Origin of isolated vertigo in rotational vertebral artery syndrome.

Rotational vertebral artery syndrome (RVAS) is characterized by recurrent attacks of paroxysmal vertigo, nystagmus, and ataxia induced by head rotation. Although recent report has described the RVAS as an important but unrecognized cause of isolated vascular vertigo, the locus of injury site responsible for isolated vertigo in RVAS is still unclear. We report here two patients with RVAS who had a stereotypic clinical presentation characterized by recurrent attacks of isolated vertigo induced by head rotation. The pattern of nystagmus observed in our patients with RVAS can be best explained by the stimulation of the vestibular labyrinth bilaterally or unilaterally. In RVAS, the isolated vertigo may occur due to transient ischemia of the superior vestibular labyrinth. RAVS should be considered in the differential diagnosis of positional vertigo, especially when vertigo is developed while sitting or standing position.