Digital voice analysis in patients with advanced Parkinson's disease undergoing deep brain stimulation therapy.

INTRODUCTION An acoustic analysis was conducted of the voice of 25 patients with Parkinson's disease (PD) subjected to deep brain stimulation (DBS) to assess the impact of therapy. MATERIALS AND METHODS We examined 25 patients with advanced PD under four different conditions: deprived of medical treatment, under medical treatment, and one week and one month after the implant of the DBS electrodes. At the four time points, the patients produced a sustained /a/ and a standard sentence in Spanish, and microphone and electroglottographic recordings were digitally analyzed using the Computerized Speech Lab program. RESULTS Waveform analysis of the sustained /a/ captured by the microphone indicated a higher fundamental frequency (F(0)) when the patients were under levodopa treatment. The frequency perturbation (jitter) decreased remarkably after the three treatments. Shimmer also fell, but differences were not significant. CONCLUSIONS Nearly all acoustic analysis parameters during phonation of a sustained /a/ improved after DBS, but the factor that was most sensitive to the impact of both surgical and medical therapy was jitter.