Presented at the 28th World Congress of the International Association of Logopedics and Phoniatrics, Athens, Greece, 22–26 August 2010

Aim: In the present study, we discuss in detail the acoustic characteristics in relation with articulatory and other cognitive motor executive tasks of speech of eight patients with Parkinson's Disease (PD), before and six months after surgical Subthalamic Nuclei Deep Brain Stimulation (STN-DBS) treatment.
Method: Eight patients with PD (N=8, mean age: 60.8) selected from the Department of Neurosurgery, Medical School, University of Athens, Greece, were assessed 3 days before the surgical procedure “on medication” state and six months post operation “on stimulation” state. The assessment protocol consisted of the Greek version of Frenchay Dysarthria Assessment (FDA), sustained phonation, reading words and texts, a descriptive monologue, a motor time reaction task, a speech/phonation reaction task and cognitive executive function tasks. Praat was used to analyze the recorded data. The Wilcoxon Signed Ranks Test was used for the statistical analysis.
Results: No significant differences were found in any tasks of articulatory functions, speech rate during reading, and acoustic measures. However, speech/phonation reaction time was found significantly increased in post-operation condition compared to pre-operation condition (p=0.0078). No such difference was found concerning the motor reaction task or the cognitive executive tasks. The variability among subjects observed in the articulatory functions was evident in these tasks too.
Discussion: Our data demonstrate that there were no significant changes in specific speech parameters in pre- and post-operational PD patients. This finding suggests that there may be no effect of STN-DBS treatment on articulatory and acoustic characteristics of speech in PD patients. However, cognitive tasks related to speech have changed.