The Effects of Non-Pharmacological Therapies for Dysphagia in Parkinson’s Disease: A Systematic Review

Background: Parkinson’s disease (PD) is currently the second most common degenerative neurological disorder globally, with aspiration pneumonia caused by difficulty swallowing being the deadliest complication. The patient’s subjective experience and the safety of swallowing have been the main focus of previous evaluations and treatment plans. The effectiveness of treatment may be attributed to the brain’s ability to adapt and compensate. However, there is a need for more accurate assessment methods for dysphagia and further research on how treatment protocols work. Objective: This systematic review was designed to assess the effectiveness and long-term impact of published treatment options for swallowing disorders in patients with PD. Methods: In adherence to the Preferred Reporting Items for Reviews and Meta-analysis (PRISMA) guidelines, we conducted a systematic review where we thoroughly searched multiple databases (PubMed, Web of Science, Elsevier, and Wiley) for clinical studies published in various languages until December, 2023. Two reviewers evaluated the studies against strict inclusion/exclusion criteria. Results: This systematic review included a total of 15 studies, including 523 participants, involving six treatment approaches, including breath training, deep brain stimulation, reduction of upper esophageal sphincter (UES) pressure, transcranial magnetic stimulation, postural compensation, and video-assisted swallowing therapy. Primary outcomes included video fluoroscopic swallowing study (VFSS), fiberoptic endoscopic evaluation of swallowing (FEES), high-resolution pharyngeal impedance manometry (HPRIM), and functional magnetic resonance imaging (fMRI). Conclusion: Treatments that reduce UES resistance may be an effective way to treat dysphagia in PD patients. HRPIM can quantify pressure changes during the pharyngeal period to identify patients with reduced swallowing function earlier. However, due to the limited number of randomized controlled trials (RCTs) included and the high risk of bias in some studies, large-scale RCTs are needed in the future, and objective indicators such as HRPIM should be used to determine the effectiveness and long-term impact of different therapies on dysphagia in PD patients.