Posterior semicircular canal type benign paroxysmal positioning vertigo with ageotropic paroxysmal positioning nystagmus

We report on 3 patients with typical benign paroxysmal positioning vertigo (BPPV) and atypical, paroxysmal positioning nystagmus. When the Dix-Hallpik e test was performed, the patients exhibited an ageotropic nystagmus, diffe rent from that classically described in posterior semicircular canal BPPV. It was torsional-vertical with the vertical component beating downwards, an d the torsional component was beating away from the lowermost ear. In both left and right Dix-Hallpike positions, the upper poles of the eyes were tur ning away from the lowermost ear. The atypical ageotropic paroxysmal positi onal nystagmus of the posterior semicircular canal was observed in the evol ution of the BPPV in 2 patients and on the first examination in the third. Two patients had changing patterns of paroxysmal positioning nystagmus. Cop yright (C) 2001 S. Karger AG, Basel.