Figure 1.

Stimulation of the posterior semicircular canal during the right Dix-Hallpike maneuver (c). On (a,b), the semicircular canals of the left and right ears, respectively, are shown. When otoconia is present in the ipsilateral (right) posterior canal (b), the maneuver causes its movement along the lumen of the canal, inducing BPPV. When otoconia is present in the contralateral (left) posterior canal (a), the maneuver does not cause any movement of the otoconia, because the head rotates orthogonally to the plane of the involved canal and the maneuver is negative.