Objective: To investigate the audio-vestibular function and the possible mechanism of benign paroxysmal positional vertigo (BPPV) and to raise the therapeutic strategy.
Methods: Patients with BPPV were tested with pure tone audiometry, high frequency ABR audiometry, bithermal caloric test and vestibular evoked myogenic potential test (VEMP). The positive rate of these otologic function test were analyzed.
Results: Primary BPPV comprised 82 percent (70/86) of patients with BPPV. Among all of the patients, the results of pure tone audiometry were abnormal in 52 percent (45/86) of the cases. High frequency auditory brainstem response (ABR) was abnormal in 60 percent (30/50) of cases. Vestibular evoked myogenic potential (VEMP) was abnormal in 34 percent (11/32) of cases who had this examination. And bithermal caloric test were abnormal in 28 percent (20/72) of cases. In the abnormal cases, 67 percent (12/18) of cases were ipsilateral with BPPV. The majority of the BPPV with abnormal results of bithermal caloric test (89%, 16/18) belong to posterior semicircular canal BPPV.
Conclusions: The incidence of primary BPPV was higher than that of secondary BPPV. The abnormality in superior labyrinth was much more correlated with the occurrence of BPPV. The inner ear ischemia might be a factor in the morbidity of BPPV, especially for the primary BPPV.