UT Health San Antonio

Parkinson's disease patients: 1. Patient must provide written informed consent prior to any clinical study related procedure. 2. Patient is 18 to 80 years of age. 3. Patient is diagnosed with Parkinson's disease for at least 4 years according to standard practice. 4. Patient is willing to maintain a constant dose of anti-Parkinson's disease medication indicated as best medical management for at least 1 month prior to study enrollment. 5. Patient is willing and able to comply with the follow-up schedule for the length of the study. 6. Patient has been implanted with an 8-channel directional Infinity deep brain stimulation system in the subthalamic nucleus (STN) within the last 12 months. 7. Patient has had stable deep brain stimulation programming settings for at least 1 month prior to study enrollment. Essential tremor patients: 1. Patient must provide written informed consent prior to any clinical study related procedure. 2. Patient is 18 to 80 years of age. 3. Patient is diagnosed with essential tremor for at least 4 years according to standard practice. 4. Patient is willing to maintain a constant dose of anti-tremor medication indicated as best medical management for at least 1 month prior to study enrollment. 5. Patient is willing and able to comply with the follow-up schedule for the length of the study. 6. Patient has been implanted with an 8-channel directional Infinity deep brain stimulation system in the ventral intermediate (Vim) thalamus within the last 12 months. 7. Patient has had stable deep brain stimulation programming settings for at least 1 month prior to study enrollment.

1. Individuals unable to make the decision to participate in a clinical investigation on their own. 2. Patient is currently programmed with segmented electrodes, and cannot tolerate omnidirectional programming. 3. Patient is being evaluated for a lead revision. 4. Patient has untreated clinically significant depression. 5. Patient has dementia that interferes with their ability to co-operate or comply with study requirements or comprehend the informed consent, as determined by the investigator. 6. Patient abuses drugs or alcohol. 7. Patient is currently enrolled or plans to enroll in another concurrent study that may confound the results of this clinical investigation. 8. Patient has a confirmation of diagnosis of a terminal illness associated with survival <12 months. 9. Presence of other anatomic or comorbid conditions, or other medical, social, or psychological conditions that, in the investigator's opinion, could limit the patient's ability to participate in the clinical study or to comply with follow-up requirements, or impact the scientific soundness of the clinical study results. 10. Pregnant or nursing patients and those who plan pregnancy during the clinical study follow-up period.