title: Persistent spontaneous nystagmus following a canalith repositioning procedure in horizontal semicircular canal benign paroxysmal positional vertigo.
abstract: OBJECTIVE
  Nystagmus can occur spontaneously from multiple causes. Direction-changing positional nystagmus on the supine roll test is a characteristic clinical feature in horizontal semicircular canal benign paroxysmal positional vertigo. One of several mechanisms of spontaneous nystagmus is plugging of the otoconia, which has been described as a canalith jam.
  
  
  METHODS
  We evaluated a 52-year-old woman with a history of geotropic variant of horizontal semicircular canal benign paroxysmal positional vertigo on the right side who had been treated with a modified Lempert maneuver 3 months earlier. The patient had persistent spontaneous nystagmus, despite a positional change after the canalith repositioning procedure. A bithermal caloric test result demonstrated unilateral canal paresis on the right side. The following day, the patient's symptoms and nystagmus had subsided. On a repeated bithermal caloric test, a normal response was demonstrated on both sides.
  
  
  CONCLUSIONS
  To our knowledge, this is the first report of a case that shows on video persistent nystagmus findings consistent with a canalith jam. We discuss a possible mechanism underlying this phenomenon.
authors.affiliation: Department of Otorhinolaryngology, Myongji Hospital, Goyang, South Korea.
authors.forename: Kyung Min
authors.initials: KM
authors.lastname: Ko
authors.affiliation: Department of Otorhinolaryngology, Myongji Hospital, Goyang, South Korea.
authors.forename: Mee Hyun
authors.initials: MH
authors.lastname: Song
authors.affiliation: Department of Otorhinolaryngology, Myongji Hospital, Goyang, South Korea.
authors.forename: Ji Hong
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Otorhinolaryngology, Myongji Hospital, Goyang, South Korea.
authors.forename: Dae Bo
authors.initials: DB
authors.lastname: Shim
mesh_terms: D000328:Adult; D065635:Benign Paroxysmal Positional Vertigo; D004584:Electronystagmography; D005260:Female; D006801:Humans; D009759:Nystagmus, Pathologic / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D026741:Physical Therapy Modalities / Q000009:adverse effects*; D011187:Posture; D012665:Semicircular Canals / Q000503:physiopathology*; D014717:Vertigo / Q000503:physiopathology / Q000628:therapy*; D014724:Vestibular Function Tests