Objective: To examine patterns of motor symptom worsening in the 2 years following deep brain stimulation (DBS) in early stage Parkinson’s disease (PD).

Background: Although preclinical studies show disease modifying effects with subthalamic nucleus stimulation in early PD, we found no significant difference in mean motor scores for the DBS plus optimal drug therapy (DBS+ODT) group versus the ODT alone group [1]. Because PD is clinically heterogeneous, we also evaluated individual subjects for motor symptom worsening after 2 years of treatment with DBS+ODT or ODT alone.

Methods: Single-blind UPDRS Part III off motor scores after a 7-day washout (medication and stimulation, if applicable) were collected at baseline and every 6 months for 2 years in a prospective, randomized, parallel-group clinical trial of DBS in early stage PD (Hoehn & Yahr II off medication, 6 months – 4 years medication duration, no history of dyskinesias or other motor fluctuations [clinicaltrials.gov NCT00282152, FDA IDE#G050016]) [1]. Each of 28 subjects was categorized based on their post washout change in UPDRS Part III off motor score from baseline to 2 years as worsened (Δ≥1) or not worsened (Δ≤0).

Results: Motor scores from baseline to 2 years worsened for 100% of ODT subjects (14/14); 35% of subjects treated with DBS+ODT (5/14) did not experience worsening of motor symptoms after 2 years (p=0.04, Fisher’s exact test for no difference in risk of motor score worsening). Motor scores were improved for 28% of subjects treated with DBS+ODT (4/14) and did not change for 1 DBS+ODT subject, which translates into a nearly four-fold increased chance of not worsening with DBS+ODT vs. ODT alone using exact logistic regression.

Conclusions: In this pilot study, more than one-third of early PD subjects treated with DBS+ODT did not experience motor symptom worsening after 2 years, while motor symptoms worsened for all subjects treated with ODT alone. Given the expectation of universal motor function worsening as PD progresses, our results suggest that DBS may be disease modifying for a significant portion of early stage PD patients. This preliminary finding will be further evaluated in the FDA approved (IDE#G050016) prospective, double-blind, placebo-controlled, phase III, pivotal clinical trial (280 subjects at 18 US centers) testing DBS in early stage PD. Reference: [1] Parkinsonism Relat Disord. 2014 Jul;20(7):731-7.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/deep-brain-stimulation-in-early-stage-parkinsons-disease-is-it-disease-modifying/