Evaluation of the word fluency in parkinson's disease patients treated with deep brain stimulation-a pilot study-

Parkinson's disease is a chronic, progressive and common disease of neurological disorders. Motor complication in parkinson's disease (PD) is resting tremor, slow movement, rigidity and postural instability. The motor symptoms of PD respond well to bilateral deep brain stimulation (DBS). Recent study, there are also reports of worsened verbal fluency, executive dysfunction, and processing speed with DBS. Whether subthalamic nuclei (STN) stimulation worsens there are under debate. The aim of this study was to explore the effects of STN stimulation verbal fluency as assessed with clinical neuropsychological tests. Eight patients treated with deep brain stimulation were enrolled, and some of the patients continued anti-PD medications. Assessments were done both with the STN stimulation turned OFF and ON. In both test conditions, the following were assessed: speech , word fluency A, and B. The score of the word fluency test of all patients have undergone DBS surgery significantly worsened as compared with before surgery. Five patients speech ware worsened, but three patients were improved when the STN stimulation was turned OFF. On the other hand, five patients were reduced the word fluency's total score when the STN stimulation was turned OFF. In this sample, STN stimulation significantly worsened the result of the word fluency test. When the STN stimulation was turned OFF, it was reduced. These finding suggests that STN-DBS might be worse speech conditions and verbal fluency.