Vestibular evoked myogenic potentials in multiple sclerosis : clinical and imaging correlations

Patients with multiple sclerosis (MS) frequently report symptoms related to vestibular disorders in the course of their disease. At present, the fundamental tests assessing vestibulospinal involvement are posturography and vestibular evoked myogenic potentials (VEMPs). While posturography cannot be performed in every subject requiring minimal stance control, VEMPs do not require any specific skill on the part of the subjects and they may be investigated in all patients able to sit. VEMPs were recorded for 40 patients (17 men, 23 women; mean age 38 years, range 17-71 years) fulfilling diagnostic criteria of clinically defined MS, by means of rarefaction clicks, recording modulation of sterno-cleido-mastoideus tonic contraction saccule-mediated modulation. VEMPs were found to be abnormal in 28 of 40 patients. In 18 of the cases the VEMPs were asymmetric, i.e., had a prolonged latency on one side. In six cases latency was increased on both sides (mean delay 4.1 ms). In four subjects VEMPs were absent on one side. Concordance with clinical findings of presence/absence of brainstem involvement was found in 55% and with MRI findings in 65% of the cases. Abnormal VEMPs indicated brainstem dysfunction in four patients (10%) with normal MRI and no specific clinical signs.