A Systematic Review and Meta-Analysis of Non-Invasive Nerve Stimulation Interventions on Dysphagia in Patients with Parkinson’s Disease

Pengbo Wang,1 Hong Huo,2 Ying Zhang,2 Qianshi Zhang,1 Xinzhe Tan,1 Shiqiang Zhang,3 Dongyan Wang1,2 1The Graduate School, Heilongjiang University of Chinese Medicine, Harbin, Heilongjiang Province, People’s Republic of China; 2Department of Acupuncture, Heilongjiang University of Chinese Medicine Second Affiliated Hospital, Harbin, Heilongjiang Province, People’s Republic of China; 3Hebei Province Key Laboratory of Integrated Traditional and Western Medicine in Neurological Rehabilitation, Hebei Province Cangzhou Hospital of Integrated Traditional Chinese and Western Medicine, Cangzhou, Hebei Province, People’s Republic of ChinaCorrespondence: Dongyan Wang, Heilongjiang University of Chinese Medicine, No. 24, Heping Road, Xiangfang District, Harbin, Heilongjiang, People’s Republic of China, Email [email protected]: Dysphagia is a non-motor symptom in patients with Parkinson’s disease (PD). Non-invasive nerve stimulation therapy is used to treat dysphagia; it has the advantages of being non-invasive, painless, safe, and easily accepted by patients.Design: Systematic review and meta-analysis.Setting: Randomized controlled trials (RCTs) conducted on dysphagia treatment in patients with PD using non-invasive nerve stimulation as an adjuvant or standalone therapy were identified by searching PubMed, Web of Science, Embase, Cochrane Library, China National Knowledge Infrastructure, Wanfang Data, VIP database, and CBMdisc. Papers published between January 1, 2013, and July 31, 2023, were retrieved.Participants: Patients with PD.Interventions: Non-invasive nerve stimulation on dysphagia.Primary and Secondary Outcome Indicators: The outcome indicators included Standardized Swallowing Assessment (SSA), Penetration-Aspiration Scale (PAS), Videofluoroscopic Swallowing Study (VFSS) scores, and clinical effectiveness rates. RevMan 5.4 software was used for the data consolidation analysis.Results: This study included nine RCTs, with five and four interventions involving neuromuscular electrical stimulation (NMES) and repetitive transcranial magnetic stimulation (rTMS), respectively. In total, 613 participants were included in the study, 303 and 310 in the control and experimental groups, respectively. The meta-analysis showed heterogeneity in the combined effects of the SSA and PAS indicators. The subgroup analysis results showed that NMES and rTMS adjuvant therapies significantly reduced SSA scores. NMES as an adjuvant therapy significantly reduced PAS scores, but rTMS had no significant difference in improving PAS scores in the experimental group compared with the control group. Non-invasive nerve stimulation can significantly improve VFSS scores and clinical effectiveness rates.Conclusion: NMES and rTMS can be an effective adjuvant therapy for treating dysphagia in patients with PD and improving their swallowing function. However, this conclusion is limited owing to the literature quality. Therefore, it should be verified using high-quality clinical RCTs.Plain Language Summary: This study searched seven databases over the past decade for research on non-invasive neural stimulation therapy for swallowing disorders in patients with Parkinson’s disease.This study summarized all non-invasive neural stimulation methods for treating swallowing disorders in patients with Parkinson’s disease and conducted a subgroup analysis.This study summarized the stimulation parameters of non-invasive neural stimulation for the treatment of swallowing disorders in patients with Parkinson’s disease.This study only searched databases in both Chinese and English, which may have led to a lack of research in other languages.Keywords: non-invasive nerve stimulation, dysphagia, Parkinson’s disease, meta-analysis, systematic review