Vestibular-evoked myogenic potential tests in orthostatic dizziness.

OBJECTIVE: As otolithic control of blood pressure has been the focus of recent interest, this study investigated the ocular and cervical vestibular-evoked myogenic potential (oVEMP and cVEMP) tests in patients with orthostatic dizziness.

METHODS: Sixty patients with orthostatic dizziness and 20 normal controls were consecutively enrolled. All subjects received a battery of tests including audiometry, and caloric, oVEMP and cVEMP tests.

RESULTS: Audiometry revealed normal hearing in all 60 patients. Caloric test identified hyperactive and normal responses in 35 and 65 % of patients, respectively. The oVEMP test showed normal responses in 36 patients, and abnormal (absent and reduced) responses in 24 patients (40 %). Most patients (22/24) with abnormal oVEMPs revealed asymmetrical responses. For the cVEMP test, 30 patients (50 %) had normal responses, and 23 and 7 patients showed delayed and absent cVEMPs, respectively. Significant differences existed in the abnormal percentage of oVEMP and cVEMP tests between the patient and control groups. When the oVEMP and cVEMP test results were combined, the abnormal rate increased to 70 % of the patients, resulting in stronger association as an elevated odds ratio of 13.2, greater than 12.7 and 5.7 in the corresponding individual oVEMP and cVEMP tests.

INTERPRETATION: Patients with orthostatic dizziness may show asymmetric oVEMPs and abnormal (delayed) cVEMPs. If both test results were combined together, a high abnormality (70 %) was obtained, indicating that in addition to conventional autonomic test battery, the two VEMP tests may serve as a supplementary tool for evaluating orthostatic dizziness.