Fig. 3.

Right anterior canalithiasis. In the upright position, the otoconia are positioned near the cupula of the right anterior canal. There is no spontaneous nystagmus. The Dix-Hallpike position brings the ampullary end of the anterior canal to a higher gravitational point. There is an excitatory downbeat rightward torsional nystagmus as the otoconia fall away from the ampulla. The slow phase velocity (SPV) profile illustrates the paroxysmal nature of the nystagmus, the quick rise to a peak velocity, and brief duration of less than 30 s.