From the Departments of Ophthalmology (Y.V., K.L., K.P.W.) and Neurology (Y.V., H.H.J., D.S., K.P.W.), University Hospital Zurich, University of Zurich, Switzerland; Department of Neurology (S.M.R.), Royal Prince Alfred Hospital, Sydney; and the Central Clinical School (S.M.R.), University of Sydney, Australia.
Neurology. 2016 Feb 16;86(7):660-8. doi: 10.1212/WNL.0000000000002383. Epub 2016 Jan 20.
To explore whether ocular vestibular evoked myogenic potentials (oVEMP) can be used to detect a decrement in the extraocular muscle activity of patients with myasthenia gravis (MG).
Twenty-seven patients with MG, including 13 with isolated ocular and 14 with generalized MG, and 28 healthy controls participated. We applied repetitive vibration stimuli to the forehead and recorded the activity of the inferior oblique muscle with 2 surface electrodes placed beneath the eyes. To identify the oVEMP parameters with the highest sensitivity and specificity, we evaluated the decrement over 10 stimulus repetitions at 3 different repetition rates (3 Hz, 10 Hz, and 20 Hz).
Repetitive stimulation at 20 Hz yielded the best differentiation between patients with MG and controls with a sensitivity of 89% and a specificity of 64% when using a unilateral decrement of ≥15.2% as cutoff. When using a bilateral decrement of ≥20.4% instead, oVEMP allowed differentiation of MG from healthy controls with 100% specificity, but slightly reduced sensitivity of 63%. For both cutoffs, sensitivity was similar in isolated ocular and generalized MG.
Our study demonstrates that the presence of an oVEMP decrement is a sensitive and specific marker for MG. This test allows direct and noninvasive examination of extraocular muscle activity, with similarly good diagnostic accuracy in ocular and generalized MG. Thus, oVEMP represents a promising diagnostic tool for MG.
This study provides Class III evidence that oVEMP testing accurately identifies patients with MG with ocular symptoms (sensitivity 89%, specificity 64%).
探讨眼性前庭诱发肌源性电位（oVEMP）能否用于检测重症肌无力（MG）患者眼外肌活动的减退。
27 例 MG 患者，包括 13 例单纯眼型和 14 例全身型，以及 28 例健康对照者参与了研究。我们应用重复振动刺激前额，并通过放置在眼睛下方的 2 个表面电极记录下斜肌的活动。为了确定具有最高敏感性和特异性的 oVEMP 参数，我们评估了在 3 种不同重复率（3 Hz、10 Hz 和 20 Hz）下 10 次刺激重复的递减。
在 20 Hz 的重复刺激下，当使用单侧递减≥15.2%作为截断值时，oVEMP 可将 MG 患者与对照组最佳地区分，其敏感性为 89%，特异性为 64%。当使用双侧递减≥20.4%作为截断值时，oVEMP 可使 100%的 MG 患者与健康对照者最佳地区分，但敏感性略有降低，为 63%。对于这两个截断值，在单纯眼型和全身型 MG 中，敏感性相似。
我们的研究表明，oVEMP 递减的存在是 MG 的一个敏感且特异的标志物。该测试可直接、无创地检查眼外肌活动，在眼型和全身型 MG 中具有类似的诊断准确性。因此，oVEMP 代表了一种有前途的 MG 诊断工具。
这项研究提供了 III 级证据，表明 oVEMP 测试能准确识别出具有眼部症状的 MG 患者（敏感性 89%，特异性 64%）。
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