Treatment effects for dysphagia in Parkinson's disease: A systematic review

Background: Dysphagia remains a common problem in Parkinson's disease (PD). Previous systematic reviews on therapy effects for oropharyngeal dysphagia in PD have shown a lack of evidence. In the past 5 years several placebo or sham-controlled trials with varying results have been published. Objective: The aim of this systematic literature review is to summarize and qualitatively analyze the published studies on this matter. Method(s): Studies published up to December 2013 were found via a systematic comprehensive electronic database search using PubMed, Embase, and The Cochrane Library. Two reviewers independently assessed the studies using strict inclusion criteria. Result(s): Twelve studies were included and qualitatively analyzed using critical appraisal items. The review includes rehabilitative (exercises, electrical stimulation, bolus modification etc.) and pharmacologic treatment. Some well-designed controlled trials were included. However, none of the included studies fulfilled all criteria for external and internal validity. A meta-analysis was not carried out as most of the studies were not of sufficient quality to warrant doing so. Conclusion: Expiratory Muscle Strength Training.(EMST) and Video-Assisted Swallowing Therapy (VAST) may be effective dysphagia treatments solely or in addition to dopaminergic therapy for PD. However, these preliminary results warrant further investigation concerning their clinical applicability, and further research should be based on randomized sham-controlled trials to determine the effectiveness and long-term effects of different therapies for dysphagia in PD.