Evaluation of vestibular evoked myogenic potentials (VEMP) and electrocochleography for the diagnosis of Ménière's disease

Abstract Introduction: Ménière's disease (MD) is an inner ear disorder characterized by episodic vertigo, tinnitus, ear fullness, and fluctuating hearing. Its diagnosis can be especially difficult in cases where vestibular symptoms are present in isolation (vestibular MD). The definitive diagnosis is made histologically and can only be performed post-mortem, after analysis of the temporal bone. Endolymphatic hydrops is a histopathological finding of the disease and occurs more often in the cochlea and saccule, followed by the utricle and semicircular canals. Vestibular evoked myogenic potentials (VEMP) emerged as the method of assessment of vestibular function in 1994. Until then, there was no unique way of assessing saccular function and the inferior vestibular nerve. Given that the saccule is responsible for most cases of severe hydrops, VEMP appears as a new tool to assist in the diagnosis of MD. Objective: To evaluate the sensitivity and specificity of VEMP and electrocochleography (EcochG) in the diagnosis of definite MD compared with clinical diagnosis. Methods: The study includes 12 patients (24 ears) diagnosed with definite MD defined according to the clinical criteria proposed by the American Academy of Otolaryngology - Head and Neck Surgery (AAO-HNS) in 1995, as well as 12 healthy volunteers allocated to the control group (24 ears). A clinical diagnosis by the AAO-HNS criteria was considered as the gold standard. All patients underwent an otoneurological examination, including pure tone and speech audiometry, VEMP, and extratympanic EcochG. The sensitivity and specificity to detect the presence or absence of disease were calculated, as well as their 95% confidence intervals. The reliability of VEMP and EcochG in both ears was assessed using the kappa index. Results: In both tests and in both ears, the ability to diagnose healthy cases was high, with specificity ranging from 84.6% to 100%. Moreover, the ability of the tests to diagnose the disease varied from low to moderate sensitivity, with values ranging from 37.5% to 63.6%. The agreement of both tests in the right ear, measured by the kappa coefficient, was equal to 0.54 (95% CI: 0.20-0.89), indicating a moderate agreement. In the left ear, that agreement was equal to 0.07 (95% CI: −0.33 to 0.46), indicating a weak correlation between the tests. The sensitivity of the VEMP for the right ear was 63.6% and for the left ear, 62.5%. The sensitivity of EcochG for the right ear was 63.6% and 37.5% for the left ear. Conclusion: The specificity of both tests was high, and the sensitivity of VEMP was higher than that of EcochG.

引言：梅尼埃病（Ménière's disease, MD）是一类以内耳发作性眩晕、耳鸣、耳胀满感及波动性听力下降为特征的内耳疾病。当患者仅表现出前庭症状时（前庭型梅尼埃病），其诊断难度显著升高。该病的确诊需依靠组织病理学检查，且仅能在死后通过颞骨分析完成。内淋巴积水是该病的病理组织学特征，更常累及耳蜗与球囊，其次为椭圆囊及半规管。前庭诱发肌源性电位（vestibular evoked myogenic potentials, VEMP）于1994年成为前庭功能评估手段，在此之前尚无针对球囊功能及前庭下神经的专属评估方法。鉴于球囊是重度内淋巴积水的主要受累部位，VEMP成为辅助MD诊断的新型工具。

研究目的：相较于临床诊断标准，评估VEMP与耳蜗电图（electrocochleography, EcochG）在确诊MD中的灵敏度与特异度。

研究方法：本研究纳入12例符合1995年美国耳鼻咽喉头颈外科学会（American Academy of Otolaryngology - Head and Neck Surgery, AAO-HNS）临床诊断标准的确诊MD患者，共计24耳；另纳入12名健康志愿者作为对照组，共计24耳。以AAO-HNS标准的临床诊断作为金标准。所有受试者均接受耳神经学检查，包括纯音测听、言语测听、VEMP检测及鼓室外耳蜗电图。计算检测疾病存在与否的灵敏度、特异度及其95%置信区间，并采用Kappa指数评估双耳VEMP与EcochG检测结果的一致性。

研究结果：两项检测在双耳中对健康个体的识别能力均较高，特异度范围为84.6%~100%。两项检测对疾病的诊断灵敏度处于低至中度水平，范围为37.5%~63.6%。Kappa系数显示，右侧耳的两项检测一致性为0.54（95%CI：0.20~0.89），提示中度一致性；左侧耳的一致性为0.07（95%CI：-0.33~0.46），提示两项检测间相关性较弱。右侧耳VEMP的灵敏度为63.6%，左侧耳为62.5%；EcochG右侧耳灵敏度为63.6%，左侧耳为37.5%。

研究结论：两项检测的特异度均较高，且VEMP的灵敏度高于EcochG。