Otolith Function Research In Patients With Recurrent Benign Paroxysmal Positional Vertigo

Objective:1.Explore the clinical features of recurrent benign paroxysmal positional vertigo (BPPV) by retrospective analysis of BPPV-related researches and clinical data.2.Explore the roles of otolith organs (utricle and saccule) in the occurrence and recurrence of BPPV by vestibular evoked myogenic potential (VEMP) test between BPPV patients and normal subjects.Methods:We enrolled26recurrent primary PC-BPPV patients and60non-recurrent primary PC-BPPV patients who referred to the Dizziness Clinic of Shandong Provincial Hospital between November2012and April2013. We also enrolled40age-and gender-matched normal subjects. Both patients and normal subjects underwent VEMP tests, using500Hz tone-burst stimuli, including ocular-VEMP(oVEMP) and cervical-VEMP(cVEMP) tests in bilateral ears. The abnormal case was defined as non-elicitation or asymmetry rate between bilateral sides is larger than30%. All the data underwent statistical analysis by SPSS17.0.Results:1. Among86BPPV patients,23(26.74%) cVEMP abnormal response cases and35(40.70%) cVEMP abnormal cases were detected. In40normal subjects, the numbers of abnormal responses of cVEMP, oVEMP were1(2.50%),2(5.00%),. Significant difference was found in abnormal rates of cVEMP, oVEMP between BPPV patients and normal subjects(P<0.01).2. No statistical significance were found in the differences of gender, age and bilateral rate between26recurrent BPPV patients and60non-recurrent patients(P>0.05).3.23(26.74%) cVEMP abnormal response cases and35(40.70%) cVEMP abnormal cases were detected in BPPV patients. Significant difference was found in abnormal rate between cVEMP and oVEMP(P<0.01). The abnormal rate of oVEMP was higher than that of cVEMP.4. In26recurrent BPPV patients,10(38.46%) cVEMP abnormal cases,16(61.54%)cVEMP abnormal cases were detected. In60non-recurrent patients, the numbers of positive case of cVEMP, oVEMP were13(21.67%),19(31.67%). Significant difference was found in abnormal rate in oVEMP test between recurrent and non-recurrent groups(P<0.01),but not in cVEMP(P>0.05).5. According to the length of BPPV course, grouped recurrent patients was divided into3groups:less than1year,1-2years and more than2years. The positive numbers of cVEMP were1(12.50%) in8,2(40.00%) in5,7(53.85%) in13, the positive numbers of oVEMP were3(37.50%),3(60.00%),10(76.92%). No significant differences were found in these groups(P>0.05).Conclusion:1. The positive rate of cVEMP and oVEMP in BPPV patients are significantly higher than those in normal subjects; higher rates are more likely to appear in oVEMP tests. It remind us that the impairments of otolith organs, especially the utricle, have a connection with BPPV.2. The positive rate of oVEMP in recurrent patients is significantly higher than that of non-recurrent patients. Dysfunction of utricle may play a role in recurrence of BPPV.