Division of Neurology, Department of Medicine, University of Ottawa, Ottawa, Canada.
Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Hsinchu, Taiwan.
Neurol Sci. 2021 Dec;42(12):5343-5352. doi: 10.1007/s10072-021-05676-3. Epub 2021 Oct 26.
Identifying dangerous causes of dizziness is a challenging task for neurologists, as it requires interpretation of subtle bedside exam findings, which become even more subtle with time. Nystagmus can be instrumental in differentiating peripheral from central vestibular disorders. Conventional teaching is that peripheral vestibular nystagmus is accentuated by removal of visual fixation. We sought to systematically test the hypothesis that, in some cases, vertical nystagmus due to central vestibular disorders may also be easier to identify when fixation is removed.
To identify patients with vertical nystagmus, we retrospectively reviewed clinical, MRI, and VNG data of consecutive patients undergoing VNG in our vestibular clinic over a 9-month period. We analyzed clinical features, bedside neuro-otological examination, MRI results, and VNG findings in fixation as well as those with fixation removed.
Two hundred and fourteen charts were reviewed. Twenty-six patients had vertical nystagmus with fixation removed on VNG. Only three (11.5%) of these patients had vertical nystagmus apparent with fixation (and only two had nystagmus observed clearly at the bedside with the unaided eye). Thirteen (50%) of the patients had posterior fossa lesions on MRI and eight of the rest (30.8%) were diagnosed with central vestibular disorders. Of the 13 patients with MRI-confirmed lesions, 3 patients (23.1%) had no neurological signs or conventional bedside oculomotor signs; in these cases, vertical nystagmus without fixation was the only sign of a central lesion.
Our findings go against conventional teaching and show that removing fixation can uncover subtle vertical nystagmus due to central vestibular disease, particularly from focal or chronic lesions.
识别导致头晕的危险病因对神经科医生来说是一项具有挑战性的任务，因为这需要对细微的床边检查结果进行解读，而随着时间的推移，这些结果会变得更加细微。眼球震颤对于区分外周性和中枢性前庭障碍具有重要作用。传统的教学观点认为，去除视觉固视可以增强外周性前庭性眼球震颤。我们旨在系统地检验这样一种假设，即某些情况下，由于中枢性前庭疾病引起的垂直眼球震颤在去除固视时可能更容易识别。
为了识别出具有垂直眼球震颤的患者，我们回顾性地分析了在我们的前庭诊所进行 VNG 的连续患者的临床、MRI 和 VNG 数据，这些患者在 9 个月的时间内接受了 VNG。我们分析了临床特征、床边神经耳科学检查、MRI 结果和 VNG 检查在固视和去除固视时的结果。
共回顾了 214 份图表。26 例患者在 VNG 时去除固视后出现垂直眼球震颤。仅有 3 例（11.5%）患者在固视时出现垂直眼球震颤（且只有 2 例在床边用未受辅助的眼睛清楚地观察到眼球震颤）。13 例患者的 MRI 显示存在后颅窝病变，其余 8 例（30.8%）被诊断为中枢性前庭障碍。在 13 例 MRI 证实存在病变的患者中，有 3 例（23.1%）无神经系统体征或常规床边眼动体征；在这些情况下，去除固视后出现的垂直眼球震颤是唯一的中枢性病变体征。
我们的研究结果与传统教学观点相矛盾，表明去除固视可以揭示出由于中枢性前庭疾病引起的细微垂直眼球震颤，尤其是对于局灶性或慢性病变。
