Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
Neuroscience. 2012 Aug 16;217:123-9. doi: 10.1016/j.neuroscience.2012.03.064. Epub 2012 Apr 24.
Balance control in Parkinson's disease is often studied using dynamic posturography, typically with serial identical balance perturbations. Because subjects can learn from the first trial, the magnitude of balance reactions rapidly habituates during subsequent trials. Changes in this habituation rate might yield a clinically useful marker. We studied balance reactions in Parkinson's disease using posturography, specifically focusing on the responses to the first, fully unpractised balance disturbance, and on the subsequent habituation rates.
Eight Parkinson patients and eight age- and gender-matched controls received eight consecutive toe-up rotations of a support-surface. Balance reactions were measured with a motion analysis system and converted to centre of mass displacements (primary outcome).
Mean centre of mass displacement during the first trial was 51% greater in patients than controls (P=0.019), due to excessive trunk flexion and greater ankle plantar-flexion. However, habituated trials were comparable in both groups. Patients also habituated slower: controls were fully habituated at trial 2, whereas habituation in patients required up to five trials (P=0.004). The number of near-falls during the first trial was significantly correlated with centre of mass displacement during the first trial and with habituation rate.
Higher first trial reactions and a slow habituation rate discriminated Parkinson's patients from controls, but habituated trials did not. Further work should demonstrate whether this also applies to clinical balance tests, such as the pull test, and whether repeated delivery of such tests offers better diagnostic value for evaluating fall risks in parkinsonian patients.
平衡控制在帕金森病中常通过动态姿势描记术来研究，通常采用连续相同的平衡扰动。由于受试者可以从第一次试验中学习，因此在随后的试验中，平衡反应的幅度会迅速习惯化。这种习惯化率的变化可能会产生一个有临床应用价值的标志物。我们使用姿势描记术研究帕金森病的平衡反应，特别是关注对第一次完全未经练习的平衡干扰的反应，以及随后的习惯化率。
8 名帕金森病患者和 8 名年龄和性别匹配的对照组接受了 8 次连续的支撑面脚趾向上旋转。平衡反应通过运动分析系统进行测量，并转换为质心位移（主要结果）。
患者在第一次试验中的质心位移平均比对照组高 51%（P=0.019），这是由于过度的躯干前屈和更大的踝关节跖屈。然而，两组的习惯化试验都是可比的。患者的习惯化速度也较慢：对照组在第 2 次试验时已经完全习惯化，而患者的习惯化需要多达 5 次试验（P=0.004）。第一次试验中的接近跌倒次数与第一次试验中的质心位移和习惯化率显著相关。
较高的第一次试验反应和较慢的习惯化率将帕金森病患者与对照组区分开来，但习惯化试验并没有。进一步的研究应该证明这是否也适用于临床平衡测试，如拉测试，以及这种测试的重复提供是否为评估帕金森病患者跌倒风险提供了更好的诊断价值。
