Bilateral neuromodulation outperforms unilateral stimulation for post-stroke dysphagia: a systematic review and meta-analysis

Background Post-stroke dysphagia is a frequent and serious complication associated with increased morbidity, mortality, and healthcare burden. Neuro-modulation techniques, such as repetitive transcranial magnetic stimulation and transcranial direct current stimulation, have shown promise in enhancing neuroplasticity and improving swallowing function. However, the comparative effectiveness of bilateral versus unilateral neuromodulation remains unclear. Aim This study aimed to systematically evaluate and compare the efficacy of bilateral versus unilateral neuromodulation in improving swallowing outcomes in patients with post-stroke dysphagia. Methods A systematic review and meta-analysis were conducted in accordance with PRISMA guidelines. A comprehensive search of PubMed, Scopus, and Web of Science was performed from inception to April 2026. Eligible studies included randomized controlled trials and cohort studies comparing bilateral and unilateral neuromodulation in adult stroke patients with dysphagia. Primary outcomes were Dysphagia Outcome and Severity Scale (DOSS) and Penetration–Aspiration Scale (PAS). Secondary outcomes included Functional Oral Intake Scale (FOIS), dysphagia assessment scales, and degree of dysphagia. Data were pooled using a random-effects model, and risk of bias was assessed using ROB2 and Newcastle–Ottawa Scale. Certainty of evidence was evaluated using GRADE. Results Seven studies (6 RCTs and 1 cohort) involving 231 patients were included. Bilateral neuromodulation was associated with significantly greater improvements than unilateral approaches across the evaluated outcomes although substantial heterogeneity was observed for the primary outcomes. DOSS improved significantly (MD = 0.97, 95% CI 0.12–1.82, p = 0.03), and PAS showed a significant reduction (MD = − 1.32, 95% CI − 2.60 to − 0.03, p = 0.04). Significant improvements were also observed in FOIS (MD = 0.92, p < 0.00001), dysphagia assessment scales (MD = 6.76, p < 0.00001), and degree of dysphagia (MD = − 1.09, 95% CI − 1.37 to − 0.80, p < 0.00001). Despite initial heterogeneity in primary outcomes, sensitivity analyses confirmed consistent direction of effect. Risk of bias was low across all RCTs, and GRADE assessment indicated moderate certainty for primary outcomes. Conclusion Bilateral neuromodulation may offer advantages over unilateral stimulation in improving swallowing function in post-stroke dysphagia. These findings suggest that bilateral neuromodulation may provide greater improvements in swallowing function than unilateral stimulation; however, substantial heterogeneity and limited number of studies warrant cautious interpretation and further large-scale trials to determine optimal stimulation protocols.