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Moreno Romero GN, Twyman AR, Bandres MF, McPherson JG. Unintentionally intentional: unintended effects of spinal stimulation as a platform for multi-modal neurorehabilitation after spinal cord injury. Bioelectron Med 2024; 10:12. [PMID: 38745334 PMCID: PMC11094943 DOI: 10.1186/s42234-024-00144-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 04/19/2024] [Indexed: 05/16/2024] Open
Abstract
Electrical stimulation of spinal neurons has emerged as a valuable tool to enhance rehabilitation after spinal cord injury. In separate parameterizations, it has shown promise for improving voluntary movement, reducing symptoms of autonomic dysreflexia, improving functions mediated by muscles of the pelvic floor (e.g., bowel, bladder, and sexual function), reducing spasms and spasticity, and decreasing neuropathic pain, among others. This diverse set of actions is related both to the density of sensorimotor neural networks in the spinal cord and to the intrinsic ability of electrical stimulation to modulate neural transmission in multiple spinal networks simultaneously. It also suggests that certain spinal stimulation parameterizations may be capable of providing multi-modal therapeutic benefits, which would directly address the complex, multi-faceted rehabilitation goals of people living with spinal cord injury. This review is intended to identify and characterize reports of spinal stimulation-based therapies specifically designed to provide multi-modal benefits and those that report relevant unintended effects of spinal stimulation paradigms parameterized to enhance a single consequence of spinal cord injury.
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Affiliation(s)
- Gerson N Moreno Romero
- Program in Physical Therapy, Washington University School of Medicine, St. Louis, MO, USA
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Avery R Twyman
- Program in Physical Therapy, Washington University School of Medicine, St. Louis, MO, USA
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Maria F Bandres
- Program in Physical Therapy, Washington University School of Medicine, St. Louis, MO, USA
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Jacob Graves McPherson
- Program in Physical Therapy, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA.
- Washington University Pain Center, Washington University School of Medicine, St. Louis, MO, USA.
- Program in Neurosciences, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA.
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Singh NK, Gandu SR, Li L, Ni L, Acioglu C, Mirabelli E, Hiester LL, Elkabes S, Firestein BL. Cypin Inhibition as a Therapeutic Approach to Treat Spinal Cord Injury-Induced Mechanical Pain. eNeuro 2024; 11:ENEURO.0451-23.2024. [PMID: 38302457 PMCID: PMC10875717 DOI: 10.1523/eneuro.0451-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/24/2023] [Accepted: 01/04/2024] [Indexed: 02/03/2024] Open
Abstract
Cypin (cytosolic postsynaptic density protein 95 interactor) is the primary guanine deaminase in the central nervous system (CNS), promoting the metabolism of guanine to xanthine, an important reaction in the purine salvage pathway. Activation of the purine salvage pathway leads to the production of uric acid (UA). UA has paradoxical effects, specifically in the context of CNS injury as it confers neuroprotection, but it also promotes pain. Since neuropathic pain is a comorbidity associated with spinal cord injury (SCI), we postulated that small molecule cypin inhibitor B9 treatment could attenuate SCI-induced neuropathic pain, potentially by interfering with UA production. However, we also considered that this treatment could hinder the neuroprotective effects of UA and, in doing so, exacerbate SCI outcomes. To address our hypothesis, we induced a moderate midthoracic contusion SCI in female mice and assessed whether transient intrathecal administration of B9, starting at 1 d postinjury (dpi) until 7 dpi, attenuates mechanical pain in hindlimbs at 3 weeks pi. We also evaluated the effects of B9 on the spontaneous recovery of locomotor function. We found that B9 alleviates mechanical pain but does not affect locomotor function. Importantly, B9 does not exacerbate lesion volume at the epicenter. In accordance with these findings, B9 does not aggravate glutamate-induced excitotoxic death of SC neurons in vitro. Moreover, SCI-induced increased astrocyte reactivity at the glial scar is not altered by B9 treatment. Our data suggest that B9 treatment reduces mechanical pain without exerting major detrimental effects following SCI.
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Affiliation(s)
- Nisha K Singh
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
- Molecular Biosciences Graduate Program, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
| | - Srinivasa R Gandu
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
- Molecular Biosciences Graduate Program, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
| | - Lun Li
- Department of Neurosurgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey 07101
| | - Li Ni
- Department of Neurosurgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey 07101
| | - Cigdem Acioglu
- Department of Neurosurgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey 07101
| | - Ersilia Mirabelli
- Department of Neurosurgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey 07101
| | - Liam L Hiester
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
| | - Stella Elkabes
- Department of Neurosurgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey 07101
| | - Bonnie L Firestein
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854
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McPherson JG, Bandres MF. Neural population dynamics reveal that motor-targeted intraspinal microstimulation preferentially depresses nociceptive transmission in spinal cord injury-related neuropathic pain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.27.550880. [PMID: 37546721 PMCID: PMC10402167 DOI: 10.1101/2023.07.27.550880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
The purpose of this study is to determine whether intraspinal microstimulation (ISMS) intended to enhance voluntary motor output after spinal cord injury (SCI) modulates neural population-level spinal responsiveness to nociceptive sensory feedback. The study was conducted in vivo in three cohorts of rats: neurologically intact, chronic SCI without behavioral signs of neuropathic pain, and chronic SCI with SCI-related neuropathic pain (SCI-NP). Nociceptive sensory feedback was induced by application of graded mechanical pressure to the plantar surface of the hindpaw before, during, and after periods of sub-motor threshold ISMS delivered within the motor pools of the L5 spinal segment. Neural population-level responsiveness to nociceptive feedback was recorded throughout the dorso-ventral extent of the L5 spinal segment using dense multi-channel microelectrode arrays. Whereas motor-targeted ISMS reduced nociceptive transmission across electrodes in neurologically intact animals both during and following stimulation, it was not associated with altered nociceptive transmission in rats with SCI that lacked behavioral signs of neuropathic pain. Surprisingly, nociceptive transmission was reduced both during and following motor-targeted ISMS in rats with SCI-NP, and to an extent comparable to that of neurologically intact animals. The mechanisms underlying the differential anti-nociceptive effects of motor-targeted ISMS are unclear, although they may be related to differences in the intrinsic active membrane properties of spinal neurons across the cohorts. Nevertheless, the results of this study support the notion that it may be possible to purposefully engineer spinal stimulation-based therapies that afford multi-modal rehabilitation benefits, and specifically that it may be possible to do so for the individuals most in need - i.e., those with SCI-related movement impairments and SCI-NP.
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Affiliation(s)
- Jacob G. McPherson
- Program in Physical Therapy, Washington University School of Medicine
- Department of Anesthesiology, Washington University School of Medicine
- Washington University Pain Center, Washington University School of Medicine
- Program in Neurosciences; Washington University School of Medicine
- Department of Biomedical Engineering; Washington University in St. Louis
| | - Maria F. Bandres
- Program in Physical Therapy, Washington University School of Medicine
- Department of Biomedical Engineering; Washington University in St. Louis
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Bandres MF, Gomes JL, Moreno Romero GN, Twyman AR, McPherson JG. Precision neuromodulation: Promises and challenges of spinal stimulation for multi-modal rehabilitation. FRONTIERS IN REHABILITATION SCIENCES 2023; 4:1135593. [PMID: 37152244 PMCID: PMC10154513 DOI: 10.3389/fresc.2023.1135593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 03/24/2023] [Indexed: 05/09/2023]
Abstract
Spinal cord injury results in multiple, simultaneous sensorimotor deficits. These include, but are not limited to, full or partial paralysis of muscles below the lesion, muscle spasms, spasticity, and neuropathic pain. Bowel, bladder, and sexual dysfunction are also prevalent. Yet, the majority of emerging spinal stimulation-based therapies focus on a single issue: locomotor rehabilitation. Despite the enormous potential of these translational advances to transform the lives of people living with spinal cord injury, meaningful recovery in other domains deemed critical priorities remains lacking. Here, we highlight the importance of considering the diverse patterns of neural transmission that underlie clinically similar presentations when developing spinal stimulation-based therapies. We also motivate advancement of multi-modal rehabilitation paradigms, which leverage the dense interconnectivity of sensorimotor spinal networks and the unique ability of electrical stimulation to modulate these networks to facilitate and guide simultaneous rehabilitation across domains.
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Affiliation(s)
- Maria F. Bandres
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States
- Program in Physical Therapy, Washington University School of Medicine in St. Louis, St. Louis, MO, United States
| | - Jefferson L. Gomes
- Program in Physical Therapy, Washington University School of Medicine in St. Louis, St. Louis, MO, United States
| | - Gerson N. Moreno Romero
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States
| | - Avery R. Twyman
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States
| | - Jacob Graves McPherson
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States
- Program in Physical Therapy, Washington University School of Medicine in St. Louis, St. Louis, MO, United States
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO, United States
- Washington University Pain Center, Washington University School of Medicine in St. Louis, St. Louis, MO, United States
- Washington University Program in Neurosciences, Washington University in St. Louis, St. Louis, MO, United States
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Bandres MF, Gomes JL, McPherson JG. Motor-targeted spinal stimulation promotes concurrent rebalancing of pathologic nociceptive transmission in chronic spinal cord injury. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.12.536477. [PMID: 37090665 PMCID: PMC10120632 DOI: 10.1101/2023.04.12.536477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Electrical stimulation of spinal networks below a spinal cord injury (SCI) is a promising approach to restore functions compromised by inadequate excitatory neural drive. The most translationally successful examples are paradigms intended to increase neural transmission in weakened yet spared motor pathways and spinal motor networks rendered dormant after being severed from their inputs by lesion. Less well understood is whether spinal stimulation is also capable of reducing neural transmission in pathways made pathologically overactive by SCI. Debilitating spasms, spasticity, and neuropathic pain are all common manifestations of hyperexcitable spinal responses to sensory feedback. But whereas spasms and spasticity can often be managed pharmacologically, SCI-related neuropathic pain is notoriously medically refractory. Interestingly, however, spinal stimulation is a clinically available option for ameliorating neuropathic pain arising from etiologies other than SCI, and it has traditionally been assumed to modulate sensorimotor networks overlapping with those engaged by spinal stimulation for motor rehabilitation. Thus, we reasoned that spinal stimulation intended to increase transmission in motor pathways may simultaneously reduce transmission in spinal pain pathways. Using a well-validated pre-clinical model of SCI that results in severe bilateral motor impairments and SCI-related neuropathic pain, we show that the responsiveness of neurons integral to the development and persistence of the neuropathic pain state can be enduringly reduced by motor-targeted spinal stimulation while preserving spinal responses to non-pain-related sensory feedback. These results suggest that spinal stimulation paradigms could be intentionally designed to afford multi-modal therapeutic benefits, directly addressing the diverse, intersectional rehabilitation goals of people living with SCI.
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