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Fogarty MJ, Zhan WZ, Mantilla CB, Sieck GC. Cervical spinal cord hemisection impacts sigh and the respiratory reset in male rats. Physiol Rep 2024; 12:e15973. [PMID: 38467570 DOI: 10.14814/phy2.15973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 02/28/2024] [Accepted: 02/29/2024] [Indexed: 03/13/2024] Open
Abstract
Cervical spinal cord injury impacts ventilatory and non-ventilatory functions of the diaphragm muscle (DIAm) and contributes to clinical morbidity and mortality in the afflicted population. Periodically, integrated brainstem neural circuit activity drives the DIAm to generate a markedly augmented effort or sigh-which plays an important role in preventing atelectasis and thus maintaining lung function. Across species, the general pattern of DIAm efforts during a normal sigh is variable in amplitude and the extent of post-sigh "apnea" (i.e., the post-sigh inter-breath interval). This post-sigh inter-breath interval acts as a respiratory reset, following the interruption of regular respiratory rhythm by sigh. We examined the impact of upper cervical (C2 ) spinal cord hemisection (C2 SH) on the transdiaphragmatic pressure (Pdi ) generated during sighs and the post-sigh respiratory reset in rats. Sighs were identified in Pdi traces by their characteristic biphasic pattern. We found that C2 SH results in a reduction of Pdi during both eupnea and sighs, and a decrease in the immediate post-sigh breath interval. These results are consistent with partial removal of descending excitatory synaptic inputs to phrenic motor neurons that results from C2 SH. Following cervical spinal cord injury, a reduction in the amplitude of Pdi during sighs may compromise the maintenance of normal lung function.
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Affiliation(s)
- Matthew J Fogarty
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Wen-Zhi Zhan
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Carlos B Mantilla
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Gary C Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
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2
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Fogarty MJ, Zhan WZ, Simmon VF, Vanderklish PW, Sarraf ST, Sieck GC. Novel regenerative drug, SPG302 promotes functional recovery of diaphragm muscle activity after cervical spinal cord injury. J Physiol 2023; 601:2513-2532. [PMID: 36815402 PMCID: PMC10404468 DOI: 10.1113/jp284004] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 02/17/2023] [Indexed: 02/24/2023] Open
Abstract
Spinal cord hemisection at C2 (C2 SH), sparing the dorsal column is widely used to investigate the effects of reduced phrenic motor neuron (PhMN) activation on diaphragm muscle (DIAm) function, with reduced DIAm activity on the injured side during eupnoea. Following C2 SH, recovery of DIAm EMG activity may occur spontaneously over subsequent days/weeks. Various strategies have been effective at improving the incidence and magnitude of DIAm recovery during eupnoea, but little is known about the effects of C2 SH on transdiaphragmatic pressure (Pdi ) during other ventilatory and non-ventilatory behaviours. We employ SPG302, a novel type of pegylated benzothiazole derivative, to assess whether enhancing synaptogenesis (i.e., enhancing spared local connections) will improve the incidence and the magnitude of recovery of DIAm EMG activity and Pdi function 14 days post-C2 SH. In anaesthetised Sprague-Dawley rats, DIAm EMG and Pdi were assessed during eupnoea, hypoxia/hypercapnia and airway occlusion prior to surgery (C2 SH or sham), immediately post-surgery and at 14 days post-surgery. In C2 SH rats, 14 days of DMSO (vehicle) or SPG302 treatments (i.p. injection) occurred. At the terminal experiment, maximum Pdi was evoked by bilateral phrenic nerve stimulation. We show that significant EMG and Pdi deficits are apparent in C2 SH compared with sham rats immediately after surgery. In C2 SH rats treated with SPG302, recovery of eupneic, hypoxia/hypercapnia and occlusion DIAm EMG was enhanced compared with vehicle rats after 14 days. Treatment with SPG302 also ameliorated Pdi deficits following C2 SH. In summary, SPG302 is an exciting new therapy to explore for use in spinal cord injuries. KEY POINTS: Despite advances in our understanding of the effects of cervical hemisection (C2 SH) on diaphragm muscle (DIAm) EMG activity, very little is understood about the impact of C2 SH on the gamut of ventilatory and non-ventilatory transdiaphragmatic pressures (Pdi ). Recovery of DIAm activity following C2 SH is improved using a variety of approaches, but very few pharmaceuticals have been shown to be effective. One way of improving DIAm recovery is to enhance the amount of latent local spared connections onto phrenic motor neurons. A novel pegylated benzothiazole derivative enhances synaptogenesis in a variety of neurodegenerative conditions. Here, using a novel therapeutic SPG302, we show that 14 days of treatment with SPG302 ameliorated DIAm EMG and Pdi deficits compared with vehicle controls. Our results show that SPG302 is a compound with very promising potential for use in improving functional outcomes post-spinal cord injury.
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Affiliation(s)
- Matthew J. Fogarty
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Wen-Zhi Zhan
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | - Vincent F. Simmon
- Spinogenix Inc, 4225 Executive Square, Suite 600 La Jolla, California, USA
| | | | - Stella T. Sarraf
- Spinogenix Inc, 4225 Executive Square, Suite 600 La Jolla, California, USA
| | - Gary C. Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
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3
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Liao SM, Kleinfeld D. A change in behavioral state switches the pattern of motor output that underlies rhythmic head and orofacial movements. Curr Biol 2023; 33:1951-1966.e6. [PMID: 37105167 PMCID: PMC10225163 DOI: 10.1016/j.cub.2023.04.008] [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: 01/12/2023] [Revised: 03/27/2023] [Accepted: 04/06/2023] [Indexed: 04/29/2023]
Abstract
The breathing rhythm serves as a reference that paces orofacial motor actions and orchestrates active sensing. Past work has reported that pacing occurs solely at a fixed phase relative to sniffing. We re-evaluated this constraint as a function of exploratory behavior. Allocentric and egocentric rotations of the head and the electromyogenic activity of the motoneurons for head and orofacial movements were recorded in free-ranging rats as they searched for food. We found that a change in state from foraging to rearing is accompanied by a large phase shift in muscular activation relative to sniffing, and a concurrent change in the frequency of sniffing, so that pacing now occurs at one of the two phases. Further, head turning is biased such that an animal gathers a novel sample of its environment upon inhalation. In total, the coordination of active sensing has a previously unrealized computational complexity. This can emerge from hindbrain circuits with fixed architecture and credible synaptic time delays.
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Affiliation(s)
- Song-Mao Liao
- Department of Physics, University of California San Diego, La Jolla, CA 92093, USA
| | - David Kleinfeld
- Department of Physics, University of California San Diego, La Jolla, CA 92093, USA; Department of Neurobiology, University of California San Diego, La Jolla, CA 92093, USA.
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4
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Apicella R, Taccola G. Passive limb training modulates respiratory rhythmic bursts. Sci Rep 2023; 13:7226. [PMID: 37142670 PMCID: PMC10160044 DOI: 10.1038/s41598-023-34422-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 04/29/2023] [Indexed: 05/06/2023] Open
Abstract
Exercise modifies respiratory functions mainly through the afferent feedback provided by exercising limbs and the descending input from suprapontine areas, two contributions that are still underestimated in vitro. To better characterize the role of limb afferents in modulating respiration during physical activity, we designed a novel experimental in vitro platform. The whole central nervous system was isolated from neonatal rodents and kept with hindlimbs attached to an ad-hoc robot (Bipedal Induced Kinetic Exercise, BIKE) driving passive pedaling at calibrated speeds. This setting allowed extracellular recordings of a stable spontaneous respiratory rhythm for more than 4 h, from all cervical ventral roots. BIKE reversibly reduced the duration of single respiratory bursts even at lower pedaling speeds (2 Hz), though only an intense exercise (3.5 Hz) modulated the frequency of breathing. Moreover, brief sessions (5 min) of BIKE at 3.5 Hz augmented the respiratory rate of preparations with slow bursting in control (slower breathers) but did not change the speed of faster breathers. When spontaneous breathing was accelerated by high concentrations of potassium, BIKE reduced bursting frequency. Regardless of the baseline respiratory rhythm, BIKE at 3.5 Hz always decreased duration of single bursts. Surgical ablation of suprapontine structures completely prevented modulation of breathing after intense training. Albeit the variability in baseline breathing rates, intense passive cyclic movement tuned fictive respiration toward a common frequency range and shortened all respiratory events through the involvement of suprapontine areas. These observations contribute to better define how the respiratory system integrates sensory input from moving limbs during development, opening new rehabilitation perspectives.
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Affiliation(s)
- Rosamaria Apicella
- Neuroscience Department, International School for Advanced Studies (SISSA), Via Bonomea 265, Trieste, Italy
- Applied Neurophysiology and Neuropharmacology Lab, Istituto Di Medicina Fisica E Riabilitazione (IMFR), Via Gervasutta 48, Udine, UD, Italy
| | - Giuliano Taccola
- Neuroscience Department, International School for Advanced Studies (SISSA), Via Bonomea 265, Trieste, Italy.
- Applied Neurophysiology and Neuropharmacology Lab, Istituto Di Medicina Fisica E Riabilitazione (IMFR), Via Gervasutta 48, Udine, UD, Italy.
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5
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Thakre PP, Rana S, Benevides ES, Fuller DD. Targeting drug or gene delivery to the phrenic motoneuron pool. J Neurophysiol 2023; 129:144-158. [PMID: 36416447 PMCID: PMC9829468 DOI: 10.1152/jn.00432.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/19/2022] [Accepted: 11/19/2022] [Indexed: 11/24/2022] Open
Abstract
Phrenic motoneurons (PhrMNs) innervate diaphragm myofibers. Located in the ventral gray matter (lamina IX), PhrMNs form a column extending from approximately the third to sixth cervical spinal segment. Phrenic motor output and diaphragm activation are impaired in many neuromuscular diseases, and targeted delivery of drugs and/or genetic material to PhrMNs may have therapeutic application. Studies of phrenic motor control and/or neuroplasticity mechanisms also typically require targeting of PhrMNs with drugs, viral vectors, or tracers. The location of the phrenic motoneuron pool, however, poses a challenge. Selective PhrMN targeting is possible with molecules that move retrogradely upon uptake into phrenic axons subsequent to diaphragm or phrenic nerve delivery. However, nonspecific approaches that use intrathecal or intravenous delivery have considerably advanced the understanding of PhrMN control. New opportunities for targeted PhrMN gene expression may be possible with intersectional genetic methods. This article provides an overview of methods for targeting the phrenic motoneuron pool for studies of PhrMNs in health and disease.
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Affiliation(s)
- Prajwal P Thakre
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
- Breathing Research and Therapeutics Center, Gainesville, Florida
| | - Sabhya Rana
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
- Breathing Research and Therapeutics Center, Gainesville, Florida
| | - Ethan S Benevides
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
- Breathing Research and Therapeutics Center, Gainesville, Florida
| | - David D Fuller
- Department of Physical Therapy, University of Florida, Gainesville, Florida
- McKnight Brain Institute, University of Florida, Gainesville, Florida
- Breathing Research and Therapeutics Center, Gainesville, Florida
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6
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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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7
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Zhang J, Luo F, Ren S, Wang Y, Li W, Xu K, Zheng Z, He C, Xia J, Xiong W, Hu ZA. Spinal Cord Mapping of Respiratory Intercostal Motoneurons in Adult Mice. Neurosci Bull 2022; 38:1588-1592. [PMID: 35616883 PMCID: PMC9723038 DOI: 10.1007/s12264-022-00883-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 03/27/2022] [Indexed: 02/07/2023] Open
Affiliation(s)
- Junhong Zhang
- Department of Geriatrics, First Affiliated Hospital, Army Medical University, Chongqing, 400038, China
| | - Fenlan Luo
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Shuancheng Ren
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Yaling Wang
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Wu Li
- Department of Geriatrics, First Affiliated Hospital, Army Medical University, Chongqing, 400038, China
| | - Kan Xu
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Ziyi Zheng
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Chao He
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Jianxia Xia
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Wei Xiong
- Department of Geriatrics, First Affiliated Hospital, Army Medical University, Chongqing, 400038, China.
| | - Zhi-An Hu
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China.
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8
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McNaughton KMD, Witherow JL, Dupuche CB, Peebles KC, Elphick TG, Hudson AL, McCaughey EJ, Boswell-Ruys CL, Butler JE. Inspiratory muscle reflex control after incomplete cervical spinal cord injury. J Appl Physiol (1985) 2022; 133:1318-1326. [PMID: 36356259 DOI: 10.1152/japplphysiol.00113.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In healthy individuals, loading inspiratory muscles by brief inspiratory occlusion produces a short-latency inhibitory reflex (IR) in the electromyographic (EMG) activity of scalene and diaphragm muscles. This IR may play a protective role to prevent aspiration and airway collapse during sleep. In people with motor and sensory complete cervical spinal cord injury (cSCI), who were able to breathe independently, this IR was predominantly absent. Here, we investigated the reflex response to brief airway occlusion in 16 participants with sensory incomplete cSCI [American spinal injury association impairment scale (AIS) score B or C]. Surface EMG was recorded from scalene muscles and the lateral chest wall (overlying diaphragm). The airway occlusion evoked a small change in mouth pressure resembling a physiological occlusion. The short-latency IR was present in 10 (63%) sensory incomplete cSCI participants; significantly higher than the IR incidence observed in complete cSCI participants in our previous study (14%; P = 0.003). When present, mean IR latency across all muscles was 58 ms (range 29-79 ms), and mean rectified EMG amplitude decreased to 37% preocclusion levels. Participants without an IR had untreated severe obstructive sleep apnea (OSA), in contrast to those with an IR, who had either had no, mild, or treated OSA (P = 0.002). Insufficient power did not allow statistical comparison between IR presence or absence and participant clinical characteristics. In conclusion, spared sensory connections or intersegmental connections may be necessary to generate the IR. Future studies to establish whether IR presence is related to respiratory morbidity in the tetraplegic population are required.NEW & NOTEWORTHY Individuals with incomplete cSCI were tested for the presence of a short latency reflex inhibition of inspiratory muscles, by brief airway occlusion. The reflex was 4.5 times more prevalent in this group compared with those with complete cSCI and is similar to the incidence in able-bodied people. Participants without this reflex all had untreated severe OSA, in contrast to those with an IR, who either had no, mild, or treated OSA. This work reveals novel differences in the reflex control of inspiratory muscles across the cSCI population.
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Affiliation(s)
- Keith M D McNaughton
- Neuroscience Research Australia, Randwick, New South Wales, Australia.,Department of Health Sciences, Macquarie University, Macquarie Park, New South Wales, Australia
| | - Jessica L Witherow
- Department of Health Sciences, Macquarie University, Macquarie Park, New South Wales, Australia
| | - Crystal B Dupuche
- Department of Health Sciences, Macquarie University, Macquarie Park, New South Wales, Australia
| | - Karen C Peebles
- Department of Health Sciences, Macquarie University, Macquarie Park, New South Wales, Australia
| | - Tom G Elphick
- School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Anna L Hudson
- Neuroscience Research Australia, Randwick, New South Wales, Australia.,School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia.,College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Euan J McCaughey
- Neuroscience Research Australia, Randwick, New South Wales, Australia.,School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia.,Queen Elizabeth National Spinal Injuries Unit, Glasgow, United Kingdom
| | - Claire L Boswell-Ruys
- Neuroscience Research Australia, Randwick, New South Wales, Australia.,Department of Physiotherapy, Prince of Wales Hospital, Randwick, New South Wales, Australia.,School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Jane E Butler
- School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia
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9
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Brown AD, Fogarty MJ, Davis LA, Dasgupta D, Mantilla CB, Sieck GC. Mitochondrial adaptations to inactivity in diaphragm muscle fibers. J Appl Physiol (1985) 2022; 133:191-204. [PMID: 35678745 PMCID: PMC9291409 DOI: 10.1152/japplphysiol.00090.2022] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Type I and IIa diaphragm muscle (DIAm) fibers comprise slow and fast fatigue-resistant motor units that are recruited to accomplish breathing and thus have a high duty cycle. In contrast, type IIx/IIb fibers comprise more fatigable fast motor units that are infrequently recruited for airway protective and straining behaviors. We hypothesize that mitochondrial structure and function in type I and IIa DIAm fibers adapt in response to inactivity imposed by spinal cord hemisection at C2 (C2SH). At 14 days after C2SH, the effect of inactivity on mitochondrial structure and function was assessed in DIAm fibers. Mitochondria in DIAm fibers were labeled using MitoTracker Green (Thermo Fisher Scientific), imaged in three-dimensions (3-D) by fluorescence confocal microscopy, and images were analyzed for mitochondrial volume density (MVD) and complexity. DIAm homogenate from either side was assessed for PGC1α, Parkin, MFN2, and DRP1 using Western blot. In alternate serial sections of the same DIAm fibers, the maximum velocity of the succinate dehydrogenase reaction (SDHmax) was determined using a quantitative histochemical technique. In all groups and both sides of the DIAm, type I and IIa DIAm fibers exhibited higher MVD, with more filamentous mitochondria and had higher SDHmax normalized to both fiber volume and mitochondrial volume compared with type IIx/IIb Diam fibers. In the inactive right side of the DIAm, mitochondria became fragmented and MVD decreased in all fiber types compared with the intact side and sham controls, consistent with the observed reduction in PGC1α and increased Parkin and DRP1 expression. In the inactive side of the DIAm, the reduction in SDHmax was found only for type I and IIa fibers. These results show that there are intrinsic fiber-type-dependent differences in the structure and function of mitochondria in DIAm fibers. Following C2SH-induced inactivity, mitochondrial structure (MVD and fragmentation) and function (SDHmax) were altered, indicating that inactivity influences all DIAm fiber types, but inactivity disproportionately affected SDHmax in the more intrinsically active type I and IIa fibers.NEW & NOTEWORTHY Two weeks of diaphragm (DIAm) inactivity imposed by C2SH caused reduced mitochondrial volume density, mitochondrial fragmentation, and a concomitant reduction of SDHmax in type I and IIa DIAm fibers on the lesioned side. Type I and IIa DIAm fibers were far more sensitive to inactivation than type IIx/IIb fibers, which exhibited little pathology. Our results indicate that mitochondria in DIAm fibers are plastic in response to varying levels of activity.
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10
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Leon Machado L, Noonan K, Bickel S, Singh G, Brothers K, Calvery M, Behrman AL. Spinal Cord Injury at Birth, Expected Medical and Health Complexity in Chronic Injury Guided Anew by Activity-Based Restorative Therapy: Case Report. Front Psychol 2022; 13:800091. [PMID: 35465488 PMCID: PMC9021874 DOI: 10.3389/fpsyg.2022.800091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 02/21/2022] [Indexed: 11/13/2022] Open
Abstract
As infancy is characterized by rapid physical growth and critical periods of development, disruptions due to illness or disease reveal vulnerability associated with this period. Spinal cord injury (SCI) has devastating consequences at any age, but its onset neonatally, at birth, or within the first year of life multiplies its impact. The immediate physical and physiological consequences are obvious and immense, but the effects on the typical trajectory of development are profound. Activity-based restorative therapies (ABRT) capitalize on activity-dependent plasticity of the neuromuscular system below the lesion and when provided to children with SCI aim to improve the child's neuromuscular capacity, health and quality of life. This is a report of an infant with a cervical SCI at birth resulting in paralysis of leg and trunk muscles and paresis of arm and hands who was enrolled in an ABRT program at 3 years of age. After 59 sessions of ABRT, the child demonstrated significant improvements in trunk control and arm function, as well as social and emotional development. Despite the chronicity of injury and low expectations for improvement with therapeutic interventions, ABRT had a positive impact on the child's physical capacity and provided benefits across multiple developmental domains.
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Affiliation(s)
- Laura Leon Machado
- UofL Health, Frazier Rehab Institute, Kosair Charities Center for Pediatric NeuroRecovery, Louisville, KY, United States
| | - Kathryn Noonan
- UofL Health, Frazier Rehab Institute, Kosair Charities Center for Pediatric NeuroRecovery, Louisville, KY, United States
| | - Scott Bickel
- Division of Pediatric Pulmonology, Allergy and Immunology, Norton Children's Hospital, Louisville, KY, United States.,School of Medicine, University of Louisville, Louisville, KY, United States
| | - Goutam Singh
- Kosair Charities School of Physical Therapy, Spalding University, Louisville, KY, United States
| | - Kyle Brothers
- Norton Children's Research Institute, Affiliated With the University of Louisville School of Medicine, Louisville, KY, United States
| | - Margaret Calvery
- Norton Children's Medical Group, Louisville, KY, United States.,Department of Pediatrics, University of Louisville, Louisville, KY, United States
| | - Andrea L Behrman
- Department of Neurological Surgery, Kentucky Spinal Cord Injury Research Center, Kosair Charities Center for Pediatric NeuroRecovery, University of Louisville, Louisville, KY, United States
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11
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Fuller DD, Rana S, Smuder AJ, Dale EA. The phrenic neuromuscular system. HANDBOOK OF CLINICAL NEUROLOGY 2022; 188:393-408. [PMID: 35965035 PMCID: PMC11135908 DOI: 10.1016/b978-0-323-91534-2.00012-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The phrenic neuromuscular system consists of the phrenic motor nucleus in the mid-cervical spinal cord, the phrenic nerve, and the diaphragm muscle. This motor system helps sustain breathing throughout life, while also contributing to posture, coughing, swallowing, and speaking. The phrenic nerve contains primarily efferent phrenic axons and afferent axons from diaphragm sensory receptors but is also a conduit for autonomic fibers. On a breath-by-breath basis, rhythmic (inspiratory) depolarization of phrenic motoneurons occurs due to excitatory bulbospinal synaptic pathways. Further, a complex propriospinal network innervates phrenic motoneurons and may serve to coordinate postural, locomotor, and respiratory movements. The phrenic neuromuscular system is impacted in a wide range of neuromuscular diseases and injuries. Contemporary research is focused on understanding how neuromuscular plasticity occurs in the phrenic neuromuscular system and using this information to optimize treatments and rehabilitation strategies to improve breathing and related behaviors.
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Affiliation(s)
- David D Fuller
- Department of Physical Therapy, University of Florida, Gainesville, FL, United States; McKnight Brain Institute, University of Florida, Gainesville, FL, United States; Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, United States.
| | - Sabhya Rana
- Department of Physical Therapy, University of Florida, Gainesville, FL, United States; McKnight Brain Institute, University of Florida, Gainesville, FL, United States; Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, United States
| | - Ashley J Smuder
- Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, United States; Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, United States
| | - Erica A Dale
- McKnight Brain Institute, University of Florida, Gainesville, FL, United States; Breathing Research and Therapeutics Center, University of Florida, Gainesville, FL, United States; Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL, United States
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12
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Gonzalez-Rothi EJ, Lee KZ. Intermittent hypoxia and respiratory recovery in pre-clinical rodent models of incomplete cervical spinal cord injury. Exp Neurol 2021; 342:113751. [PMID: 33974878 DOI: 10.1016/j.expneurol.2021.113751] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 04/24/2021] [Accepted: 05/06/2021] [Indexed: 10/21/2022]
Abstract
Impaired respiratory function is a common and devastating consequence of cervical spinal cord injury. Accordingly, the development of safe and effective treatments to restore breathing function is critical. Acute intermittent hypoxia has emerged as a promising therapeutic strategy to treat respiratory insufficiency in individuals with spinal cord injury. Since the original report by Bach and Mitchell (1996) concerning long-term facilitation of phrenic motor output elicited by brief, episodic exposure to reduced oxygen, a series of studies in animal models have led to the realization that acute intermittent hypoxia may have tremendous potential for inducing neuroplasticity and functional recovery in the injured spinal cord. Advances in our understanding of the neurobiology of acute intermittent hypoxia have prompted us to begin to explore its effects in human clinical studies. Here, we review the basic neurobiology of the control of breathing and the pathophysiology and respiratory consequences of two common experimental models of incomplete cervical spinal cord injury (i.e., high cervical hemisection and mid-cervical contusion). We then discuss the impact of acute intermittent hypoxia on respiratory motor function in these models: work that has laid the foundation for translation of this promising therapeutic strategy to clinical populations. Lastly, we examine the limitations of these animal models and intermittent hypoxia and discuss how future work in animal models may further advance the translation and therapeutic efficacy of this treatment.
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Affiliation(s)
- Elisa J Gonzalez-Rothi
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Kun-Ze Lee
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan; Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan.
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13
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Abstract
Spinal cord injury (SCI) triggers a complex cascade of molecular and cellular events that leads to progressive cell loss and tissue damage. In this review, the authors outline the temporal profile of SCI pathogenesis, focusing on key mediators of the secondary injury, and highlight cutting edge insights on the alterations in neural circuits that largely define the chronic injury environment. They bridge these important basic science concepts with clinical implications for informing novel experimental therapies. Furthermore, emerging concepts in the study of SCI pathogenesis that are transforming fundamental research into innovative clinical treatment paradigms are outlined.
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Affiliation(s)
- Laureen D Hachem
- Division of Neurosurgery, Department of Surgery, University of Toronto, 149 College Street, Toronto, Ontario M5T 1P5, Canada; Division of Neurosurgery, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Suite 4W-449, Toronto, Ontario M5T 2S8, Canada
| | - Michael G Fehlings
- Division of Neurosurgery, Department of Surgery, University of Toronto, 149 College Street, Toronto, Ontario M5T 1P5, Canada; Division of Neurosurgery, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Suite 4W-449, Toronto, Ontario M5T 2S8, Canada.
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14
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Teng YD, Zafonte RD. Prelude to the special issue on novel neurocircuit, cellular and molecular targets for developing functional rehabilitation therapies of neurotrauma. Exp Neurol 2021; 341:113689. [PMID: 33745921 DOI: 10.1016/j.expneurol.2021.113689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 03/07/2021] [Indexed: 11/15/2022]
Abstract
The poor endogenous recovery capacity and other impediments to reinstating sensorimotor or autonomic function after adult neurotrauma have perplexed modern neuroscientists, bioengineers, and physicians for over a century. However, despite limited improvement in options to mitigate acute pathophysiological sequalae, the past 20 years have witnessed marked progresses in developing efficacious rehabilitation strategies for chronic spinal cord and brain injuries. The achievement is mainly attributable to research advancements in elucidating neuroplastic mechanisms for the potential to enhance clinical prognosis. Innovative cross-disciplinary studies have established novel therapeutic targets, theoretical frameworks, and regiments to attain treatment efficacy. This Special Issue contained eight papers that described experimental and human data along with literature reviews regarding the essential roles of the conventionally undervalued factors in neural repair: systemic inflammation, neural-respiratory inflammasome axis, modulation of glutamatergic and monoaminergic neurotransmission, neurogenesis, nerve transfer, recovery neurobiology components, and the spinal cord learning, respiration and central pattern generator neurocircuits. The focus of this work was on how to induce functional recovery from manipulating these underpinnings through their interactions with secondary injury events, peripheral and supraspinal inputs, neuromusculoskeletal network, and interventions (i.e., activity training, pharmacological adjuncts, electrical stimulation, and multimodal neuromechanical, brain-computer interface [BCI] and robotic assistance [RA] devices). The evidence suggested that if key neurocircuits are therapeutically reactivated, rebuilt, and/or modulated under proper sensory feedback, neurological function (e.g., cognition, respiration, limb movement, locomotion, etc.) will likely be reanimated after neurotrauma. The efficacy can be optimized by individualizing multimodal rehabilitation treatments via BCI/RA-integrated drug administration and neuromechanical protheses.
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Affiliation(s)
- Yang D Teng
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, USA; Neurotrauma Recovery Research, Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital Network, Mass General Brigham, and Harvard Medical School, Boston, MA, USA; Spaulding Research Institute, Spaulding Rehabilitation Hospital Network, Boston, MA, USA.
| | - Ross D Zafonte
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, USA; Neurotrauma Recovery Research, Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital Network, Mass General Brigham, and Harvard Medical School, Boston, MA, USA; Spaulding Research Institute, Spaulding Rehabilitation Hospital Network, Boston, MA, USA.
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15
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Rana S, Zhan WZ, Mantilla CB, Sieck GC. Disproportionate loss of excitatory inputs to smaller phrenic motor neurons following cervical spinal hemisection. J Physiol 2020; 598:4693-4711. [PMID: 32735344 DOI: 10.1113/jp280130] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 07/20/2020] [Indexed: 12/18/2022] Open
Abstract
KEY POINTS Motor units, comprising a motor neuron and the muscle fibre it innervates, are activated in an orderly fashion to provide varying amounts of force. A unilateral C2 spinal hemisection (C2SH) disrupts predominant excitatory input from medulla, causing cessation of inspiratory-related diaphragm muscle activity, whereas higher force, non-ventilatory diaphragm activity persists. In this study, we show a disproportionately larger loss of excitatory glutamatergic innervation to small phrenic motor neurons (PhMNs) following C2SH, as compared with large PhMNs ipsilateral to injury. Our data suggest that there is a dichotomy in the distribution of inspiratory-related descending excitatory glutamatergic input to small vs. large PhMNs that reflects their differential recruitment. ABSTRACT Excitatory glutamatergic input mediating inspiratory drive to phrenic motor neurons (PhMNs) emanates primarily from the ipsilateral ventrolateral medulla. Unilateral C2 hemisection (C2SH) disrupts this excitatory input, resulting in cessation of inspiratory-related diaphragm muscle (DIAm) activity. In contrast, after C2SH, higher force, non-ventilatory DIAm activity persists. Inspiratory behaviours require recruitment of only smaller PhMNs, whereas with more forceful expulsive/straining behaviours, larger PhMNs are recruited. Accordingly, we hypothesize that C2SH primarily disrupts glutamatergic synaptic inputs to smaller PhMNs, whereas glutamatergic synaptic inputs to larger PhMNs are preserved. We examined changes in glutamatergic presynaptic input onto retrogradely labelled PhMNs using immunohistochemistry for VGLUT1 and VGLUT2. We found that 7 days after C2SH there was an ∼60% reduction in glutamatergic inputs to smaller PhMNs compared with an ∼35% reduction at larger PhMNs. These results are consistent with a more pronounced impact of C2SH on inspiratory behaviours of the DIAm, and the preservation of higher force behaviours after C2SH. These results indicate that the source of glutamatergic synaptic input to PhMNs varies depending on motor neuron size and reflects different functional control - perhaps separate central pattern generator and premotor circuits. For smaller PhMNs, the central pattern generator for inspiration is located in the pre-Bötzinger complex and premotor neurons in the ventrolateral medulla, sending predominantly ipsilateral projections via the dorsolateral funiculus. C2SH disrupts this glutamatergic input. For larger PhMNs, a large proportion of excitatory inputs appear to exist below the C2 level or from contralateral regions of the brainstem and spinal cord.
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Affiliation(s)
- Sabhya Rana
- Departments of Physiology & Biomedical Engineering and
| | - Wen-Zhi Zhan
- Departments of Physiology & Biomedical Engineering and
| | - Carlos B Mantilla
- Departments of Physiology & Biomedical Engineering and.,Anaesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN
| | - Gary C Sieck
- Departments of Physiology & Biomedical Engineering and.,Anaesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN
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