Neuromotor Rehabilitation Research Group, Department of Rehabilitation Sciences, KU Leuven, Leuven, Belgium.
School of Allied Health, Human Services and Sports, La Trobe University, Victoria, Australia.
J Parkinsons Dis. 2021;11(3):1367-1380. doi: 10.3233/JPD-202370.
People with Parkinson's disease and freezing of gait (FOG; freezers) suffer from pronounced postural instability. However, the relationship between these phenomena remains unclear and has mostly been tested in paradigms requiring step generation.
To determine if freezing-related dynamic balance deficits are present during a task without stepping and determine the influence of dopaminergic medication on dynamic balance control.
Twenty-two freezers, 16 non-freezers, and 20 healthy age-matched controls performed mediolateral weight-shifts at increasing frequencies when following a visual target projected on a screen (MELBA task). The amplitude and phase shift differences between center of mass and target motion were measured. Balance scores (Mini-BESTest), 360° turning speed and the freezing ratio were also measured. Subjects with Parkinson's disease were tested ON and partial OFF (overnight withdrawal) dopaminergic medication.
Freezers had comparable turning speed and balance scores to non-freezers and took more levodopa. Freezers produced hypokinetic weight-shift amplitudes throughout the MELBA task compared to non-freezers (p = 0.002), which were already present at task onset (p < 0.001). Freezers also displayed an earlier weight-shift breakdown than controls when OFF-medication (p = 0.008). Medication improved mediolateral weight-shifting in freezers and non-freezers. Freezers decreased their freezing ratio in response to medication.
Hypokinetic weight-shifting proved a marked postural control deficit in freezers, while balance scores and turning speed were similar to non-freezers. Both weight-shift amplitudes and the freezing ratio were responsive to medication in freezers, suggesting axial motor vigor is levodopa-responsive. Future work needs to test whether weight-shifting and freezing severity can be further ameliorated through training.
患有帕金森病和冻结步态（FOG；冻结者）的人会出现明显的姿势不稳。然而，这些现象之间的关系尚不清楚，并且大多在需要生成步幅的范式中进行了测试。
确定在无需迈步的任务中是否存在与冻结相关的动态平衡缺陷，并确定多巴胺能药物对动态平衡控制的影响。
22 名冻结者、16 名非冻结者和 20 名年龄匹配的健康对照组在跟随屏幕上投射的视觉目标时，以增加的频率进行侧向体重转移（MELBA 任务）。测量质心和目标运动之间的幅度和相位偏移差。还测量了平衡评分（Mini-BESTest）、360°转弯速度和冻结率。帕金森病患者在服用多巴胺能药物和部分停药（夜间停药）时接受测试。
冻结者的转弯速度和平衡评分与非冻结者相当，并且服用更多的左旋多巴。与非冻结者相比，冻结者在整个 MELBA 任务中产生的动力性体重转移幅度较小（p=0.002），在任务开始时就已经存在（p<0.001）。当停药时，冻结者也比对照组更早出现体重转移失败（p=0.008）。药物改善了冻结者和非冻结者的侧向体重转移。冻结者的冻结率随着药物的使用而降低。
动力性体重转移证明冻结者存在明显的姿势控制缺陷，而平衡评分和转弯速度与非冻结者相似。在冻结者中，体重转移幅度和冻结率均对药物有反应，这表明轴向运动活力对左旋多巴有反应。未来的工作需要测试通过训练是否可以进一步改善体重转移和冻结的严重程度。
