title: Benign paroxysmal positional vertigo: concomitant involvement of different semicircular canals.
abstract: OBJECTIVE
  We evaluated the simultaneous ipsilateral or contralateral involvement of the posterior and lateral, anterior and lateral, or posterior and anterior semicircular canals in patients with benign paroxysmal positional vertigo (BPPV).
  
  
  METHODS
  The files of 2345 patients with BPPV were analyzed.
  
  
  RESULTS
  Single-canal BPPV occurred in 2310 cases (98.5%)--unilaterally in 2058 (89.1%) and bilaterally in 252 (10.9%). Multiple-canal BPPV occurred in 35 cases (1.5%). Of these 35 cases, there was simultaneous involvement of the posterior and lateral canals on the same side (23) or on opposite sides (9) in 32 cases (91.4%). Simultaneous involvement of the anterior canal on one side and the posterior canal on the opposite side occurred in 2 cases (5.7%), and that of the anterior canal on one side and the lateral canal on the opposite side occurred in 1 case (2.9%). All cases represented canalithiasis.
  
  
  CONCLUSIONS
  Multiple-canal BPPV was rare, and usually involved canals on the same side; simultaneous involvement of the posterior and lateral canals was much more common than involvement of the anterior and posterior canals or the anterior and lateral canals. Trauma increased the risk for multiple-canal BPPV, but not the risk for bilateral single-canal BPPV. Cupulolithiasis was not a factor in multiple-canal BPPV.
authors.affiliation: Department of Human Communication Disorders, Federal University of São Paulo, Brazil.
authors.forename: Andreza
authors.initials: A
authors.lastname: Tomaz
authors.forename: Maurício Malavasi
authors.initials: MM
authors.lastname: Ganança
authors.forename: Cristina Freitas
authors.initials: CF
authors.lastname: Ganança
authors.forename: Fernando Freitas
authors.initials: FF
authors.lastname: Ganança
authors.forename: Heloisa Helena
authors.initials: HH
authors.lastname: Caovilla
authors.forename: Lee
authors.initials: L
authors.lastname: Harker