Anodic Stimulation in Parkinson's Disease

Patient's preferred stimulation parameter setting (with or without anodic stimulation) determined by their responses to the questionnaire and patient's stated preference. The score ranges from 0-100, with lower scores reflecting better quality of life of patients.

Change in UPDRS part III motor scores obtained ON stimulation/OFF medications at 4 weeks on each parameter setting relative to UPDRS part III motor scores obtained OFF stimulation/OFF medications at baseline. Scores range from 0-132. 0 indicates no motor impairment, 32 or below is considered mild impairment, and a score of 59 and above indicates severe impairment.

Change in UPDRS part III motor sub-scores (tremor, rigidity, bradykinesia, postural stability/gait) obtained ON stimulation/OFF medications at 4 weeks on each parameter setting relative to UPDRS part III motor scores obtained OFF stimulation/OFF medications at baseline. 8 sub-scores for each section of the scale. Each sub-section is scored from 0-4, or a score of 8 if "untestable". A score of 0 in each sub-section or a lower score normal or absence of symptom.

CGI-P at 4 weeks following mixed cathodic/anodic stimulation. The scale uses a 7-point severity scale with 1 indicating normal or no positive symptoms and 7 indicating most severely ill patients with positive symptoms. Each item is rated independently on the 7-point scale.

CGI-P scores at 4 weeks following pure cathodic stimulation. The scale uses a 7-point severity scale with 1 indicating normal or no positive symptoms and 7 indicating most severely ill patients with positive symptoms. Each item is rated independently on the 7-point scale.

CGI-P scores at 4 weeks following pure anodic stimulation. The scale uses a 7-point severity scale with 1 indicating normal or no positive symptoms and 7 indicating most severely ill patients with positive symptoms. Each item is rated independently on the 7-point scale.

PGI-C scores at 4 weeks following mixed cathodic/anodic stimulation. The scale uses a 7-point Likert scale for scoring. Scores of 1 and 2 indicate significant improvement, score of 4 indicates no change in patient's status, and scores of 5 or higher indicate worsening or deteriorating changes in patient.

PGI-C scores at 4 weeks following pure cathodic stimulation. The scale uses a 7-point Likert scale for scoring. Scores of 1 and 2 indicate significant improvement, score of 4 indicates no change in patient's status, and scores of 5 or higher indicate worsening or deteriorating changes in patient.

PGI-C scores at 4 weeks following pure anodic stimulation. The scale uses a 7-point Likert scale for scoring. Scores of 1 and 2 indicate significant improvement, score of 4 indicates no change in patient's status, and scores of 5 or higher indicate worsening or deteriorating changes in patient.

Minimum stimulation amplitude required to achieve a predefined clinical benefit at each stimulation parameter setting, including mixed cathodic/anodic stimulation, pure cathodic stimulation, and pure anodic stimulation. Clinical benefit will be determined based on investigator assessment of motor symptom improvement during stimulation programming. The unit of measure is "Stimulation amplitude (mA)".

Minimum stimulation amplitude at which a stimulation-related adverse effect is first observed or reported during programming at each stimulation parameter setting, including mixed cathodic/anodic stimulation, pure cathodic stimulation, and pure anodic stimulation. Adverse effects will be identified through participant report and investigator assessment during systematic amplitude titration. Unit of Measure: "Stimulation amplitude (mA)".

Model of the VTA resulting from each stimulation parameter setting compared with respect to the regional anatomy as derived from patient-specific segmentation of pre-operative MRI and post-operative/post-enrollment CT studies. Relative location, extent, and spread out of the boundaries of the Subthalamic Nucleus (STN) of VTAs obtained with all stimulation parameter settings.