Comparative efficacy and mechanistic insights of non-invasive neuromodulation and motor rehabilitation on functional reorganization of the supplementary motor area in subacute stroke: a narrative review

Subacute stroke patients frequently experience significant motor impairment. The supplementary motor area (SMA), a critical hub for motor control and functional brain reorganization, plays a pivotal role in recovery. However, traditional interventions such as drug therapy and conventional physical therapy often lack the spatial precision and causal efficacy required for directly and accurately remodeling specific dysfunctional circuits like the SMA in subacute stroke, which results in key challenges in current rehabilitation practice for correcting specific network imbalances and efficiently inducing task-related plasticity. This narrative review elucidates how two advanced, mechanism-driven strategies address these challenges. Non-invasive neuromodulation provides a precise top-down intervention method that can directly regulate the cortical excitability of SMA and its related networks, correcting pathological network imbalances, which is unmatched by traditional methods. In contrast, motor rehabilitation provides a powerful bottom-up, experience-dependent intervention that drives Hebbian plasticity through intensive, task-oriented training, specifically enhancing SMA activation and functional connectivity. Crucially, the major innovation lies in their strategic combination. Non-invasive neuromodulation primes the brain network for learning, while motor rehabilitation consolidates the induced plasticity, thereby yielding synergistic effects that maximize functional recovery. This review synthesizes current evidence on the efficacy and mechanisms of these interventions in promoting SMA reorganization following subacute stroke, analyzing their impacts on network modulation, neuroimaging correlates, and clinical outcomes. By integrating foundational research and clinical insights, it aims to establish a theoretical framework for refining precision, network-targeted rehabilitation strategies for post-stroke motor deficits in the subacute phase.