Identifying the ideal location for Deep Brain Stimulation (DBS) in the Treatment of Parkinson's Disease.

All participants undergoing DBS for Parkinson’s disease will have bioelectric signals (including ERNA) recorded during surgery at the time of DBS lead implantation. The bioelectric signals will be measured using the Bionics Institute customised neurostimulator and recording system (ADEPT). The customised device will be operated by a highly trained researcher from the Bionics Institute. The collection of this bioelectric signal data will occur during the DBS surgery and take approximately 15-20 minutes. The surgeon will not be blinded to the ERNA signal data intra-operatively. However, this ERNA signal data will not be used to guide electrode placement. Except for the recording of bioelectric signals using the ADEPT device, the DBS implantation surgery will proceed as per standard of care. The DBS procedure may vary according to the preferences of the treating team. The final DBS lead location will be determined as per standard of care using a combination of brain imaging guided stereotactic surgery +/- intra-operative clinical evaluation +/- brain microelectrode recordings on a commercially available recording device. The total duration of surgery varies between treating teams, though it is routinely 3 – 5 hours. All participants will have standard of care brain imaging (MRI brain, CT brain) prior to and after surgery, to identify the location of the DBS electrodes implanted into the brain. All participants will also have an additional (non-standard of care) cranial x-ray within 2 weeks of the first post-operative study visit, 4 months after surgery. The DBS electrodes (standard of care) implanted during surgery have directionality to enable steering of stimulation in a certain direction. This cranial x-ray is required to confirm the directionality of the DBS leads relative to the adjacent anatomical structures. This will enable ERNA signals recorded on each electrode to be accurately referenced to the anatomical location of the electrode. All participants will have a baseline visit prior to DBS surgery and follow-up study visits at 4 months and 12 months after surgery. At these visits, observational data including motor scores, questionnaires (to measure motor, cognitive and neuropsychiatric outcomes) and the medications and DBS parameters prescribed by the treating doctor will be collected. A subset of participants will attend an Acute Clinical Evaluation experimental session over two days, 4 months after DBS surgery. Participants for the Acute Clinical Evaluation study will need to meet the additional inclusion criteria of an upper limb rigidity score of equal or greater than 2 on the worse affected side, as rated by the Unified Parkinson’s Disease Rating Scale part III. General circumstances including a good post-operative recovery, geographical location and ease of access to sessions will be considered when selecting participants for this sub-study. During these sessions, the DBS will be adjusted temporarily by a movement disorders clinician with the resultant changes in motor symptoms measured. The participant's DBS parameters will be returned to those prescribed by the treating doctor at the end of the experimental session.