Vestibular evoked myogenic potential (VEMP) testing: normative threshold response curves and effects of age.
OBJECTIVE Vestibular evoked myogenic potential (VEMP) is applied to explore the integrity of sacculocollic reflex. Although tests to evaluate vestibular-ocular reflex pathway have shown that vestibular function is adversely affected by aging, VEMP, in this study, is used as a novel test to define how aging influences sacculocollic reflex pathway. STUDY DESIGN Prospective study. SETTING Academic tertiary referral center. SUBJECTS Eighty normal subjects, equally divided into four groups according to their age, were enrolled to this study. Group I included patients aged <20 years, Group II patient ages ranged from 21 to 40 years, Group III patients were 41 to 60 years, and Group IV included patients older than 60 years. INTERVENTIONS Recordings of VEMP responses. MAIN OUTCOME MEASURES The response rate and parameters of VEMP, including p13 latency, n23 latency, amplitude, and interaural difference ratio. RESULTS The VEMP response rates from Groups I to IV was 98%, 98%, 90%, and 60%, respectively, disclosing a significant difference only between Group IV and other groups (p < 0.05). The amplitude was negatively correlated with age in contrast to the n23 latency, correlating positively with age; both reached a significant difference (p < 0.05). Although the p13 latency had a trend to prolong as age increased, no significant correlation existed (p < 0.06). Moreover, the interaural difference ratio was also not significantly correlated with age. CONCLUSIONS As age increased over 60 years, the VEMP response rate decreased dramatically. While age increased, the VEMP amplitude decreased in comparison to n23 latency prolonged. These findings might suggest that aging could deteriorate the saccular and corresponding neural functions. When interpreting the VEMP parameters, it should be kept in mind that aging could affect VEMP responses. Based on this study, we suggest establishing different reference values according to different age groups when evaluating VEMP response in patients with vestibular diseases.