title: Three-dimensional analysis of benign paroxysmal positional nystagmus in a patient with anterior semicircular canal variant.
abstract: OBJECTIVE
  To show the positional nystagmus in a patient who had suffered from benign paroxysmal positional vertigo (BPPV) that was thought to be caused by involvement of the anterior semicircular canal (ASCC) (A-BPPV).
  
  
  METHODS
  Retrospective case report.
  
  
  METHODS
  City hospital.
  
  
  METHODS
  The present study reports a rare case of A-BPPV in a 41-year-old woman.
  
  
  METHODS
  The patient is 41-year-old woman who developed a positional vertigo after playing volleyball on March 22, 2005 and consulted our hospital the next day. When left Dix-Hallpike maneuver was performed, she showed a positional nystagmus of which fast phase direction of the torsional component was clockwise while that of the vertical component was downward. We plotted the slow phase eye velocity of the positional nystagmus during the left Dix-Hallpike maneuver on three-dimensional coordinates that showed the axis of the positional nystagmus to be perpendicular to the plane of the right ASCC.
  
  
  CONCLUSIONS
  These results suggested that the patient was suffering from A-BPPV.
authors.affiliation: Department of Otolaryngology, Kansai-Rosai Hospital, Hyogo, and Department of Otolaryngology and Sensory Organ Surgery, Osaka University Graduate School of Medicine, Osaka, Japan. imaitakao@hotmail.com
authors.forename: Takao
authors.initials: T
authors.lastname: Imai
authors.forename: Noriaki
authors.initials: N
authors.lastname: Takeda
authors.forename: Mahito
authors.initials: M
authors.lastname: Ito
authors.forename: Koji
authors.initials: K
authors.lastname: Nakamae
authors.forename: Hideki
authors.initials: H
authors.lastname: Sakae
authors.forename: Hiromu
authors.initials: H
authors.lastname: Fujioka
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000328:Adult; D004584:Electronystagmography; D005133:Eye Movements; D005260:Female; D019416:Head Movements; D006801:Humans; D021621:Imaging, Three-Dimensional; D009759:Nystagmus, Pathologic / Q000175:diagnosis / Q000503:physiopathology*; D011187:Posture; D012189:Retrospective Studies; D012665:Semicircular Canals / Q000473:pathology* / Q000503:physiopathology; D014717:Vertigo / Q000503:physiopathology*; D014724:Vestibular Function Tests; D014743:Videotape Recording