To clarify the extent of the vestibular lesions in idiopathic sudden hearing loss with vertigo using vestibular evoked myogenic potentials (VEMPs) in response to click (click-VEMP) and galvanic (galvanic-VEMP) stimulation, as well as caloric tests.Design: Retrospective study.Setting: University hospital. Patients:We enrolled 22 patients with idiopathic sudden hearing loss with vertigo in this study. All patients underwent audiometry and click-VEMP and caloric tests. Eight patients underwent a galvanic-VEMP test.Results: Among the 22 patients, 17 (77%) showed an absence of click-VEMPs on the affected side. In response to caloric testing, 10 patients (45%) showed a decreased response on the affected side. All 8 patients who underwent galvanic-VEMP testing showed normal re-sponses. Most patients with decreased caloric responses (9 [90%] of 10 patients) showed an absence of click-VEMPs, whereas 9 (53%) of the 17 patients who showed abnormal click-VEMPs showed decreased caloric responses. Initial hearing level and hearing outcome significantly correlated with abnormalities on the vestibular test results.

Apart from Ménière's disease, acoustic neuroma, and sudden deafness with vertigo, which are already known as diseases with abnormal VEMP responses but normal caloric test responses, some patients might be diagnosed as having a disease that involves only the inferior vestibular nerve region.

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To reduce the testing time of vestibular evoked myogenic potentials (VEMP) and the physical efforts of subjects, we studied if VEMP recording by binaural simultaneous stimulation in patients with vestibulo-cochlear disorders can be applicable as a screening test. Twenty-eight patients with vestibulo-cochlear disorders (12 men and 16 women, 22 to 77 years of age) were enrolled in this study. Patients were presented with binaural or monaural click (95 dBnHL) stimulation to record VEMPs. Their VEMP responses to binaural simultaneous stimulation were compared with those of monaural individual stimulation. Twenty-six of the 28 patients (93%) showed the same results in binaural simultaneous stimulation as in monaural individual stimulation. Amplitudes of p13-n23 to binaural simultaneous stimulation showed significant correlation to those of monaural individual stimulation ( r =0.774, P <0.0001 t -test). Peak latencies of p13 and n23 of binaural simultaneous stimulation also showed significant correlation to those of monaural individual stimulation (p13: r =0.684, P <0.0001 t -test, n23: r =0.657, P <0.0001 t -test). The binaural simultaneous stimulation method for VEMP recording is applicable for patients with vestibulo-cochlear disorders as a screening test in the clinic.

Deviation of SVH in patients with definite unilateral vestibular deafferentation can be long term, lasting more than 2 years at least.