Revision of a furosemide-loading vestibular-evoked myogenic potential protocol for detecting endolymphatic hydrops.

OBJECTIVE: The presence of endolymphatic hydrops can be suggested by improving the amplitude of vestibular-evoked myogenic potential (VEMP) after furosemide administration (furosemide loading VEMP [FVEMP]). The authors aimed to determine a stimulation frequency and judgment criteria to ascertain whether a revised FVEMP protocol can be applied to clinical settings.

METHODS: The study included 25 individuals with unilateral Meniere's disease (MD) and 11 normal healthy volunteers. Normalized amplitude of VEMP, using a tone burst sound at 250, 500, 700, 1000, 1500 and 2000 Hz, was measured before and after furosemide administration in the two groups. Improvement ratio (IR) of amplitude was calculated at each frequency.

RESULTS: There were no significant differences in IR between the control group and the MD group at each frequency, except at 500 Hz. Receiver operating characteristic curve analysis revealed an IR cut-off value of 14.2% at 500 Hz, with a sensitivity of 0.706 and a specificity of 0.810.

CONCLUSIONS: The revised FVEMP protocol using a 500 Hz tone burst stimulus and normalized amplitudes was defined as positive when IR exceeded 14.2% or when a biphasic wave could be detected after furosemide administration in cases without a detectable biphasic wave before administration.