Subthalamic Theta-Alpha Local Field Potentials in OFF-Levodopa Dystonia in Parkinson's Disease

Background: Dystonia affects an estimated 30% of patients with Parkinson's Disease (PD). While pallidal theta-alpha oscillations (4–10 Hz) have been found to characterize primary dystonia compared to beta oscillations (12–30 Hz) in PD, the electrophysiology underlying dystonia in PD remains unexplored. Objectives: Explore the electrophysiology underlying dystonia in PD. Methods: Subthalamic nucleus (STN) local field potentials (LFPs) in PD patients with and without dystonia were compared using a bidirectional deep brain stimulation (DBS) device. Results: Fourteen PD patients with bilateral STN-DBS were included, four (28.6%) with lower extremity dystonia. In 3/7 hemispheres affected by dystonia (42.9%), maximum amplitude LFP activity occurred in the theta-alpha band (4–10 Hz). Conversely, all 21 hemispheres not associated with dystonia had maximum STN activity around the beta-band (11.5–35 Hz, P = 0.011). Conclusions: STN theta-alpha activity in patients with PD may be associated with dystonic symptoms. Although other motor and non-motor features may correlate with STN theta-alpha, this biomarker warrants further investigation in closed-loop DBS.