Complexity of treatment decisions with older patients: who, when and what to treat?

Abstract

<h3>ABSTRACT</h3> <h3>Background</h3> Dystonia is an under-studied motor feature of Parkinson disease (PD). Although considerable efforts have focused on brain oscillations related to the cardinal symptoms of PD, whether dystonia is associated with specific electrophysiological features is unclear. <h3>Objectives</h3> To investigate subcortical and cortical field potentials at rest and during contralateral hand and foot movements in PD patients with and without dystonia. <h3>Methods</h3> We examined the prevalence and distribution of dystonia in PD patients undergoing deep brain stimulation surgery and recorded intracranial electrophysiology from motor cortex and directional electrodes in subthalamic nucleus (STN) both at rest and during self-paced repetitive contralateral hand and foot movements. Wavelet transforms and mixed models characterized changes in spectral content in patients with and without dystonia. <h3>Results</h3> Dystonia was highly prevalent at enrollment (61%) and occurred most commonly in the foot. Regardless of dystonia status, cortical recordings display beta (13-30 Hz) desynchronization during movements versus rest, while STN signals show increased power in low frequencies (6.0±3.3 and 4.2±2.9 Hz peak frequencies for hand and foot movements respectively). PD patients with dystonia during DBS surgery displayed greater M1 beta power at rest and STN low frequency power during movements versus those without dystonia. <h3>Conclusions</h3> Spectral power in motor cortex and STN field potentials differs markedly during repetitive limb movements, with cortical beta desynchronization and subcortical low frequency synchronization, especially in PD patients with dystonia. Greater knowledge on field potential dynamics in human motor circuits can inform dystonia pathophysiology in PD and guide novel approaches to therapy.