Bilateral cerebellar intermittent theta-burst stimulation combined with laryngeal elevation training promotes neurorestoration in post-stroke dysphagia

Previous studies have shown that pharyngeal elevation training can improve swallowing function in stroke patients, but the central nervous system interventions have limited effects. Intermittent theta burst stimulation (iTBS) applied to bilateral cerebellar hemispheres may enhance cortical excitability. However, the efficacy and underlying mechanisms of combining bilateral cerebellar iTBS with real-time biofeedback-guided pharyngeal elevation training for post-stroke dysphagia remain unclear. This study aims to investigate the combined effect of bilateral cerebellar iTBS and biofeedback-guided pharyngeal elevation training on swallowing function and cortical activity in stroke patients during the recovery phase. Methods: 45 stroke patients were randomized into the Control, Sham-iTBS + SET, or Active-iTBS + SET groups (n = 15 each). The latter two groups received additional interventions: Sham or active bilateral cerebellar iTBS combined with swallowing exercises. 42 participants (n = 14 per group) completed the study and were included in the final analysis, following 3 dropouts (n = 1 per group). Swallowing function was assessed using the Standardized Swallowing Assessment (SSA) and Penetration-Aspiration Scale (PAS) before and after 4 weeks of treatment. Functional near-infrared spectroscopy (fNIRS) recorded cortical activation during tasks and resting-state functional connectivity. After 4 weeks of intervention, all groups demonstrated significant improvements in the primary outcome (SSA) and the secondary behavioral outcome (PAS) scores (p < 0.05). Compared to the Control Group, both Sham-iTBS + SET and Active-iTBS + SET showed superior clinical improvements (p < 0.05); notably, the Active-iTBS + SET group significantly outperformed the Sham-iTBS + SET Group (p < 0.05) in both SSA and PAS recovery. Secondary fNIRS analysis revealed that the Active-iTBS + SET group significantly increased activation of the right prefrontal cortex (RPFC) and premotor areas (PM). This was accompanied by enhancing interhemispheric and intra-network functional connectivity, particularly between the PFC and other regions, and between M1 and PM (p < 0.05). Furthermore, local node connectivity was increased (p < 0.05). Correlation analysis indicated that the clinical improvements in SSA scores were positively correlated with neural activation observed in RPM and RPFC (p < 0.05). Bilateral cerebellar iTBS combined with pharyngeal elevation training significantly improves swallowing function in post-stroke dysphagia patients, may be associated with increased activation of the right prefrontal cortex and premotor areas, and enhanced cortico-cortical connectivity. The RPM region may serve as a potential neural target for cerebellar iTBS in stroke rehabilitation.