title: Mechanisms of esophago-pharyngeal acid regurgitation in human subjects.
abstract: Esophago-pharyngeal regurgitation is implicated in various otolaryngologic and respiratory disorders. The pathophysiological mechanisms causing regurgitation are still largely unknown.
  
  
  OBJECTIVE
  To determine the principal mechanisms behind esophago-pharyngeal regurgitation.
  
  
  METHODS
  We studied 11 patients with extra-esophageal GORD symptoms in whom esophago-pharyngeal acid regurgitation had previously been demonstrated using ambulatory, dual (pharyngo-esophageal) pH metry (>2 episodes/day using previously validated pH-metric criteria). Patients underwent continuous, 24 hr, stationary monitoring of pharyngo-esophageal manometry and dual (pharyngeal and esophageal) pH recordings. They were intubated with a 14-channel manometric assembly incorporating 2 sleeve sensors monitoring the upper and lower esophageal sphincters simultaneously. A dual pH catheter recorded pH signals 2 cm above the UES midpoint and 7 cm above the LES midpoint.
  
  
  RESULTS
  A total of 32 episodes of spontaneous esophago-pharyngeal acid regurgitation were recorded. All episodes occurred in the upright posture and 91% occurred within 3 hrs post-prandium. All regurgitation events were associated with a relaxation of the UES, which were classified as transient non-swallow related relaxations in 29 (91%) and swallow-related in the remaining 3 (9%). Straining was an additional associated factor in 41% of regurgitation events, but strain alone was not sufficient to cause esophago-pharyngeal regurgitation.
  
  
  CONCLUSIONS
  Some form of active UES relaxation is necessary for regurgitation to occur. The dominant mechanism underlying esophago-pharyngeal acid regurgitation is the non-swallow related, transient UES relaxation.
  
  
  METHODS
  N/A.
authors.affiliation: Department of Gastroenterology, University of New South Wales and St George Hospital, Sydney, New South Wales, Australia. m.szczesniak@unsw.edu.au
authors.forename: Michal Marcin
authors.initials: MM
authors.lastname: Szczesniak
authors.forename: Rohan Benjamin
authors.initials: RB
authors.lastname: Williams
authors.forename: Ian James
authors.initials: IJ
authors.lastname: Cook
mesh_terms: D000328:Adult; D000368:Aged; D049631:Esophageal Sphincter, Upper / Q000503:physiopathology; D004947:Esophagus / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057045:Laryngopharyngeal Reflux / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009126:Muscle Relaxation; D011312:Pressure