The effect of levodopa on vocal function in Parkinson's disease

Phonatory and articulatory dysfunctions are frequent observations in Parkin son's disease. We have investigated, using acoustic measures, the effects o f levodopa treatment on vocal function in 20 patients with Parkinson's dise ase before and after levodopa. These patients were also compared with a mat ched control group. The mean age was 63.5 +/- 9.66 years, Hoehn-Yahr stage was 2.38 +/- 0.45, and onset mean age was 56.5 +/- 10.36 years. Paired Wilc oxon tests were performed to compare measurements before and after levodopa . The acoustic analysis using Computerized Speech Lab and MultiDimensional Voice Program software programs (Kay Elemetrics, Lincoln Park, NJ, USA) sho wed that measurements of fundamental frequency (p < 0.017) were significant ly increased after medication, whereas short-term frequency perturbation ji tter (p < 0.033), soft phonation index (noise parameter) (p < 0.015), and f requency tremor intensity index (p < 0.018) were significantly decreased af ter medication. The objective measurements of acoustic analysis are useful in evaluating the dopaminergic pharmacologic response in Parkinson's diseas e. The improvement in fundamental frequency and other vocal parameters may be a result of decrease in laryngeal hypokinesia and rigidity.