Abstract
Investigate the association between levodopa therapy and vocal characteristics in Parkinson's disease patients. Studies published at MEDLINE, LILACS, and SciELO, from 1960 to December 2016. A systematic review and meta-analysis was performed using the following keywords: Parkinson's disease; levodopa; L-dopa; voice; speech disorders; dysphonia; dysarthria. After analyzing titles and abstracts, two independent reviewers selected all clinical trials that met the eligibility criteria and selected the articles and the data recorded in a previously standardized table. Trials published in English between 1960 and December 2016 individuals with clinical diagnosis of Parkinson's disease; use of levodopa therapy in stable doses; acoustic analysis combined or not with auditory-perceptual analysis to evaluate the vocal parameters under investigation. The following vocal parameters were analyzed: fundamental frequency (F 0), jitter, and vocal intensity. Standardized mean differences (SMD) were calculated using the Comprehensive Meta-analysis V2 software. Nine articles met the eligibility criteria and were selected, with a total of 119 individuals. From these, six articles with 83 individuals were included in the meta-analysis. During the levodopa therapy "on" state, modifications in F 0 (SMD=0.39; 95% CI - 0.21-0.57) and jitter (SMD=0.23; 95% CI - 0.02-0.45) were observed. Vocal intensity was not affected (SMD=0.09; 95% CI - 0.22-0.39) by levodopa ingestion. Data of the included studies were controversial in the auditory-perceptual analysis of voice. Levodopa therapy modifies F0 and jitter. No changes in vocal intensity were observed in either the "on" or "off" states of levodopa therapy.
Highlights
Parkinson’s disease (PD) is characterized by bradykinesia, rigidity, tremor, and postural instability, associated with non-motor symptoms such as dementia, mood disorders, and pain[1]
Nine articles were included in this systematic review with a total of 119 individuals
In the third study, which analyzed the acoustic of prosody, no modifications in fundamental frequency (F0) and vocal intensity after levodopa therapy were found in ten individuals with Parkinson’s disease (PD)(23)
Summary
Parkinson’s disease (PD) is characterized by bradykinesia, rigidity, tremor, and postural instability, associated with non-motor symptoms such as dementia, mood disorders, and pain[1]. In the third study, which analyzed the acoustic of prosody, no modifications in fundamental frequency (F0) and vocal intensity after levodopa therapy were found in ten individuals with Parkinson’s disease (PD)(23). The meta-analysis included six articles that used acoustic analysis to evaluate the vocal outcomes through the following analytical programs: Kay Elemetrics, Cspeech 4.0, and Praat.
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