Long-term efficacy of deep brain stimulation in Parkinson's disease: over 10-year follow-up and insights into the "DBS honeymoon".

Background: Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder globally. Deep brain stimulation (DBS) has become a critical therapeutic option for advanced PD. The efficacy of DBS has been well established for up to 1 or 2 years; however, long-term outcome data for Chinese cohorts are limited, and the duration of the "DBS honeymoon" remains underexplored. Objective: This study aimed to evaluate the long-term efficacy (⩾10 years) of subthalamic nucleus (STN)-DBS in patients with PD in Southern China, and to investigate the duration of "DBS honeymoon." Design: Retrospective study. Methods: Thirty-one patients who underwent bilateral STN-DBS between 2010 and 2011 were assessed. Motor symptoms were evaluated using the Unified Parkinson's Disease Rating Scale-Part III (UPDRS-III) in the off- and on-medication states with stimulation. Nonmotor symptoms and the quality of life (QOL) were measured using validated scales. The levodopa equivalent daily dose (LEDD), stimulation parameters, and adverse events were recorded. Genetic testing was performed for seven patients. Results: Thirteen patients completed the follow-up at 1, 3, and ⩾10 years. The UPDRS-III (off-state) scores improved by 53.02%, 44.79%, and 22.56% at 1, 3, and ⩾10 years, respectively. Tremor and rigidity showed sustained improvement; sleep remained stable postoperatively. In contrast, emotion, cognition, and QOL improved at 3 years; however, they returned to baseline or declined beyond 10 years. The LEDD reductions were 36.29%, 40.40%, and 29.10% at 1, 3, and ⩾10 years, respectively. Stimulation frequency decreased from 141.70 ± 15.72 Hz at 1 year to 110.00 ± 18.22 Hz ⩾10 years. Additionally, genetic testing identified three mutation carriers and rare complications such as DBS withdrawal syndrome appeared beyond 10 years. Conclusion: STN-DBS provided sustained motor improvement, with tremor and rigidity showing the most significant benefits after 10 years. The initial 3 years likely represented a "DBS honeymoon," with peak improvements in motor and nonmotor symptoms. Genotype may influence the efficacy of DBS, and monitoring rare complications is essential. These findings should be interpreted with caution, given the small sample size and the retrospective design of the study.