Department of Ophthalmology, University Hospital Zurich, University of Zurich, Frauenklinikstrasse 24, 8091 Zurich, Switzerland.
Department of Neurology, University Hospital Zurich, University of Zurich, Frauenklinikstrasse 26, 8091 Zurich, Switzerland.
Clin Neurophysiol. 2019 Jul;130(7):1125-1134. doi: 10.1016/j.clinph.2019.03.033. Epub 2019 Apr 25.
To determine the most effective stimulation parameters for the diagnosis of ocular myasthenia gravis (MG) using repetitive ocular vestibular evoked myogenic potentials (oVEMP) for quantification of the extraocular muscle response decrement.
Repetitive bone-conducted oVEMPs were elicited in 18 MG patients and 20 healthy subjects. We compared four different stimulus repetition rates (20 Hz, 30 Hz, 40 Hz, 50 Hz) and 100 Hz continuous stimulation, as well as recordings from the inferior oblique muscles and the lateral rectus muscles to determine the most sensitive and specific oVEMP parameters for decrement detection.
Repetitive stimulation at all tested repetition rates with recordings from inferior oblique muscles allowed for effective differentiation between MG patients and healthy subjects. Among all repetition rates, 30 Hz showed a trend towards superiority, with a sensitivity of 71% and a specificity of 94% (area under the curve (AUC) 0.88) when using the smaller decrement of the two eyes and -10% as cutoff. Considering the larger decrement for analysis (-9% as cutoff), sensitivity increased to 82%, but specificity decreased to 78% (AUC 0.81).
Our study demonstrates, that repetitive oVEMP stimulation elicits a robust decrement in the inferior oblique muscles of MG patients at repetition rates between 20 Hz and 50 Hz, with a probable optimum at 30 Hz.
Repetitive inferior oblique oVEMP stimulation with optimal stimulus parameters facilitates early and accurate diagnosis of ocular MG.
通过定量评估眼外肌反应递减，确定重复眼前庭诱发肌源性电位（oVEMP）在诊断眼肌型重症肌无力（MG）时最有效的刺激参数。
对 18 例 MG 患者和 20 例健康对照者进行重复骨导 oVEMP 刺激。我们比较了四种不同的刺激重复率（20Hz、30Hz、40Hz、50Hz）和 100Hz 连续刺激，以及记录下斜肌和外直肌，以确定最敏感和特异的 oVEMP 参数用于递减检测。
所有测试重复率下，记录下斜肌的重复刺激均可有效区分 MG 患者和健康对照者。在所有重复率中，30Hz 具有优势趋势，使用双眼较小的递减值（-10%作为截断值）时，敏感性为 71%，特异性为 94%（曲线下面积（AUC）为 0.88）。考虑到较大的递减值（-9%作为截断值）进行分析，敏感性增加到 82%，但特异性降低至 78%（AUC 为 0.81）。
我们的研究表明，在 20Hz 至 50Hz 的重复率下，重复 oVEMP 刺激在下斜肌中可引起 MG 患者的明显递减，最佳刺激参数可能在 30Hz。
使用最佳刺激参数对下斜肌重复 oVEMP 刺激有助于早期和准确诊断眼肌型 MG。
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