title: What is the true incidence of horizontal semicircular canal benign paroxysmal positional vertigo?
abstract: OBJECTIVE
  To assess the correct incidence of horizontal semicircular canal (H-SCC) benign paroxysmal positional vertigo (BPPV).
  
  
  METHODS
  Retrospective assessment of patients with BPPV.
  
  
  METHODS
  All patients with BPPV were included and the rates of involvement of posterior, horizontal, and anterior SCCs were determined.
  
  
  RESULTS
  One hundred sixty-nine patients with the diagnosis of BPPV were evaluated. One hundred forty-four patients (85.2%) were found to have posterior SCC (P-SCC) involvement, and there were 20 patients (11.8%) with horizontal SCC (H-SCC) and 2 patients (1.2%) with anterior SCC (A-SCC) involvement. Three patients (1.8%) had simultaneous H-SCC and P-SCC BPPV ipsilaterally. Geotropic nystagmus was seen in 17 out of 23 patients (73.9%) in roll test, and ageotropic nystagmus was seen in the remaining 6 patients (26.1%).
  
  
  CONCLUSIONS
  H-SCC constitutes 13.6% of all BPPV cases. H-SCC BPPV with geotropic nystagmus is more common. H-SCC BPPV can coexist with ipsilateral P-SCC BPPV. However, in some cases of H-SCC BPPV, Dix-Hallpike maneuver can cause vertigo and horizontal nystagmus. This may be confused with P-SCC BPPV. Therefore, the roll test must be performed in all cases in addition to Dix-Hallpike maneuver and both ears must be evaluated with respect to all SCCs for BPPV.
  
  
  METHODS
  C-4.
authors.affiliation: Sisli Etfal Education and Research Hospital, I. Department of Otorhinolaryngology-Head and Neck Surgery, Kagithane, Istanbul, Turkey. burak_cakir@hotmail.com
authors.forename: Burak Omür
authors.initials: BO
authors.lastname: Cakir
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Ercan
authors.forename: Zeynep Alkan
authors.initials: ZA
authors.lastname: Cakir
authors.forename: Senol
authors.initials: S
authors.lastname: Civelek
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Sayin
authors.forename: Suat
authors.initials: S
authors.lastname: Turgut
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001301:Audiometry, Pure-Tone; D002150:Caloric Tests; D004584:Electronystagmography; D005133:Eye Movements / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009760:Nystagmus, Physiologic / Q000502:physiology; D011187:Posture; D012189:Retrospective Studies; D012399:Rotation; D012665:Semicircular Canals / Q000503:physiopathology*; D013997:Time Factors; D014717:Vertigo / Q000145:classification* / Q000503:physiopathology