Cont. of a Study to Evaluate Implanting Peripheral Nerve Grafts Into Subjects With Parkinson's Disease (PD) During DBS

This pilot study is designed to follow up on a previous, preliminary study and test the long-term safety and feasibility of the implantation of autologous peripheral nerve grafts into the substantia nigra, basal forebrain, putamen, and/or STN of participants with PD undergoing deep brain stimulation (DBS) surgery. Peripheral nerve tissue contains Schwann cells which produce growth factors that have been demonstrated to support the survival and function of neurons. Participants will serve as their own donor for the tissue, which will be implanted at the time they undergo DBS surgery.