Transient Evoked Otoacoustic Emissions in Vestibular Neuritis

Abstract

Partial or total degeneration of the vestibulocochlear anastomosis at its takeoff from the saccular ganglion and regenerating efferent neural buds under the cochlear outer hair cells (OHCs) have been found in the temporal bones of human patients with a history of vestibular neuritis (VN). We sought to test whether VN has any functional impact on the ipsilateral OHCs by means of transient evoked otoacoustic emission (TEOAE) testing. We retrospectively analyzed prospectively collected TEOAE data of 28 patients (19 female, 9 male; age range, 21 to 60 years; median age, 42.5 years). The pure tone air conduction hearing thresholds at each standard audiometric frequency (0.125 to 8 kHz) and the amplitudes of the TEOAEs at the 1-, 2-, 3-, and 4-kHz frequency bands were compared between the lesional and contralateral sides by use of the nonparametric sign test for 2 paired samples. No significant difference was found in the pure tone air conduction hearing thresholds between the lesional and contralateral ears at any of the 11 standard tested frequencies. No significant difference was found between the TEOAE amplitudes of the lesional and contralateral sides. Subclinical OHC functional impairment is not present in VN. Moreover, no apparent significant changes in medial olivocochlear bundle resting activity accompany VN.