Deep brain stimulation of the subthalamic nucleus in PD: an analysis of the exclusion causes

Objective: Deep Brain Stimulation (DBS) of the Subthalamic Nucleus (STN) represents a proper choice for the treatment of advanced Parkinson's disease (PD). A correct selection of the patients as candidates for the surgery is essential for a good outcome. In this study, we analyzed the exclusion causes of a series of PD patients hospitalized for the selection protocol. Methods: Ninety-eight PD patients as potential candidates for the STN DBS were studied. All patients were hospitalized and underwent a clinical evaluation of the PD stage, a levodopa challenge, a MR of the brain and a neuropsychological assessment. Results: The percentage of subjects considered not suitable for the surgery was 29.6%. A single cause of exclusion was present in 65.5% of not suitable patients, while multiple causes were present in 34.5%. The most frequent cause of exclusion was the finding of neuropsychological or psychic disorders (48.3%); in 37.9% of the patients, the motor disability was not severe enough to justify the surgery, while in 31%, we found relevant abnormalities at the brain MR. Three patients (10.3%) were poorly motivated for the surgery, while in three others (10.3%), we found a significant illness other than PD. Conclusions: The finding that about 30% of the PD patients potentially suitable for STN DBS presents some exclusion causes underlines the importance of a careful selection of the candidates for this surgery.