title: A single therapy for all subtypes of horizontal canal positional vertigo.
abstract: OBJECTIVE
  To demonstrate that a single therapy is effective for treating all subtypes of horizontal canal benign paroxysmal positional vertigo (HC-BPPV).
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Patients with HC-BPPV (n = 89) were diagnosed when the supine to the head-lateral test resulted in geotropic or ageotropic bilateral horizontal nystagmus. Three subtypes of HC-BPPV were defined by their characteristic patterns of nystagmus as well as by their speculative mechanism. Canalolithiasis (Can) denotes geotropic nystagmus induced by free-moving otoliths in the HC. Two forms of cupulolithiasis, characterized by otoliths attached either on the utricle-sided (Cup-U) or the canal-sided (Cup-C) cupula, were identified by whether ageotropic nystagmus resolved or changed to geotropic nystagmus on follow-up tests. Forced prolonged position (FPP), lying on the healthy side for 12 hours to easily move free otoliths to the utricle, has proven successful in treating Can. Although Cup-U and contralateral Cup-C were associated with the same positional nystagmus pattern, FPP with lying on the side of the weaker nystagmus was found to be effective treatment, as well as consistent with the speculated underlying mechanism.
  
  
  RESULTS
  All HC-BPPV patients including 49 with Can, 11 with Cup-C and 29 with Cup-U had complete resolution of symptoms and positional nystagmus after less than four treatment sessions.
  
  
  CONCLUSIONS
  FPP with lying on the side of the weaker nystagmus, combined with careful observation of nystagmus evolvement, was found to be effective treatment for all subtypes of HC-BPPV in this series.
authors.affiliation: Department of Otolaryngology, Songshan Armed Forces Hospital, National Defense Medical Center, No. 48, Lane 155, Kuang Fu North Road, Taipei, Taiwan, ROC. chiou.wy@msa.hinet.net
authors.forename: Wen-Yaw
authors.initials: WY
authors.lastname: Chiou
authors.forename: Hui-Ling
authors.initials: HL
authors.lastname: Lee
authors.forename: Shih-Che
authors.initials: SC
authors.lastname: Tsai
authors.forename: Tu-Hsueh
authors.initials: TH
authors.lastname: Yu
authors.forename: Xin-Xian
authors.initials: XX
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004584:Electronystagmography; D005260:Female; D005500:Follow-Up Studies; D019416:Head Movements; D006801:Humans; D008297:Male; D008875:Middle Aged; D009759:Nystagmus, Pathologic / Q000175:diagnosis / Q000628:therapy*; D010036:Otolaryngology / Q000379:methods*; D011446:Prospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014717:Vertigo / Q000175:diagnosis* / Q000628:therapy*