Effects of behavioural swallowing therapy in patients with Parkinson's disease: A systematic review

Abstract

Purpose: A previous 2014 systematic review outlining the treatment effects of swallowing therapies in Parkinson's disease (PD) demonstrated a lack of well-designed randomised controlled studies. This current review presents and evaluates the latest evidence for behaviour swallowing therapies for PD-related dysphagia to enhance speech-language pathologists' evidence-based decision-making around treatment choices. Method: A systematic review of articles published in English and Korean was conducted from January 2014 through June 2020 using the electronic databases PubMed, Embase, and Cochrane Library. Two authors independently searched the literature and differences after the search were settled following discussion and consensus. Identified studies were evaluated for quality with the ABC rating scale and critical appraisal criteria. Result: Eight studies after initial search and three additional studies which met our original criteria but were not freely available, or published after the initial search period were also included. Eleven studies included the following treatments: biofeedback therapy (N = 1), respiratory-swallow coordination training (N = 2), neuromuscular electrical stimulation (NMES) (N = 1), expiratory muscle strength training (EMST) (N = 2), intensive exercise-based swallowing program (ISP) (N = 1), chin-down strategy (N = 2), Lee Silverman Voice Treatment (N = 1), and therapeutic singing (N = 1). Conclusion: Most of the behavioural therapies improved swallowing function in PD. Treatments that enhanced airway function globally demonstrated positive effects on swallow function as did intensive, targeted swallowing treatment. However, the chin-down strategy did not show a significant effect on swallowing measured by flexible endoscopic evaluations of swallowing. EMST detraining effects implied a need to design maintenance training in PD. In the future, well-designed randomised controlled trials are needed to consolidate the effects of these therapies.