[Clinical features of benign paroxysmal positional vertigo].

Our understanding of the pathomechanism of benign paroxysmal positional vertigo (BPPV) has improved dramatically. A type of BPPV featuring mixed torsional and vertical nystagmus induced by the Dix-Hallpike maneuver involves the posterior semicircular canal (P-BPPV). The other type of BPPV featuring horizontal nystagmus induced by spine-to-lateral head positioning involves the horizontal canal BPPV (H-BPPV). In complaints of vertigo or dizziness, 619 patients visited our department last year. Of these, 142 (23%) was had positional nystagmus consistent with a diagnosis of BPPV, 118 (19%) had no nystagmus but were suspected of BPPV due to vertigo episodes. BPPV was the most frequent diagnosis. H-BPPV was not rare, but accounted for 30% of BPPV. Of H-BPPV, 73% featured direction changing geotropic nystagmus, and 27% direction changing apogeotropic nystagmus. H-BPPV resolved faster than P-BPPV. Most cases caused by head trauma were P-BPPV. Transition between P- and H-BPPV was found in 6 cases. Women outnumbered men by about 3 to 2 in both P- and H-BPPV. Peak incidence was found in the those in their 60s and 70s, suggesting that the etiologies of both types of BPPV are essentially the same.