Benign paroxysmal positional vertigo showing sequential translations of four types of nystagmus.

Objective: We report a case of benign paroxysmal positional vertigo (BPPV) showing sequential translation of four types of nystagmus and discuss its pathophysiology.
Methods: The case was 65-year-old female. We analyzed her nystagmus three-dimensionally.
Results: At the first visit, she showed vertical-torsio nystagmus of the posterior canal type of BPPV (P-BPPV) and subsequently showed recently reported geotropic nystagmus with a long time constant. Two weeks later, she showed apogeotropic nystagmus of the horizontal canal type of BPPV (AH-BPPV) and subsequently a geotropic nystagmus with a short time constant of the horizontal canal type of BPPV (GH-BPPV).
Conclusions: Three kind of nystagmus, namely P-BPPV, AH-BPPV and GH-BPPV can be explained by the otoconial debris hypothesis of the same ear. Finally, the recently reported geotropic nystagmus with a long time constant may be explained by a reversible lesion such as the denatured cupula or utricular imbalance of the same ear.
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