Objective: To assess the effect of speech and language therapy (SLT) on Hypokinetic dysarthria (HD) in Parkinson's disease.
Design: Systematic review and meta-analysis of randomized controlled trials.
Methods: We performed a literature search of randomized controlled trials using PubMed, Web of Science, Science Direct and Cochrane database (last search October 2020). Quality assessment and risk of bias were assessed using the Downs and Black scale and the Cochrane tool. The data were pooled and a meta-analysis was completed for sound pressure levels, perceptual intelligibility and inflection of voice fundamental frequency.
Results: We selected 15 high to moderate quality studies, which included 619 patients with Parkinson's disease. After pooling the data, 7 studies, which compared different speech language therapies to no treatment, control groups and 3 of their variables, (sound pressure level, semitone standard deviation and perceptual intelligibility) were included in the analysis.Results showed significant differences in favor of SLT for sound pressure level sustained phonation tasks (standard mean difference = 1.79; 95% confidence interval = 0.86, 2.72; p ⩽ 0.0001). Significant results were also observed for sound pressure level and semitone standard deviation in reading tasks (standard mean difference = 1.32; 95% confidence interval = 1.03, 1.61; p ⩽ 0.0001). Additionally, sound pressure levels in monologue tasks showed similar results when SLT was compared to other treatments (standard mean difference = 0.87; 95% confidence interval = 0.46, 1.28; p ⩽ 0.0001).
Conclusion: This meta-analysis suggests a beneficial effect of SLT for reducing Hypokinetic Dysarthria in Parkinson's disease, improving perceptual intelligibility, sound pressure level and semitone standard deviation.
Keywords: Hypokinetic Dysarthria; Lee Silverman Voice Treatment; Parkinson’s disease; language disorders; speech language therapy.