Anson Eric R, Bigelow Robin T, Carey John P, Xue Qian-Li, Studenski Stephanie, Schubert Michael C, Agrawal Yuri
Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University School of Medicine Baltimore, MD, USA.
Department of Medicine, Johns Hopkins University School of MedicineBaltimore, MD, USA; Center on Aging and Health, Johns Hopkins Medical InstitutionsBaltimore, MD, USA.
Front Aging Neurosci. 2016 Jun 24;8:150. doi: 10.3389/fnagi.2016.00150. eCollection 2016.
Vestibulo-ocular reflex (VOR) gain is well-suited for identifying rotational vestibular dysfunction, but may miss partial progressive decline in age-related vestibular function. Since compensatory saccades might provide an alternative method for identifying subtle vestibular decline, we describe the relationship between VOR gain and compensatory saccades in healthy older adults.
Horizontal VOR gain was measured in 243 subjects age 60 and older from the Baltimore Longitudinal Study of Aging using video head impulse testing (HIT). Saccades in each HIT were identified as either "compensatory" or "compensatory back-up," i.e., same or opposite direction as the VOR response respectively. Saccades were also classified as "covert" (occurring during head movement) and "overt" (occurring after head movement). The relationship between VOR gain and percentage of HITs with saccades, as well as the relationship between VOR gain and saccade latency and amplitude, were evaluated using regression analyses adjusting for age, gender, and race.
In adjusted analyses, the percentage of HITs with compensatory saccades increased 4.5% for every 0.1 decrease in VOR gain (p < 0.0001). Overt compensatory saccade amplitude decreased 0.6° (p < 0.005) and latency increased 90 ms (p < 0.001) for every 0.1 increase in VOR gain. Covert back-up compensatory saccade amplitude increased 0.4° for every 0.1 increase in VOR gain.
We observed significant relationships between VOR gain and compensatory saccades in healthy older adults. Lower VOR gain was associated with larger amplitude, shorter latency compensatory saccades. Compensatory saccades reflect underlying rotational vestibular hypofunction, and may be particularly useful at identifying partial vestibular deficits as occur in aging adults.
前庭眼反射（VOR）增益非常适合用于识别旋转性前庭功能障碍，但可能会遗漏与年龄相关的前庭功能的部分渐进性下降。由于代偿性扫视可能为识别细微的前庭功能下降提供一种替代方法，我们描述了健康老年人中VOR增益与代偿性扫视之间的关系。
使用视频头脉冲测试（HIT）对巴尔的摩纵向衰老研究中243名60岁及以上的受试者测量水平VOR增益。每次HIT中的扫视被识别为“代偿性”或“代偿性备用”，即分别与VOR反应方向相同或相反。扫视也被分类为“隐蔽性”（在头部运动期间发生）和“显性”（在头部运动之后发生）。使用针对年龄、性别和种族进行调整的回归分析，评估VOR增益与伴有扫视的HIT百分比之间的关系，以及VOR增益与扫视潜伏期和幅度之间的关系。
在调整分析中，VOR增益每降低0.1，伴有代偿性扫视的HIT百分比增加4.5%（p<0.0001）。VOR增益每增加0.1，显性代偿性扫视幅度降低0.6°（p<0.005），潜伏期增加90毫秒（p<0.001）。VOR增益每增加0.1，隐蔽性备用代偿性扫视幅度增加0.4°。
我们观察到健康老年人中VOR增益与代偿性扫视之间存在显著关系。较低的VOR增益与幅度较大、潜伏期较短的代偿性扫视相关。代偿性扫视反映了潜在的旋转性前庭功能减退，并且在识别老年人中出现的部分前庭缺陷时可能特别有用。
