All study participants will have the study device surgically implanted. After implant surgery, study participants will return to the clinic for evaluation 30 days after surgery, three months after surgery, six months after surgery and twelve months after surgery. At the baseline, three, six and twelve month visits the patient's Parkinson's symptoms and ability to perform daily activities will be evaluated using a number of accepted assessment tools including a Dyskinesia diary, evaluation of PD symptoms, quality of life scoring and patient extension study to monitor the safety and efficacy of the ANS Libra/Libra Deep Brain Stimulation System.