Abstract

Background
and Objective: Vestibular evoked myogenic potentials (VEMP) has been promoted as a means of assessing the integrity of saccular function. Even though sacculospinal reflex may not be influenced by abnormality of cochlear pathway, saccule is closely related with cochlea in its embryological development and also in geographic location. So authors hypothesized the presence of functional alterations of saccule in patients with sudden sensorineural hearing loss who do not complain of vertigo, since saccular dysfunction may not induce subjective vestibular symptoms or signs. Authors tested saccular function in those patients using VEMP and analyzed the parameters according to other clinical indicators. Materials and Method: From July to September 2005, 22 patients who diagnosed with unilateral sudden sensorineural hearing loss without vertigo were enrolled. The patients who had vertigo as initial symptom or showed spontaneous nystagmus were excluded. All patients received conventional audiometry, tone-burst VEMP test, and caloric test. We analyzed P13 and N23 latency, interpeak amplitude and asymmetric ratio of amplitude. The patients divided to complete hearing recovery, partial recovery, and no response group according to treatment outcome. The correlation between parameters and treatment result was analyzed.
Results
In 2 out of 22 patients (9.1%), VEMP waves were not detected. There was no latency delay in affected ear. But the interpeak amplitude of the affected ear was significantly smaller than that of healthy side (paired t test, p=0.02). Patients who did not respond to treatment showed smaller interpeak amplitude than those who showed complete recovery.
Conclusion
Most patients of idiopathic sudden sensorineural hearing loss without vertigo seem to show normal VEMP waves. But some parameters regarding amplitude had abnormal findings in affected ear. Further studies with larger sample size seem to be necessary to elucidate such outcomes.

• Keywords: Sensorineural hearing loss;Saccule;Vestibular function tests;Evoked potential;Vertigo;