Contralateral Suppression of Transient Evoked Otoacoustic Emission in Vestibular Neuritis

Woo, Hoon Young; Sohn, Jung Hyeob; Yoo, Young Sam; Choi, Jeong Hwan

Abstract

BACKGROUND AND OBJECTIVES
The etiology of vestibular neuritis is unknown. Many investigators have suggested that this condition spares the inferior vestibular nerve system. However, others have reported that the lesion sometimes affects the inferior vestibular nerve system based on vestibular evoked myogenic potential. The function of the inferior vestibular nerve was studied in acute vestibular neuritis by monitoring medial olivocochlear bundle (MOCB) function. Under normal conditions, contralateral acoustic stimulation has inhibitory effects on ipsilateral otoacoustic emissions through the MOCB.
MATERIALS AND METHODS
Twenty patients that presented with dizziness and spontaneous nystagmus, and were confirmed to have acute vestibular neuritis by rotatory chair and caloric testing were enrolled in this study. We evaluated the evoked otoacoustic emissions with and without contralateral acoustic stimulation in both ears in all patients. The percent loss of normal inhibitory action on otoacoustic emissions was determined in the normal and affected ears.
RESULTS
All patients showed inhibitory effects in response to contralateral acoustic stimulation on evoked otoacoustic emissions in normal ears. Fifteen patients (75%) had an absence of contralateral suppression of otoacoustic emissions on the affected side.
CONCLUSION
The findings of this study suggest the presence of dysfunction of the MOCB in patients with acute vestibular neuritis.