Short-Term Effect of Bilateral Subthalamic Stimulation for Advanced Parkinson's Disease

Background: Subthalamic nucleus (STN) hyperactivity is a pathophysiological phenomenonof Parkinson's disease (PD). Inhibition of this hyperactivity by chronicdeep brain stimulation (DBS) can possibly reset the aberrant function of thecortico-striato-thalamal circuit and improve the parkinsonian symptoms.DBS was introduced as a safe and alternative way of performing functionalstereotaxic surgery for treating PD.Methods: Seven advanced PD patients with complicated motor fluctuations and dyskinesiawere enrolled in the study. A quadripolar electrode was bilaterallyinstalled in the STN. Patients were evaluated before and 6 months afterimplantation using a battery of clinical assessments, including the motorscore of the unified Parkinson's disease rating scale (UPDRS), modifiedHoehn and Yahr (HY) staging, and the Schwab and England activities ofdaily living scale (SEADL). Preoperative baseline evaluations included both"off-medication" periods and "on-medication" periods, while postoperativeevaluations included a cross-over of the above 2 periods with and withoutDBS.Results: The motor disability, HY staging, and SEADL all significantly improved inboth the off- and on-medication periods 6 months after STN DBS. Comparedto the baseline off-medication score, a significant improvement was found inthe UPDRS motor and other subscores including tremors, rigidity, andbradykinesia. The SEADL score showed a great improvement of 205.6%.Ballism/chorea, mood changes, and blepharospasm may have been inducedby DBS. Neither serious nor permanent side effects appeared.Conclusions: Bilateral STN DBS improved the motor symptoms in advanced PD patientsin both the off- and on-medication periods. They showed improvements notonly in motor disabilities of tremors, rigidity, bradykinesia, and postural andgait instability, but also in levodopa-related dyskinesia and psychosis.