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Electrically Evoked Compound Action Potentials in Spinal Cord Stimulation: Implications for Preclinical Research Models

Lookup NU author(s): Dr Quoc Vuong, Dr Ilona Obara



This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).


© 2021 The Authors. Neuromodulation: Technology at the Neural Interface published by Wiley Periodicals LLC on behalf of International Neuromodulation Society. Objectives: The study aimed to assess the feasibility of recording electrically evoked compound action potentials (ECAPs) from the rat spinal cord. To achieve this, we characterized electrophysiological responses of dorsal column (DC) axons from electrical stimulation and quantified the relationship between ECAP and motor thresholds (ECAPTs and MTs). Material and Methods: Naïve, anesthetized and freely behaving rats were implanted with a custom-made epidural spinal cord stimulation (SCS) lead. Epidural stimulation and recordings were performed on the same lead using specifically designed equipment. Results: The ECAPs recorded from the rat spinal cord demonstrated the expected triphasic morphology. Using 20 μsec pulse duration and 2 Hz frequency rate, the current required in anesthetized rats to generate ECAPs was 0.13 ± 0.02 mA, while the average current required to observe MT was 1.49 ± 0.14 mA. In unanesthetized rats, the average current required to generate ECAPs was 0.09 ± 0.02 mA, while the average current required to observe MT was 0.27 ± 0.04 mA. Thus, there was a significant difference between the ECAPT and MT in both anesthetized and unanesthetized rats (MT was 13.39 ± 2.40 and 2.84 ± 0.33 times higher than ECAPT, respectively). Signal analysis revealed average conduction velocities (CVs) suggesting that predominantly large, myelinated fibers were activated. In addition, a morphometric evaluation of spinal cord slices indicated that the custom-made lead may preferentially activate DC axons. Conclusions: This is the first evidence demonstrating the feasibility of recording ECAPs from the rat spinal cord, which may be more useful in determining parameters of SCS in preclinical SCS models than MTs. Thus, this approach may allow for the development of a novel model of SCS in rats with chronic pain that will translate better between animals and humans.

Publication metadata

Author(s): Dietz BE, Mugan D, Vuong QC, Obara I

Publication type: Article

Publication status: Published

Journal: Neuromodulation

Year: 2022

Volume: 25

Issue: 1

Pages: 64-74

Print publication date: 01/01/2022

Online publication date: 05/07/2021

Acceptance date: 17/05/2021

Date deposited: 19/07/2021

ISSN (print): 1094-7159

ISSN (electronic): 1525-1403

Publisher: Wiley


DOI: 10.1111/ner.13480


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