A 27-year-old patient with a chief complaint of mild veigo of 3-months duration is seen by a neurologist. Examination reveals a positional (horizontal and veical) nystagmus that is bidirectional. The patient repos the absence of tinnitus. Which of the following is the most likely etiology of veigo?

Pathologic veigo is generally classified as peripheral (labyrinthine) or central (brainstem or cerebellum).The clinical presentation, in this case, is most consistent with central veigo. Positional (especially horizontal) nystagmus (to-and-fro oscillation of the eyes) is common in the veigo of central origin, but absent or uncommon in peripheral veigo. The chronicity of the veigo is characteristic of central veigo, whereas the symptoms of peripheral veigo generally have a finite duration and may be recurring.Tinnitus and/or deafness is often present in peripheral veigo, but absent in central veigo. The flocculonodular lobe, or vestibulocerebellum, is connected to the vestibular nuclei and paicipates in the control of balance and eye movements, paicularly changes in the vestibuloocular reflex (VOR), which serves to maintain visual stability during head movement.A lesion of this area of the cerebellum may result in veigo and nystagmus, whereas the spinocerebellum is involved in the coordination of limb movement.