Kukkar Komal K, Rao Nishant, Huynh Diana, Shah Sheel, Contreras-Vidal Jose L, Parikh Pranav J
Center for Neuromotor and Biomechanics Research, Department of Health and Human Performance, University of Houston, Houston, Texas.
Haskins Laboratories, Yale University, New Haven, Connecticut.
medRxiv. 2023 Jul 23:2023.07.17.23292472. doi: 10.1101/2023.07.17.23292472.
Balance control is an important indicator of mobility and independence in activities of daily living. How the changes in functional integrity of corticospinal tract due to stroke affects the maintenance of upright stance remains to be known. We investigated the changes in functional coupling between the cortex and lower limb muscles during a challenging balance task over multiple frequency bands in chronic stroke survivors. Eleven stroke patients and nine healthy controls performed a challenging balance task. They stood on a computerized platform with/without somatosensory input distortion created by sway-referencing the support surface, thereby varying the difficulty levels of the task. We computed corticomuscular coherence between Cz (electroencephalography) and leg muscles and assessed balance performance using Berg Balance scale (BBS), Timed-up and go (TUG) and center of pressure (COP) measures. We found lower delta frequency band coherence in stroke patients when compared with healthy controls under medium difficulty condition for distal but not proximal leg muscles. For both groups, we found similar coherence at other frequency bands. On BBS and TUG, stroke patients showed poor balance. However, similar group differences were not consistently observed across COP measures. The presence of distal versus proximal effect suggests differences in the (re)organization of the corticospinal connections across the two muscles groups for balance control. We argue that the observed group difference in the delta coherence might be due to altered mechanisms for the detection of somatosensory modulation resulting from sway-referencing of the support platform for balance control.
平衡控制是日常生活活动中运动能力和独立性的重要指标。中风导致的皮质脊髓束功能完整性变化如何影响直立姿势的维持仍有待了解。我们研究了慢性中风幸存者在具有挑战性的平衡任务中多个频段上皮质与下肢肌肉之间功能耦合的变化。11名中风患者和9名健康对照者进行了一项具有挑战性的平衡任务。他们站在一个计算机化平台上，通过对支撑面进行摇摆参考来创建/不创建体感输入失真，从而改变任务的难度级别。我们计算了Cz（脑电图）与腿部肌肉之间的皮质肌肉相干性，并使用伯格平衡量表（BBS）、计时起立行走测试（TUG）和压力中心（COP）测量来评估平衡性能。我们发现，在中等难度条件下，中风患者远端而非近端腿部肌肉的δ频段相干性低于健康对照者。对于两组，我们在其他频段发现了相似的相干性。在BBS和TUG测试中，中风患者表现出平衡能力较差。然而，在COP测量中并未始终观察到类似的组间差异。远端与近端效应的存在表明，在平衡控制方面，两个肌肉群的皮质脊髓连接（重新）组织存在差异。我们认为，观察到的δ相干性组间差异可能是由于平衡控制中支撑平台摇摆参考导致的体感调制检测机制改变所致。
