Acoustic tensor tympani response and vestibular-evoked myogenic potential.

Abstract

To investigate the acoustic response properties and the vestibular-evoked myogenic potential (VEMP) in various lesions. Retrospective study of the clinical records of patients. Neurotological tests including acoustic response and VEMP were performed and analyzed in 62 patients with facial palsy, otosclerosis, ossicular chain interruption, sensorineural hearing loss, or acoustic tumor. Inverted acoustic responses were observed in 25 of 38 (65.8%) patients with facial palsy, in 5 of 6 (83.3%) patients with acoustic tumor, and in all patients with otosclerosis, ossicular chain interruption, or sensorineural hearing loss. These inverted responses were obtained only when ipsilateral stimulation was used. The thresholds of the inverted responses were statistically significantly higher than those of the normal response. The vibration of the eardrum is thought to stimulate the ipsilateral trigeminal nerve, leading to contraction of the tensor tympani muscle. The stapedius response had an inhibitory effect on the inverted response. Vibration of the stapes footplate (which requires a normal middle ear conduction system) is necessary to induce the VEMP, whereas the functioning of the facial and cochlear nerves is independent of the VEMP response.