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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 PMCID: PMC11135909 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] [Grants] [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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Li RV, Potrakhov NN, Ukhov AA, Shapovalov SV, Klyachkin LE, Bagraev NT, Malyarenko AM, Mazurok VA. A Device for Transcutaneous Stimulation of the Diaphragm. BIOMEDICAL ENGINEERING 2023; 56:378-383. [PMID: 36883136 PMCID: PMC9975814 DOI: 10.1007/s10527-023-10240-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Indexed: 03/05/2023]
Abstract
Results obtained during the development of an original device for noninvasive transcutaneous stimulation of the diaphragm using electromagnetic radiation in the terahertz frequency range are presented. The block diagram and design of a terahertz emitter and a controlled current source for its power supply are presented, along with specialized software for selecting and setting the amplitude and time parameters of the stimulating signal.
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Affiliation(s)
- R. V. Li
- Department of Electronic Instruments and Devices, St. Petersburg V. I. Ul’yanov (Lenin) State Electrotechnical University (LETI), St. Petersburg, Russia
| | - N. N. Potrakhov
- Department of Electronic Instruments and Devices, St. Petersburg V. I. Ul’yanov (Lenin) State Electrotechnical University (LETI), St. Petersburg, Russia
| | - A. A. Ukhov
- Department of Electronic Instruments and Devices, St. Petersburg V. I. Ul’yanov (Lenin) State Electrotechnical University (LETI), St. Petersburg, Russia
| | - S. V. Shapovalov
- Department of Electronic Instruments and Devices, St. Petersburg V. I. Ul’yanov (Lenin) State Electrotechnical University (LETI), St. Petersburg, Russia
| | | | | | | | - V. A. Mazurok
- Department of Anesthesiology and Resuscitation with Clinical Services, V. A. Almazov National Medical Research Center, Russian Federation Ministry of Health, St. Petersburg, Russia
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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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Hachmann JT, Yousak A, Wallner JJ, Gad PN, Edgerton VR, Gorgey AS. Epidural spinal cord stimulation as an intervention for motor recovery after motor complete spinal cord injury. J Neurophysiol 2021; 126:1843-1859. [PMID: 34669485 DOI: 10.1152/jn.00020.2021] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 10/12/2021] [Indexed: 12/19/2022] Open
Abstract
Spinal cord injury (SCI) commonly results in permanent loss of motor, sensory, and autonomic function. Recent clinical studies have shown that epidural spinal cord stimulation may provide a beneficial adjunct for restoring lower extremity and other neurological functions. Herein, we review the recent clinical advances of lumbosacral epidural stimulation for restoration of sensorimotor function in individuals with motor complete SCI and we discuss the putative neural pathways involved in this promising neurorehabilitative approach. We focus on three main sections: review recent clinical results for locomotor restoration in complete SCI; discuss the contemporary understanding of electrical neuromodulation and signal transduction pathways involved in spinal locomotor networks; and review current challenges of motor system modulation and future directions toward integrative neurorestoration. The current understanding is that initial depolarization occurs at the level of large diameter dorsal root proprioceptive afferents that when integrated with interneuronal and latent residual supraspinal translesional connections can recruit locomotor centers and augment downstream motor units. Spinal epidural stimulation can initiate excitability changes in spinal networks and supraspinal networks. Different stimulation parameters can facilitate standing or stepping, and it may also have potential for augmenting myriad other sensorimotor and autonomic functions. More comprehensive investigation of the mechanisms that mediate the transformation of dysfunctional spinal networks to higher functional states with a greater focus on integrated systems-based control system may reveal the key mechanisms underlying neurological augmentation and motor restoration after severe paralysis.
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Affiliation(s)
- Jan T Hachmann
- Department of Neurological Surgery, Virginia Commonwealth University, Richmond, Virginia
| | - Andrew Yousak
- Spinal Cord Injury and Disorders Center, Hunter Holmes McGuire VAMC, Richmond, Virginia
| | - Josephine J Wallner
- Spinal Cord Injury and Disorders Center, Hunter Holmes McGuire VAMC, Richmond, Virginia
| | - Parag N Gad
- Department of Neurobiology, University of California, Los Angeles, California
| | - V Reggie Edgerton
- Department of Neurobiology, University of California, Los Angeles, California
- Fundación Institut Guttmann, Institut Universitari de Neurorehabilitació Badalona, Barcelona, Spain
| | - Ashraf S Gorgey
- Spinal Cord Injury and Disorders Center, Hunter Holmes McGuire VAMC, Richmond, Virginia
- Physical Medicine and Rehabilitation, Virginia Commonwealth University, Richmond, Virginia
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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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DiMarco AF, Kowalski KE. Activation of the expiratory muscles via lower thoracic high frequency spinal cord stimulation in awake animals. Respir Physiol Neurobiol 2020; 276:103360. [PMID: 32045702 DOI: 10.1016/j.resp.2019.103360] [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: 10/23/2019] [Revised: 12/03/2019] [Accepted: 12/14/2019] [Indexed: 11/28/2022]
Abstract
Lower thoracic spinal cord stimulation is an effective method of restoring an effective cough in participants with complete spinal cord injury. The high voltage requirements however significantly limits this application in subjects with intact lower chest wall sensation. In anesthetized animals, we have shown that the expiratory muscles can also be effectively activated with low stimulus currents (1 mA) but with high stimulus frequencies (HF-SCS -500 Hz). In 3 intact, awake pigs the responses to HF-SCS, were evaluated. HF-SCS was associated with marked expansion of the abdominal wall and external oblique EMG activity without any associated changes in heart rate or vocalization. During a terminal procedure under general anesthesia, responses to HF-SCS were re-assessed. Abdominal movement and EMG were similar to that observed in the awake state. HF-SCS (1.5 mA) resulted in an airway pressure of 65 ± 2cmH2O. Our results indicate that lower thoracic HF-SCS may be a useful method to restore an effective cough in patients with intact chest wall sensation.
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Affiliation(s)
- Anthony F DiMarco
- Department of Physical Medicine and Rehabilitation, Cleveland, OH, USA; Department of Research, Case Western Reserve University, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA.
| | - Krzysztof E Kowalski
- Department of Medicine, Cleveland, OH, USA; Department of Research, Case Western Reserve University, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA; Research Service, Louis Stokes Cleveland VA Medical Center, 10701, East Boulevard, Cleveland, OH, USA.
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7
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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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DiMarco AF, Kowalski KE. Restoration of Cough via Functional Electrical Stimulation. Neuromodulation 2018. [DOI: 10.1016/b978-0-12-805353-9.00113-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Hachmann JT, Calvert JS, Grahn PJ, Drubach DI, Lee KH, Lavrov IA. Review of Epidural Spinal Cord Stimulation for Augmenting Cough after Spinal Cord Injury. Front Hum Neurosci 2017; 11:144. [PMID: 28400726 PMCID: PMC5368218 DOI: 10.3389/fnhum.2017.00144] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 03/13/2017] [Indexed: 12/13/2022] Open
Abstract
Spinal cord injury (SCI) remains a debilitating condition for which there is no cure. In addition to loss of somatic sensorimotor functions, SCI is also commonly associated with impairment of autonomic function. Importantly, cough dysfunction due to paralysis of expiratory muscles in combination with respiratory insufficiency can render affected individuals vulnerable to respiratory morbidity. Failure to clear sputum can aggravate both risk for and severity of respiratory infections, accounting for frequent hospitalizations and even mortality. Recently, epidural stimulation of the lower thoracic spinal cord has been investigated as novel means for restoring cough by evoking expiratory muscle contraction to generate large positive airway pressures and expulsive air flow. This review article discusses available preclinical and clinical evidence, current challenges and clinical potential of lower thoracic spinal cord stimulation (SCS) for restoring cough in individuals with SCI.
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Affiliation(s)
- Jan T Hachmann
- Department of Neurologic Surgery, Mayo Clinic Rochester, MN, USA
| | | | - Peter J Grahn
- Department of Neurologic Surgery, Mayo Clinic Rochester, MN, USA
| | - Dina I Drubach
- Department of Neurologic Surgery, Mayo Clinic Rochester, MN, USA
| | - Kendall H Lee
- Department of Neurologic Surgery, Mayo ClinicRochester, MN, USA; Department of Physiology and Biomedical Engineering, Mayo ClinicRochester, MN, USA; Department of Physical Medicine and Rehabilitation, Mayo ClinicRochester, MN, USA
| | - Igor A Lavrov
- Department of Neurologic Surgery, Mayo Clinic Rochester, MN, USA
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Miura M, Seki K, Ito O, Handa Y, Kohzuki M. Electrical Stimulation of the Abdomen Preserves Motor Performance in the Inactive Elderly: A Randomized Controlled Trial. TOHOKU J EXP MED 2012; 228:93-101. [DOI: 10.1620/tjem.228.93] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Misa Miura
- Department of Internal Medicine and Rehabilitation, Tohoku University Graduate School of Medicine
| | | | - Osamu Ito
- Department of Internal Medicine and Rehabilitation, Tohoku University Graduate School of Medicine
| | - Yasunobu Handa
- Division of Developmental Neuroscience, Tohoku University Graduate School of Medicine
| | - Masahiro Kohzuki
- Department of Internal Medicine and Rehabilitation, Tohoku University Graduate School of Medicine
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Treatments to restore respiratory function after spinal cord injury and their implications for regeneration, plasticity and adaptation. Exp Neurol 2011; 235:18-25. [PMID: 22200541 DOI: 10.1016/j.expneurol.2011.12.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 11/18/2011] [Accepted: 12/09/2011] [Indexed: 02/04/2023]
Abstract
Spinal cord injury (SCI) often leads to impaired breathing. In most cases, such severe respiratory complications lead to morbidity and death. However, in the last few years there has been extensive work examining ways to restore this vital function after experimental spinal cord injury. In addition to finding strategies to rescue breathing activity, many of these experiments have also yielded a great deal of information about the innate plasticity and capacity for adaptation in the respiratory system and its associated circuitry in the spinal cord. This review article will highlight experimental SCI resulting in compromised breathing, the various methods of restoring function after such injury, and some recent findings from our own laboratory. Additionally, it will discuss findings about motor and CNS respiratory plasticity and adaptation with potential clinical and translational implications.
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Cough following low thoracic hemisection in the cat. Exp Neurol 2010; 222:165-70. [PMID: 20043908 DOI: 10.1016/j.expneurol.2009.12.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 12/14/2009] [Accepted: 12/17/2009] [Indexed: 01/15/2023]
Abstract
A function of the abdominal expiratory muscles is the generation of cough, a critical respiratory defense mechanism that is often disrupted following spinal cord injury. We assessed the effects of a lateral T9/10 hemisection on cough production at 4, 13 and 21 weeks post-injury in cats receiving extensive locomotor training. The magnitudes of esophageal pressure as well as of bilateral rectus abdominis electromyogram activity during cough were not significantly different from pre-injury values at all time points evaluated. The results show that despite considerable interruption of the descending pre-motor drive from the brainstem to the expiratory motoneuron pools, the cough motor system shows a significant function by 4 weeks following incomplete thoracic injury.
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Lower thoracic spinal cord stimulation to restore cough in patients with spinal cord injury: results of a National Institutes of Health-sponsored clinical trial. Part I: methodology and effectiveness of expiratory muscle activation. Arch Phys Med Rehabil 2009; 90:717-25. [PMID: 19406289 DOI: 10.1016/j.apmr.2008.11.013] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 10/30/2008] [Accepted: 11/04/2008] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Evaluation of the capacity of lower thoracic spinal cord stimulation (SCS) to activate the expiratory muscles and generate large airway pressures and high peak airflows characteristic of cough, in subjects with tetraplegia. DESIGN Clinical trial. SETTING Inpatient hospital setting for electrode insertion; outpatient setting for measurement of respiratory pressures; home setting for application of SCS. PARTICIPANTS Subjects (N=9; 8 men, 1 woman) with cervical spinal cord injury and weak cough. INTERVENTIONS A fully implantable electrical stimulation system was surgically placed in each subject. Partial hemilaminectomies were made to place single-disk electrodes in the epidural space at the T9, T11, and L1 spinal levels. A radiofrequency receiver was placed in a subcutaneous pocket over the anterior portion of the chest wall. Electrode wires were tunneled subcutaneously and connected to the receiver. Stimulation was applied by activating a small portable external stimulus controller box powered by a rechargeable battery to each electrode lead alone and in combination. MAIN OUTCOME MEASURES Peak airflow and airway pressure generation achieved with SCS. RESULTS Supramaximal SCS resulted in high peak airflow rates and large airway pressures during stimulation at each electrode lead. Maximum peak airflow rates and airway pressures were achieved with combined stimulation of any 2 leads. At total lung capacity, mean maximum peak airflow rates and airway pressure generation were 8.6+/-1.8 (mean +/- SE) L/s and 137+/-30 cmH2O (mean +/- SE), respectively. CONCLUSIONS Lower thoracic SCS results in near maximum activation of the expiratory muscles and the generation of high peak airflow rates and positive airway pressures in the range of those observed with maximum cough efforts in healthy persons.
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