Effects of Motion-Style Scalp Acupuncture on External Capsule Microstructure and Spinal Reflex Excitability in a Rat Model of Post-Stroke Spasticity.

Post-stroke spasticity (PSS) severely impairs motor function and quality of life after stroke. Disruption of the cortico-reticulospinal pathway and impaired supraspinal descending inhibition are considered important pathological mechanisms; however, the neural and microstructural mechanisms underlying the therapeutic effects of motion-style scalp acupuncture (MSSA) remain incompletely understood. This study aimed to investigate the effects of MSSA on PSS using a multimodal assessment integrating neuroimaging, electrophysiology, and histology in a rat model of middle cerebral artery occlusion. T2-weighted magnetic resonance imaging was performed to quantify cerebral infarct volume, and diffusion tensor imaging was used to evaluate the microstructural integrity of the external capsule white matter. Luxol Fast Blue (LFB) staining assessed myelin integrity within the external capsule, while H-reflex recordings evaluated spinal reflex excitability. Correlation analyses were performed to examine the relationships among infarct volume, white matter microstructure, spinal reflex excitability, and spasticity severity. MSSA reduced cerebral infarct volume, alleviated external capsule microstructural damage, and attenuated demyelination. In addition, MSSA improved abnormal H-reflex parameters, normalized spinal reflex excitability, and reduced spasticity. Correlation analyses showed that larger infarcts were associated with greater external capsule injury, whereas better-preserved white matter integrity was associated with improved spinal reflex regulation and less severe spasticity. These findings suggest that MSSA may alleviate PSS by reducing ischemic brain injury, preserving external capsule microstructural integrity, and improving cortico-reticulospinal pathway-associated descending inhibitory function, providing preclinical evidence supporting its therapeutic application.