STN LFP and SUA characterization of dyskinesia in PD using microelectrode recordings (P4.7-006)

Objective: To describe the single unit activity (SUA) and local field potential (LFP) characteristics of a patient with idiopathic Parkinson’s disease (PD) during a dyskinesia episode. Background: SUA and LFPs in the unmedicated state of patients with PD undergoing deep brain stimulation (DBS) procedures are well characterized. Although LFP spectral dynamics are known to change in the ON state, less is understood about how this corresponds to changes in SUA, or how either LFP or SUA interacts during dyskinesia episodes. Design/Methods: We describe a case report of an individual undergoing bilateral subthalamic nucleus (STN) DBS for treatment of motor complications associated with PD. Intraoperative left hemispheric microelectrode recordings (NeuroProbe, AlphaOmega) of SUA and LFP were made simultaneously approximately 2.5 hours after the last known levodopa intake. Recordings started from 10mm above and extended to 5mm below the dorsal border of the STN. During the recordings, the patient exhibited generalized dyskinesia. Results: Of 14 neurons isolated, almost all showed tonic firing (fast and some irregular) with a mean firing rate of 63.0 ± 29.8Hz, (higher than previously reported in the unmedicated state). No neurons showed bursting activity as quantified with ISI histograms showing single peaks. LFP activity was characterized by weak beta (22Hz) oscillations, a sharp gamma (80Hz) peak, and strong high frequency oscillations (HFOs) around 300Hz. No coupling between beta and HFO was seen, as previously reported in medicated patients. The SUA was not phase coupled to beta LFP (unlike previously described unmedicated PD patients). Interestingly, sharp gamma activity commenced 10mm above the STN, indicating broader network synchronization. Contralateral dyskinesia improved during stimulation testing of the DBS lead. Conclusions: This case demonstrates unique SUA and LFP findings during a dyskinesia episode in PD, highlighting the need for a more complete understanding of local and network dynamics in PD for use in closed loop DBS systems. Disclosure: Dr. Jimenez Shahed has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with St. Jude Medical/Abbott, Medtronic, Teva, Bracket, Nuvelution, Sunovion,. Dr. Jimenez Shahed has received research support from Biotie/Accorda, Medtronic, St. Jude Medical/Abbott, Eli Lilly & Company, Wilsons Therapeutics. Dr. Ozturk has nothing to disclose. Dr. Kaku has nothing to disclose. Dr. Viswanathan has received research support from Medtronic, St Jude/Abbott. Dr. Ince has received research support from Medtronic, St Jude/Abbott.