Rao Ashwini K, Louis Elan D
Department of Rehabilitation & Regenerative Medicine (Physical Therapy), College of Physicians and Surgeons, Columbia University, New York, NY USA ; G.H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY USA ; Neurological Institute, 8th Floor, 710 West 168th Street, New York, NY 10032 USA.
Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT USA ; Department of Chronic Disease Epidemiology, Yale School of Medicine, Yale University, New Haven, CT USA ; Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, Yale University, New Haven, CT USA.
Cerebellum Ataxias. 2016 Mar 2;3:5. doi: 10.1186/s40673-016-0043-5. eCollection 2016.
Essential tremor (ET) is a common movement disorder characterized by kinetic, postural and intention tremors. Mounting evidence suggests an underlying dysfunction of the cerebellum or cerebellar system. While few recent studies report impairments in timing control of finger movements in ET, timing control of gait has not been examined to date. We compared timing control of gait in ET patients vs. controls, and further assessed the association of these timing impairments with tremor severity among the ET patients. One-hundred-fifty-five ET patients and 60 age-matched controls underwent a comprehensive neurological assessment and gait analysis, which included walking at a criterion step frequency (cadence) with a metronome (timing production) and walking at a criterion step frequency after the metronome was turned off (timing reproduction). Outcomes of interest for both conditions were timing accuracy (measured by cadence error) and timing precision (measured by cadence variability). We also assessed cadence and step time across conditions.
Cadence was lower in ET patients than controls (p < 0.03), whereas step time was similar for ET patients and controls. Accuracy (cadence error) and precision (cadence variability) were not different in ET patients compared with controls. Cranial tremor score was significantly associated with cadence (timing production condition, p = 0.003 and timing reproduction condition, p = 0.0001) and cadence error (timing production condition, p = 0.01). Kinetic tremor and intention tremor scores were not associated with gait measures.
ET patients do not demonstrate impairments in timing control of gait as compared with matched controls. Prior work shows that patients with cerebellar dysfunction demonstrate selective impairments in timing of discrete movements (such as finger tapping) but not continuous movements (such as circle drawing). Taken together, these results support the hypothesis that the cerebellum may be important for timing control of discrete rather than continuous movements.
特发性震颤（ET）是一种常见的运动障碍，其特征为运动性、姿势性和意向性震颤。越来越多的证据表明存在小脑或小脑系统的潜在功能障碍。虽然最近很少有研究报道ET患者手指运动的时间控制受损，但迄今为止尚未对步态的时间控制进行研究。我们比较了ET患者与对照组的步态时间控制，并进一步评估了这些时间控制受损与ET患者震颤严重程度之间的关联。155例ET患者和60例年龄匹配的对照组接受了全面的神经学评估和步态分析，其中包括在节拍器的标准步频（步幅）下行走（时间产生）以及在节拍器关闭后以标准步频行走（时间再现）。两种情况下感兴趣的结果均为时间准确性（以步幅误差衡量）和时间精度（以步幅变异性衡量）。我们还评估了不同条件下的步幅和步长。
ET患者的步幅低于对照组（p < 0.03），而ET患者和对照组的步长相似。与对照组相比，ET患者的准确性（步幅误差）和精度（步幅变异性）没有差异。头部震颤评分与步幅（时间产生条件下，p = 0.003；时间再现条件下，p = 0.0001）和步幅误差（时间产生条件下，p = 0.01）显著相关。运动性震颤和意向性震颤评分与步态指标无关。
与匹配的对照组相比，ET患者在步态时间控制方面未表现出受损。先前的研究表明，小脑功能障碍患者在离散运动（如手指敲击）的时间控制上表现出选择性受损，但在连续运动（如画圈）中则未受损。综上所述，这些结果支持以下假设：小脑可能对离散而非连续运动的时间控制很重要。
