Otolith function in cerebellar ataxia due to mutations in the calcium channel gene CACNA1A.
Otolith function in cerebellar ataxia due to mutations in the calcium channel gene CACNA1A.
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DOI：
10.1093/brain/124.12.2407
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发表时间：
2001-12
期刊：
影响因子：
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通讯作者：
G. Wiest;J. Tian;R. Baloh;B. Crane;J. Demer
中科院分区：
文献类型：
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作者：
G. Wiest;J. Tian;R. Baloh;B. Crane;J. Demer
在头部运动时，前庭-眼反射稳定视网膜图像。虽然关于小脑与半规管介导的前庭-眼反射之间的相互作用有丰富的信息，但关于小脑在耳石介导的线性前庭-眼反射（LVOR）的产生中的作用知之甚少。通过沿耳间轴的瞬时线性加速度，我们检测了6例由钙通道基因CACNA1A突变引起的遗传性小脑共济失调患者的LVOR，其中5例为脊髓小脑共济失调6型（SCA6）， 1例为发作性共济失调2型（EA-2）。6名年龄匹配的正常受试者作为对照。利用0.5 g的峰值加速度，结合双目巩膜磁搜索线圈法的记录，可以研究运动开始后150 ms LVOR的潜伏期和灵敏度。正常LVOR与观测距离密切相关，并与会聚角共变，可因可见目标的存在而增强。相比之下，共济失调患者的LVOR潜伏期正常，但敏感性明显降低，尽管正常收敛，但可见或更近的靶标并未增强。在运动开始后150-250 ms，共济失调患者用追赶性扫视代替正常的LVOR慢期。这些发现表明小脑在耳石-眼信号的调节中起着关键作用，而这种作用独立于运动收敛。
The vestibulo-ocular reflexes stabilize retinal images during head movements. While there is a wealth of information about the interaction between the cerebellum and vestibulo-ocular reflexes mediated by the semicircular canals, little is known about the role of the cerebellum in the generation of the otolith-mediated linear vestibulo-ocular reflex (LVOR). By means of transient linear acceleration of the whole body along the interaural axis, we examined the LVOR in six patients with hereditary cerebellar ataxia due to mutations of the calcium channel gene CACNA1A, five with spinocerebellar ataxia type 6 (SCA6) and one with episodic ataxia type 2 (EA-2). Six age-matched normal subjects served as controls. Using a peak acceleration of 0.5 g in combination with recording by the binocular scleral magnetic search coil method, it was possible to study the latency and sensitivity of the LVOR in the first 150 ms after motion onset. The normal LVOR showed a significant dependence on viewing distance and covaried with vergence angle, and could be enhanced by the presence of a visible target. In contrast, the LVOR of ataxic patients had normal latency but significantly decreased sensitivity that was not enhanced with visible or nearer targets despite normal vergence. Substituting for the normal smooth LVOR slow phase, ataxic patients employed catch-up saccades 150-250 ms after motion onset. These findings suggest a critical role of the cerebellum in the modulation of otolith-ocular signals that is independent of motor vergence.