Effect of unilateral electrostimula nucleus on different speech subsyste

This paper reports our findings on the articulatory subsystem from an on-going investigation of the effect of unilateral deep brain stimulation (DBS) in Subthalamic Nucleus (STN) on different speech subsystems in Parkinson’s disease (PD). Previously, we have reported findings on the respiratory/phonatory subsystems. Speech recordings were made under three clinical conditions: before the surgery in the medication-off state (Baseline), and three months post surgery in the medication-off state with the Stimulation-off, and with Stimulation-on, in six consecutive subjects with a clinical diagnosis of idiopathic PD (five males, one female). The mean age was 55 (SD 9) years and the mean duration of disease 14.33 (SD 2.25) years. Based on which side of the body was more impaired, three of the six patients had the stimulator implanted in the left STN and three in the right STN. The off-medication state was achieved with the subjects withholding their PD medications for at least 12 hours before the assessment. Evaluators and subjects were blinded to the subjects' stimulator condition until after the data were analyzed. Speech tasks included six maximally sustained vowel phonation (MSVP), three diadochokinetic rates, reading sentences with varying stress, and a structured monologue. Acoustic analyses of diadochokinetic rates were reported. The results were compared to the subjects’ performance on non-speech motor tasks and measures in the respiratory/phonatory subsystems, both were reported previously [7]. It was found that for non-speech tasks, stimulation-on improved performance in all six subjects. For speech tasks, significant improvement in the respiratory/phonatory subsystems was only associated with the right STN stimulation. Measures in the articulatory subsystem was much less consistent across different testing conditions, indicating that the responses to the DBS in STN may not be as uniform in different speech subsystems.