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Benevides ES, Thakre PP, Rana S, Sunshine MD, Jensen VN, Oweiss K, Fuller DD. Chemogenetic stimulation of phrenic motor output and diaphragm activity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.12.589188. [PMID: 38659846 PMCID: PMC11042184 DOI: 10.1101/2024.04.12.589188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Impaired diaphragm activation contributes to morbidity and mortality in many neurodegenerative diseases and neurologic injuries. We conducted experiments to determine if expression of an excitatory DREADD (designer receptors exclusively activation by designer drugs) in the mid-cervical spinal cord would enable respiratory-related activation of phrenic motoneurons to increase diaphragm activation. Wild type (C57/bl6) and ChAT-Cre mice received bilateral intraspinal (C4) injections of an adeno-associated virus (AAV) encoding the hM3D(Gq) excitatory DREADD. In wild type mice, this produced non-specific DREADD expression throughout the mid-cervical ventral horn. In ChAT-Cre mice, a Cre-dependent viral construct was used to drive DREADD expression in C4 ventral horn motoneurons, targeting the phrenic motoneuron pool. Diaphragm EMG was recorded during spontaneous breathing at 6-8 weeks post-AAV delivery. The selective DREADD ligand JHU37160 (J60) caused a bilateral, sustained (>1 hr) increase in inspiratory EMG bursting in both groups; the relative increase was greater in ChAT-Cre mice. Additional experiments in a ChAT-Cre rat model were conducted to determine if spinal DREADD activation could increase inspiratory tidal volume (VT) during spontaneous breathing without anesthesia. Three to four months after intraspinal (C4) injection of AAV driving Cre-dependent hM3D(Gq) expression, intravenous J60 resulted in a sustained (>30 min) increase in VT assessed using whole-body plethysmography. Subsequently, direct nerve recordings confirmed that J60 evoked a >50% increase in inspiratory phrenic output. The data show that mid-cervical spinal DREADD expression targeting the phrenic motoneuron pool enables ligand-induced, sustained increases in the neural drive to the diaphragm. Further development of this technology may enable application to clinical conditions associated with impaired diaphragm activation and hypoventilation.
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Affiliation(s)
- Ethan S Benevides
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32601
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32601
| | - Prajwal P Thakre
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32601
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32601
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32601
| | - Sabhya Rana
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32601
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32601
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32601
| | - Michael D Sunshine
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32601
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32601
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32601
| | - Victoria N Jensen
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32601
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32601
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32601
| | - Karim Oweiss
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32601
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, 32601
| | - David D Fuller
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32601
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32601
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32601
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2
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Chalif JI, Chavarro VS, Mensah E, Johnston B, Fields DP, Chalif EJ, Chiang M, Sutton O, Yong R, Trumbower R, Lu Y. Epidural Spinal Cord Stimulation for Spinal Cord Injury in Humans: A Systematic Review. J Clin Med 2024; 13:1090. [PMID: 38398403 PMCID: PMC10889415 DOI: 10.3390/jcm13041090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 02/09/2024] [Accepted: 02/12/2024] [Indexed: 02/25/2024] Open
Abstract
(1) Background: Spinal cord injury (SCI) represents a major health challenge, often leading to significant and permanent sensorimotor and autonomic dysfunctions. This study reviews the evolving role of epidural spinal cord stimulation (eSCS) in treating chronic SCI, focusing on its efficacy and safety. The objective was to analyze how eSCS contributes to the recovery of neurological functions in SCI patients. (2) Methods: We utilized the PRISMA guidelines and performed a comprehensive search across MEDLINE/PubMed, Embase, Web of Science, and IEEE Xplore databases up until September 2023. We identified studies relevant to eSCS in SCI and extracted assessments of locomotor, cardiovascular, pulmonary, and genitourinary functions. (3) Results: A total of 64 studies encompassing 306 patients were identified. Studies investigated various stimulation devices, parameters, and rehabilitation methods. Results indicated significant improvements in motor function: 44% of patients achieved assisted or independent stepping or standing; 87% showed enhanced muscle activity; 65% experienced faster walking speeds; and 80% improved in overground walking. Additionally, eSCS led to better autonomic function, evidenced by improvements in bladder and sexual functions, airway pressures, and bowel movements. Notable adverse effects included device migration, infections, and post-implant autonomic dysreflexia, although these were infrequent. (4) Conclusion: Epidural spinal cord stimulation is emerging as an effective and generally safe treatment for chronic SCI, particularly when combined with intensive physical rehabilitation. Future research on standardized stimulation parameters and well-defined therapy regimens will optimize benefits for specific patient populations.
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Affiliation(s)
- J. I. Chalif
- Department of Neurosurgery, Brigham and Women’s Hospital, Boston, MA 02115, USA; (J.I.C.); (V.S.C.); (B.J.)
- Harvard Medical School, Boston, MA 02115, USA; (M.C.); (R.Y.); (R.T.)
| | - V. S. Chavarro
- Department of Neurosurgery, Brigham and Women’s Hospital, Boston, MA 02115, USA; (J.I.C.); (V.S.C.); (B.J.)
- Harvard Medical School, Boston, MA 02115, USA; (M.C.); (R.Y.); (R.T.)
- Department of Physical Medicine and Rehabilitation, Spaulding Hospital Cambridge, Cambridge, MA 02115, USA
| | - E. Mensah
- Chan School of Public Health, Harvard University, Boston, MA 02115, USA;
| | - B. Johnston
- Department of Neurosurgery, Brigham and Women’s Hospital, Boston, MA 02115, USA; (J.I.C.); (V.S.C.); (B.J.)
- Harvard Medical School, Boston, MA 02115, USA; (M.C.); (R.Y.); (R.T.)
| | - D. P. Fields
- Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA 15261, USA;
| | - E. J. Chalif
- Department of Neurosurgery, Brigham and Women’s Hospital, Boston, MA 02115, USA; (J.I.C.); (V.S.C.); (B.J.)
- Harvard Medical School, Boston, MA 02115, USA; (M.C.); (R.Y.); (R.T.)
| | - M. Chiang
- Harvard Medical School, Boston, MA 02115, USA; (M.C.); (R.Y.); (R.T.)
- Department of Physical Medicine and Rehabilitation, Spaulding Hospital Cambridge, Cambridge, MA 02115, USA
- Department of Anesthesiology Perioperative and Pain Management, Brigham and Women’s Hospital, Boston, MA 02115, USA;
| | - O. Sutton
- Department of Anesthesiology Perioperative and Pain Management, Brigham and Women’s Hospital, Boston, MA 02115, USA;
| | - R. Yong
- Harvard Medical School, Boston, MA 02115, USA; (M.C.); (R.Y.); (R.T.)
- Department of Anesthesiology Perioperative and Pain Management, Brigham and Women’s Hospital, Boston, MA 02115, USA;
| | - R. Trumbower
- Harvard Medical School, Boston, MA 02115, USA; (M.C.); (R.Y.); (R.T.)
- Department of Physical Medicine and Rehabilitation, Spaulding Hospital Cambridge, Cambridge, MA 02115, USA
| | - Y. Lu
- Department of Neurosurgery, Brigham and Women’s Hospital, Boston, MA 02115, USA; (J.I.C.); (V.S.C.); (B.J.)
- Harvard Medical School, Boston, MA 02115, USA; (M.C.); (R.Y.); (R.T.)
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3
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Mickle AR, Peñaloza-Aponte JD, Coffey R, Hall NA, Baekey D, Dale EA. Closed-loop cervical epidural stimulation partially restores ipsilesional diaphragm EMG after acute C 2 hemisection. Respir Physiol Neurobiol 2024; 320:104182. [PMID: 37923238 DOI: 10.1016/j.resp.2023.104182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 10/22/2023] [Accepted: 10/22/2023] [Indexed: 11/07/2023]
Abstract
Cervical spinal cord injury creates lasting respiratory deficits which can require mechanical ventilation long-term. We have shown that closed-loop epidural stimulation (CL-ES) elicits respiratory plasticity in the form of increased phrenic network excitability (Malone et. al., E Neuro, Vol 9, 0426-21.2021, 2022); however, the ability of this treatment to create functional benefits for breathing function per se after injury has not been demonstrated. Here, we demonstrate in C2 hemisected anesthetized rats, a 20-minute bout of CL-ES administered at current amplitudes below the motor threshold restores paralyzed hemidiaphragm activity in-phase with breathing while potentiating contralesional activity. While this acute bout of stimulation did not elicit the increased network excitability seen in our chronic model, a subset of stimulated animals continued spontaneous ipsilesional diaphragm activity for several seconds after stopping stimulation. These results support the use of CL-ES as a therapeutic to rescue breathing after high cervical spinal cord injury, with the potential to lead to lasting recovery and device independence.
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Affiliation(s)
- Alyssa R Mickle
- Department of Neuroscience, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; Breathing Research and Therapeutics Center, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; McKnight Brain Institute, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States.
| | - Jesús D Peñaloza-Aponte
- Department of Neuroscience, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; Breathing Research and Therapeutics Center, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; McKnight Brain Institute, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States
| | - Richard Coffey
- Department of Physiology and Aging, University of Florida, 1600 SW Archer Rd M552, Gainesville, FL 32603, United States
| | - Natale A Hall
- Department of Physiology and Aging, University of Florida, 1600 SW Archer Rd M552, Gainesville, FL 32603, United States
| | - David Baekey
- Department of Neuroscience, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; Breathing Research and Therapeutics Center, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; McKnight Brain Institute, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States
| | - Erica A Dale
- Department of Neuroscience, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; Breathing Research and Therapeutics Center, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; McKnight Brain Institute, University of Florida, 1149 Newell Dr, Gainesville, FL 32610, United States; Department of Physiology and Aging, University of Florida, 1600 SW Archer Rd M552, Gainesville, FL 32603, United States
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Shandybina ND, Kuropatenko MV, Moshonkina TR. Regulation of Human Respiration by Electrical Stimulation. J EVOL BIOCHEM PHYS+ 2022; 58:1879-1891. [PMID: 36573159 PMCID: PMC9773692 DOI: 10.1134/s0022093022060175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/28/2022] [Accepted: 09/29/2022] [Indexed: 12/24/2022]
Abstract
The review addresses modern methods of electrical stimulation used to regulate the function of external respiration in humans. The methods include abdominal functional stimulation of respiratory muscles, diaphragmatic stimulation, phrenic nerve stimulation, epidural and transcutaneous spinal cord stimulation. The physiological rationale of their application is described along with the examples of their use in clinical practice, including stimulation parameters and electrode placement diagrams for each of the methods. We analyze the effectiveness of each of the methods in patients with respiratory muscle paresis and the features of their use depending on the level of spinal cord injury. Special attention is paid to the method of epidural spinal cord stimulation because this technique is widely used in electrophysiological studies on animal models, providing deeper insight into the spinal levels of the functional control of external respiration. The review substantiates the great potential of using the method of transcutaneous electrical spinal cord stimulation both in fundamental studies of external respiration and in clinical practice.
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Affiliation(s)
- N. D. Shandybina
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia
- Institute of Experimental Medicine, St. Petersburg, Russia
| | | | - T. R. Moshonkina
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia
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5
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Locke KC, Randelman ML, Hoh DJ, Zholudeva LV, Lane MA. Respiratory plasticity following spinal cord injury: perspectives from mouse to man. Neural Regen Res 2022; 17:2141-2148. [PMID: 35259820 PMCID: PMC9083159 DOI: 10.4103/1673-5374.335839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 09/18/2021] [Accepted: 10/20/2021] [Indexed: 12/03/2022] Open
Abstract
The study of respiratory plasticity in animal models spans decades. At the bench, researchers use an array of techniques aimed at harnessing the power of plasticity within the central nervous system to restore respiration following spinal cord injury. This field of research is highly clinically relevant. People living with cervical spinal cord injury at or above the level of the phrenic motoneuron pool at spinal levels C3-C5 typically have significant impairments in breathing which may require assisted ventilation. Those who are ventilator dependent are at an increased risk of ventilator-associated co-morbidities and have a drastically reduced life expectancy. Pre-clinical research examining respiratory plasticity in animal models has laid the groundwork for clinical trials. Despite how widely researched this injury is in animal models, relatively few treatments have broken through the preclinical barrier. The three goals of this present review are to define plasticity as it pertains to respiratory function post-spinal cord injury, discuss plasticity models of spinal cord injury used in research, and explore the shift from preclinical to clinical research. By investigating current targets of respiratory plasticity research, we hope to illuminate preclinical work that can influence future clinical investigations and the advancement of treatments for spinal cord injury.
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Affiliation(s)
- Katherine C. Locke
- Department of Neurobiology & Anatomy, Drexel University, Philadelphia, PA, USA
- Marion Murray Spinal Cord Research Center, Philadelphia, PA, USA
| | - Margo L. Randelman
- Department of Neurobiology & Anatomy, Drexel University, Philadelphia, PA, USA
- Marion Murray Spinal Cord Research Center, Philadelphia, PA, USA
| | - Daniel J. Hoh
- Lillian S. Wells Department of Neurosurgery, University of Florida, Gainesville, FL, USA
| | - Lyandysha V. Zholudeva
- Marion Murray Spinal Cord Research Center, Philadelphia, PA, USA
- Cardiovascular Disease, Gladstone Institutes, San Francisco, CA, USA
| | - Michael A. Lane
- Department of Neurobiology & Anatomy, Drexel University, Philadelphia, PA, USA
- Marion Murray Spinal Cord Research Center, Philadelphia, PA, USA
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6
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Kandhari S, Sharma D, Tomar AK, Matis G, Lavrov IA, Majumdar P. Epidural electrical spinal cord stimulation of the thoracic segments (T2-T5) facilitates respiratory function in patients with complete spinal cord injury. Respir Physiol Neurobiol 2022; 300:103885. [PMID: 35276344 DOI: 10.1016/j.resp.2022.103885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 02/26/2022] [Accepted: 03/05/2022] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Patients with high cervical Spinal Cord Injury (SCI) usually require mechanical ventilation support. Phrenic Nerve Stimulation (PNS) both direct and indirect is the main alternative for these patients to wean off ventilator although PNS has several limitations and phrenic nerve could be also damaged after cervical spinal cord injury. OBJECTIVE In this study, we assessed if the spinal cord Epidural Electrical Stimulation (EES) at the segments T2-T5, related to intercostal muscles, can facilitate respiratory function and particularly inspired tidal volume during mechanic ventilation. METHODS Two patients with a high cervical injury were selected for this study with ethical committee permission and under review board supervision. A phrenic nerve conduction study with diaphragm electromyography (DEMG) was performed before and after trial of EES. RESULTS Results demonstrate that EES at T2-T5 substantially increase the inspired volume. The results of this study also demonstrate that EES at spinal segments T2-T5 can bring patients dependent from mechanical ventilation to pressure support (on CPAP), preventing Baro-trauma and other complications related to mechanical ventilation. CONCLUSION These findings suggest that tested approach applied alone or in combination with the phrenic nerve stimulation could help to reduce time on mechanical ventilation and related complications.
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Affiliation(s)
- Sachin Kandhari
- Department of Functional Neurosurgery and Neuromodulation, Institute of Brain and Spine Hospitals, India
| | - Dewaker Sharma
- Department of Functional Neurosurgery and Neuromodulation, Institute of Brain and Spine Hospitals, India
| | - Amit Kumar Tomar
- Department of Anesthesia, Institute of Brain and Spine Hospitals, India
| | - Georgios Matis
- Deaprtment of Functional Neurosurgery, University of Cologne, Germany
| | - Igor A Lavrov
- Department of Neurology, Department of Biomedical Engineering, Mayo Clinic, Rochester, NY, USA; Kazan Federal University, Kazan, Tatarstan, Russia
| | - Pritam Majumdar
- Department of Neuromodulation, Institute of Brain and Spine Hospitals, India; Deaprtment of Functional Neurosurgery and Neuromodulation, University of Cologne, Germany.
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7
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Malone IG, Nosacka RL, Nash MA, Otto KJ, Dale EA. Electrical epidural stimulation of the cervical spinal cord: implications for spinal respiratory neuroplasticity after spinal cord injury. J Neurophysiol 2021; 126:607-626. [PMID: 34232771 DOI: 10.1152/jn.00625.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Traumatic cervical spinal cord injury (cSCI) can lead to damage of bulbospinal pathways to the respiratory motor nuclei and consequent life-threatening respiratory insufficiency due to respiratory muscle paralysis/paresis. Reports of electrical epidural stimulation (EES) of the lumbosacral spinal cord to enable locomotor function after SCI are encouraging, with some evidence of facilitating neural plasticity. Here, we detail the development and success of EES in recovering locomotor function, with consideration of stimulation parameters and safety measures to develop effective EES protocols. EES is just beginning to be applied in other motor, sensory, and autonomic systems; however, there has only been moderate success in preclinical studies aimed at improving breathing function after cSCI. Thus, we explore the rationale for applying EES to the cervical spinal cord, targeting the phrenic motor nucleus for the restoration of breathing. We also suggest cellular/molecular mechanisms by which EES may induce respiratory plasticity, including a brief examination of sex-related differences in these mechanisms. Finally, we suggest that more attention be paid to the effects of specific electrical parameters that have been used in the development of EES protocols and how that can impact the safety and efficacy for those receiving this therapy. Ultimately, we aim to inform readers about the potential benefits of EES in the phrenic motor system and encourage future studies in this area.
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Affiliation(s)
- Ian G Malone
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, Florida.,Breathing Research and Therapeutics Center (BREATHE), University of Florida, Gainesville, Florida
| | - Rachel L Nosacka
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
| | - Marissa A Nash
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
| | - Kevin J Otto
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, Florida.,Breathing Research and Therapeutics Center (BREATHE), University of Florida, Gainesville, Florida.,J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida.,Department of Neuroscience, University of Florida, Gainesville, Florida.,Department of Neurology, University of Florida, Gainesville, Florida.,Department of Materials Science and Engineering, University of Florida, Gainesville, Florida.,McKnight Brain Institute, University of Florida, Gainesville, Florida
| | - Erica A Dale
- Breathing Research and Therapeutics Center (BREATHE), University of Florida, Gainesville, Florida.,Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida.,Department of Neuroscience, University of Florida, Gainesville, Florida.,McKnight Brain Institute, University of Florida, Gainesville, Florida
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8
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High frequency repetitive Transcranial Magnetic Stimulation promotes long lasting phrenic motoneuron excitability via GABAergic networks. Respir Physiol Neurobiol 2021; 292:103704. [PMID: 34058433 DOI: 10.1016/j.resp.2021.103704] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 05/17/2021] [Accepted: 05/25/2021] [Indexed: 11/21/2022]
Abstract
Repetitive transcranial magnetic stimulation (rTMS) is a promising, innovative, and non-invasive therapy used clinically. Efficacy of rTMS has been demonstrated to ameliorate psychiatric disorders and neuropathic pain through neuromodulation of affected neural circuits. However, little is known about the mechanisms and the specific neural circuits via which rTMS facilitates these functional effects. The aim of this study was to begin revealing the mechanisms by which rTMS may tap into existing neural circuits, by using a well characterized spinal motor circuit - the phrenic circuit. Here we hypothesized that rTMS can be used to enhance phrenic motoneuron excitability in anesthetized Sprague Dawley rats. Multiple acute rTMS protocols were used revealing 10 Hz rTMS protocol induced a robust, long-lasting increase in phrenic motoneuron excitability, functionally evaluated by diaphragm motor evoked potentials (59.1 ± 21.1 % of increase compared to baseline 60 min after 10 Hz protocol against 6.0 ± 5.8 % (p = 0.007) for Time Control, -5.8 ± 7.4 % (p < 0.001) for 3 Hz, and 5.2 ± 12.5 % (p = 0.008) for 30 Hz protocols). A deeper analyze allowed to discriminate "responder" and "non-responder" subgroups among 10 Hz rTMS treated animals. Intravenous injections of GABAA and GABAB receptor agonists prior to 10 Hz rTMS treatment, abolished the enhanced phrenic motoneuron excitability, suggesting GABAergic input plays a mechanistic role in rTMS-induced phrenic excitability. These data demonstrate that a single high frequency rTMS protocol at 10 Hz increases phrenic motoneuron excitability, mediated by a local GABAergic "disinhibition". By understanding how rTMS can be used to affect neural circuits non-invasively we can begin to harness the therapeutic potential of this neuromodulatory strategy to promote recovery after disease or injury to the central nervous system.
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9
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Zander HJ, Kowalski KE, DiMarco AF, Lempka SF. Model-Based Optimization of Spinal Cord Stimulation for Inspiratory Muscle Activation. Neuromodulation 2021; 25:1317-1329. [PMID: 33987918 DOI: 10.1111/ner.13415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 04/14/2021] [Accepted: 04/26/2021] [Indexed: 11/29/2022]
Abstract
OBJECTIVE High-frequency spinal cord stimulation (HF-SCS) is a potential method to provide natural and effective inspiratory muscle pacing in patients with ventilator-dependent spinal cord injuries. Experimental data have demonstrated that HF-SCS elicits physiological activation of the diaphragm and inspiratory intercostal muscles via spinal cord pathways. However, the activation thresholds, extent of activation, and optimal electrode configurations (i.e., lead separation, contact spacing, and contact length) to activate these neural elements remain unknown. Therefore, the goal of this study was to use a computational modeling approach to investigate the direct effects of HF-SCS on the spinal cord and to optimize electrode design and stimulation parameters. MATERIALS AND METHODS We developed a computer model of HF-SCS that consisted of two main components: 1) finite element models of the electric field generated during HF-SCS, and 2) multicompartment cable models of axons and motoneurons within the spinal cord. We systematically evaluated the neural recruitment during HF-SCS for several unique electrode designs and stimulation configurations to optimize activation of these neural elements. We then evaluated our predictions by testing two of these lead designs with in vivo canine experiments. RESULTS Our model results suggested that within physiological stimulation amplitudes, HF-SCS activates both axons in the ventrolateral funiculi (VLF) and inspiratory intercostal motoneurons. We used our model to predict a lead design to maximize HF-SCS activation of these neural targets. We evaluated this lead design via in vivo experiments, and our computational model predictions demonstrated excellent agreement with our experimental testing. CONCLUSIONS Our computational modeling and experimental results support the potential advantages of a lead design with longer contacts and larger edge-to-edge contact spacing to maximize inspiratory muscle activation during HF-SCS at the T2 spinal level. While these results need to be further validated in future studies, we believe that the results of this study will help improve the efficacy of HF-SCS technologies for inspiratory muscle pacing.
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Affiliation(s)
- Hans J Zander
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.,Biointerfaces Institute, University of Michigan, Ann Arbor, MI, USA
| | | | - Anthony F DiMarco
- Department of Physical Medicine and Rehabilitation, Case Western Reserve University, Cleveland, OH, USA
| | - Scott F Lempka
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.,Biointerfaces Institute, University of Michigan, Ann Arbor, MI, USA.,Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA
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10
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Sunshine MD, Cassarà AM, Neufeld E, Grossman N, Mareci TH, Otto KJ, Boyden ES, Fuller DD. Restoration of breathing after opioid overdose and spinal cord injury using temporal interference stimulation. Commun Biol 2021; 4:107. [PMID: 33495588 PMCID: PMC7835220 DOI: 10.1038/s42003-020-01604-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 12/14/2020] [Indexed: 01/05/2023] Open
Abstract
Respiratory insufficiency is a leading cause of death due to drug overdose or neuromuscular disease. We hypothesized that a stimulation paradigm using temporal interference (TI) could restore breathing in such conditions. Following opioid overdose in rats, two high frequency (5000 Hz and 5001 Hz), low amplitude waveforms delivered via intramuscular wires in the neck immediately activated the diaphragm and restored ventilation in phase with waveform offset (1 Hz or 60 breaths/min). Following cervical spinal cord injury (SCI), TI stimulation via dorsally placed epidural electrodes uni- or bilaterally activated the diaphragm depending on current and electrode position. In silico modeling indicated that an interferential signal in the ventral spinal cord predicted the evoked response (left versus right diaphragm) and current-ratio-based steering. We conclude that TI stimulation can activate spinal motor neurons after SCI and prevent fatal apnea during drug overdose by restoring ventilation with minimally invasive electrodes.
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Affiliation(s)
- Michael D Sunshine
- Rehabilitation Science PhD Program, University of Florida, Gainesville, FL, 32611, USA
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32611, USA
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32611, USA
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32611, USA
| | - Antonino M Cassarà
- Foundation for Research on Information Technologies in Society (IT'IS), 8004, Zurich, Switzerland
| | - Esra Neufeld
- Foundation for Research on Information Technologies in Society (IT'IS), 8004, Zurich, Switzerland
| | - Nir Grossman
- Division of Brain Sciences, Imperial College London, London, SW7 2BU, United Kingdom
- United Kingdom Dementia Research Institute, Imperial College London, London, SW7 2BU, United Kingdom
| | - Thomas H Mareci
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, 32611, USA
| | - Kevin J Otto
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, 32611, USA
- Department of Neuroscience, University of Florida, Gainesville, FL, 32611, USA
- Department of Neurology, University of Florida, Gainesville, FL, 32611, USA
- Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Edward S Boyden
- Departments of Brain and Cognitive Sciences, Media Arts and Sciences, and Biological Engineering, McGovern and Koch Institutes, MIT, Cambridge, MA, 02139, USA
- Howard Hughes Medical Institute, Cambridge, MA, 02138, USA
| | - David D Fuller
- Department of Physical Therapy, University of Florida, Gainesville, FL, 32611, USA.
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, 32611, USA.
- McKnight Brain Institute, University of Florida, Gainesville, FL, 32611, USA.
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11
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Gad P, Kreydin E, Zhong H, Edgerton VR. Enabling respiratory control after severe chronic tetraplegia: an exploratory case study. J Neurophysiol 2020; 124:774-780. [PMID: 32755339 PMCID: PMC7509292 DOI: 10.1152/jn.00320.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/27/2020] [Accepted: 07/28/2020] [Indexed: 01/07/2023] Open
Abstract
Respiratory dysfunction is one of the most debilitating effects of spinal cord injury (SCI) impacting the quality of life of patients and caregivers. In addition, breathing difficulties impact the rehabilitation routine a patient may potentially undergo. Transcutaneous electrical spinal cord neuromodulation (TESCoN) is a novel approach to reactivate and retrain spinal circuits after paralysis. We demonstrate that acute and chronic TESCoN therapy over the cervical spinal cord positively impacts the breathing and coughing ability in a patient with chronic tetraplegia. ln addition, we show that the improved breathing and coughing ability are not only observed in the presence of TESCoN but persisted for a few days after TESCoN was stopped.NEW & NOTEWORTHY Noninvasive spinal neuromodulation improves breathing and coughing in a patient with severe and complete tetraplegia.
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Affiliation(s)
- Parag Gad
- Department of Neurobiology, University of California, Los Angeles, California
- Rancho Research Institute, Rancho Los Amigos National Rehabilitation Center, Downey, California
| | - Evgeniy Kreydin
- Department of Urology, Keck School of Medicine of University of Southern California, Los Angeles, California
- Rancho Research Institute, Rancho Los Amigos National Rehabilitation Center, Downey, California
| | - Hui Zhong
- Department of Neurobiology, University of California, Los Angeles, California
- Rancho Research Institute, Rancho Los Amigos National Rehabilitation Center, Downey, California
| | - V Reggie Edgerton
- Department of Neurobiology, University of California, Los Angeles, California
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California
- Department of Neurosurgery, University of California, Los Angeles, California
- Brain Research Institute, University of California, Los Angeles, California
- Institut Guttmann. Hospital de Neurorehabilitació, Institut Universitari adscrit a la Universitat Autònoma de Barcelona, Barcelona, Badalona, Spain
- The Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales, Australia
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12
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Sunshine MD, Sutor TW, Fox EJ, Fuller DD. Targeted activation of spinal respiratory neural circuits. Exp Neurol 2020; 328:113256. [PMID: 32087253 DOI: 10.1016/j.expneurol.2020.113256] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 01/31/2020] [Accepted: 02/18/2020] [Indexed: 12/30/2022]
Abstract
Spinal interneurons which discharge in phase with the respiratory cycle have been repeatedly described over the last 50 years. These spinal respiratory interneurons are part of a complex propriospinal network that is synaptically coupled with respiratory motoneurons. This article summarizes current knowledge regarding spinal respiratory interneurons and emphasizes chemical, electrical and physiological methods for activating spinal respiratory neural circuits. Collectively, the work reviewed here shows that activating spinal interneurons can have a powerful impact on spinal respiratory motor output, and can even drive rhythmic bursting in respiratory motoneuron pools under certain conditions. We propose that the primary functions of spinal respiratory neurons include 1) shaping the respiratory pattern into the final efferent motor output from the spinal respiratory nerves; 2) coordinating respiratory muscle activation across the spinal neuraxis; 3) coordinating postural, locomotor and respiratory movements, and 4) enabling plasticity of respiratory motor output in health and disease.
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Affiliation(s)
- Michael D Sunshine
- Department of Physical Therapy, University of Florida, United States of America; McKnight Brain Institute, University of Florida, United States of America; Rehabilitation Science PhD Program, University of Florida, United States of America; Center for Respiratory Research and Rehabilitation, University of Florida, United States of America
| | - Tommy W Sutor
- Department of Physical Therapy, University of Florida, United States of America; Rehabilitation Science PhD Program, University of Florida, United States of America; Center for Respiratory Research and Rehabilitation, University of Florida, United States of America
| | - Emily J Fox
- Department of Physical Therapy, University of Florida, United States of America; Center for Respiratory Research and Rehabilitation, University of Florida, United States of America; Clinical Research Center, Brooks Rehabilitation, Jacksonville, FL, United States of America
| | - David D Fuller
- Department of Physical Therapy, University of Florida, United States of America; McKnight Brain Institute, University of Florida, United States of America; Center for Respiratory Research and Rehabilitation, University of Florida, United States of America.
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13
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Sunshine MD, Ganji CN, Fuller DD, Moritz CT. Respiratory resetting elicited by single pulse spinal stimulation. Respir Physiol Neurobiol 2019; 274:103339. [PMID: 31734416 DOI: 10.1016/j.resp.2019.103339] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 11/04/2019] [Accepted: 11/12/2019] [Indexed: 01/21/2023]
Abstract
Intraspinal microstimulation (ISMS) can effectively activate spinal motor circuits, but the impact on the endogenous respiratory pattern has not been systematically evaluated. Here we delivered ISMS in spontaneously breathing adult rats while simultaneously recording diaphragm and external intercostal electromyography activity. ISMS pulses were delivered from C2-T1 along two rostrocaudal tracts located 0.5 or 1 mm lateral to midline. A tungsten electrode was incrementally advanced from the dorsal spinal surface and 300μs biphasic pulses (10-90 μA) were delivered at depth increments of 600 μm. Dorsal ISMS often produced fractionated inspiratory bursting or caused early termination of the inspiratory effort. Conversely, ventral stimulation had no discernable impact on respiratory resetting. We conclude that ISMS targeting the ventral spinal cord is unlikely to directly alter the respiratory rhythm. Dorsal ISMS, however, may terminate the inspiratory burst through activation of spinobulbar pathways. We suggest that respiratory patterns should be included as an outcome variable in preclinical studies of ISMS.
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Affiliation(s)
- Michael D Sunshine
- Department of Rehabilitation Medicine, University of Washington, United States; Center for Neurotechnology, an NSF ERC, United States; Department of Physical Therapy, University of Florida, United States; McKnight Brain Institute, University of Florida, United States; Rehabilitation Science PhD Program, University of Florida, United States; Center for Respiratory Research and Rehabilitation, University of Florida, United States.
| | - Comron N Ganji
- Department of Rehabilitation Medicine, University of Washington, United States
| | - David D Fuller
- Department of Physical Therapy, University of Florida, United States; McKnight Brain Institute, University of Florida, United States; Center for Respiratory Research and Rehabilitation, University of Florida, United States
| | - Chet T Moritz
- Department of Rehabilitation Medicine, University of Washington, United States; Center for Neurotechnology, an NSF ERC, United States; Center for Respiratory Research and Rehabilitation, University of Florida, United States; Department of Electrical and Computer Engineering, United States; University of Washington, Institute for Neuroengineering (UWIN), University of Washington, United States; Department of Physiology and Biophysics, University of Washington, United States
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14
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DiMarco AF, Kowalski KE. High-frequency spinal cord stimulation in a subacute animal model of spinal cord injury. J Appl Physiol (1985) 2019; 127:98-102. [PMID: 31095462 DOI: 10.1152/japplphysiol.00006.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
High-frequency spinal cord stimulation (HF-SCS) applied at the T2 spinal level results in physiologic activation of the inspiratory muscles in C2 spinal-sectioned dogs. Although the bulbo-spinal fibers were cut, they likely survived the duration of acute experiments, and inspiratory muscle activation may have involved stimulation of these fibers. In two anesthetized, C2 paralyzed, intubated, and mechanically ventilated dogs, HF-SCS (300 Hz) was applied at the T2 level. The effectiveness of HF-SCS in generating inspired volume (V) and negative airway pressures (P) was evaluated over a period of 5 days during which time the bulbo-spinal fibers would have degenerated. Because the effectiveness of HF-SCS may be adversely affected by deterioration of these fibers and/or the condition of the animal, low-frequency (50 Hz) SCS (LF-SCS) was also performed and served as a control. All vital signs, oxygen saturation, and end-tidal Pco2 remained stable over the 5-day period. V and P also remained stable over the study period. For example, mean V and P were 771 ± 25 ml and 64 ± 1 cmH2O with HF-SCS (3 mA) during the initial and 674 ± 59 ml and 63 ± 5 cmH2O on the final day. Comparable values during LF-SCS (8 mA) were 467 ± 12 ml and 48 ± 1 cmH2O during the initial and 397 ± 20 ml and 42 ± 2 cmH2O on the final day. Because V and P in response to HF-SCS remained stable over a 5-day period following which the bulbo-spinal fibers would have degenerated, the mechanism of HF-SCS does not depend upon the viability of these tracts. HF-SCS therefore may be a useful method to restore ventilation in chronic ventilator dependent tetraplegics. NEW & NOTEWORTHY This study indicates that the respiratory responses to high-frequency spinal cord stimulation applied at the T2 level results in activation of the inspiratory motoneuron pools via interneuronal circuits and/or the inspiratory motoneurons directly and does not depend upon activation of long descending inspiratory bulbo-spinal fibers. This method therefore, may provide an alternative method to restore ventilation in ventilator dependent spinal cord injured patients.
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Affiliation(s)
- Anthony F DiMarco
- Department of Physical Medicine and Rehabilitation, Case Western Reserve University, MetroHealth Medical Center , Cleveland, Ohio.,Department of Research, Case Western Reserve University, MetroHealth Medical Center , Cleveland, Ohio
| | - Krzysztof E Kowalski
- Department of Research, Case Western Reserve University, MetroHealth Medical Center , Cleveland, Ohio.,Department of Medicine, Case Western Reserve University, MetroHealth Medical Center , Cleveland, Ohio.,Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center , Cleveland, Ohio
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15
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Wilson RD, Bryden AM, Kilgore KL, Makowski N, Bourbeau D, Kowalski KE, DiMarco AF, Knutson JS. Neuromodulation for Functional Electrical Stimulation. Phys Med Rehabil Clin N Am 2019; 30:301-318. [DOI: 10.1016/j.pmr.2018.12.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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16
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Hudson AL, Gandevia SC, Butler JE. A Principle of Neuromechanical Matching for Motor Unit Recruitment in Human Movement. Exerc Sport Sci Rev 2019; 47:157-168. [DOI: 10.1249/jes.0000000000000191] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Kowalski KE, Romaniuk JR, Kirkwood PA, DiMarco AF. Inspiratory muscle activation via ventral lower thoracic high-frequency spinal cord stimulation. J Appl Physiol (1985) 2019; 126:977-983. [DOI: 10.1152/japplphysiol.01054.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In animals, high-frequency spinal cord stimulation (HF-SCS) applied on the ventral epidural surface at the T2 level results in negative airway pressure generation consistent with inspiratory muscle activation. In the present study, in anesthetized dogs, we found that ventral HF-SCS (500 Hz) applied at all thoracic levels resulted in negative airway pressure generation. In the region of the lower thoracic spinal cord, negative airway pressure generation was most pronounced at the T9 level. At this level, airway pressure generation was monitored: 1) during ventral HF-SCS over a wide range of stimulus amplitudes (0.5–15 mA) and frequencies (50–1,000 Hz) and 2) following spinal sections at C8 (to assess potential diaphragm activation) and subsequently at T6 (to assess potential intercostal muscle activation). The application of low stimulus currents between 1 and 2 mA and high stimulus frequencies (>300 Hz) resulted in the development of large negative airway pressure generation. Stimulation with 1 mA, 500 Hz resulted in a highest negative airway pressure generation of 47 ± 2 cmH2O. Increasing stimulus current was associated with progressive reductions in the magnitude of negative airway pressure generation. HF-SCS (500 Hz) with 15 mA resulted in a negative airway pressure generation of 7 ± 3 cmH2O. C8 section markedly reduced negative airway pressure generation, and subsequent T6 section resulted in positive airway pressure generation after HF-SCS. Our results indicate the existence of pathways with connections to both the phrenic and inspiratory intercostal motoneuron pools in the ventral part of the lower thoracic spinal cord. We speculate that the circuits mediating the previously described excitatory intercostal-to-phrenic reflex mediate the observed responses. NEW & NOTEWORTHY This study suggests that, in contrast to dorsal high-frequency spinal cord stimulation at the T9 spinal level, which results in positive pressure generation, ventral high-frequency spinal cord stimulation at the same spinal level results in large negative airway pressure generation with low stimulus currents. This method, therefore, may provide an alternative method to restore ventilation in ventilator-dependent spinal cord-injured patients.
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Affiliation(s)
- Krzysztof E. Kowalski
- Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio
- Department of Medicine, Case Western Reserve University, Cleveland, Ohio
- MetroHealth Research Institute, MetroHealth Medical Center, Cleveland, Ohio
| | | | - Peter A. Kirkwood
- UCL Queen Square Institute of Neurology, Queen Square, London, United Kingdom
| | - Anthony F. DiMarco
- Department of Physical Medicine and Rehabilitation, Case Western Reserve University, Cleveland, Ohio
- MetroHealth Research Institute, MetroHealth Medical Center, Cleveland, Ohio
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18
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Zannou AL, Khadka N, Truong DQ, Zhang T, Esteller R, Hershey B, Bikson M. Temperature increases by kilohertz frequency spinal cord stimulation. Brain Stimul 2018; 12:62-72. [PMID: 30482674 DOI: 10.1016/j.brs.2018.10.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 10/09/2018] [Accepted: 10/10/2018] [Indexed: 12/14/2022] Open
Abstract
INTRODUCTION Kilohertz frequency spinal cord stimulation (kHz-SCS) deposits significantly more power in tissue compared to SCS at conventional frequencies, reflecting increased duty cycle (pulse compression). We hypothesize kHz-SCS increases local tissue temperature by joule heat, which may influence the clinical outcomes. METHODS To establish the role of tissue heating in KHZ-SCS, a decisive first step is to characterize the range of temperature changes expected during conventional and KHZ-SCS protocols. Fiber optic probes quantified temperature increases around an experimental SCS lead in a bath phantom. These data were used to verify a SCS lead heat-transfer model based on joule heat. Temperature increases were then predicted in a seven-compartment (soft tissue, vertebral bone, fat, intervertebral disc, meninges, spinal cord with nerve roots) geometric human spinal cord model under varied parameterization. RESULTS The experimentally constrained bio-heat model shows SCS waveform power (waveform RMS) determines tissue heating at the spinal cord and surrounding tissues. For example, we predict temperature increased at dorsal spinal cord of 0.18-1.72 °C during 3.5 mA peak 10 KHz stimulation with a 40-10-40 μs biphasic pulse pattern, 0.09-0.22 °C during 3.5 mA 1 KHz 100-100-100 μs stimulation, and less than 0.05 °C during 3.5 mA 50 Hz 200-100-200 μs stimulation. Notably, peak heating of the spinal cord and other tissues increases superlinearly with stimulation power and so are especially sensitive to incremental changes in SCS pulse amplitude or frequency (with associated pulse compression). Further supporting distinct SCS intervention strategies based on heating; the spatial profile of temperature changes is more uniform compared to electric fields, which suggests less sensitivity to lead position. CONCLUSIONS Tissue heating may impact short and long-term outcomes of KHZ-SCS, and even as an adjunct mechanism, suggests distinct strategies for lead position and programming optimization.
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Affiliation(s)
- Adantchede L Zannou
- Department of Biomedical Engineering, The City College of New York, New York, NY, 10031, USA
| | - Niranjan Khadka
- Department of Biomedical Engineering, The City College of New York, New York, NY, 10031, USA
| | - Dennis Q Truong
- Department of Biomedical Engineering, The City College of New York, New York, NY, 10031, USA
| | - Tianhe Zhang
- Boston Scientific Inc., Neuromodulation Research and Advanced Concepts, Valencia, CA, USA
| | - Rosana Esteller
- Boston Scientific Inc., Neuromodulation Research and Advanced Concepts, Valencia, CA, USA
| | - Brad Hershey
- Boston Scientific Inc., Neuromodulation Research and Advanced Concepts, Valencia, CA, USA
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York, New York, NY, 10031, USA.
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19
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The Neuroplastic and Therapeutic Potential of Spinal Interneurons in the Injured Spinal Cord. Trends Neurosci 2018; 41:625-639. [PMID: 30017476 DOI: 10.1016/j.tins.2018.06.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 06/06/2018] [Accepted: 06/12/2018] [Indexed: 12/25/2022]
Abstract
The central nervous system is not a static, hard-wired organ. Examples of neuroplasticity, whether at the level of the synapse, the cell, or within and between circuits, can be found during development, throughout the progression of disease, or after injury. One essential component of the molecular, anatomical, and functional changes associated with neuroplasticity is the spinal interneuron (SpIN). Here, we draw on recent multidisciplinary studies to identify and interrogate subsets of SpINs and their roles in locomotor and respiratory circuits. We highlight some of the recent progress that elucidates the importance of SpINs in circuits affected by spinal cord injury (SCI), especially those within respiratory networks; we also discuss potential ways that spinal neuroplasticity can be therapeutically harnessed for recovery.
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20
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Walter JS, Posluszny J, Dieter R, Dieter RS, Sayers S, Iamsakul K, Staunton C, Thomas D, Rabbat M, Singh S. Stimulation of abdominal and upper thoracic muscles with surface electrodes for respiration and cough: Acute studies in adult canines. J Spinal Cord Med 2018; 41:326-336. [PMID: 28614985 PMCID: PMC6055958 DOI: 10.1080/10790268.2017.1335447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
OBJECTIVE To optimize maximal respiratory responses with surface stimulation over abdominal and upper thorax muscles and using a 12-Channel Neuroprosthetic Platform. METHODS Following instrumentation, six anesthetized adult canines were hyperventilated sufficiently to produce respiratory apnea. Six abdominal tests optimized electrode arrangements and stimulation parameters using bipolar sets of 4.5 cm square electrodes. Tests in the upper thorax optimized electrode locations, and forelimb moment was limited to slight-to-moderate. During combined muscle stimulation tests, the upper thoracic was followed immediately by abdominal stimulation. Finally, a model of glottal closure for cough was conducted with the goal of increased peak expiratory flow. RESULTS Optimized stimulation of abdominal muscles included three sets of bilateral surface electrodes located 4.5 cm dorsal to the lateral line and from the 8th intercostal space to caudal to the 13th rib, 80 or 100 mA current, and 50 Hz stimulation frequency. The maximal expired volume was 343 ± 23 ml (n=3). Optimized upper thorax stimulation included a single bilateral set of electrodes located over the 2nd interspace, 60 to 80 mA, and 50 Hz. The maximal inspired volume was 304 ± 54 ml (n=4). Sequential stimulation of the two muscles increased the volume to 600 ± 152 ml (n=2), and the glottal closure maneuver increased the flow. CONCLUSIONS Studies in an adult canine model identified optimal surface stimulation methods for upper thorax and abdominal muscles to induce sufficient volumes for ventilation and cough. Further study with this neuroprosthetic platform is warranted.
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Affiliation(s)
- James S. Walter
- Research Services, Edward Hines Jr. VA Hospital, Hines, Illinois, USA,Urology Departments, Loyola University, Stritch School of Medicine, Maywood, Illinois, USA,Correspondence to: James S. Walter, Edward Hines Jr. VA Hospital (151), 5000 South 5th Avenue, Hines, IL 60141, USA.
| | - Joseph Posluszny
- Research Services, Edward Hines Jr. VA Hospital, Hines, Illinois, USA,Surgery Services, Edward Hines Jr. VA Hospital, Hines, Illinois, USA
| | - Raymond Dieter
- Research Services, Edward Hines Jr. VA Hospital, Hines, Illinois, USA
| | - Robert S. Dieter
- Cardiology Services, Edward Hines Jr. VA Hospital, Hines, Illinois, USA,Cardiology Departments, Loyola University, Stritch School of Medicine, Maywood, Illinois, USA
| | - Scott Sayers
- Research Services, Edward Hines Jr. VA Hospital, Hines, Illinois, USA,Thoracic and Cardiovascular Surgery Departments, Loyola University, Stritch School of Medicine, Maywood, Illinois, USA
| | | | | | - Donald Thomas
- Research Services, Edward Hines Jr. VA Hospital, Hines, Illinois, USA,Surgery Services, Edward Hines Jr. VA Hospital, Hines, Illinois, USA
| | - Mark Rabbat
- Cardiology Services, Edward Hines Jr. VA Hospital, Hines, Illinois, USA,Cardiology Departments, Loyola University, Stritch School of Medicine, Maywood, Illinois, USA
| | - Sanjay Singh
- Research Services, Edward Hines Jr. VA Hospital, Hines, Illinois, USA
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21
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Sunshine MD, Ganji CN, Reier PJ, Fuller DD, Moritz CT. Intraspinal microstimulation for respiratory muscle activation. Exp Neurol 2018; 302:93-103. [PMID: 29305050 DOI: 10.1016/j.expneurol.2017.12.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 12/20/2017] [Accepted: 12/26/2017] [Indexed: 11/17/2022]
Abstract
A complex propriospinal network is synaptically coupled to phrenic and intercostal motoneurons, and this makes it difficult to predict how gray matter intraspinal microstimulation (ISMS) will recruit respiratory motor units. We therefore mapped the cervical and high thoracic gray matter at locations which ISMS activates diaphragm (DIA) and external intercostal (EIC) motor units. Respiratory muscle electromyography (EMG) was recorded in anesthetized female spinally intact adult rats while a stimulating electrode was advanced ventrally into the spinal cord in 600μm increments. At each depth, single biphasic stimuli were delivered at 10-90μA during both the inspiratory and expiratory phase independently. Twenty electrode tracks were made from C2-T1 at medial and lateral gray matter locations. During inspiration, ISMS evoked DIA and EIC activity throughout C2-T1 gray matter locations, with mutual activation occurring at 17±9% of sites. During inspiratory phase ISMS the average latency for DIA activation was 4.40±0.70ms. During the expiratory phase, ISMS-induced DIA activation required electrodes to be in close proximity to the phrenic motoneuron pool, and average activation latency was 3.30±0.50ms. We conclude that appropriately targeted ISMS can co-activate DIA and EIC motor units, and endogenous respiratory drive has a powerful impact on ISMS-induced respiratory motor unit activation. The long latency diaphragm motor unit activation suggests the presence of a complex propriospinal network that can modulate phrenic motor output.
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Affiliation(s)
- Michael D Sunshine
- Rehabilitation Medicine, University of Washington, Seattle, WA, United States; Center for Sensorimotor Neural Engineering (CSNE), Seattle, WA, United States; Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL, United States.
| | - Comron N Ganji
- Rehabilitation Medicine, University of Washington, Seattle, WA, United States; Center for Sensorimotor Neural Engineering (CSNE), Seattle, WA, United States
| | - Paul J Reier
- Neuroscience, University of Florida, Gainesville, FL, United States
| | - David D Fuller
- Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL, United States; Center for Respiratory Research and Rehabilitation, University of Florida, Gainesville, FL, United States
| | - Chet T Moritz
- Rehabilitation Medicine, University of Washington, Seattle, WA, United States; Center for Sensorimotor Neural Engineering (CSNE), Seattle, WA, United States; Physiology & Biophysics, University of Washington, Seattle, WA, United States; University of Washington Institute for Neuroengineering (UWIN), University of Washington, Seattle, WA, United States
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22
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Affiliation(s)
- D D Fuller
- Department of Physical Therapy, McKnight Brain Institute, Center for Respiratory Research and Rehabilitation, University of Florida, Gainesville, FL, 32610, USA
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23
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Hachmann JT, Grahn PJ, Calvert JS, Drubach DI, Lee KH, Lavrov IA. Electrical Neuromodulation of the Respiratory System After Spinal Cord Injury. Mayo Clin Proc 2017; 92:1401-1414. [PMID: 28781176 DOI: 10.1016/j.mayocp.2017.04.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 03/22/2017] [Accepted: 04/03/2017] [Indexed: 12/12/2022]
Abstract
Spinal cord injury (SCI) is a complex and devastating condition characterized by disruption of descending, ascending, and intrinsic spinal circuitry resulting in chronic neurologic deficits. In addition to limb and trunk sensorimotor deficits, SCI can impair autonomic neurocircuitry such as the motor networks that support respiration and cough. High cervical SCI can cause complete respiratory paralysis, and even lower cervical or thoracic lesions commonly result in partial respiratory impairment. Although electrophrenic respiration can restore ventilator-independent breathing in select candidates, only a small subset of affected individuals can benefit from this technology at this moment. Over the past decades, spinal cord stimulation has shown promise for augmentation and recovery of neurologic function including motor control, cough, and breathing. The present review discusses the challenges and potentials of spinal cord stimulation for restoring respiratory function by overcoming some of the limitations of conventional respiratory functional electrical stimulation systems.
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Affiliation(s)
- Jan T Hachmann
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN
| | - Peter J Grahn
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN
| | - Jonathan S Calvert
- Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN
| | - Dina I Drubach
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN
| | - Kendall H Lee
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN; Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN
| | - Igor A Lavrov
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN.
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24
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Gonzalez-Rothi EJ, Streeter KA, Hanna MH, Stamas AC, Reier PJ, Baekey DM, Fuller DD. High-frequency epidural stimulation across the respiratory cycle evokes phrenic short-term potentiation after incomplete cervical spinal cord injury. J Neurophysiol 2017; 118:2344-2357. [PMID: 28615341 DOI: 10.1152/jn.00913.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 06/13/2017] [Accepted: 06/14/2017] [Indexed: 01/15/2023] Open
Abstract
C2 spinal hemilesion (C2Hx) paralyzes the ipsilateral diaphragm, but recovery is possible through activation of "crossed spinal" synaptic inputs to ipsilateral phrenic motoneurons. We tested the hypothesis that high-frequency epidural stimulation (HF-ES) would potentiate ipsilateral phrenic output after subacute and chronic C2Hx. HF-ES (300 Hz) was applied to the ventrolateral C4 or T2 spinal cord ipsilateral to C2Hx in anesthetized and mechanically ventilated adult rats. Stimulus duration was 60 s, and currents ranged from 100 to 1,000 µA. Bilateral phrenic nerve activity and ipsilateral hypoglossal (XII) nerve activity were recorded before and after HF-ES. Higher T2 stimulus currents potentiated ipsilateral phasic inspiratory activity at both 2 and 12 wk post-C2Hx, whereas higher stimulus currents delivered at C4 potentiated ipsilateral phasic phrenic activity only at 12 wk (P = 0.028). Meanwhile, tonic output in the ipsilateral phrenic nerve reached 500% of baseline values at the high currents with no difference between 2 and 12 wk. HF-ES did not trigger inspiratory burst-frequency changes. Similar responses occurred following T2 HF-ES. Increases in contralateral phrenic and XII nerve output were induced by C4 and T2 HF-ES at higher currents, but the relative magnitude of these changes was small compared with the ipsilateral phrenic response. We conclude that following incomplete cervical spinal cord injury, HF-ES of the ventrolateral midcervical or thoracic spinal cord can potentiate efferent phrenic motor output with little impact on inspiratory burst frequency. However, the substantial increases in tonic output indicate that the uninterrupted 60-s stimulation paradigm used is unlikely to be useful for respiratory muscle activation after spinal injury.NEW & NOTEWORTHY Previous studies reported that high-frequency epidural stimulation (HF-ES) activates the diaphragm following acute spinal transection. This study examined HF-ES and phrenic motor output following subacute and chronic incomplete cervical spinal cord injury. Short-term potentiation of phrenic bursting following HF-ES illustrates the potential for spinal stimulation to induce respiratory neuroplasticity. Increased tonic phrenic output indicates that alternatives to the continuous stimulation paradigm used in this study will be required for respiratory muscle activation after spinal cord injury.
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Affiliation(s)
- Elisa J Gonzalez-Rothi
- McKnight Brain Institute, Department of Physical Therapy, College of Public Health and Health Professions, University of Florida, Gainesville, Florida;
| | - Kristi A Streeter
- McKnight Brain Institute, Department of Physical Therapy, College of Public Health and Health Professions, University of Florida, Gainesville, Florida
| | - Marie H Hanna
- McKnight Brain Institute, Department of Physical Therapy, College of Public Health and Health Professions, University of Florida, Gainesville, Florida
| | - Anna C Stamas
- McKnight Brain Institute, Department of Physical Therapy, College of Public Health and Health Professions, University of Florida, Gainesville, Florida
| | - Paul J Reier
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, Florida; and
| | - David M Baekey
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida
| | - David D Fuller
- McKnight Brain Institute, Department of Physical Therapy, College of Public Health and Health Professions, University of Florida, Gainesville, Florida
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Kowalski KE, Romaniuk JR, Brose SW, Richmond MA, Kowalski T, DiMarco AF. High frequency spinal cord stimulation-New method to restore cough. Respir Physiol Neurobiol 2016; 232:54-6. [PMID: 27395446 DOI: 10.1016/j.resp.2016.07.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 07/05/2016] [Accepted: 07/06/2016] [Indexed: 10/21/2022]
Abstract
Spinal cord stimulation (SCS, 50Hz) is a useful method to restore an effective cough in persons with spinal cord injury (SCI). However, high stimulus amplitudes and potential activation of pain fibers, significantly limits this application. It is our hypothesis that high frequency SCS (HF-SCS), with low stimulus amplitudes may provide the same level of expiratory muscle activation. In 6 dogs, the effects of SCS, with varying stimulus parameters on positive pressure (P) generation was evaluated. At any given level of stimulus current, mean P was largest at 500Hz, compared to all other stimulus frequencies. For example, with stimulation at 1mA and frequencies of 200, 500 and 600Hz, P were 25±3, 58±4, 51±6cmH2O, respectively. By comparison, P achieved with conventional SCS parameters was 61±5cmH2O. HF-SCS results in a comparable P compared to that achieved with conventional stimulus parameters but with much lower stimulus amplitudes. This method may be useful to restore cough even in subjects with intact sensation.
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Affiliation(s)
- K E Kowalski
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, USA; Department of Medicine, Case Western Reserve University, Cleveland, OH, USA; MetroHealth Research Institute, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA.
| | - J R Romaniuk
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, USA
| | - S W Brose
- Department of Spinal Cord Injury, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, USA; Department of Physical Medicine and Rehabilitation, Case Western Reserve University, Cleveland, OH, USA; Ohio University Heritage College of Osteopathic Medicine, Cleveland, OH, USA
| | - M A Richmond
- Department of Spinal Cord Injury, Louis Stokes Cleveland VA Medical Center, Cleveland, OH, USA; Department of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - T Kowalski
- MetroHealth Research Institute, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
| | - A F DiMarco
- Department of Physical Medicine and Rehabilitation, Case Western Reserve University, Cleveland, OH, USA; MetroHealth Research Institute, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
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Gonzalez-Rothi EJ, Lee KZ, Dale EA, Reier PJ, Mitchell GS, Fuller DD. Intermittent hypoxia and neurorehabilitation. J Appl Physiol (1985) 2015; 119:1455-65. [PMID: 25997947 DOI: 10.1152/japplphysiol.00235.2015] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/18/2015] [Indexed: 02/05/2023] Open
Abstract
In recent years, it has become clear that brief, repeated presentations of hypoxia [i.e., acute intermittent hypoxia (AIH)] can boost the efficacy of more traditional therapeutic strategies in certain cases of neurologic dysfunction. This hypothesis derives from a series of studies in animal models and human subjects performed over the past 35 yr. In 1980, Millhorn et al. (Millhorn DE, Eldridge FL, Waldrop TG. Respir Physiol 41: 87-103, 1980) showed that electrical stimulation of carotid chemoafferent neurons produced a persistent, serotonin-dependent increase in phrenic motor output that outlasts the stimulus for more than 90 min (i.e., a "respiratory memory"). AIH elicits similar phrenic "long-term facilitation" (LTF) by a mechanism that requires cervical spinal serotonin receptor activation and de novo protein synthesis. From 2003 to present, a series of studies demonstrated that AIH can induce neuroplasticity in the injured spinal cord, causing functional recovery of breathing capacity after cervical spinal injury. Subsequently, it was demonstrated that repeated AIH (rAIH) can induce recovery of limb function, and the functional benefits of rAIH are greatest when paired with task-specific training. Since uncontrolled and/or prolonged intermittent hypoxia can elicit pathophysiology, a challenge of intermittent hypoxia research is to ensure that therapeutic protocols are well below the threshold for pathogenesis. This is possible since many low dose rAIH protocols have induced functional benefits without evidence of pathology. We propose that carefully controlled rAIH is a safe and noninvasive modality that can be paired with other neurorehabilitative strategies including traditional activity-based physical therapy or cell-based therapies such as intraspinal transplantation of neural progenitors.
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Affiliation(s)
- Elisa J Gonzalez-Rothi
- Department of Physical Therapy College of Public Health and Health Professions, University of Florida, Gainesville, Florida
| | - Kun-Ze Lee
- Department of Biological Sciences, College of Science, National Sun Yat-sen University, Kaohsiung City, Taiwan
| | - Erica A Dale
- Department of Integrative Biology and Physiology, University of California-Los Angeles, Los Angeles, California; and
| | - Paul J Reier
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, Florida
| | - Gordon S Mitchell
- Department of Physical Therapy College of Public Health and Health Professions, University of Florida, Gainesville, Florida
| | - David D Fuller
- Department of Physical Therapy College of Public Health and Health Professions, University of Florida, Gainesville, Florida;
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Hartley NA. Spinal cord injury (SCI) rehabilitation: systematic analysis of communication from the biopsychosocial perspective. Disabil Rehabil 2015; 37:2383-2392. [DOI: 10.3109/09638288.2015.1027008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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28
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DiMarco AF, Kowalski KE. Electrical activation to the parasternal intercostal muscles during high-frequency spinal cord stimulation in dogs. J Appl Physiol (1985) 2014; 118:148-55. [PMID: 25342707 DOI: 10.1152/japplphysiol.01321.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
High-frequency spinal cord stimulation (HF-SCS) is a novel technique of inspiratory muscle activation involving stimulation of spinal cord pathways, which may have application as a method to provide inspiratory muscle pacing in ventilator-dependent patients with spinal cord injury. The purpose of the present study was to compare the spatial distribution of motor drive to the parasternal intercostal muscles during spontaneous breathing with that occurring during HF-SCS. In nine anesthetized dogs, HF-SCS was applied at the T2 spinal level. Fine-wire recording electrodes were used to assess single motor unit (SMU) pattern of activation in the medial bundles of the 2nd and 4th and lateral bundles of the 2nd interspaces during spontaneous breathing and HF-SCS following C1 spinal section. Stimulus amplitude during HF-SCS was adjusted such that inspired volumes matched that occurring during spontaneous breathing (protocol 1). During HF-SCS mean peak SMU firing frequency was highest in the medial bundles of the 2nd interspace (17.1 ± 0.6 Hz) and significantly lower in the lateral bundles of the 2nd interspace (13.5 ± 0.5 Hz) and medial bundles of the 4th (15.2 ± 0.7 Hz) (P < 0.05 for each comparison). Similar rostrocaudal and mediolateral gradients of activity were observed during spontaneous breathing prior to C1 section. Since rib cage movement was greater and peak discharge frequencies of the SMUs higher during HF-SCS compared with spontaneous breathing, stimulus amplitude during HF-SCS was adjusted such that rib cage movement matched that occurring during spontaneous breathing (protocol 2). Under this protocol, mean peak SMU frequencies and rostrocaudal and mediolateral gradients of activity during HF-SCS were not significantly different compared with spontaneous breathing. This study demonstrates that 1) the topographic pattern of electrical activation of the parasternal intercostal muscles during HF-SCS is similar to that occurring during spontaneous breathing, and 2) differential spatial distribution of parasternal intercostal activation does not depend upon differential descending synaptic input from supraspinal centers.
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Affiliation(s)
- Anthony F DiMarco
- Department of Physical Medicine and Rehabilitation and MetroHealth Research Institute, Case Western Reserve University and The MetroHealth System, Cleveland, Ohio; and
| | - Krzysztof E Kowalski
- Department of Medicine and MetroHealth Research Institute, Case Western Reserve University and The MetroHealth System, Cleveland, Ohio
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Clinical challenges to ventilatory control. Respir Physiol Neurobiol 2013; 189:211-2. [PMID: 24056024 DOI: 10.1016/j.resp.2013.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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30
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Hoh DJ, Mercier LM, Hussey SP, Lane MA. Respiration following spinal cord injury: evidence for human neuroplasticity. Respir Physiol Neurobiol 2013; 189:450-64. [PMID: 23891679 DOI: 10.1016/j.resp.2013.07.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 07/01/2013] [Accepted: 07/01/2013] [Indexed: 12/17/2022]
Abstract
Respiratory dysfunction is one of the most devastating consequences of cervical spinal cord injury (SCI) with impaired breathing being a leading cause of morbidity and mortality in this population. However, there is mounting experimental and clinical evidence for moderate spontaneous respiratory recovery, or "plasticity", after some spinal cord injuries. Pre-clinical models of respiratory dysfunction following SCI have demonstrated plasticity at neural and behavioral levels that result in progressive recovery of function. Temporal changes in respiration after human SCI have revealed some functional improvements suggesting plasticity paralleling that seen in experimental models-a concept that has been previously under-appreciated. While the extent of spontaneous recovery remains limited, it is possible that enhancing or facilitating neuroplastic mechanisms may have significant therapeutic potential. The next generation of treatment strategies for SCI and related respiratory dysfunction should aim to optimize these recovery processes of the injured spinal cord for lasting functional restoration.
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Affiliation(s)
- Daniel J Hoh
- Department of Neuroscience, College of Medicine, University of Florida, McKnight Brain Institute, Gainesville, FL 32611, USA; Neurological Surgery, College of Medicine, University of Florida, McKnight Brain Institute, Gainesville, FL, 32611, USA
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