.initials: J
authors.lastname: Brun
authors.forename: Asbjørn M
authors.initials: AM
authors.lastname: Drewes
mesh_terms: D000328:Adult; D004560:Electricity; D004947:Esophagus / Q000503:physiopathology*; D005764:Gastroesophageal Reflux / Q000503:physiopathology; D006358:Hot Temperature; D006801:Humans; D006851:Hydrochloric Acid / Q000494:pharmacology; D008297:Male; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology*; D010147:Pain Measurement; D017288:Pain Threshold; D012016:Reference Values; D055815:Young Adult
chemical_list: D006851:Hydrochloric Acid