title: Symptom perception in gastroesophageal reflux disease is dependent on spatiotemporal reflux characteristics.
abstract: OBJECTIVE
  The mechanisms responsible for the development of symptoms in gastroesophageal reflux disease (GERD) are poorly understood. The aims of this study were to identify differences in spatiotemporal reflux characteristics (proximal extent and duration of reflux episodes, ascending velocity of the refluxate) between symptomatic and asymptomatic reflux episodes and to assess the influence of different pH sensor positions on the yield of symptom analysis.
  
  
  METHODS
  Esophageal pH was measured for 24 hours at 3, 6, 9, 12, and 15 cm above the lower esophageal sphincter (LES) in 18 symptomatic patients with GERD, and spatiotemporal reflux characteristics were assessed for symptomatic and asymptomatic reflux episodes. Additionally, the symptom-association probability (SAP) was calculated for each esophageal level.
  
  
  RESULTS
  The median episode duration (at 3 cm above the LES) was longer and the proximal extent was higher in symptomatic than in asymptomatic reflux episodes (P = 0.006 and P = 0.01). The ascending velocity of the refluxate was not significantly different. The SAP decreased significantly (P < 0.05) from distal to proximal, but no significant differences were found between distal and proximal esophageal levels for the proportion of patients with positive (> 95%) SAP values.
  
  
  CONCLUSIONS
  The perception of reflux symptoms depends on the duration of acid-exposure episodes and on the proximal extent of the refluxate. Small changes in pH-sensor position do not significantly influence the yield of symptom analysis.
authors.affiliation: Department of Gastroenterology, University Hospital Utrecht, The Netherlands.
authors.forename: B L
authors.initials: BL
authors.lastname: Weusten
authors.forename: L M
authors.initials: LM
authors.lastname: Akkermans
authors.forename: G P
authors.initials: GP
authors.lastname: vanBerge-Henegouwen
authors.forename: A J
authors.initials: AJ
authors.lastname: Smout
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005764:Gastroesophageal Reflux / Q000503:physiopathology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D010465:Perception; D011336:Probability