title: Benign paroxysmal positional vertigo can interfere with the cardiac response to head-down tilt.
abstract: OBJECTIVE
  To assess the pulse rate and the respiratory rate responses to head-down tilt of the whole body in the plane of the posterior canals in healthy subjects and in patients with benign paroxysmal positional vertigo (BPPV).
  
  
  BACKGROUND
  Although BPPV attacks are usually accompanied by autonomic symptoms, there are no studies assessing autonomic responses during triggering maneuvers for BPPV, neither in healthy subjects nor in patients.
  
  
  METHODS
  We evaluated nine healthy subjects and four BPPV patients (3 unilateral and 1 bilateral). Using a two-axis rotator, from an upright position they were rotated 135 degrees backwards to head-down tilt, either in the plane of the right or the left posterior canal.
  
  
  RESULTS
  In healthy subjects, head-down tilt always induced a significant decrease of the pulse rate, which was similar after rotation to the right and to the left posterior canals. This response was observed in patients with unilateral BPPV only when they were rotated toward the nonaffected side, and it was not evident when they were rotated toward the affected side (p < 0.025). In the patient with bilateral BPPV, no change of the pulse rate was observed after rotation toward the right or to the left posterior canal. Although, in all the patients, the respiratory rate increased during the tilt, a similar increase was observed in two healthy subjects.
  
  
  CONCLUSIONS
  After rotation in the plane of the affected semicircular canal, BPPV can interfere with the cardiac response to head-down tilt of the whole body.
authors.affiliation: Unidad de Investigación Médica HG CMN La Raza, Instituto Mexicano del Seguro Social, México City, México. kjauren@data.net.mx
authors.forename: Kathrine
authors.initials: K
authors.lastname: Jáuregui-Renaud
authors.forename: Swee T
authors.initials: ST
authors.lastname: Aw
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Todd
authors.forename: Leigh A
authors.initials: LA
authors.lastname: McGarvie
authors.forename: G Michael
authors.initials: GM
authors.lastname: Halmagyi
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D018475:Head-Down Tilt; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture; D011674:Pulse; D015656:Respiratory Mechanics; D012399:Rotation; D012665:Semicircular Canals / Q000503:physiopathology; D014717:Vertigo / Q000209:etiology* / Q000503:physiopathology*