Retrospective review of factors leading to dissatisfaction with subthalamic nucleus deep brain stimulation during long-term management

BACKGROUND Subthalamic nucleus deep brain stimulation is effective in reducing motor symptoms in appropriately selected patients with Parkinson's disease. We identified factors that contribute to poor outcomes during early, middle and late stages of stimulation management in a series of patients that were referred for troubleshooting poor outcomes. METHODS We performed a retrospective review of 50 patients with bilateral STN DBS seen in our movement disorders clinic with unsatisfactory clinical response and/or patient dissatisfaction with deep brain stimulation outcome. All patients underwent a systematic evaluation to assess the primary cause of suboptimal outcome including lead position, hardware integrity, patient selection, patient expectations, effective use of stimulation settings, and pre- and postoperative levodopa responsive symptoms. The data was also analyzed by duration of stimulation to determine if these factors varied by stage of DBS management. RESULTS Our series included patients implanted 4-68 months. We identified the following primary factors impacting outcome: Suboptimal stimulation settings (52%), disease progression (16%), inappropriate patient selection (10%), hardware damage (8%), lead malposition (8%), met expected motor outcomes (6%). Lead revision surgery occurred in 14%. Reversible factors accounted for dissatisfaction in 74%. Suboptimal stimulation was the dominant factor affecting outcomes in early and long-term management phases. CONCLUSION STN DBS outcomes can be improved even years after implantation. Stimulation parameters warrant investigation throughout the continuum of DBS management as a reversible cause of poor outcomes.