Department of Neurophysiology, Liverpool Hospital, Sydney, New South Wales, Australia.
South Western Sydney Clinical School, University of New South Wales, Sydney, New South Wales, Australia.
Eur J Neurol. 2024 Dec;31(12):e16513. doi: 10.1111/ene.16513. Epub 2024 Oct 15.
This study was undertaken to examine vestibulo-ocular reflex (VOR) characteristics in myotonic dystrophy type 1 (DM1) and type 2 (DM2) using video head impulse testing (vHIT).
VOR gain, refixation saccade prevalence, first saccade amplitude, onset latency, peak velocity, and duration were compared in DM1, DM2, age-matched normal controls, and patients with peripheral and central vestibulopathies.
Fifty percent of DM1 and 37.5% of DM2 patients demonstrated reduced VOR gain. Refixation saccade prevalence for horizontal canal (HC) and posterior canal (PC) was significantly higher in DM1 (101 ± 42%, 82 ± 47%) and DM2 (70 ± 45%, 61 ± 38%) compared to controls (40 ± 28% and 43 ± 33%, p < 0.05). The first saccade amplitudes and peak velocities were higher in HC and PC planes in DM1 and DM2 compared to controls (p < 0.05). HC slow phase eye velocity profiles in DM1 showed delayed peaks. The asymmetry ratio, which represents the percentage difference between the first and second halves of the slow phase eye velocity response, was therefore negative (-22.5 ± 17%, -2.3 ± 16%, and - 4.7 ± 8% in DM1, DM2, and controls). HC VOR gains were lower and gain asymmetry ratio was larger and negative in patients with DM1 with moderate to severe ptosis and a history of imbalance and falls compared to the remaining DM1 patients (p < 0.05). In peripheral vestibulopathies, saccade amplitude was larger, peak velocity was higher, and onset latency was shorter (p < 0.05) than in DM1. In central vestibulopathy (posterior circulation strokes), saccade peak velocity was higher, but amplitude and onset latency were not significantly different from DM1.
VOR impairment is common in DM1 and DM2. In DM1, refixation saccade characteristics are closer to central than peripheral vestibulopathies. Delayed peaks in the vHIT eye velocity profile observed in patients with DM1 may reflect extraocular muscle weakness. VOR impairment and VOR asymmetry in DM1 are associated with imbalance and falls.
本研究旨在使用视频头脉冲测试（vHIT）检查 1 型肌强直性营养不良（DM1）和 2 型肌强直性营养不良（DM2）的前庭眼反射（VOR）特征。
比较 DM1、DM2、年龄匹配的正常对照组以及周围性和中枢性前庭病变患者的 VOR 增益、重定位扫视发生率、第一扫视幅度、起始潜伏期、峰值速度和持续时间。
50%的 DM1 患者和 37.5%的 DM2 患者的 VOR 增益降低。DM1（101±42%，82±47%）和 DM2（70±45%，61±38%）患者的水平半规管（HC）和后半规管（PC）重定位扫视发生率明显高于对照组（40±28%和 43±33%，p<0.05）。与对照组相比，DM1 和 DM2 患者的 HC 和 PC 平面的第一扫视幅度和峰值速度更高（p<0.05）。DM1 的 HC 慢相眼速度曲线显示峰延迟。因此，代表慢相眼速度反应前半部分和后半部分之间差异的不对称比为负值（-22.5±17%，-2.3±16%和-4.7±8%，分别为 DM1、DM2 和对照组）。与其余 DM1 患者相比，患有中度至重度上睑下垂、平衡和跌倒史的 DM1 患者的 HC VOR 增益较低，增益不对称比较大且为负值（p<0.05）。在周围性前庭病变中，扫视幅度较大，峰值速度较高，起始潜伏期较短（p<0.05）。与 DM1 相比，在后循环卒中（中枢性前庭病变）中，扫视峰值速度较高，但幅度和起始潜伏期无显著差异。
VOR 损害在 DM1 和 DM2 中很常见。在 DM1 中，重定位扫视特征更接近中枢性而非周围性前庭病变。在 DM1 患者中观察到的 vHIT 眼速度曲线的峰延迟可能反映了眼外肌无力。DM1 中的 VOR 损害和 VOR 不对称与平衡和跌倒有关。
