title: Nystagmus discordance with 2-dimensional videonystagmography in posterior semicircular canal benign paroxysmal positional vertigo.
abstract: OBJECTIVE
  The Dix-Hallpike test is a standard component of the videonystagmography test battery and can diagnose posterior semicircular canal benign paroxysmal positional vertigo. The purpose of this study is to determine the prevalence of discordant, equivocal, and concordant nystagmus tracings in active posterior semicircular canal benign paroxysmal positional vertigo when compared directly with the eye video.
  
  
  METHODS
  Case series with chart review of patients diagnosed with posterior semicircular canal benign paroxysmal positional vertigo by 2-dimensional videonystagmography from August 1, 2007, to August 1, 2012.
  
  
  METHODS
  A tertiary vestibular test laboratory.
  
  
  METHODS
  Ninety-six adults (4 had bilateral involvement) with posterior semicircular canal benign paroxysmal positional vertigo were included. A total of 100 videos with accompanying videonystagmography tracings were reviewed to determine nystagmus trajectory as well as globe position. Descriptive statistics were used to describe prevalence. Fisher exact test was used to compare proportions.
  
  
  RESULTS
  Sixty-two percent of cases involved benign paroxysmal positional vertigo of the right posterior semicircular canal, while 38% involved the left posterior semicircular canal. The prevalence of discordant, equivocal, and concordant tracings was 65% (65/100), 29% (29/100), and 6% (6/100). All tracing errors involved the horizontal channel. There was no association between tracing accuracy and the ear of involvement or globe position (P > .05).
  
  
  CONCLUSIONS
  Two-dimensional videonystagmography tracings are not reliable for identifying nystagmus trajectory in posterior semicircular canal benign paroxysmal positional vertigo.
authors.affiliation: Division of Otology-Neurotology, Department of Otolaryngology- Head and Neck Surgery, University of Michigan Health System, Ann Arbor, Michigan, USA.
authors.forename: Crystal M
authors.initials: CM
authors.lastname: VanDerHeyden
authors.affiliation: Division of Otology-Neurotology, Department of Otolaryngology- Head and Neck Surgery, University of Michigan Health System, Ann Arbor, Michigan, USA.
authors.forename: Wendy J
authors.initials: WJ
authors.lastname: Carender
authors.affiliation: Division of Otology-Neurotology, Department of Otolaryngology- Head and Neck Surgery, University of Michigan Health System, Ann Arbor, Michigan, USA kheidenr@med.umich.edu.
authors.forename: Katherine D
authors.initials: KD
authors.lastname: Heidenreich
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D065635:Benign Paroxysmal Positional Vertigo / Q000150:complications / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009759:Nystagmus, Pathologic / Q000150:complications / Q000175:diagnosis*; D012665:Semicircular Canals; D014724:Vestibular Function Tests; D014741:Video Recording; D055815:Young Adult
keywords: benign paroxysmal positional vertigo; posterior semicircular canal; tracing; videonystagmography