Characterizing the Specificity and Stability of Local Field Potentials in the Globus Pallidus Internus of Patients Undergoing Deep Brain Stimulation for Parkinson's Disease

Overview

Deep brain stimulation for Parkinson's disease is a well established therapy. Current practice requires tedious adjustment of stimulation settings based on frequent patient assessments. Ultimately, the goal is to develop a system that can program itself using signals that are recorded directly from the brain on a continuous basis. Our previous work has identified abnormal electrical signals in the brain that are targeted for stimulation that can potentially be used to develop a self-programming system. In this study, the investigators will test the safety and utility of a novel adapted device that can not only deliver stimulation to the brain but also record brain signals in a patient that is implanted with a deep brain stimulation system. The purpose of this Phase I study is to understand the safety of the device as well as the relationship between these electrical signals measured from deep within the brain and Parkinson's symptoms and how these signals can be used to guide a self-programmed system. The study will entail implanting this special device (Activa PC+S) in place of the standard generator (Activa PC) and to compare clinical symptoms, recorded brain signals, and stimulation patterns during a one year period after implantation. Specifically, the investigators will use the Activa PC+S to record GPi (internal globus pallidus) local field potentials between and during programming visits, allowing the surgeon to better characterize a patient's disease. At the same time, the investigators will evaluate the safety of this new device.

The device being tested is the Activa Primary Cell and Sensing (PC+S) system which consists of a deep brain stimulation (DBS) generator, specially adapted extension leads, and DBS leads implanted in the globus pallidus internus (GPi) in patients with Parkinson's disease (PD). The Activa PC+S system differs from currently FDA-approved devices in that it is not only capable of delivering therapeutic stimulation through the DBS leads but also recording electrophysiological signals through the same leads. The goal of this pilot study is to evaluate (1) to assess the specificity and stability of the electrophysiological signals recorded with the Activa PC+S system, (2) how the signals recorded by this system correlate with clinical parameters and non-invasive measures of movement, and (3) and the safety of the PC+S system. The Medtronic Activa Primary Cell (PC) DBS system has a proven record of safety and reliability through extensive human clinical use over the years1. The potential risks associated with the placement and the use of the device have been thoroughly described in previous human trials and retrospective reports. The PC+S device is based on the currently approved device but with added sensing capabilities. In this protocol, we will evaluate the Activa PC+S system using additional sensing components with stimulation parameters commonly used for the treatment of movement disorder. This trial will follow a non-randomized design with rigorous and comprehensive follow-ups, as described below. The study will be conducted at the Ronald Reagan UCLA Medical Center and associated facilities through the combined neurology and neurosurgery movement disorders program, which manages over 1,000 patients with PD. The study will provide close follow-up of patients after DBS surgery by a team involving functional neurosurgeons and neurologists with expertise in clinical care of patients with PD. Patients will be screened according to the inclusion/exclusion criteria. Each patient will be informed about the study to see if they are interested in participating. After the patient signs the informed consent, they will undergo baseline evaluations, and if they qualify, they will undergo surgery to implant the deep brain stimulation system. After device implantation, patients will complete comprehensive follow-up as described in the protocol below. The patients will return to the clinic at least monthly for the first 3 months for on and off medication assessments and programming. Primary assessments will be administered monthly for the first 3 months, and then every 3 months up to 12 months post-operatively. LFPs will be recorded across time (intraoperative, during programming, and chronically), across activity states (with quantitative accelerometer and gyroscope measurements), and across disease states (off and on medication, off and on stimulation) to address the primary research questions proposed. A comparison of measures within the same person from pre-treatment to post-treatment will be performed. Also, pre-treatment and post-treatment group means and standard deviations will be determined. Correlations between LFP biosignals and non-invasive measures and clinical assessment of movement will be performed. In addition, correlation between LFP signals and clinically-defined stimulation parameters will be evaluated.