Predictors of the emergence of apathy after bilateral stimulation of the subthalamic nucleus in patients with Parkinson's disease.

Abstract

Subthalamic nucleus deep brain stimulation (STN-DBS) is a valid therapeutic tool that ameliorates motor symptoms in patients with Parkinson's disease (PD). However, apathy is one of the neuropsychiatric complications that may occur after STN-DBS surgery, and this may adversely influence the quality of life of patients despite significant motor improvement. This study aimed to elucidate preoperative predictive factors for the presence of postoperative apathy in patients treated with STN-DBS. Twenty-five consecutive PD patients receiving bilateral STN-DBS were recruited. The assessment instruments include modified Hoehn & Yahr stages, Unified Parkinson's Disease Rating Scale motor (part III) and dyskinesia (part IVa) scores, Parkinson's Disease Questionnaire-39 scores, Self-Rating Depression Scale scores, and Apathy Scale scores. Predictive factors for postoperative apathy were assessed. While STN-DBS resulted in a significant improvement in motor symptoms, six patients (24%) developed significant apathy after surgery. In multiple logistic regression analyses, preoperative severity of dyskinesia was found to be an independent predictor for the acute phase of postoperative apathy with STN-DBS (odds ratio = 89.993, p = 0.003). This study suggests that preoperative dyskinesia may predict postoperative apathy in the acute phase in patients with PD treated with STN-DBS. The pathogenesis of postoperative apathy remains unknown, but in patients with severe dyskinesia before STN-DBS, attention should be given to monitoring for postoperative apathy.