Based on the Parkinson's Disease Symptom Diary. "On" time is when PD symptoms are well controlled by the drug. "Off" time is when PD symptoms are not adequately controlled by the drug. The diary is completed every 30 minutes for the full 24 hours of each of 3 days prior to selected clinic visits. It reflects both time awake and time asleep. Daily totals are normalized to a 16-hour scale (i.e. 16 hours of awake time). The normalized totals for the 3 days prior to the visit are averaged for the analysis. Negative change from baseline for "off" time indicates improvement.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

Based on the Parkinson's Disease Symptom Diary. "On" time is when PD symptoms are well controlled by the drug. "Off" time is when PD symptoms are not adequately controlled by the drug. "On" time without troublesome dyskinesia (involuntary muscle movement) is defined as "on" time without dyskinesia and "on" time with non-troublesome dyskinesia. The diary is completed every 30 minutes for the full 24 hours of each of 3 days prior to selected clinic visits. It reflects both time awake and time asleep. Daily totals are normalized to a 16-hour scale (i.e. 16 hours of awake time). The normalized totals for the 3 days prior to the visit are averaged for the analysis. Positive change from Baseline for "on" time without troublesome dyskinesia indicates improvement.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The PDQ-39 is a self-administered questionnaire which comprises 39 items addressing 8 domains of health in Parkinson's disease patients. These include: mobility, activities of daily living, emotional well-being, stigma, social support, cognition, communication, and bodily discomfort. The PDQ-39 Summary Index is the sum of all answers divided by the highest score possible (i.e. number of answers multiplied by 4) which is multiplied by 100 to put the score on a 0-100 scale. Higher scores are associated with more severe symptoms.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The CGI-S is a global assessment by the Investigator of current symptomatology and impact of illness on functioning. The ratings of the CGI-S are as follows: 1 = normal, 2 = borderline ill, 3 = mildly ill, 4 = moderately ill, 5 = markedly ill, 6 = severely ill, and 7 = among the most extremely ill. The CGI-I is a global assessment by the Investigator of the change in clinical status since the start of treatment. The CGI-I ratings are as follows: 1 = very much improved, 2 = much improved, 3 = minimally improved, 4 = no change, 5 = minimally worse, 6 = much worse, 7 = very much worse.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The UPDRS is an Investigator-used rating tool to follow the longitudinal course of Parkinson's disease. The Part II score is the sum of the answers to the 13 questions that comprise Part II, each of which are measured on a 5-point scale (0-4). The Part II score ranges from 0-52 and higher scores are associated with more disability.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The UPDRS is an Investigator-used rating tool to follow the longitudinal course of Parkinson's disease. The Part III score is the sum of the 27 answers provided to the 14 Part III questions, each of which are measured on a 5-point scale (0-4). The Part III score ranges from 0-108 and higher scores are associated with more disability.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The EQ-5D is a participant answered questionnaire scoring 5 dimensions: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. EQ-5D health states, defined by the EQ-5D descriptive system, are converted into a single summary index by applying a formula that essentially attaches values (also called QOL weights or QOL utilities) to each of the levels in each dimension. EQ-5D Summary Index values range from -0.11 to 1.00 with positive change indicating improvement.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The ZBI is a 22-item questionnaire regarding the caregiver/subject relationship and evaluates the caregiver's health condition, psychological well-being, finances and social life. Each question is answered on a 5-point scale (0=Never, 1=Rarely, 2=Sometimes, 3=Quite frequently, and 4= Nearly always). The caregiver burden is evaluated by the total score (Range 0 to 88) obtained from the sum of the answers to the 22 questions. Higher scores are associated with a higher level of burden for the caregiver.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

Based on the Parkinson's Disease Symptom Diary. "On" time is when PD symptoms are well controlled by the drug. "Off" time is when PD symptoms are not adequately controlled by the drug. The diary is completed every 30 minutes for the full 24 hours of each of 3 days prior to selected clinic visits. It reflects both time awake and time asleep. Daily totals are normalized to a 16-hour scale (i.e. 16 hours of awake time). The normalized totals for the 3 days prior to the visit are averaged for the analysis.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The PDQ-39 is a self-administered questionnaire which comprises 39 items addressing 8 domains of health in Parkinson's disease patients. The PDQ-39 Domain: Mobility (e.g., fear of falling when walking) includes 10 questions, each answered on a 5-point scale. The domain scores are calculated by first summing the answers to the questions in the domain. The sum is divided by the highest score possible (i.e., number of answers multiplied by 4) and the quotient is multiplied by 100 to put the score on a scale from 0 to 100, where lower scores indicate a better perceived health status. Higher scores are consistently associated with the more severe symptoms of the disease such as tremor and stiffness.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The PDQ-39 is a self-administered questionnaire which comprises 39 items addressing 8 domains of health in Parkinson's disease patients. The PDQ-39 Domain: Activities of Daily Living (e.g., difficulty cutting food) includes 6 questions, each answered on a 5-point scale. The domain scores are calculated by first summing the answers to the questions in the domain. The sum is divided by the highest score possible (i.e., number of answers multiplied by 4) and the quotient is multiplied by 100 to put the score on a scale from 0 to 100, where lower scores indicate a better perceived health status. Higher scores are consistently associated with the more severe symptoms of the disease such as tremor and stiffness.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The PDQ-39 is a self-administered questionnaire which comprises 39 items addressing 8 domains of health in Parkinson's disease patients. The PDQ-39 Domain: Emotional Well-being (e.g., feelings of isolation) includes 6 questions, each answered on a 5-point scale. The domain scores are calculated by first summing the answers to the questions in the domain. The sum is divided by the highest score possible (i.e., number of answers multiplied by 4) and the quotient is multiplied by 100 to put the score on a scale from 0 to 100, where lower scores indicate a better perceived health status. Higher scores are consistently associated with the more severe symptoms of the disease such as tremor and stiffness.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The PDQ-39 is a self-administered questionnaire which comprises 39 items addressing 8 domains of health in Parkinson's disease patients. The PDQ-39 Domain: Stigma (e.g., social embarrassment) consists of 4 questions, each answered on a 5-point scale. The domain scores are calculated by first summing the answers to the questions in the domain. The sum is divided by the highest score possible (i.e., number of answers multiplied by 4) and the quotient is multiplied by 100 to put the score on a scale from 0 to 100, where lower scores indicate a better perceived health status. Higher scores are consistently associated with the more severe symptoms of the disease such as tremor and stiffness.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The PDQ-39 is a self-administered questionnaire which comprises 39 items addressing 8 domains of health in Parkinson's disease patients. The PDQ-39 Domain: Social Support includes 3 questions, each answered on a 5-point scale. The domain scores are calculated by first summing the answers to the questions in the domain. The sum is divided by the highest score possible (i.e., number of answers multiplied by 4) and the quotient is multiplied by 100 to put the score on a scale from 0 to 100, where lower scores indicate a better perceived health status. Higher scores are consistently associated with the more severe symptoms of the disease such as tremor and stiffness.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The PDQ-39 is a self-administered questionnaire which comprises 39 items addressing 8 domains of health in Parkinson's disease patients. The PDQ-39 Domain: Cognition includes 4 questions, each answered on a 5-point scale. The domain scores are calculated by first summing the answers to the questions in the domain. The sum is divided by the highest score possible (i.e., number of answers multiplied by 4) and the quotient is multiplied by 100 to put the score on a scale from 0 to 100, where lower scores indicate a better perceived health status. Higher scores are consistently associated with the more severe symptoms of the disease such as tremor and stiffness.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The PDQ-39 is a self-administered questionnaire which comprises 39 items addressing 8 domains of health in Parkinson's disease patients. The PDQ-39 Domain: Communication includes 3 questions, each answered on a 5-point scale. The domain scores are calculated by first summing the answers to the questions in the domain. The sum is divided by the highest score possible (i.e., number of answers multiplied by 4) and the quotient is multiplied by 100 to put the score on a scale from 0 to 100, where lower scores indicate a better perceived health status. Higher scores are consistently associated with the more severe symptoms of the disease such as tremor and stiffness.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The PDQ-39 is a self-administered questionnaire which comprises 39 items addressing 8 domains of health in Parkinson's disease patients. The PDQ-39 Domain: Bodily Discomfort includes 3 questions, each answered on a 5-point scale. The domain scores are calculated by first summing the answers to the questions in the domain. The sum is divided by the highest score possible (i.e., number of answers multiplied by 4) and the quotient is multiplied by 100 to put the score on a scale from 0 to 100, where lower scores indicate a better perceived health status. Higher scores are consistently associated with the more severe symptoms of the disease such as tremor and stiffness.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The UPDRS is an Investigator-used rating tool to follow the longitudinal course of Parkinson's disease. The Part I Score is the sum of the answers to the 4 questions that comprise Part I, each of which are measured on a 5-point scale (0-4). The Part I score ranges from 0-16 and higher scores are associated with more disability.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment. No missing data was imputed.

The UPDRS is an Investigator-used rating tool to follow the longitudinal course of Parkinson's disease. The Part IV Score is the sum of the answers to the 11 questions that comprise Part IV, each of which are measured on a 5-point scale (0-4) or a 2-point scale (0 or 1). The Part IV score ranges from 0-23 and higher scores are associated with more disability.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The UPDRS is an Investigator-used rating tool to follow the longitudinal course of Parkinson's disease. Questions 32, 33, and 34 on UPDRS Part IV were totaled to evaluate dyskinesias. Each of these questions is measured on a 5-point scale (0-4). The Part IV dyskinesia score will range from 0-12 and higher scores are associated with more disability.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment. No missing data was imputed.

The UPDRS is an Investigator-used rating tool to follow the longitudinal course of Parkinson's disease. The total score is the sum of the responses to the 31 questions (44 answers) that comprise Parts I-III of the scale. The total score will range from 0-176, with 176 representing the worst (total) disability, and 0 no disability.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The EQ-5D VAS records the participant's self-rated health on a scale from 0-100 where 100 is the 'best imaginable health state' and 0 is the 'worst imaginable health state.'

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment.

The EMP instruments are designed to collect information regarding employment and ability to run a household. EMP I questions include: Are you currently in paid employment? (If yes, at which percentage have you been working during the last 4 weeks?); Have you got someone to run your household for you? (If yes, how much time per week does he/she spend in your household?); Are you retired? (If yes, for which reason?).

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment. Missing data was not imputed.

The EMP instruments are designed to collect information regarding employment and ability to run a household. EMP I questions include: Are you currently in paid employment? (If yes, at which percentage have you been working during the last 4 weeks?); Have you got someone to run your household for you? (If yes, how much time per week does he/she spend in your household?); Are you retired? (If yes, for which reason?) The retirement question (from EMP I) is excluded from the EMP II instrument.

Full Analysis Set: randomized participants who had the study device implanted and had data for baseline and at least 1 post-baseline assessment. Missing data was not imputed.