The Injectrode - A Truly Injectable Electrode for Dorsal Root Ganglion Stimulation to Treat Pain

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Abstract Given the pressures from the ‘opioid epidemic’ and the substantial harm the addictive drugs may have on patients, there is a substantial unmet need for non-opioid alternatives to treat back pain. Dorsal Root Ganglion (DRG) stimulation has recently been tested in clinical studies in direct comparison to traditional epidural spinal cord stimulation (SCS) strategies for intractable pain in a 152 patient study. Although the percentage of subjects received greater than 50 percent decrease in back pain at 3 months was significantly greater in the DRG (81.2%) arm vs SCS (55.7%), the adverse event rate related to the neural stimulator/device or the implant procedure was significantly higher in the DRG arm (36.8% to 26.4% and 46.1% to 26.3%, respectively). As the procedure for DRG and SCS involve implanting a complex electrode/lead/implantable pulse generator system, the cost of both procedures is also a significant barrier. To overcome these issues, we have developed a novel electrode called the ‘Injectrode’, which is pre-polymer liquid composite in a syringe and cures in a neural sheathe or foramen quickly after injection with a Young’s Modulus substantially closer to human tissue than contemporary DRG or SCS electrodes. We have previously demonstrated the ability to inject on a deep nerve, connect via a simple wire to an Injectrode ‘collector’ that is injected under the skin, and reliably stimulate the deep nerve using a standard inexpensive non-invasive TENS unit without any wire connection spanning the skin. This system has only simple passive components injected to create a conductive conduit from just under the skin to complex neural structures like the foramen/DRG, dramatically reducing the number of failure points leading to adverse events. Moreover, as the stimulating system is entirely external, it is both much more cost efficient and easily upgradable once new stimulation strategies are discovered to reduce pain. In this study, we propose to directly compare the Injectrode/Injectrode collector concept to established electrode stimulation strategies for the DRG as an alternative to opioid administration. We will perform benchtop characterization and refinement necessary as a precursor to an FDA enabled clinical study, use modeling and animal testing in appropriate sized animal models to refine the efficiency of energy transfer from a TENS unit to an Injectrode/Injectrode collector concept, and optimize the injection surgical procedure for the complex anatomy of the DRG.