Burst-Type Deep Brain Stimulation of the Subthalamic Nucleus in Parkinson's Disease

Five (N = 5) subjects that have bilateral subthalamic nucleus deep brain stimulation (STN-DBS), with Boston Scientific Gevia or Genus technology, implanted for Parkinson's Disease (PD). Subjects should be on stable DBS programming settings and stable medication regimens defined as no DBS programming changes or Parkinson's disease medication changes over the past 2 weeks. The DBS implantation should have been performed by either Dr. Nestor D. Tomycz MD or Dr. Donald M. Whiting MD at Allegheny General Hospital and implantation surgery must have occurred a minimum of 6 months prior to the day of enrollment. Screening Visit- All interested patients will undergo a screening visit during which their eligibility into the study will be determined. Screening will including the following: * Review and signing of informed consent document. * Demographics: Date of birth, Gender, Ethnicity, Handedness * Medical history: Surgical/Interventional Procedure History, Parkinson's Disease History (presence of symptoms required for eligibility will be documented), presence and in some cases severity of selected symptoms of either PD or PD medications that can also occur as a side effect of STN-DBS dopamine dysregulation syndrome (DDS); * Review of current Parkinson's disease medications: Dosage/frequency (Start Date, Stop Date) * Review of concomitant medications Visit 1- Baseline (less than or equal to 30 days after Screening * Parkinson's disease dopaminergic medications will be withdrawn overnight to establish medication-OFF state and DBS will be turned OFF overnight for establishing DBS-OFF state. Examiner will establish a UPDRS-III baseline with medication-OFF, DBS-OFF state. * Unblinded examiner will then turn the DBS ON to the patient's baseline DBS settings continuously ON or to burst DBS mode (baseline DBS settings for the patient with DBS set to 1 sec ON, 4 sec OFF), based on results of randomization. The patient will be blinded to this programming change and will be kept at this initial setting for 30 minutes. * Next, a blinded examiner who did not perform the programming change will perform a UPDRS-III evaluation. Next, the DBS will be turned off for 15 minutes to permit for a washout period. * Next, the DBS will be turned on by the unblinded examiner to the alternate setting (burst DBS in case that the patient first was turned on with their baseline DBS setting or baseline DBS setting in case that the patient was first turned on with burst DBS setting) and kept on this setting for 30 minutes. * After 30 minutes, the blinded examiner will perform another UPDRS-III evaluation. Patients, who are blinded to the stimulation setting, will be asked if they preferred one stimulation mode over the other. * If any adverse events occur with burst DBS mode, the unblinded examiner will decrease the amplitude of the DBS by 0.5 milliamp (mA) increments until the adverse events abate. If there are not persistent adverse events with 30 minutes of burst DBS mode, the patient will be kept in burst DBS mode at the end of first visit and will be allowed to take their Parkinson's disease medications. Randomization- Subjects will be randomized to determine which DBS setting is initially programmed during visit one. All subjects will be programmed to both settings over the course of the visit, but the order is randomized to ensure appropriate blinding of the UPDRS assessor. Subjects have a 50% chance of being randomized to the "burst" mode, and a 50% chance of being randomized to the "baseline" mode. Visit Two (6 months +/- 30 Days) * Parkinson's disease dopaminergic medications will be withdrawn overnight to establish medication-OFF state and DBS will be turned OFF overnight for establishing DBS-OFF state. * Examiner will establish a UPDRS-III baseline with medication-OFF, DBS-OFF state. Examiner will then turn the DBS ON to the burst DBS state and keep ON for 30 minutes. After 30 minutes the examiner will perform another UPDRS-III evaluation and will ask about any adverse effects. Patients will then be allowed to take their Parkinson's disease medications and will be kept on the burst mode DBS state. * Patients will be asked if they prefer the burst mode DBS state to their baseline settings before the study. Visit Three (12 months +/- 30 days) * Parkinson's disease dopaminergic medications will be withdrawn overnight to establish medication-OFF state and DBS will be turned OFF overnight for establishing DBS-OFF state. * Examiner will establish a UPDRS-III baseline with medication-OFF, DBS-OFF state. Examiner will then turn the DBS ON to the burst DBS state and keep ON for 30 minutes. After 30 minutes the examiner will perform another UPDRS-III evaluation and will ask about any adverse effects. Patients will then be allowed to take their Parkinson's disease medications and will be kept on the burst mode DBS state. * Patients will be asked if they prefer the burst mode DBS state to their baseline settings before the study. At the conclusion of the study, patients will be asked if they want to continue to use burst DBS state or if would prefer to be programmed back to their pre-study baseline DBS settings.