Lack of Motor Symptoms Progression in Parkinson's Disease Patients With Long-Term Bilateral Subthalamic Deep Brain Stimulation

To evaluate the long-term progression of motor symptoms in Parkinson's disease (PD) patients treated with subthalamic nucleus deep brain stimulation (STN-DBS), we retrospectively analyzed data from 50 PD patients with bilateral STN-DBS. Clinical records at baseline and at several yearly intervals were reviewed. The Unified Parkinson's Disease Rating scale (UPDRS) was performed preoperatively after withholding medications for at least 12 hr (OFF) and after taking the usual dose of levodopa. Postoperative evaluations were completed in four clinical states: OFF medications-stimulators OFF (OFF/OFF); OFF medications-stimulators ON; ON medications-stimulators OFF; and ON medications-stimulators ON. The UPDRS motor scores OFF/OFF were virtually unmodified up to 5 years when compared with preoperative OFF scores. There was no significant difference between OFF/OFF score variations from baseline in patients with shorter (<11 years) and longer PD duration at the time of surgery. No consistent deterioration from untreated baseline was noted for each UPDRS motor subscore (tremor, rigidity, bradykinesia, and axial). Untreated PD motor scores did not worsen over time in patients undergoing STN-DBS, suggesting that there is no progression of motor severity. These results could be explained either by a natural stabilization of PD motor symptoms after many years or neuroprotective properties of STN-DBS.