Pallidal low‐frequency activity in dystonia after cessation of long‐term deep brain stimulation

Objective This study investigates the association between pallidal low‐frequency activity and motor sign severity in dystonia after chronic deep brain stimulation for several months. Methods Local field potentials were recorded in 9 dystonia patients at 5 timepoints (T1–T5) during an OFF‐stimulation period of 5 to 7 hours in parallel with clinical assessment using Burke‐Fahn‐Marsden Dystonia Rating Scale. A linear mixed effects model was used to investigate the potential association of motor signs with local field potential activity in the low frequency (3–12 Hz) and beta range (13–30 Hz). Results A significant association of Burke‐Fahn‐Marsden Dystonia Rating Scale scores with low‐frequency activity (3–12 Hz; b = 4.4; standard error = 1.5, degrees of freedom = 43, P = 0.006, 95% confidence interval, 1.3–7.5), but not beta activity (13–30 Hz) was revealed within participants across timepoints. Conclusion Low‐frequency activity is associated with dystonic motor sign severity, even months after chronic deep brain stimulation. Our findings corroborate the pathophysiological role of low‐frequency activity in dystonia and highlight the potential utility as a biomarker for adaptive neuromodulation. © 2019 International Parkinson and Movement Disorder Society