Study of vestibular evoked myogenic potentials in unilateral vestibulopathy: Otolithic versus canal function testing

The study provides a qualitative evaluation of unilateral vestibulopathy by comparing otolithic and canal function, to establish possible relationships between the type of dysfunction observed and the evolving clinical pictures associated with it. Retrospective study of a series of cases. Department of Medical-Surgical Specialization, Otolaryngology and Cervicofacial Surgery Division, University of Perugia, Perugia, Italy. Twenty patients whose medical history showed at least one episode corresponding to the clinical parameters of acute vestibulopathy. Study of vestibular function by recording VEMPs and repeating canal function testing at least 6 months after the first episode of vertigo. Relationship between the type of vestibulopathy (canal and otolithic) and the clinical pictures observed. Paroxysmal positional vertigo, observed in 4 patients, was correlated with the presence of vestibular evoked myogenic potentials (VEMPs) and the absence of an ipsilateral canal response in all cases (100%). Persistent dizziness was observed in nine patients, and VEMPs were absent in all of them (100%); three (33.3%) showed the recovery of previously absent canal function. Comparison of responses in six patients with recurrent acute vestibulopathy showed persistent and complete loss of canal function in five cases (83.3%), whereas impairment of otolithic response was less constant (40%). The combined VEMPs-canal test study shows predictive value regarding certain evolving clinical pictures of vestibulopathy. The absence of VEMPs confirms the role of otolithic dysfunction in the onset of dizziness. Likewise, it suggests that a vestibular origin of these disorders should be considered in cases that have shown aspecific symptoms since onset, without frank vertigo and with normal vestibular response to canal function testing.