German Center for Vertigo and Balance Disorders (DSGZ), Ludwig-Maximilians-University of Munich, Munich, Germany.
Department of Neurology, Ludwig-Maximilians-University of Munich, Munich, Germany.
J Parkinsons Dis. 2022;12(5):1611-1618. doi: 10.3233/JPD-213127.
Postural instability is a major disabling factor in patients with advanced Parkinson's disease (PD) and often resistant to treatment. Previous studies indicated that imbalance in PD may be reduced by low-intensity noisy galvanic vestibular stimulation (nGVS).
To investigate the potential mode of action of this therapeutic effect. In particular, we examined whether nGVS-induced reductions of body sway in PD are compatible with stochastic resonance (SR), a mechanism by which weak sensory noise stimulation can paradoxically enhance sensory information transfer.
Effects of nGVS of varying intensities (0-0.7 mA) on body sway were examined in 15 patients with PD standing with eye closed on a posturographic force plate. We assumed a bell-shaped response curve with maximal reductions of sway at intermediate nGVS intensities to be indicative of SR. An established SR-curve model was fitted on individual patient outcomes and three experienced human raters had to judge whether responses to nGVS were consistent with the exhibition of SR.
nGVS-induced reductions of body sway compatible with SR were found in 10 patients (67%) with optimal improvements of 23±13%. In 7 patients (47%), nGVS-induced sway reductions exceeded the minimally important clinical difference (optimal improvement: 30±10%), indicative of strong SR. This beneficial effect was more likely in patients with advanced PD (R = 0.45; p = 0.045).
At least half of the assessed patients showed robust improvements in postural balance compatible with SR when treated with low-intensity nGVS. In particular, patients with more advanced disease stages and imbalance may benefit from the non-invasive and well-tolerated treatment with nGVS.
姿势不稳是晚期帕金森病（PD）患者的主要致残因素，且往往对治疗有抗性。先前的研究表明，PD 患者的平衡障碍可以通过低强度噪声电刺激（nGVS）来减轻。
探讨这种治疗效果的潜在作用模式。特别是，我们检查了 nGVS 是否可以降低 PD 患者的身体摆动，这是否与随机共振（SR）兼容，后者是一种通过弱感觉噪声刺激可以反常地增强感觉信息传递的机制。
在 15 名闭眼站立在测姿平台上的 PD 患者中，检查了不同强度（0-0.7 mA）的 nGVS 对身体摆动的影响。我们假设存在一个钟形响应曲线，中间 nGVS 强度下的摆动最大减少表明存在 SR。对个体患者的结果进行了已建立的 SR 曲线模型拟合，并且三位经验丰富的人类评估者必须判断 nGVS 的反应是否与 SR 的表现一致。
在 10 名患者（67%）中发现 nGVS 诱导的身体摆动减少与 SR 兼容，最佳改善为 23±13%。在 7 名患者（47%）中，nGVS 诱导的摆动减少超过了最小的重要临床差异（最佳改善：30±10%），表明存在强烈的 SR。在晚期 PD 患者中，这种有益的效果更有可能发生（R = 0.45；p = 0.045）。
在接受低强度 nGVS 治疗的患者中，至少有一半患者的姿势平衡得到了与 SR 兼容的显著改善。特别是，处于更晚期疾病阶段和平衡障碍的患者可能会受益于 nGVS 这种非侵入性和耐受性良好的治疗方法。
