LONG-TERM OUTCOMES OF DEEP BRAIN STIMULATION IN PATIENTS WITH PARKINSON'S DISEASE

Аннотация

Deep Brain Stimulation (DBS) has established itself over the past two decades as an effective method for comprehensive treatment of Parkinson's disease when conservative therapy proves ineffective or insufficiently effective. The method is based on the implantation of electrodes into specific brain structures (predominantly the subthalamic nucleus, globus pallidus, or ventral intermediate nucleus of the thalamus) with subsequent activation through a subcutaneously implanted neurostimulator. Electrical stimulation modulates pathological neuronal activity in the basal ganglia, which leads to a reduction in the main motor symptoms of the disease and allows for a significant decrease in the dosage of antiparkinsonian medications. Keywords: Parkinson's disease, deep brain stimulation, neurostimulation, subthalamic nucleus, globus pallidus, long-term outcomes, long-term effects, motor symptoms, non-motor manifestations, motor fluctuations, dyskinesias Research Objective: To evaluate the long-term neurological, cognitive, and behavioral outcomes of deep brain stimulation of the subthalamic nucleus in patients with Parkinson's disease at timepoints exceeding 2 years post- implantation. Materials and Methods: The study included 48 patients with idiopathic Parkinson's disease (PD) who underwent deep brain stimulation (DBS) surgery between 2022 and 2025 at the neurosurgical department of the 1st Multidisciplinary Clinic of Samarkand Medical University. The mean age of patients was 61.2 ± 7.8 years, with disease duration of 11.6 ± 3.4 years. Patients were divided into 2 groups: Group 1 (n=24): patients receiving active neurostimulation for ≥3 years, without parameter changes for more than 6 months. Group 2 (n=24): patients requiring reprogramming or adjustment of DBS, or with episodes of stimulation interruption due to technical or medical reasons. Assessment was conducted using the following scales: UPDRS III — motor symptoms, MoCA — cognitive function, BDI-II — depression level; PDQ- 39 — quality of life; L-dopa dependency level (in milligrams) was compared. 58 ACADEMIC RESEARCH IN MODERN SCIENCE International scientific-online conference Data analysis was performed using SPSS v.26.0. Statistical significance was determined at p < 0.05. Results: Analysis of the obtained data showed significant differences between groups of patients under different deep brain stimulation regimens across various clinical and psychometric parameters. Motor functions (UPDRS III scale): the mean UPDRS III score in Group 1 patients (with stable DBS parameters) was 22.5 ± 3.1, indicating a relatively low level of motor deficit. Meanwhile, in Group 2 patients (with episodes of stimulation disruption or reprogramming needs), the mean score was significantly higher — 28.4 ± 4.8. The differences between groups were statistically significant (p = 0.003), demonstrating better control of motor symptoms with stable stimulation. Cognitive functions (MoCA scale): the mean MoCA score in Group 1 patients was 25.1 ± 2.3, corresponding to normal cognitive functioning. In Group 2 patients, this indicator was lower — 22.6 ± 3.0, indicating mild cognitive impairment. The difference between groups was significant (p = 0.011), confirming the impact of DBS regimen on cognitive status. Depression level (BDI-II scale): in the group with stable stimulation, the mean depression score on the BDI-II scale was 9.2 ± 2.4, indicating the absence of clinically significant depression. Group 2 patients showed a higher level of depressive symptoms — 13.6 ± 3.5, bordering on moderate depression (p = 0.007). Quality of life (PDQ-39 scale): the total score on the PDQ-39 questionnaire, reflecting subjective assessment of quality of life, was 28.7 ± 5.2 in Group 1, whereas in Group 2 it was 36.3 ± 6.1. The difference was significant (p = 0.009), indicating the negative impact of unstable stimulation on patients' general well-being and daily activities. Daily levodopa dose: patients with properly functioning DBS systems took an average of 410 ± 80 mg of levodopa daily, while patients from the second group required greater medication support — 560 ± 90 mg/day. The differences were statistically significant (p = 0.015), confirming reduced need for dopaminergic therapy with effective neurostimulation. Group 1 patients demonstrated consistently better motor and cognitive function, less severe depression, and better subjective quality of life assessment. Repeated device adjustments and therapy interruptions in Group 2 were associated with a higher risk of developing dyskinesias, apathy, and cognitive decline. Conclusions: The obtained data convincingly demonstrate that stable and properly configured deep brain stimulation contributes to better control of motor disorders, reduces medication burden, and positively affects the cognitive and emotional state of patients with Parkinson's disease. Conversely, unstable 59 ACADEMIC RESEARCH IN MODERN SCIENCE International scientific-online co