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.