Objective: To prospectively assess the impact of subthalamic nucleus (STN) deep brain stimulation (DBS) at 12 months after surgery in a series of 100 consecutive patients treated in a single center. The primary objective was to describe the clinical outcome in terms of efficacy and tolerance in STN-DBS patients. A secondary objective was to discuss presurgery clinical characteristics a posteriori as a function of outcome.
Methods: One hundred and three consecutive patients with severe Parkinson's disease received bilateral STN-DBS in our clinic between May 1998 and March 2003. Clinical assessment was performed before and 12 months after surgery and was based on the Unified Parkinson's Disease Rating Scale, Parts II, III, and IV A; the Schwab and England Scale; and cognitive evaluation. Patient-rated overall improvement was also evaluated.
Results: Twelve months after surgery, the Unified Parkinson's Disease Rating Scale Part III score decreased by 43%, the Unified Parkinson's Disease Rating Scale Part II score (activities of daily living) fell by 34%, and the severity of dyskinesia-related disability decreased by 61%. The main surgical complications after STN-DBS were as follows: infection (n = 7), intracerebral hematoma (n = 5), electrode fracture (n = 4), and incorrect lead placement (n = 8). We observed cognitive decline and depression in 7.7 and 18% of the patients, respectively. The mean patient-rated overall improvement score was 70.7%.
Conclusion: The efficacy and safety of STN-DBS in our center's large cohort of Parkinsonian patients are generally similar to the results obtained by other groups, albeit at the lower limit of the range of reported values. In contrast to efficacy, the occurrence of adverse events cannot be predicted. Younger patients with Parkinson's disease (i.e., those younger than 60 yr) often show an excellent response to levodopa. However, in view of our data on overall patient satisfaction and the occurrence of adverse events, we suggest that older patients (but not those older than 70 yr) and less dopa-sensitive patients (but not those with a response <50%) should still be offered the option of STN-DBS.