title: Effect of different swallow time intervals on the nutcracker esophagus.
abstract: OBJECTIVE
  Nutcracker esophagus (NE) is defined as the presence of peristaltic contractions in which the average distal esophageal amplitude is greater than 180 mm Hg. The underlying mechanism responsible for these abnormalities is not known. The aim of this study was to test the hypothesis that NE might be caused by a defect in the inhibitory pathway controlling esophageal peristalsis.
  
  
  METHODS
  Eight patients with NE (seven women, 1 man, mean age 50 yr) and eight age- and sex-matched normal volunteers (seven women, 1 man, mean age 48 yr) underwent a special protocol using three-channel (3, 8, and 16 cm above the lower esophageal sphincter) solid state esophageal manometry to evaluate deglutitive inhibition. Ten pairs of 5 ml of wet swallows were given at each of five different time intervals (30, 20, 15, 10, and 5 s). Pairs of swallows were spaced by 30 s, and different time intervals were spaced by 1 min. Tracings were recorded using a computer program and blindly automatically analyzed for both amplitude and duration of the contraction separately for the first and second swallow of each pair. Presence of deglutitive inhibition or muscle refractoriness was assessed according to interactions between the first and second swallow of the pair. Results were found abnormal when larger than the mean percent variation of the second and first swallow calculated for the 30-s interval, considered as baseline for each participant. Statistics included paired and nonpaired nonparametrical comparisons as appropriate.
  
  
  RESULTS
  The median amplitude for the NE was 202 mm Hg (range 186-376) and for the controls was 118 mm Hg (range 64-167) (p = 0.0002). The median duration in the NE group was 5.1 s (range 4-9.3) versus 4.1 (range 3.3-5.0) for the controls (p = 0.02). The percent variation in duration (p = 0.31), amplitude (p = 0.42), and propagation velocity of the peristaltic waves (p = 0.69) did not differ between the control and NE groups. Peristalsis frequency dropped at the 5-s interval for both studied groups (p = 0.84).
  
  
  CONCLUSIONS
  Central and local inhibitory mechanisms induced by closely timed swallows are preserved in the NE and do not explain the mechanism of the high amplitude and long duration contractions.
authors.affiliation: Department of Medicine, Graduate Hospital, Philadelphia, Pennsylvania, USA.
authors.forename: Eliza Maria
authors.initials: EM
authors.lastname: Brito
authors.forename: Luciana
authors.initials: L
authors.lastname: Camacho-Lobato
authors.forename: Vera
authors.initials: V
authors.lastname: Paoletti
authors.forename: Mathew
authors.initials: M
authors.lastname: Gideon
authors.forename: Philip O
authors.initials: PO
authors.lastname: Katz
authors.forename: Donald O
authors.initials: DO
authors.lastname: Castell
mesh_terms: D000328:Adult; D000368:Aged; D003679:Deglutition; D015154:Esophageal Motility Disorders / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008365:Manometry; D008875:Middle Aged; D010528:Peristalsis; D013997:Time Factors