Lee Silverman Voice Treatment for dysarthria in patients with Parkinson's Disease: a systematic review and a meta-analysis.

BACKGROUND AND OBJECTIVE Approximately 89% of patients with Parkinson's disease (PD) suffer from dysarthria. Lee Silverman Voice Treatment (LSVT), a behavioral therapy, aims at improving speech and voice functions. The objective was to assess the effectiveness of LSVT compared with other/no speech interventions for dysarthria in patients with PD. METHODS Electronic databases, including PubMed, Embase and the Cochrane Library, were searched. The publication date of all included studies was prior to 6 March 2020. Only randomized controlled trials (RCTs) that evaluated the LSVT intervention compared to other/no speech intervention were considered. The data obtained from the included studies were described and the mean differences were calculated. RESULTS Eight RCTs were included in this meta-analysis comparing LSVT with other /no speech interventions. In the comparison of LSVT versus no intervention, vocal intensity for sustained "Ah" phonation, reading the "Rainbow passage", monologue and describing a picture increased by 8.87 dB, 4.34 dB, 3.25 dB, 3.31 dB, respectively, after 1 month of therapy. Compared with the respiratory therapy group, the LSVT group also showed significant improvement in vocal intensity for sustained "Ah" phonation, reading the "Rainbow passage" and monologue immediately after treatment (13.39 dB, 6.66 dB, 3.19 dB). Positive improvement still existed after 24 months. There was no difference in the therapeutic effect between face-to-face LSVT and online-LSVT. CONCLUSIONS The effectiveness of LSVT for dysarthria in patients with PD was verified in these trials. However, future RCTs with sufficient participants are still essential to evaluate the effectiveness of LSVT for dysarthria.