Palmer Jacqueline A, Payne Aiden M, Mirdamadi Jasmine L, Ting Lena H, Borich Michael R
Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University, Atlanta, GA, USA.
Department of Psychology, College of Arts and Sciences, Florida State University, Tallahassee, FL, USA.
Neurorehabil Neural Repair. 2025 Jan;39(1):16-30. doi: 10.1177/15459683241282786. Epub 2024 Sep 27.
Slowed balance and mobility after stroke have been well-characterized. Yet the effects of unilateral cortical lesions on whole-body neuromechanical control is poorly understood, despite increased reliance on cortical resources for balance and mobility with aging. We tested whether individuals post stroke show impaired cortical responses evoked during reactive balance, and the effect of asymmetrical interlimb contributions to balance recovery and the evoked cortical response.
Using electroencephalography, we assessed cortical N1 responses evoked over fronto-midline regions (Cz) during backward support-surface perturbations loading both legs and posterior-lateral directions that preferentially load the paretic or nonparetic leg in individuals' post-stroke and age-matched controls. We tested relationships between cortical responses and clinical balance/mobility function, as well as to center of pressure (CoP) rate of rise (RoR) during balance recovery.
Cortical N1 responses were smaller and delayed after stroke ( < .047), regardless of perturbation condition. In contrast to controls, slower cortical response latencies associated with lower clinical function in stroke (Mini Balance Evaluation Systems Test: = -.61, = .007; Timed-Up-and-Go: = .53, = .024; walking speed: = -.46, = .055). Paretic-loaded balance recovery revealed slower CoP RoR ( = .012) that was associated with delayed cortical response latencies ( = -.70, = .003); these relationships were not present during bilateral and nonparetic-loaded conditions, nor in the older adults control group.
Individuals after stroke may be limited in their balance ability by the slowed speed of their cortical responses to destabilization. In particular, paretic leg loading may reveal cortical response impairments that reflect reduced paretic motor capacity.
中风后平衡和运动能力减缓已得到充分描述。然而，尽管随着年龄增长，平衡和运动对皮质资源的依赖增加，但单侧皮质损伤对全身神经力学控制的影响却知之甚少。我们测试了中风后个体在反应性平衡过程中诱发的皮质反应是否受损，以及不对称肢体间对平衡恢复和诱发皮质反应的影响。
我们使用脑电图，评估了在向后支撑面扰动期间，在额中线区域（Cz）诱发的皮质N1反应，该扰动使双腿负重，并在中风后个体和年龄匹配的对照组中，在向后外侧方向优先使患侧或非患侧腿负重。我们测试了皮质反应与临床平衡/运动功能之间的关系，以及与平衡恢复过程中压力中心（CoP）上升速率（RoR）的关系。
无论扰动条件如何，中风后皮质N1反应均较小且延迟（<0.047）。与对照组相比，中风患者中较慢的皮质反应潜伏期与较低的临床功能相关（简易平衡评估系统测试：r = -0.61，P = 0.007；计时起立行走测试：r = 0.53，P = 0.024；步行速度：r = -0.46，P = 0.055）。患侧负重的平衡恢复显示CoP RoR较慢（P = 0.012），这与延迟的皮质反应潜伏期相关（r = -0.70，P = 0.003）；在双侧和非患侧负重条件下以及老年对照组中不存在这些关系。
中风后的个体可能因其皮质对失稳反应速度减慢而限制了平衡能力。特别是，患侧腿负重可能揭示皮质反应受损，这反映了患侧运动能力下降。
