Sander T, Sprenger A, Neumann G, Machner B, Gottschalk S, Rambold H, Helmchen C
Department of Neurology, University Hospitals Schleswig-Holstein, Campus Lübeck, Lübeck, Germany.
Brain. 2009 Jan;132(Pt 1):103-15. doi: 10.1093/brain/awn306. Epub 2008 Nov 26.
The cerebellum is part of the cortico-ponto-cerebellar circuit for conjugate eye movements. Recent animal data suggest an additional role of the cerebellum for the control of binocular alignment and disconjugate, i.e. vergence eye movements. The latter is separated into two different components: fast vergence (to step targets) and slow vergence (to ramp and sinusoidal targets). The aim of this study was to investigate whether circumscribed cerebellar lesions affect these dynamic vergence eye movements. Disconjugate fast and slow vergence, conjugate smooth pursuit and saccades were binocularly recorded by a scleral search coil system in 20 patients with acute cerebellar lesions (all ischemic strokes except for one) and 20 age-matched healthy controls. Patients showed impairment of slow vergence while fast vergence was unaffected. Slow vergence gain to sinusoidal targets was significantly reduced, both in convergence and divergence direction. Divergence but not convergence velocity to ramp targets was reduced. Conjugate smooth pursuit eye movements to sinusoidal and to step-ramp targets were impaired. Patients had saccadic hypometria. All defects were particularly expressed in patients with vermis lesions. In contrast to recent animal data fast vergence was not impaired in any of our patient subgroups. We conclude that (i) the human cerebellum, in particular the vermis, is involved in the processing of dynamic vergence eye movements and (ii) cerebellar lesions elicit dissociable effects on fast and slow vergence.
小脑是共轭眼球运动的皮质-脑桥-小脑回路的一部分。最近的动物数据表明，小脑在控制双眼对齐和非共轭（即辐辏眼球运动）方面还有额外作用。后者可分为两个不同的成分：快速辐辏（针对阶跃目标）和慢速辐辏（针对斜坡和正弦目标）。本研究的目的是调查局限性小脑病变是否会影响这些动态辐辏眼球运动。通过巩膜搜索线圈系统对20例急性小脑病变患者（除1例为缺血性中风外，其余均为缺血性中风）和20名年龄匹配的健康对照者进行双眼记录，测量非共轭快速和慢速辐辏、共轭平稳跟踪和扫视。患者表现出慢速辐辏受损，而快速辐辏未受影响。在会聚和发散方向上，对正弦目标的慢速辐辏增益均显著降低。对斜坡目标的发散速度降低，但会聚速度未降低。对正弦和阶跃-斜坡目标的共轭平稳跟踪眼球运动受损。患者存在眼球扫视幅度减小。所有缺陷在蚓部病变患者中表现尤为明显。与最近的动物数据相反，在我们的任何患者亚组中，快速辐辏均未受损。我们得出结论：（i）人类小脑，尤其是蚓部，参与动态辐辏眼球运动的处理；（ii）小脑病变对快速和慢速辐辏产生不同的影响。
