Department of Neurology, University Hospital Zurich, University of Zurich, Frauenklinikstr. 26, 8091, Zurich, Switzerland,
J Neurol. 2015 Aug;262(8):1837-49. doi: 10.1007/s00415-015-7773-9. Epub 2015 May 16.
The vestibulo-cerebellum calibrates the output of the inherently leaky brainstem neural velocity-to-position integrator to provide stable gaze holding. In healthy humans small-amplitude centrifugal nystagmus is present at extreme gaze-angles, with a non-linear relationship between eye-drift velocity and eye eccentricity. In cerebellar degeneration this calibration is impaired, resulting in pathological gaze-evoked nystagmus (GEN). For cerebellar dysfunction, increased eye drift may be present at any gaze angle (reflecting pure scaling of eye drift found in controls) or restricted to far-lateral gaze (reflecting changes in shape of the non-linear relationship) and resulting eyed-drift patterns could be related to specific disorders. We recorded horizontal eye positions in 21 patients with cerebellar neurodegeneration (gaze-angle = ±40°) and clinically confirmed GEN. Eye-drift velocity, linearity and symmetry of drift were determined. MR-images were assessed for cerebellar atrophy. In our patients, the relation between eye-drift velocity and gaze eccentricity was non-linear, yielding (compared to controls) significant GEN at gaze-eccentricities ≥20°. Pure scaling was most frequently observed (n = 10/18), followed by pure shape-changing (n = 4/18) and a mixed pattern (n = 4/18). Pure shape-changing patients were significantly (p = 0.001) younger at disease-onset compared to pure scaling patients. Atrophy centered around the superior/dorsal vermis, flocculus/paraflocculus and dentate nucleus and did not correlate with the specific drift behaviors observed. Eye drift in cerebellar degeneration varies in magnitude; however, it retains its non-linear properties. With different drift patterns being linked to age at disease-onset, we propose that the gaze-holding pattern (scaling vs. shape-changing) may discriminate early- from late-onset cerebellar degeneration. Whether this allows a distinction among specific cerebellar disorders remains to be determined.
前庭小脑校准固有渗漏脑干神经速度到位置积分器的输出，以提供稳定的凝视保持。在健康的人类中，小振幅离心性眼球震颤出现在极端凝视角度，眼漂移速度和眼偏心之间存在非线性关系。在小脑变性中，这种校准受到损害，导致病理性凝视诱发的眼球震颤（GEN）。对于小脑功能障碍，任何凝视角度都可能出现眼球漂移增加（反映了在对照组中发现的眼球漂移的纯缩放）或仅限于远外侧凝视（反映了非线性关系形状的变化），并且由此产生的眼球漂移模式可能与特定疾病有关。我们记录了 21 例小脑神经退行性变患者（凝视角度= ±40°）和临床确诊的 GEN 的水平眼球位置。确定了眼球漂移速度、线性度和漂移对称性。评估了磁共振成像的小脑萎缩情况。在我们的患者中，眼漂移速度和凝视偏心之间的关系是非线性的，导致（与对照组相比）在凝视偏心度≥20°时出现明显的 GEN。最常观察到纯缩放（n=10/18），其次是纯形状变化（n=4/18）和混合模式（n=4/18）。与纯缩放患者相比，纯形状变化患者的疾病发病年龄明显（p=0.001）较小。萎缩集中在上/背蚓部、绒球/旁绒球和齿状核，与观察到的特定漂移行为无关。小脑变性中的眼球漂移在幅度上有所不同；然而，它保持其非线性特性。不同的漂移模式与疾病发病年龄相关，我们提出凝视保持模式（缩放与形状变化）可区分早发性和晚发性小脑变性。这是否可以区分特定的小脑疾病还有待确定。
