Subthalamic Steering for Therapy Optimization in Parkinson's Disease (SANTOP)

Twenty patients with idiopathic Parkinson's disease (PD) will be included into this single center randomized controlled double-blind clinical trial (RCT) in a cross-over design. The treatment consists of two different stimulation settings using (i) conventional omnidirectional stimulation of the subthalamic nucleus [STN_O] as active comparator and (ii) directional steering of STN stimulation via a segmented electrode contact [STN_D].

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).

Deep brain stimulation impairment scale (DBS-IS): the scale consists of 22 questions and 6 subscales; subscales: 1. postural instability and gait difficulties (range 0-20), 2. cognitive impaiment (range 0-20), 3. speaking problems (range 0-12), 4. apathy (range 0-12), 5. impulsivity (range 0-12), and 6. difficulties related to DBS device (range 0-12); Ʃ 1-6 DBS-IS total range: 0-88; Ʃ 1-5 DBS-IS total range: 0-76; higher values represent worsening of symptoms

Executive functions with One Touch Tower of London (Cambridge Neuropsychological Test Automated Battery, CANTAB)

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

Department for Neurodegenerative Diseases, Centre for Neurology, Tuebingen, Germany, and Hertie-Institute for Clinical Brain Research

University Hospital Tuebingen, Dep. of Neurosurgery (Functional Neurosurgery) and Neurology (Neurodegenerative Diseases)

Levin J, Krafczyk S, Valkovic P, Eggert T, Claassen J, Botzel K. Objective measurement of muscle rigidity in Parkinsonian patients treated with subthalamic stimulation. Mov Disord. 2009 Jan 15;24(1):57-63. doi: 10.1002/mds.22291.