Subthalamic Steering for Therapy Optimization in Parkinson's Disease

Twenty PD patients will be enrolled in this cross-over double-blind RCT to evaluate both the safety and efficacy of directional STN stimulation [STN_D] compared with standard omnidirectional STN stimulation [STN_O]. The primary outcome measure is objectively quantified muscle rigidity of the upper extremity, i.e., surface EMG recordings of the biceps and triceps muscle during standardized extension/flexion of the elbow joint (Levin et al., 2009) assessed 6 months after implantation in cross-over design. The trial is designed to detect with an 80% power a change of 0.27 mA of the therapeutic stimulation threshold with two-tailed P < 0.05 (Wilcoxon rank sum test). Secondary outcome measures address clinical motor, non-motor, neurocognitive and neuropsychiatric symptoms, freezing of gait, and quality of life. Visits are scheduled at weeks 1 (V1), 6 (V2), 24 (V3), 27 (V4), and 30 (V5) from baseline (V0).

Inclusion criteria

• Written informed consent
• Idiopathic Parkinson's disease (according to the "British Brain Bank criteria" (Hughes, 1992) including genetic forms

Exclusion criteria

• Cognitive impairment (Mini Mental State Exam < 20)
• Suicidality, Psychosis
• Other severe pathological chronic condition that might confound treatment effects or interpretation of the data
• Pregnancy