Abstract

Benign paroxysmal positional vertigo (BPPV) of anterior semicircular canal (ASC) is the rarest variant of BPPV, which is thought to be due to the anatomically superior position of ASC during most activities. This type of BPPV is currently diagnosed by detecting positional down-beating nystagmus in the Dix-Hallpike test. A 62-year-old female presented with positional vertigo, especially when sitting up. No nystagmus was induced by both Dix-Hallpike tests, however, positional down-beating nystagmus was observed with the left torsional component when sitting up from both Dix-Hallpike positions and supine position. After the reverse Epley maneuver, up-beating nystagmus was newly observed in the left Dix-Hallpike test, which was compatible with BPPV of the left posterior semicircular canal. This patient was thought to suffer from canalithiasis of the left ASC.

• Keywords: Benign paroxysmal positional vertigo;Anterior semicircular canal;Dix-Hallpike test;