title: Intractable benign paroxysmal positioning vertigo: long-term follow-up and inner ear abnormality detected by three-dimensional magnetic resonance imaging.
abstract: OBJECTIVE
  To investigate the occurrence rate, prognosis, and inner ear abnormality in intractable benign paroxysmal positioning vertigo (BPPV).
  
  
  METHODS
  A prospective study.
  
  
  METHODS
  Tertiary referral university hospital.
  
  
  METHODS
  Intractable BPPV was defined in case of either a persistent nystagmus or a frequent relapse each lasting more than 1 year after the initial diagnosis.
  
  
  METHODS
  T2-weighted 3-dimensional fast imaging employing steady-state acquisition sequences of magnetic resonance imaging (MRI) were reconstructed 3-dimensionally for 13 intractable BPPV patients and 14 control volunteers.
  
  
  METHODS
  Transition and relapse of nystagmus were monitored. Semicircular canals were evaluated for a stenosis or filling defect (obturation).
  
  
  RESULTS
  Eighteen patients (4 with posterior canal type, 2 with horizontal canal type with geotropic nystagmus, and 12 with apogeotropic nystagmus) fulfilled the above criteria for intractability among 495 BPPV patients. The occurrence rate of intractable BPPV was 3.6%. Also, the rate of nystagmus transition was significantly higher in patients with geotropic nystagmus and the posterior canal type (100%) compared with those with apogeotropic nystagmus (33.3%). Of the 13 intractable BPPV patients who underwent MRI, 11 (84.6%) had a total of 23 canals with abnormal appearance (29.5%), showing a significantly higher incidence compared with controls. There was no correlation between the affected canal diagnosed by MRI and the type of nystagmus.
  
  
  CONCLUSIONS
  The low incidence of nystagmus transition in patients with apogeotropic nystagmus suggests a difference in pathophysiology between apogeotropic nystagmus and other types of BPPV. Stenosis and filling defect (obturation) of canals on MRI, which would indicate an innate narrowing and/or an otoconial jam of the semicircular canal, may account for the intractability of BPPV.
authors.affiliation: Department of Otolaryngology, Suita Municipal Hospital, Osaka University School of Medicine, Osaka, Japan. ahorii@ent.med.osaka-u.ac.jp
authors.forename: Arata
authors.initials: A
authors.lastname: Horii
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kitahara
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Osaki
authors.forename: Takao
authors.initials: T
authors.lastname: Imai
authors.forename: Kazuyasu
authors.initials: K
authors.lastname: Fukuda
authors.forename: Masafumi
authors.initials: M
authors.lastname: Sakagami
authors.forename: Hidenori
authors.initials: H
authors.lastname: Inohara
mesh_terms: D007758:Ear, Inner / Q000002:abnormalities / Q000473:pathology*; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008134:Long-Term Care; D008279:Magnetic Resonance Imaging; D009759:Nystagmus, Pathologic / Q000473:pathology; D011379:Prognosis; D012665:Semicircular Canals / Q000002:abnormalities / Q000473:pathology; D014717:Vertigo / Q000175:diagnosis* / Q000473:pathology