Modulation of specific components of sleep disturbances by simultaneous subthalamic and nigral stimulation in Parkinson's disease

Objective: To compare the effect of simultaneous deep brain stimulation of the subthalamic nucleus and substantia nigra pars reticulata (STN+SNr-DBS) to conventional subthalamic stimulation (STN-DBS) on sleep quality in Parkinson's disease (PD) patients. Methods: The study was a single-center, randomized, double-blind, cross-over clinical trial to compare the effect of STN-DBS vs. combined STN+SNr-DBS on subjective measures of sleep quality. Fifteen PD patients (2 female, age 62.5 +/- 6.7 years) suffering from moderate idiopathic PD (disease duration: 12.0 +/- 5.0 years, Hoehn & Yahr stage: 2.2 +/- 0.4 in the MED-ON & STN-DBS-ON condition, Hoehn & Yahr stage: 2.6 +/- 0.8 in the MED-OFF condition preoperatively) participated in the study. Sleep quality was evaluated in both stimulation conditions using the PDSS-2 score as a self-rating questionnaire covering several aspects of sleep disturbances. Results: PD patients showed mild-moderate sleep disturbances (STN-DBS: PDSS-2 score 17.0 +/- 11.0; STN+SNr-DBS: 14.7 +/- 9.5) with slight but not significant differences between both stimulation conditions. Considering the different subitems of the PDSS-2, combined STN+SNr stimulation was superior to conventional STN stimulation in improving restless legs symptoms (RLS) at night (STN-DBS = 1.9 +/- 2.7 STN+SNr-DBS = 1.0 +/- 1.8; W = -2.06, p = 0.039) and immobility at night (STN-DBS = 1.5 +/- 1.4 STN+SNr-DBS = 0.6 +/- 0.8; W = -2.041, p = 0.041). Conclusion: This study demonstrates the safety of STN+SNr-DBS compared to conventional STN-DBS on sleep in general with potential beneficial input on RLS symptoms and akinesia at night.