title: Sleep position and laterality of benign paroxysmal positional vertigo.
abstract: OBJECTIVE
  The aim of this study was to investigate the frequency of posterior semicircular canal benign paroxysmal positional vertigo in each ear, and to assess the association between the ear affected by benign paroxysmal positional vertigo and the head-lying side during sleep onset. Based on a previous study which used objective methods to prove the preference of the elderly for the right head-lying side during sleep, we hypothesised that a predominance of the same head-lying side in benign paroxysmal positional vertigo patients may affect the pathophysiology of otoconia displacement.
  
  
  METHODS
  We conducted a prospective study of out-patients with posterior semicircular canal benign paroxysmal positional vertigo, confirmed by a positive Dix-Hallpike test.
  
  
  METHODS
  One hundred and forty-two patients with posterior semicircular canal benign paroxysmal positional vertigo were interviewed about their past medical history, focusing on factors predisposing to benign paroxysmal positional vertigo. All patients included in the study were able to define a predominant, favourite head-lying side, right or left, during sleep onset.
  
  
  RESULTS
  The Dix-Hallpike test was found to be positive on the right side in 82 patients and positive on the left side in 54; six patients were found to be positive bilaterally. During sleep onset, 97 patients habitually laid their head on the right side and the remaining 45 laid their head on the left. The association between the affected ear and the head-lying side during sleep onset was statistically significant (p < 0.001).
  
  
  CONCLUSIONS
  Our study found a predominance of right-sided benign paroxysmal positional vertigo, a subjective preference amongst patients for a right head-lying position during sleep onset, and an association between the ear affected by benign paroxysmal positional vertigo and the preferred head-lying side during sleep onset. The clinical and therapeutical implications of this observation are discussed.
authors.affiliation: ENT Department of Hippokration Hospital, National University of Athens, Greece.
authors.forename: S G
authors.initials: SG
authors.lastname: Korres
authors.forename: C E
authors.initials: CE
authors.lastname: Papadakis
authors.forename: M G
authors.initials: MG
authors.lastname: Riga
authors.forename: D G
authors.initials: DG
authors.lastname: Balatsouras
authors.forename: D G
authors.initials: DG
authors.lastname: Dikeos
authors.forename: C R
authors.initials: CR
authors.lastname: Soldatos
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009759:Nystagmus, Pathologic / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D010037:Otolithic Membrane / Q000293:injuries / Q000503:physiopathology; D011446:Prospective Studies; D012665:Semicircular Canals / Q000503:physiopathology*; D012890:Sleep / Q000502:physiology; D016683:Supine Position / Q000502:physiology; D014717:Vertigo / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D014722:Vestibule, Labyrinth / Q000503:physiopathology*; D055815:Young Adult