Fluctuations in Vestibular Afferent Excitability in Meniere's Disease.

OBJECTIVE: To determine if Meniere's disease is associated with fluctuations in afferent excitability in four human subjects previously implanted with vestibular stimulators. STUDY DESIGN: Longitudinal repeated measures. SETTING: Tertiary referral center, human vestibular research laboratory. PATIENTS: Four human subjects with previously uncontrolled Meniere's disease unilaterally implanted in each semicircular canal with a vestibular stimulator. One subject had only two canals implanted. INTERVENTION(S): Repeated measures of electrically-evoked slow phase eye velocity and vestibular electrically-evoked compound action potentials (vECAP) over 2 to 4 years. MAIN OUTCOME MEASURE(S): Slow phase eye velocity and N1-P1 vECAP amplitudes as a function of time. RESULTS: There were statistically significant fluctuations in electrically evoked slow phase eye velocity over time in at least one semicircular canal of each subject. vECAP N1-P1 amplitudes measured at similar time intervals and stimulus intensities seem to show somewhat correlated fluctuations. One of the subjects had a single Meniere's attack during this time period. The others did not. CONCLUSIONS: In these four subjects originally diagnosed with Meniere's disease, there was fluctuating electrical excitability of the ampullar nerve of at least one canal in each subject. These fluctuations occurred without active symptoms of Meniere's disease.