Sleep spindle variation in patients with Parkinson's disease on first nights of sub-optimal deep brain stimulation

Deep brain stimulation (DBS) targeting the subthalamic nucleus (STN) is a common treatment for motor symptoms of Parkinson's disease but its influence on non-motor symptoms is less clear. Sleep spindles are known to be reduced in patients with Parkinson's disease, but the effect of STN DBS is unknown. The objective of our study was to address this knowledge gap.

Polysomnograms were recorded for three consecutive nights in 15 patients with advanced Parkinson's disease (11 male, 4 female; age: 53-75 years), including at least one night each of unilateral STN DBS stimulation ON and OFF. Stimulation ON was set to 70 % of clinical amplitude to mitigate sleep being altered via changing motor symptoms or due to patient awareness of stimulation. Sleep spindles were detected in electroencephalogram (EEG) data by two previously published, validated automated sleep spindle detection algorithms: Ferrarelli et al. (2007) and Martin et al. (2013).

Sleep spindle density was higher during stimulation ON than OFF nights in 11 of 12 subjects using either sleep spindle detection algorithm (p<=0.01, Wilcoxon rank sum). Stimulation ON versus OFF had no statistically significant effect on sleep spindle duration or amplitude.

Our analysis indicates that a single night of sub-optimal STN stimulation significantly increases sleep spindle density in Parkinson's disease patients.

These results further our understanding of how DBS impacts non-motor symptoms of Parkinson's disease.