Effects of Deep Brain Stimulation of the Subthalamic Nucleus on the Postoperative Levodopa Response: One Year Follow Up.

Aim: To investigate the effect of preoperative levodopa responsiveness to clinical outcomes in the first postoperative year, and to evaluate the changes in the postoperative levodopa responsiveness in patients undergoing subthalamic nucleus (STN) deep brain stimulation (DBS).
Material and Methods: Forty-nine Parkinson?s Disease (PD) patients undergoing bilateral DBS of the STN were included in this study. Their clinical motor symptoms were assessed preoperatively by UPDRS Part III score in both OFF and ON medication states. Postoperatively, the assessments were obtained in three consecutive conditions. Preoperatively and postoperatively, the percentage difference between these two scores was evaluated as levodopa response.
Results: Mean age was 54.6 ± 9 years (27?70). Levodopa response significantly decreased postoperatively by 56% a year. Compared with preoperative med on and postoperative stim on / med on scores, the clinical results of the first year were obtained and an improvement of 25% on the UPDRS 3 score was observed. Compared with preoperative levodopa response and clinical outcomes, better clinical results were obtained in patients with higher preoperative levodopa response (p < 0.05).
Conclusion: In this study, we confirm that the response of L-dopa decreases after DBS of the STN. The reasons for this finding are not clear. However, DBS of the STN allows for the reduction of PD medications and improvement of daily life activities, motor function, motor fluctuations, and dyskinesia.