STN DBS improves QoL in PD patients, but long-term data beyond 5 years is limited.

To report quality of life (QoL) in Parkinson’s disease (PD) patients after bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) up to 25 years after initial DBS implantation.

This prospective observational study included 399 PD patients who underwent bilateral STN DBS. Annual assessments included the Parkinson's Disease Questionnaire (PDQ-39), Unified Parkinson's Disease Rating Scale (UPDRS), Levodopa equivalent daily dose (LEDD), and the Montreal Cognitive Assessment (MoCA).

PDQ39 total score (baseline, n=382, 35.34±14.79) improved in years 1-7 after surgery (year 7, n=155, 32.55±16.00, p=0.0314) and after that stabilized with little difference in PDQ39 compared to baseline between year 8 (n=143) through year 25 (n=2). There was mild worsening in PDQ39 seen only at year 14 (n=43) and 22 (n=5), possibly related to the fewer number of patients at those visits. Similarly, UPDRS Motor medication OFF scores at baseline (n=387, 64.54±13.56) compared to medication OFF/stimulation ON improved in years 1-12 (year 12, n=41, 57.95±15.39, p=0.0091), but returned to showing no difference compared to baseline in years 13-19 (year 19, n=5, 66.00±12.33, p=0.8046). MoCA scores (baseline, n=321, 25.49±3.11) were stable at year 1 (n=303, 25.49±3.43, p=0.9848) but worsened beginning at year 2 onwards (year 2, n=279, 24.89 ± 4.09, p=0.0144). LEDD (n=399, 1366.34±653.85) was reduced at year 1 (n=359, 659.14±411.87, p=0.0000) and continued to remain reduced until at least year 19 (n=9, 884.22±552.79, p=0.0308).

STN DBS provides long term improvement in QoL and PD motor symptoms. PDQ39 and UPDRS Motor scores in the medication OFF/stimulation ON state are improved for many years then gradually return to baseline without significant worsening long term. Cognition gradually worsens over time. Medications are reduced immediately and maintained long term.