Neuroplastic Mechanisms of Acupuncture in Post-Stroke Motor Recovery: A Randomized Multimodal MRI Trial

Abstract

Background: Hemiplegia is a common motor impairment following ischemic stroke. Post-stroke recovery involves extensive reorganization of structural and functional brain networks, which correlates with clinical deficits and recovery. While acupuncture has demonstrated safety and efficacy in improving motor function, robust neuroimaging evidence elucidating its central mechanisms remains limited. This study aimed to investigate the specific neuroplastic effects of acupuncture by focusing on its modulation of cortical gray matter volume (GMV) and multilayer dynamic functional network topology. Methods: Patients with stroke were randomly allocated in a 2:1 ratio to receive either true-acupoint (TA) or sham-acupoint (SA) over a two-week intervention period. Clinical outcomes were assessed using the Fugl-Meyer Assessment (FMA), Brunnstrom Scale, and the National Institutes of Health Stroke Scale (NIHSS). Neuroplastic changes were evaluated through GMV analysis and dynamic functional network metrics. Correlation analyses were performed to examine the relationships between post-acupuncture improvements in clinical scores and changes in neuroimaging indices. Results: The results demonstrated that: (1) Clinically, post-treatment improvements in NIHSS and FMA scores, but only the TA group exhibited significant gains in Brunnstrom scores, indicating superior motor recovery. (2) Functionally, TA modulated default mode network (DMN) dynamics, manifesting as significantly reduced disjointedness and a trend toward decreased flexibility. These changes correlated with better motor outcomes. No such modulatory effect was observed in the SA group. (3) Structurally, TA increased GMV in the right middle frontal gyrus, right postcentral gyrus, right angular gyrus, left superior parietal gyrus, left cerebellar Crus 1–2, 4–5, 7, bilateral middle occipital gyrus, superior temporal gyrus, angular gyrus of inferior parietal margin, dorsolateral superior frontal gyrus, inferior frontal gyrus of operculum, and cerebellar area 10. Increases in GMV in the right opercular inferior frontal gyrus, postcentral gyrus, and cerebellar region 10 were positively correlated with motor recovery in the TA group. No significant changes in GMV were detected in the SA group. Conclusions: TA treatment significantly alleviated neurological impairment and enhanced motor recovery. Its therapeutic effect is underpinned by specific neuroplastic changes: Functional modulation of DMN dynamics and structural promotion of gray matter plasticity in regions critical for sensorimotor and cognitive-motor integration, which are essential for movement control.