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Patel D, Banerjee R, Farooque K, Gupta D, Garg B, Kumar N, Thukral GH, Kochhar KP, Jain S. Restoring initial steps by intermittent theta burst stimulation in complete spinal cord injury patient: a case report. Spinal Cord Ser Cases 2024; 10:56. [PMID: 39098854 PMCID: PMC11298536 DOI: 10.1038/s41394-024-00669-8] [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: 02/19/2024] [Revised: 07/19/2024] [Accepted: 07/26/2024] [Indexed: 08/06/2024] Open
Abstract
INTRODUCTION Spinal cord injury (SCI) causes damage to neurons and results in motor and sensory dysfunction. Intermittent theta burst stimulation (iTBS) has been used to induce neuronal and synaptic plasticity by applying a magnetic field in the brain. The plasticity induced in the cortex has an imperative role in the recovery of motor and sensory functioning. However, the effect of iTBS in complete SCI patients is still elusive. CASE PRESENTATION We report here the case of a 27-year-old female who sustained an L1 complete spinal cord injury (SCI) with an ASIA score of A. The patient lost all the sensory and motor functions below the level of injury. Intermittent theta burst stimulation (iTBS) was administered at 80% of the resting motor threshold over the M1 motor cortex, along with intensive rehabilitation training to promote sensorimotor function. DISCUSSION There was a partial recovery in functional, electrophysiological, and neurological parameters. The case report also demonstrates the safety and efficacy of iTBS in complete SCI patients. No adverse event has been observed in the patient during intervention sessions.
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Affiliation(s)
- Deeksha Patel
- Brain Stimulation and Neuromodulation Laboratory, Department of Physiology, All India Institute of Medical Sciences, Delhi, 110029, India
| | - Rohit Banerjee
- Brain Stimulation and Neuromodulation Laboratory, Department of Physiology, All India Institute of Medical Sciences, Delhi, 110029, India
| | - Kamran Farooque
- Department of Orthopaedics, All India Institute of Medical Sciences, Delhi, 110029, India
| | - Deepak Gupta
- Department of Neurosurgery, All India Institute of Medical Sciences, Delhi, 110029, India
| | - Bhavuk Garg
- Department of Orthopaedics, All India Institute of Medical Sciences, Delhi, 110029, India
| | - Nand Kumar
- Department of Psychiatry, All India Institute of Medical Sciences, Delhi, 110029, India
| | - Gita H Thukral
- Department of Physical Medicine and Rehabilitation, All India Institute of Medical Sciences, Delhi, 110029, India
| | - Kanwal Preet Kochhar
- Brain Stimulation and Neuromodulation Laboratory, Department of Physiology, All India Institute of Medical Sciences, Delhi, 110029, India
| | - Suman Jain
- Brain Stimulation and Neuromodulation Laboratory, Department of Physiology, All India Institute of Medical Sciences, Delhi, 110029, India.
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Lo YL, Hwang R, Teng PPC, Tan YE. Corpus Callosum-Mediated Interhemispheric Interactions in Cervical Spondylotic Myelopathy. J Clin Neurophysiol 2024; 41:473-477. [PMID: 38922289 DOI: 10.1097/wnp.0000000000000979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2024] Open
Abstract
PURPOSE The corpus callosum is crucial for interhemispheric interactions in the motor control of limb functions. Human and animal studies suggested spinal cord pathologies may induce cortical reorganization in sensorimotor areas. We investigate participation of the corpus callosum in executions of a simple motor task in patients with cervical spondylotic myelopathy (CSM) using transcranial magnetic stimulation. METHODS Twenty patients with CSM with various MRI grades of severity of cord compression were compared with 19 normal controls. Ipsilateral silent period, contralateral silent period, central motor conduction time, and transcallosal conduction time (TCT) were determined. RESULTS In both upper and lower limbs, TCTs were significantly increased for patients with CSM than normal controls ( p < 0.001 for all), without side-to-side differences. Ipsilateral silent period and contralateral silent period durations were significantly increased bilaterally for upper limbs in comparison to controls ( p < 0.01 for all), without side-to-side differences. There were no significant correlations of TCT with central motor conduction time nor severity of CSM for both upper and lower limbs ( p > 0.05 for all) bilaterally. CONCLUSIONS Previous transcranial magnetic stimulation studies show increased motor cortex excitability in CSM; hence, increased TCTs observed bilaterally may be a compensatory mechanism for effective unidirectional and uniplanar execution of muscle activation in the distal limb muscles. Lack of correlation of TCTs with severity of CSM or central motor conduction time may be in keeping with a preexistent role of the corpus callosum as a predominantly inhibitory pathway for counteracting redundant movements resulting from increased motor cortex excitability occurring after spinal cord lesions.
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Affiliation(s)
- Yew Long Lo
- National Neuroscience Institute, Singapore General Hospital, Singapore, Singapore
- Duke-NUS Medical School, Singapore, Singapore; and
- Singapore General Hospital, Singapore, Singapore
| | - Ruby Hwang
- Singapore General Hospital, Singapore, Singapore
| | | | - Yam Eng Tan
- Singapore General Hospital, Singapore, Singapore
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Boaro A, Nunes S, Bagattini C, Di Caro V, Siddi F, Moscolo F, Soda C, Sala F. Motor Pathways Reorganization following Surgical Decompression for Degenerative Cervical Myelopathy: A Combined Navigated Transcranial Magnetic Stimulation and Clinical Outcome Study. Brain Sci 2024; 14:124. [PMID: 38391699 PMCID: PMC10887348 DOI: 10.3390/brainsci14020124] [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: 12/20/2023] [Revised: 01/14/2024] [Accepted: 01/17/2024] [Indexed: 02/24/2024] Open
Abstract
(1) Background: Degenerative cervical myelopathy is one of the main causes of disability in the elderly. The treatment of choice in patients with clear symptomatology and radiological correlation is surgical decompression. The application of navigated transcranial magnetic stimulation (nTMS) techniques has the potential to provide additional insights into the cortical and corticospinal behavior of the myelopathic cord and to better characterize the possible extent of clinical recovery. The objective of our study was to use nTMS to evaluate the effect of surgical decompression on neurophysiological properties at the cortical and corticospinal level and to better characterize the extent of possible clinical recovery. (2) Methods: We conducted a longitudinal study in which we assessed and compared nTMS neurophysiological indexes and clinical parameters (modified Japanese Orthopedic Association score and nine-hole pegboard test) before surgery, at 6 months, and at 12 months' follow-up in a population of 15 patients. (3) Results: We found a significant reduction in resting motor threshold (RMT; average 7%), cortical silent period (CSP; average 15%), and motor area (average 25%) at both 6 months and 12 months. A statistically significant linear correlation emerged between recruitment curve (RC) values obtained at follow-up appointments and at baseline (r = 0.95 at 6 months, r = 0.98 at 12 months). A concomitant improvement in the mJOA score and in the nine-hole pegboard task was observed after surgery. (4) Conclusions: Our results suggest that surgical decompression of the myelopathic spinal cord improves the neurophysiological balance at the cortical and corticospinal level, resulting in clinically significant recovery. Such findings contribute to the existing evidence characterizing the brain and the spinal cord as a dynamic system capable of functional and reversible plasticity and provide useful clinical insights to be used for patient counseling.
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Affiliation(s)
- Alessandro Boaro
- Section of Neurosurgery, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, 37124 Verona, Italy
| | - Sonia Nunes
- Section of Neurosurgery, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, 37124 Verona, Italy
| | - Chiara Bagattini
- Section of Neurosurgery, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, 37124 Verona, Italy
| | - Valeria Di Caro
- Section of Neurosurgery, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, 37124 Verona, Italy
| | - Francesca Siddi
- Section of Neurosurgery, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, 37124 Verona, Italy
| | - Fabio Moscolo
- Neurosurgery Unit, Carlo Poma Hospital, 46100 Mantova, Italy
| | - Christian Soda
- Institute of Neurosurgery, Azienda Ospedaliera Universitaria Integrata, 37126 Verona, Italy
| | - Francesco Sala
- Section of Neurosurgery, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, 37124 Verona, Italy
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Vucic S, Stanley Chen KH, Kiernan MC, Hallett M, Benninger DH, Di Lazzaro V, Rossini PM, Benussi A, Berardelli A, Currà A, Krieg SM, Lefaucheur JP, Long Lo Y, Macdonell RA, Massimini M, Rosanova M, Picht T, Stinear CM, Paulus W, Ugawa Y, Ziemann U, Chen R. Clinical diagnostic utility of transcranial magnetic stimulation in neurological disorders. Updated report of an IFCN committee. Clin Neurophysiol 2023; 150:131-175. [PMID: 37068329 PMCID: PMC10192339 DOI: 10.1016/j.clinph.2023.03.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 02/28/2023] [Accepted: 03/09/2023] [Indexed: 03/31/2023]
Abstract
The review provides a comprehensive update (previous report: Chen R, Cros D, Curra A, Di Lazzaro V, Lefaucheur JP, Magistris MR, et al. The clinical diagnostic utility of transcranial magnetic stimulation: report of an IFCN committee. Clin Neurophysiol 2008;119(3):504-32) on clinical diagnostic utility of transcranial magnetic stimulation (TMS) in neurological diseases. Most TMS measures rely on stimulation of motor cortex and recording of motor evoked potentials. Paired-pulse TMS techniques, incorporating conventional amplitude-based and threshold tracking, have established clinical utility in neurodegenerative, movement, episodic (epilepsy, migraines), chronic pain and functional diseases. Cortical hyperexcitability has emerged as a diagnostic aid in amyotrophic lateral sclerosis. Single-pulse TMS measures are of utility in stroke, and myelopathy even in the absence of radiological changes. Short-latency afferent inhibition, related to central cholinergic transmission, is reduced in Alzheimer's disease. The triple stimulation technique (TST) may enhance diagnostic utility of conventional TMS measures to detect upper motor neuron involvement. The recording of motor evoked potentials can be used to perform functional mapping of the motor cortex or in preoperative assessment of eloquent brain regions before surgical resection of brain tumors. TMS exhibits utility in assessing lumbosacral/cervical nerve root function, especially in demyelinating neuropathies, and may be of utility in localizing the site of facial nerve palsies. TMS measures also have high sensitivity in detecting subclinical corticospinal lesions in multiple sclerosis. Abnormalities in central motor conduction time or TST correlate with motor impairment and disability in MS. Cerebellar stimulation may detect lesions in the cerebellum or cerebello-dentato-thalamo-motor cortical pathways. Combining TMS with electroencephalography, provides a novel method to measure parameters altered in neurological disorders, including cortical excitability, effective connectivity, and response complexity.
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Affiliation(s)
- Steve Vucic
- Brain, Nerve Research Center, The University of Sydney, Sydney, Australia.
| | - Kai-Hsiang Stanley Chen
- Department of Neurology, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu, Taiwan
| | - Matthew C Kiernan
- Brain and Mind Centre, The University of Sydney; and Department of Neurology, Royal Prince Alfred Hospital, Australia
| | - Mark Hallett
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health, Bethesda, Maryland, United States
| | - David H Benninger
- Department of Neurology, University Hospital of Lausanne (CHUV), Switzerland
| | - Vincenzo Di Lazzaro
- Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, University Campus Bio-Medico of Rome, Rome, Italy
| | - Paolo M Rossini
- Department of Neurosci & Neurorehab IRCCS San Raffaele-Rome, Italy
| | - Alberto Benussi
- Centre for Neurodegenerative Disorders, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
| | - Alfredo Berardelli
- IRCCS Neuromed, Pozzilli; Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | - Antonio Currà
- Department of Medico-Surgical Sciences and Biotechnologies, Alfredo Fiorini Hospital, Sapienza University of Rome, Terracina, LT, Italy
| | - Sandro M Krieg
- Department of Neurosurgery, Technical University Munich, School of Medicine, Klinikum rechts der Isar, Munich, Germany
| | - Jean-Pascal Lefaucheur
- Univ Paris Est Creteil, EA4391, ENT, Créteil, France; Clinical Neurophysiology Unit, Henri Mondor Hospital, AP-HP, Créteil, France
| | - Yew Long Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore, and Duke-NUS Medical School, Singapore
| | | | - Marcello Massimini
- Dipartimento di Scienze Biomediche e Cliniche, Università degli Studi di Milano, Milan, Italy; Istituto Di Ricovero e Cura a Carattere Scientifico, Fondazione Don Carlo Gnocchi, Milan, Italy
| | - Mario Rosanova
- Department of Biomedical and Clinical Sciences University of Milan, Milan, Italy
| | - Thomas Picht
- Department of Neurosurgery, Charité-Universitätsmedizin Berlin, Cluster of Excellence: "Matters of Activity. Image Space Material," Humboldt University, Berlin Simulation and Training Center (BeST), Charité-Universitätsmedizin Berlin, Germany
| | - Cathy M Stinear
- Department of Medicine Waipapa Taumata Rau, University of Auckland, Auckland, Aotearoa, New Zealand
| | - Walter Paulus
- Department of Neurology, Ludwig-Maximilians-Universität München, München, Germany
| | - Yoshikazu Ugawa
- Department of Human Neurophysiology, School of Medicine, Fukushima Medical University, Japan
| | - Ulf Ziemann
- Department of Neurology and Stroke, Eberhard Karls University of Tübingen, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany; Hertie Institute for Clinical Brain Research, Eberhard Karls University of Tübingen, Otfried-Müller-Straße 27, 72076 Tübingen, Germany
| | - Robert Chen
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital-UHN, Division of Neurology-University of Toronto, Toronto Canada
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Roumengous T, Thakkar B, Peterson CL. Paired pulse transcranial magnetic stimulation in the assessment of biceps voluntary activation in individuals with tetraplegia. Front Hum Neurosci 2022; 16:976014. [DOI: 10.3389/fnhum.2022.976014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022] Open
Abstract
After spinal cord injury (SCI), motoneuron death occurs at and around the level of injury which induces changes in function and organization throughout the nervous system, including cortical changes. Muscle affected by SCI may consist of both innervated (accessible to voluntary drive) and denervated (inaccessible to voluntary drive) muscle fibers. Voluntary activation measured with transcranial magnetic stimulation (VATMS) can quantify voluntary cortical/subcortical drive to muscle but is limited by technical challenges including suboptimal stimulation of target muscle relative to its antagonist. The motor evoked potential (MEP) in the biceps compared to the triceps (i.e., MEP ratio) may be a key parameter in the measurement of biceps VATMS after SCI. We used paired pulse TMS, which can inhibit or facilitate MEPs, to determine whether the MEP ratio affects VATMS in individuals with tetraplegia. Ten individuals with tetraplegia following cervical SCI and ten non-impaired individuals completed single pulse and paired pulse VATMS protocols. Paired pulse stimulation was delivered at 1.5, 10, and 30 ms inter-stimulus intervals (ISI). In both the SCI and non-impaired groups, the main effect of the stimulation pulse (paired pulse compared to single pulse) on VATMS was not significant in the linear mixed-effects models. In both groups for the stimulation parameters we tested, the MEP ratio was not modulated across all effort levels and did not affect VATMS. Linearity of the voluntary moment and superimposed twitch moment relation was lower in SCI participants compared to non-impaired. Poor linearity in the SCI group limits interpretation of VATMS. Future work is needed to address methodological issues that limit clinical application of VATMS.
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Arora T, Desai N, Kirshblum S, Chen R. Utility of transcranial magnetic stimulation in the assessment of spinal cord injury: Current status and future directions. FRONTIERS IN REHABILITATION SCIENCES 2022; 3:1005111. [PMID: 36275924 PMCID: PMC9581184 DOI: 10.3389/fresc.2022.1005111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 09/16/2022] [Indexed: 11/06/2022]
Abstract
Comprehensive assessment following traumatic spinal cord injury (SCI) is needed to improve prognostication, advance the understanding of the neurophysiology and better targeting of clinical interventions. The International Standards for Neurological Classification of Spinal Cord Injury is the most common clinical examination recommended for use after a SCI. In addition, there are over 30 clinical assessment tools spanning across different domains of the International Classification of Functioning, Disability, and Health that have been validated and recommended for use in SCI. Most of these tools are subjective in nature, have limited value in predicting neurologic recovery, and do not provide insights into neurophysiological mechanisms. Transcranial magnetic stimulation (TMS) is a non-invasive neurophysiology technique that can supplement the clinical assessment in the domain of body structure and function during acute and chronic stages of SCI. TMS offers a better insight into neurophysiology and help in better detection of residual corticomotor connectivity following SCI compared to clinical assessment alone. TMS-based motor evoked potential and silent period duration allow study of excitatory and inhibitory mechanisms following SCI. Changes in muscle representations in form of displacement of TMS-based motor map center of gravity or changes in the map area can capture neuroplastic changes resulting from SCI or following rehabilitation. Paired-pulse TMS measures help understand the compensatory reorganization of the cortical circuits following SCI. In combination with peripheral stimulation, TMS can be used to study central motor conduction time and modulation of spinal reflexes, which can be used for advanced diagnostic and treatment purposes. To strengthen the utility of TMS in SCI assessment, future studies will need to standardize the assessment protocols, address population-specific concerns, and establish the psychometric properties of TMS-based measurements in the SCI population.
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Affiliation(s)
- Tarun Arora
- Krembil Research Institute, University Health Network, Toronto, ON, Canada,Correspondence: Tarun Arora Robert Chen
| | - Naaz Desai
- Krembil Research Institute, University Health Network, Toronto, ON, Canada
| | - Steven Kirshblum
- Department of Physical Medicine and Rehabilitation, Rutgers New Jersey Medical School, Newark, NJ, United States,Kessler Institute for Rehabilitation, West Orange, NJ, United States,Kessler Foundation, West Orange, NJ, United States,Rutgers New Jersey Medical School, Newark, NJ, United States
| | - Robert Chen
- Krembil Research Institute, University Health Network, Toronto, ON, Canada,Edmond J. Safra Program in Parkinson’s Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital, UHN, Toronto, ON, Canada,Division of Neurology, University of Toronto, Toronto, ON, Canada,Correspondence: Tarun Arora Robert Chen
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Tazoe T, Perez MA. Abnormal changes in motor cortical maps in humans with spinal cord injury. J Physiol 2021; 599:5031-5045. [PMID: 34192806 PMCID: PMC9109877 DOI: 10.1113/jp281430] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 06/28/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The functional role of motor cortical reorganization following spinal cord injury (SCI) remains largely unknown. Here, we tested motor maps in a hand muscle at rest and during voluntary contraction of the hand with and without voluntary contraction of a proximal arm muscle. Motor map area in participants with SCI decreased during hand voluntary contraction and further decreased during additional contraction of a proximal arm muscle compared with rest. In contrast, motor map area in controls increased during the same motor tasks. Participants with SCI with more severe sensory deficits in the hand showed larger decreases in motor map area. Ten minutes of hand muscle-tendon vibration increased the motor map area during voluntary contraction in SCI participants. These novel findings suggest that abnormal changes in motor cortical maps during voluntary contraction after SCI can be reshaped by sensory input, knowledge that can have implications for rehabilitation. ABSTRACT Motor cortical representations reorganize following cervical spinal cord injury (SCI). The functional role of this reorganization remains largely unknown. Using neuronavigated transcranial magnetic stimulation, we examined motor cortical maps during voluntary contraction in humans with chronic cervical SCI and age-matched controls. We constructed motor maps in the first dorsal interosseous (FDI) muscle at rest and during voluntary contraction of the FDI with and without voluntary contraction of the biceps brachi (BB). The role of sensory input into this reorganization was examined by muscle-tendon vibration. We found that, at rest, motor maps were larger in SCI (22.3 cm2 ) compared with control (12.6 cm2 , P < 0.001) participants. Motor map area increased during voluntary contraction of the FDI (120.7%) and further increased during contraction of the BB (143.9%) compared with rest in control subjects; however, motor map area decreased during voluntary contraction of the FDI (69.5%) and further decreased during contraction of the BB (55.5%) in individuals with SCI. SCI participants with larger decreases in map area during voluntary contraction of the FDI were those with larger sensory deficits in the hand and 10 min of hand muscle-tendon vibration increased motor map area. These results provide the first evidence of abnormal changes in motor cortical maps in humans with chronic SCI during voluntary contraction, suggesting that sensory input can help to reshape this reorganization.
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Affiliation(s)
- Toshiki Tazoe
- Arms + Hands Lab, Shirley Ryan AbilityLab, Northwestern
University, Chicago, IL 60611 and Hines Veterans Affairs Medical Center, Chicago, IL
60141, USA
- Neural Prosthesis Project, Department of Brain and
Neurosciences, Tokyo Metropolitan Institute of Medial Science, Tokyo 156-8506,
Japan
| | - Monica A. Perez
- Arms + Hands Lab, Shirley Ryan AbilityLab, Northwestern
University, Chicago, IL 60611 and Hines Veterans Affairs Medical Center, Chicago, IL
60141, USA
- The Miami Project to Cure Paralysis, Department of
Neurological Surgery, University of Miami, Miami FL 33136 and Bruce W. Carter
Department of Veterans Affairs Medical Center, Miami, FL 33125, USA
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Duration and reliability of the silent period in individuals with spinal cord injury. Spinal Cord 2021; 59:885-893. [PMID: 34099882 DOI: 10.1038/s41393-021-00649-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 05/19/2021] [Accepted: 05/21/2021] [Indexed: 11/08/2022]
Abstract
DESIGN Prospective cohort study. OBJECTIVES We aim to better understand the silent period (SP), an inhibitory counterpart to the well-known motor evoked potential (MEP) elicited by transcranial magnetic stimulation (TMS), in individuals with spinal cord injury (SCI). SETTING Veterans Affairs Hospital in New York. METHODS EMG responses were measured in the target abductor pollicis brevis at rest (TMS at 120% of resting motor threshold (RMT)) and during maximal effort (TMS at 110% of RMT). Participants with chronic cervical SCI (n = 9) and AB participants (n = 12) underwent between 3 and 7 sessions of testing on separate days. The primary outcomes were the magnitude and reliability of SP duration, resting and active MEP amplitudes, and RMT. RESULTS SCI participants showed significantly lower MEP amplitudes compared to AB participants. SCI SP duration was not significantly different from AB SP duration. SP duration demonstrated reduced intra-participant variability within and across sessions compared with MEP amplitudes. SCI participants also demonstrated a higher prevalence of SP 'interruptions' compared to AB participants. CONCLUSIONS In a small group of individuals with chronic cervical SCI, we confirmed the well-known findings that SCI individuals have lower TMS evoked potential amplitudes and a tendency toward higher TMS motor thresholds relative to able-bodied controls. We did not observe a significant difference in SP duration between individuals with versus without SCI. However, SP duration is a more reliable outcome within and across multiple sessions than MEP amplitude.
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Vastano R, Perez MA. Changes in motoneuron excitability during voluntary muscle activity in humans with spinal cord injury. J Neurophysiol 2020; 123:454-461. [PMID: 31461361 PMCID: PMC7052637 DOI: 10.1152/jn.00367.2019] [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: 06/12/2019] [Revised: 08/19/2019] [Accepted: 08/19/2019] [Indexed: 11/22/2022] Open
Abstract
The excitability of resting motoneurons increases following spinal cord injury (SCI). The extent to which motoneuron excitability changes during voluntary muscle activity in humans with SCI, however, remains poorly understood. To address this question, we measured F waves by using supramaximal electrical stimulation of the ulnar nerve at the wrist and cervicomedullary motor-evoked potentials (CMEPs) by using high-current electrical stimulation over the cervicomedullary junction in the first dorsal interosseous muscle at rest and during 5 and 30% of maximal voluntary contraction into index finger abduction in individuals with chronic cervical incomplete SCI and aged-matched control participants. We found higher persistence (number of F waves present in each set) and amplitude of F waves at rest in SCI compared with control participants. With increasing levels of voluntary contraction, the amplitude, but not the persistence, of F waves increased in both groups but to a lesser extent in SCI compared with control participants. Similarly, the CMEP amplitude increased in both groups but to a lesser extent in SCI compared with controls. These results were also found at matched absolutely levels of electromyographic activity, suggesting that these changes were not related to decreases in voluntary motor output after SCI. F-wave and CMEP amplitudes were positively correlated across conditions in both groups. These results support the hypothesis that the responsiveness of the motoneuron pool during voluntary activity decreases following SCI, which could alter the generation and strength of voluntary muscle contractions.NEW & NOTEWORTHY How the excitability of motoneurons changes during voluntary muscle activity in humans with spinal cord injury (SCI) remains poorly understood. We found that F-wave and cervicomedullary motor-evoked potential amplitude, outcomes reflecting motoneuronal excitability, increased during voluntary activity compared with rest in SCI participants but to a lesser extent that in controls. These results suggest that the responsiveness of motoneurons during voluntary activity decreases following SCI, which might affect functionally relevant plasticity after the injury.
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Affiliation(s)
- Roberta Vastano
- The Miami Project to Cure Paralysis, University of Miami, Miami, Florida
- Department of Neurological Surgery, University of Miami, Miami, Florida
- Bruce W. Carter Department of Veterans Affairs Medical Center, Miami, Florida
| | - Monica A Perez
- The Miami Project to Cure Paralysis, University of Miami, Miami, Florida
- Department of Neurological Surgery, University of Miami, Miami, Florida
- Bruce W. Carter Department of Veterans Affairs Medical Center, Miami, Florida
- Shirley Ryan Ability Laboratory, Northwestern University, Chicago, Illinois
- Hines Veterans Affairs Medical Center, Chicago, Illinois
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Lucci G, Pisotta I, Berchicci M, Di Russo F, Bonavita J, Scivoletto G, Spinelli D, Molinari M. Proactive Cortical Control in Spinal Cord Injury Subjects with Paraplegia. J Neurotrauma 2019; 36:3347-3355. [DOI: 10.1089/neu.2018.6307] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Giuliana Lucci
- Electrophysiology of Cognition Lab and Fondazione Santa Lucia IRCCS, Rome, Italy
- Department of Human Sciences, Guglielmo Marconi University, Rome, Italy
| | - Iolanda Pisotta
- SPInal REhabilitation Lab–SPIRE, Fondazione Santa Lucia IRCCS, Rome, Italy
| | - Marika Berchicci
- Department of Movement, Human and Health Sciences, University of Rome “Foro Italico,” Rome, Italy
| | - Francesco Di Russo
- Electrophysiology of Cognition Lab and Fondazione Santa Lucia IRCCS, Rome, Italy
- Department of Movement, Human and Health Sciences, University of Rome “Foro Italico,” Rome, Italy
| | - Jacopo Bonavita
- Spinal Unit, Montecatone Rehabilitation Institute, Imola (Bologna), Italy
| | - Giorgio Scivoletto
- SPInal REhabilitation Lab–SPIRE, Fondazione Santa Lucia IRCCS, Rome, Italy
| | - Donatella Spinelli
- Electrophysiology of Cognition Lab and Fondazione Santa Lucia IRCCS, Rome, Italy
- Department of Movement, Human and Health Sciences, University of Rome “Foro Italico,” Rome, Italy
| | - Marco Molinari
- SPInal REhabilitation Lab–SPIRE, Fondazione Santa Lucia IRCCS, Rome, Italy
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Imbalanced Corticospinal and Reticulospinal Contributions to Spasticity in Humans with Spinal Cord Injury. J Neurosci 2019; 39:7872-7881. [PMID: 31413076 DOI: 10.1523/jneurosci.1106-19.2019] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/22/2019] [Accepted: 07/25/2019] [Indexed: 02/04/2023] Open
Abstract
Damage to the corticospinal and reticulospinal tract has been associated with spasticity in humans with upper motor neuron lesions. We hypothesized that these descending motor pathways distinctly contribute to the control of a spastic muscle in humans with incomplete spinal cord injury (SCI). To test this hypothesis, we examined motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation over the leg representation of the primary motor cortex, maximal voluntary contractions (MVCs), and the StartReact response (shortening in reaction time evoked by a startling stimulus) in the quadriceps femoris muscle in male and females with and without incomplete SCI. A total of 66.7% of the SCI participants showed symptoms of spasticity, whereas the other 33.3% showed no or low levels of spasticity. We found that participants with spasticity had smaller MEPs and MVCs and larger StartReact compared with participants with no or low spasticity and control subjects. These results were consistently present in spastic subjects but not in the other populations. Clinical scores of spasticity were negatively correlated with MEP-max and MVC values and positively correlated with shortening in reaction time. These findings provide evidence for lesser corticospinal and larger reticulospinal influences to spastic muscles in humans with SCI and suggest that these imbalanced contributions are important for motor recovery.SIGNIFICANCE STATEMENT Although spasticity is one of the most common symptoms manifested in humans with spinal cord injury (SCI) to date, its mechanisms of action remain poorly understood. We provide evidence, for the first time, of imbalanced contributions of the corticospinal and reticulospinal tract to control a spastic muscle in humans with chronic incomplete SCI. We found that participants with SCI with spasticity showed small corticospinal responses and maximal voluntary contractions and larger reticulospinal gain compared with participants with no or low spasticity and control subjects. These results were consistently present in spastic subjects but not in the other populations. We showed that imbalanced corticospinal and reticulospinal tract contributions are more pronounced in participants with chronic incomplete SCI with lesser recovery.
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Thompson AK, Cote RH, Sniffen JM, Brangaccio JA. Operant conditioning of the tibialis anterior motor evoked potential in people with and without chronic incomplete spinal cord injury. J Neurophysiol 2018; 120:2745-2760. [PMID: 30207863 DOI: 10.1152/jn.00362.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The activity of corticospinal pathways is important in movement control, and its plasticity is essential for motor skill learning and re-learning after central nervous system (CNS) injuries. Therefore, enhancing the corticospinal function may improve motor function recovery after CNS injuries. Operant conditioning of stimulus-induced muscle responses (e.g., reflexes) is known to induce the targeted plasticity in a targeted pathway. Thus, an operant conditioning protocol to target the corticospinal pathways may be able to enhance the corticospinal function. To test this possibility, we investigated whether operant conditioning of the tibialis anterior (TA) motor evoked potential (MEP) to transcranial magnetic stimulation can enhance corticospinal excitability in people with and without chronic incomplete spinal cord injury (SCI). The protocol consisted of 6 baseline and 24 up-conditioning/control sessions over 10 wk. In all sessions, TA MEPs were elicited at 10% above active MEP threshold while the sitting participant provided a fixed preset level of TA background electromyographic activity. During baseline sessions, MEPs were simply measured. During conditioning trials of the conditioning sessions, the participant was encouraged to increase MEP and was given immediate feedback indicating whether MEP size was above a criterion. In 5/8 participants without SCI and 9/10 with SCI, over 24 up-conditioning sessions, MEP size increased significantly to ~150% of the baseline value, whereas the silent period (SP) duration decreased by ~20%. In a control group of participants without SCI, neither MEP nor SP changed. These results indicate that MEP up-conditioning can facilitate corticospinal excitation, which is essential for enhancing motor function recovery after SCI. NEW & NOTEWORTHY We investigated whether operant conditioning of the motor evoked potential (MEP) to transcranial magnetic stimulation can systematically increase corticospinal excitability for the ankle dorsiflexor tibialis anterior (TA) in people with and without chronic incomplete spinal cord injury. We found that up-conditioning can increase the TA MEP while reducing the accompanying silent period (SP) duration. These findings suggest that MEP up-conditioning produces the facilitation of corticospinal excitation as targeted, whereas it suppresses inhibitory mechanisms reflected in SP.
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Affiliation(s)
- Aiko K Thompson
- Department of Health Sciences and Research, College of Health Professions, Medical University of South Carolina , Charleston, South Carolina
| | - Rachel H Cote
- Department of Health Sciences and Research, College of Health Professions, Medical University of South Carolina , Charleston, South Carolina
| | - Janice M Sniffen
- Department of Physical Therapy, School of Health Technology and Management, Stony Brook University , Stony Brook, New York
| | - Jodi A Brangaccio
- Helen Hayes Hospital, New York State Department of Health, West Haverstraw, New York
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Potter-Baker KA, Janini DP, Lin YL, Sankarasubramanian V, Cunningham DA, Varnerin NM, Chabra P, Kilgore KL, Richmond MA, Frost FS, Plow EB. Transcranial direct current stimulation (tDCS) paired with massed practice training to promote adaptive plasticity and motor recovery in chronic incomplete tetraplegia: A pilot study. J Spinal Cord Med 2018; 41:503-517. [PMID: 28784042 PMCID: PMC6117576 DOI: 10.1080/10790268.2017.1361562] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
OBJECTIVE Our goal was to determine if pairing transcranial direct current stimulation (tDCS) with rehabilitation for two weeks could augment adaptive plasticity offered by these residual pathways to elicit longer-lasting improvements in motor function in incomplete spinal cord injury (iSCI). DESIGN Longitudinal, randomized, controlled, double-blinded cohort study. SETTING Cleveland Clinic Foundation, Cleveland, Ohio, USA. PARTICIPANTS Eight male subjects with chronic incomplete motor tetraplegia. INTERVENTIONS Massed practice (MP) training with or without tDCS for 2 hrs, 5 times a week. OUTCOME MEASURES We assessed neurophysiologic and functional outcomes before, after and three months following intervention. Neurophysiologic measures were collected with transcranial magnetic stimulation (TMS). TMS measures included excitability, representational volume, area and distribution of a weaker and stronger muscle motor map. Functional assessments included a manual muscle test (MMT), upper extremity motor score (UEMS), action research arm test (ARAT) and nine hole peg test (NHPT). RESULTS We observed that subjects receiving training paired with tDCS had more increased strength of weak proximal (15% vs 10%), wrist (22% vs 10%) and hand (39% vs. 16%) muscles immediately and three months after intervention compared to the sham group. Our observed changes in muscle strength were related to decreases in strong muscle map volume (r=0.851), reduced weak muscle excitability (r=0.808), a more focused weak muscle motor map (r=0.675) and movement of weak muscle motor map (r=0.935). CONCLUSION Overall, our results encourage the establishment of larger clinical trials to confirm the potential benefit of pairing tDCS with training to improve the effectiveness of rehabilitation interventions for individuals with SCI. TRIAL REGISTRATION NCT01539109.
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Affiliation(s)
- Kelsey A. Potter-Baker
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA,Advanced Platform Technology Center, Louis Stokes Cleveland Department of Veteran’s Affairs, Cleveland, Ohio, USA
| | - Daniel P. Janini
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Yin-Liang Lin
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | | | - David A. Cunningham
- Kessler Foundation, Human Performance & Engineering Laboratory, West Orange, New Jersey, USA
| | - Nicole M. Varnerin
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Patrick Chabra
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Kevin L. Kilgore
- Functional Electrical Stimulation Center, Louis Stokes Cleveland Department of Veteran’s Affairs, Cleveland, Ohio, USA,Department of Orthopaedics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA,Department of Orthopaedics, MetroHealth Medical Center, Cleveland, Ohio, USA
| | - Mary Ann Richmond
- Spinal Cord Injury and Disorders Service, Louis Stokes Cleveland Department of Veteran’s Affairs, Cleveland, Ohio, USA,Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Frederick S. Frost
- Department of Physical Medicine and Rehabilitation, Neurological Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA
| | - Ela B. Plow
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA,Department of Physical Medicine and Rehabilitation, Neurological Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA,Center for Neurological Restoration, Neurosurgery, Neurological Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA,Correspondence to: Ela B. Plow Assistant Staff, Department of Biomedical Engineering, Assistant Professor, Cleveland Clinic Lerner College of Medicine, Cleveland Clinic Foundation, 9500 Euclid Ave., ND20 Cleveland, OH 44195, USA; Ph: 216-445-4589, Fax: 216-444-9198;
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Li RQ, Wan MY, Shi J, Wang HL, Liu FL, Liu CM, Huang J, Liu RC, Ma L, Feng XD. Catgut implantation at acupoints increases the expression of glutamate aspartate transporter and glial glutamate transporter-1 in the brain of rats with spasticity after stroke. Neural Regen Res 2018; 13:1013-1018. [PMID: 29926828 PMCID: PMC6022480 DOI: 10.4103/1673-5374.233444] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Catgut implantation at acupoints has been shown to alleviate spasticity after stroke in rats. However, the underlying mechanisms are poorly understood. In this study, we used the rat middle cerebral artery occlusion model of stroke. Three days after surgery, absorbable surgical catgut sutures were implanted at Dazhui (GV14), Jizhong (GV6), Houhui, Guanyuan (CV4) and Zhongwan (CV12). The Zea Longa score was used to assess neurological function. The Modified Ashworth Scale was used to evaluate muscle tension. The 2,3,5-triphenyl-tetrazolium chloride assay was used to measure infarct volume. Immunohistochemical staining was performed for glutamate aspartate transporter (GLAST) and glial glutamate transporter-1 (GLT-1) expression. Western blot assay was used to analyze the expression of GLAST and GLT-1. Reverse transcription and polymerase chain reaction were carried out to assess the expression of GLAST and GLT-1 mRNAs. After catgut implantation at the acupoints, neurological function was substantially improved, muscle tension was decreased, and infarct volume was reduced in rats with spasticity after stroke. Furthermore, the expression of GLAST and GLT-1 mRNAs was increased on the injured (left) side. Our findings demonstrate that catgut implantation at acupoints alleviates spasticity after stroke, likely by increasing the expression of GLAST and GLT-1.
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Affiliation(s)
- Rui-Qing Li
- Rehabilitation Center, First Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou, Henan Province, China
| | - Ming-Yue Wan
- Major in Rehabilitation Medicine and Physiotherapy, Henan University of Traditional Chinese Medicine, Zhengzhou, Henan Province, China
| | - Jing Shi
- Major in Rehabilitation Medicine and Physiotherapy, Henan University of Traditional Chinese Medicine, Zhengzhou, Henan Province, China
| | - Hui-Ling Wang
- Major in Rehabilitation Medicine and Physiotherapy, Henan University of Traditional Chinese Medicine, Zhengzhou, Henan Province, China
| | - Fei-Lai Liu
- Rehabilitation Center, First Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou, Henan Province, China
| | - Cheng-Mei Liu
- Rehabilitation Center, First Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou, Henan Province, China
| | - Jin Huang
- Major in Rehabilitation Medicine and Physiotherapy, Henan University of Traditional Chinese Medicine, Zhengzhou, Henan Province, China
| | - Ren-Chao Liu
- Major in Rehabilitation Medicine and Physiotherapy, Henan University of Traditional Chinese Medicine, Zhengzhou, Henan Province, China
| | - Le Ma
- Department of Oncology, Third People's Hospital of Luoyang, Luoyang, Henan Province, China
| | - Xiao-Dong Feng
- Rehabilitation Center, First Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou, Henan Province, China
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Theriault ER, Huang V, Whiteneck G, Dijkers MP, Harel NY. Antispasmodic medications may be associated with reduced recovery during inpatient rehabilitation after traumatic spinal cord injury. J Spinal Cord Med 2018; 41:63-71. [PMID: 27841095 PMCID: PMC5810808 DOI: 10.1080/10790268.2016.1245010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
OBJECTIVE To determine whether antispasmodic medications are associated with neurological and functional outcomes during the first year after traumatic spinal cord injury (SCI). DESIGN/METHODS Retrospective analysis of prospectively collected data from six inpatient SCI rehabilitation centers. Baseline-adjusted outcomes at discharge and one-year follow-up were compared using analysis of covariance between patients who received antispasmodic medication on at least 5 days during inpatient rehabilitation and patients who did not. OUTCOME MEASURES Rasch-transformed motor subscore of the Functional Independence Measure (FIM); International Standards for Neurological Classification of Spinal Cord Injury motor scores, grade, and level. RESULTS Of 1,259 patients, 59.8%, 35.4%, and 4.8% were injured at the cervical, thoracic, and lumbosacral levels, respectively. 65.6% had motor complete injury. Rasch-transformed motor FIM score at admission averaged 23.3 (95% confidence interval (CI) 22.4-24.2). Total motor score averaged 39.2 (95% CI 37.8-40.6). 685 patients (54.4%) received one or more antispasmodic medications on at least 5 days. After controlling for demographic and injury variables at admission, Rasch-transformed motor FIM scores at discharge were significantly lower (P = 0.018) in patients receiving antispasmodic medications than in those who did not. This trend persisted in secondary analyses for cervical, thoracic, and lumbosacral subgroups. Multivariate regression showed that receiving antispasmodic medication significantly contributed to discharge motor FIM outcome. At one-year follow-up, no outcomes significantly differed between patients ON or OFF antispasmodics. CONCLUSIONS Antispasmodic medications may be associated with decreased functional recovery at discharge from inpatient traumatic SCI rehabilitation. Randomized prospective studies are needed to directly evaluate the effects of antispasmodic medication on recovery.
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Affiliation(s)
- Eric R. Theriault
- New York Institute of Technology, Department of Physical Therapy, Old Westbury, NY, USA
| | - Vincent Huang
- Icahn School of Medicine at Mount Sinai, Department of Rehabilitation Medicine, New York, NY, USA
| | | | - Marcel P. Dijkers
- Icahn School of Medicine at Mount Sinai, Department of Rehabilitation Medicine, New York, NY, USA,Department of Physical Medicine and Rehabilitation, Wayne State University, Detroit, MI, USA
| | - Noam Y. Harel
- Icahn School of Medicine at Mount Sinai, Department of Rehabilitation Medicine, New York, NY, USA,James J. Peters VA Medical Center, Spinal Cord Damage Research Center, Bronx, NY, USA,Correspondence to: Noam Y. Harel, James J. Peters VA Medical Center, 130 West Kingsbridge Road, 7A-13G, Bronx, NY, 10468; 718-584-9000 x1742.
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Long J, Federico P, Perez MA. A novel cortical target to enhance hand motor output in humans with spinal cord injury. Brain 2017; 140:1619-1632. [PMID: 28549131 DOI: 10.1093/brain/awx102] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 03/04/2017] [Indexed: 01/01/2023] Open
Abstract
A main goal of rehabilitation strategies in humans with spinal cord injury is to strengthen transmission in spared neural networks. Although neuromodulatory strategies have targeted different sites within the central nervous system to restore motor function following spinal cord injury, the role of cortical targets remain poorly understood. Here, we use 180 pairs of transcranial magnetic stimulation for ∼30 min over the hand representation of the motor cortex at an interstimulus interval mimicking the rhythmicity of descending late indirect (I) waves in corticospinal neurons (4.3 ms; I-wave protocol) or at an interstimulus interval in-between I-waves (3.5 ms; control protocol) on separate days in a randomized order. Late I-waves are thought to arise from trans-synaptic cortical inputs and have a crucial role in the recruitment of spinal motor neurons following spinal cord injury. Motor evoked potentials elicited by transcranial magnetic stimulation, paired-pulse intracortical inhibition, spinal motor neuron excitability (F-waves), index finger abduction force and electromyographic activity as well as a hand dexterity task were measured before and after both protocols in 15 individuals with chronic incomplete cervical spinal cord injury and 17 uninjured participants. We found that motor evoked potentials size increased in spinal cord injury and uninjured participants after the I-wave but not the control protocol for ∼30 to 60 min after the stimulation. Intracortical inhibition decreased and F-wave amplitude and persistence increased after the I-wave but not the control protocol, suggesting that cortical and subcortical networks contributed to changes in corticospinal excitability. Importantly, hand motor output and hand dexterity increased in individuals with spinal cord injury after the I-wave protocol. These results provide the first evidence that late synaptic input to corticospinal neurons may represent a novel therapeutic target for improving motor function in humans with paralysis due to spinal cord injury.
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Affiliation(s)
- Jinyi Long
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, University of Miami, Bruce W. Carter Department of Veterans Affairs Medical Center, Miami, FL, USA
| | - Paolo Federico
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, University of Miami, Bruce W. Carter Department of Veterans Affairs Medical Center, Miami, FL, USA
| | - Monica A Perez
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, University of Miami, Bruce W. Carter Department of Veterans Affairs Medical Center, Miami, FL, USA
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Ozdemir RA, Perez MA. Afferent input and sensory function after human spinal cord injury. J Neurophysiol 2017; 119:134-144. [PMID: 28701541 DOI: 10.1152/jn.00354.2017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Spinal cord injury (SCI) often disrupts the integrity of afferent (sensory) axons projecting through the spinal cord dorsal columns to the brain. Examinations of ascending sensory tracts, therefore, are critical for monitoring the extent of SCI and recovery processes. In this review, we discuss the most common electrophysiological techniques used to assess transmission of afferent inputs to the primary motor cortex (i.e., afferent input-induced facilitation and inhibition) and the somatosensory cortex [i.e., somatosensory evoked potentials (SSEPs), dermatomal SSEPs, and electrical perceptual thresholds] following human SCI. We discuss how afferent input modulates corticospinal excitability by involving cortical and spinal mechanisms depending on the timing of the effects, which need to be considered separately for upper and lower limb muscles. We argue that the time of arrival of afferent input onto the sensory and motor cortex is critical to consider in plasticity-induced protocols in humans with SCI. We also discuss how current sensory exams have been used to detect differences between control and SCI participants but might be less optimal to characterize the level and severity of injury. There is a need to conduct some of these electrophysiological examinations during functionally relevant behaviors to understand the contribution of impaired afferent inputs to the control, or lack of control, of movement. Thus the effects of transmission of afferent inputs to the brain need to be considered on multiple functions following human SCI.
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Affiliation(s)
- Recep A Ozdemir
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, University of Miami , Miami, Florida.,Bruce W. Carter Department of Veterans Affairs Medical Center , Miami, Florida
| | - Monica A Perez
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, University of Miami , Miami, Florida.,Bruce W. Carter Department of Veterans Affairs Medical Center , Miami, Florida
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Federico P, Perez MA. Altered corticospinal function during movement preparation in humans with spinal cord injury. J Physiol 2016; 595:233-245. [PMID: 27485306 DOI: 10.1113/jp272266] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 07/25/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS In uninjured humans, transmission in the corticospinal pathway changes in a task-dependent manner during movement preparation. We investigated whether this ability is preserved in humans with incomplete chronic cervical spinal cord injury (SCI). Our results show that corticospinal excitability is altered in the preparatory phase of an upcoming movement when there is a need to suppress but not to execute rapid index finger voluntary contractions in individuals with SCI compared with controls. This is probably related to impaired transmission at a cortical and spinal level after SCI. Overall our findings indicate that deficits in corticospinal transmission in humans with chronic incomplete SCI are also present in the preparatory phase of upcoming movements. ABSTRACT Corticospinal output is modulated in a task-dependent manner during the preparatory phase of upcoming movements in humans. Whether this ability is preserved after spinal cord injury (SCI) is unknown. In this study, we examined motor evoked potentials elicited by cortical (MEPs) and subcortical (CMEPs) stimulation of corticospinal axons and short-interval intracortical inhibition in the first dorsal interosseous muscle in the preparatory phase of a reaction time task where individuals with chronic incomplete cervical SCI and age-matched controls needed to suppress (NOGO) or initiate (GO) ballistic index finger isometric voluntary contractions. Reaction times were prolonged in SCI participants compared with control subjects and stimulation was provided ∼90 ms prior to movement onset in each group. During NOGO trials, both MEPs and CMEPs remained unchanged compared to baseline in SCI participants but were suppressed in control subjects. Notably, during GO trials, MEPs increased to a similar extent in both groups but CMEPs increased only in controls. The magnitude of short-interval intracortical inhibition increased in controls but not in SCI subjects during NOGO trials and decreased in both groups in GO trials. These novel observations reveal that humans with incomplete cervical SCI have an altered ability to modulate corticospinal excitability during movement preparation when there is a need to suppress but not to execute upcoming rapid finger movements, which is probably related to impaired transmission at a cortical and spinal level. Thus, deficits in corticospinal transmission after human SCI extend to the preparatory phase of upcoming movements.
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Affiliation(s)
- Paolo Federico
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, University of Miami, Miami, FL, USA
| | - Monica A Perez
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, University of Miami, Miami, FL, USA
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Finnegan J, Ye H. Cell therapy for spinal cord injury informed by electromagnetic waves. Regen Med 2016; 11:675-91. [DOI: 10.2217/rme-2016-0019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Spinal cord injury devastates the CNS, besetting patients with symptoms including but not limited to: paralysis, autonomic nervous dysfunction, pain disorders and depression. Despite the identification of several molecular and genetic factors, a reliable regenerative therapy has yet to be produced for this terminal disease. Perhaps the missing piece of this puzzle will be discovered within endogenous electrotactic cellular behaviors. Neurons and stem cells both show mediated responses (growth rate, migration, differentiation) to electromagnetic waves, including direct current electric fields. This review analyzes the pathophysiology of spinal cord injury, the rationale for regenerative cell therapy and the evidence for directing cell therapy via electromagnetic waves shown by in vitro experiments.
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Affiliation(s)
- Jack Finnegan
- Department of Biology, Loyola University Chicago, 1032 W. Sheridan Rd, Chicago, IL 60660, USA
| | - Hui Ye
- Department of Biology, Loyola University Chicago, 1032 W. Sheridan Rd, Chicago, IL 60660, USA
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Squintani G, Donato F, Turri M, Deotto L, Teatini F, Moretto G, Erro R. Cortical and spinal excitability in patients with multiple sclerosis and spasticity after oromucosal cannabinoid spray. J Neurol Sci 2016; 370:263-268. [PMID: 27772772 DOI: 10.1016/j.jns.2016.09.054] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 09/21/2016] [Accepted: 09/26/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND Delta-9-tetrahydrocannabinol and cannabidiol (THC:CBD) oromucosal spray (Sativex®) has been recently approved for the management of treatment-resistant multiple sclerosis (MS) spasticity. Although the symptomatic relief of Sativex® on MS-spasticity has been consistently demonstrated, the pathogenetic implications remain unclear and the few electrophysiological studies performed to address this topic yielded controversial results. We therefore aimed to investigate the mechanisms underpinning the modulation of spastic hypertonia by Sativex®, at both central and spinal levels, through an extensive neurophysiological battery in patients with MS. METHODS Nineteen MS patients with treatment-resistant spasticity were recruited. Before and after 4weeks of treatment with Sativex® patients were clinically assessed with the Modified Ashworth Scale (MAS) and underwent a large neurophysiological protocol targeting measures of excitability and inhibition at both cortical [e.g., intracortical facilitation (ICF), short (SICI) and long (LICI) intracortical inhibition, cortical silent period (CSP)] and spinal level [e.g., H-reflex, H/M ratio and recovery curve of the H-reflex (HRC)]. A group of 19 healthy subjects served as controls. RESULTS A significant reduction of the MAS score after 4weeks of Sativex® treatment was detected. Before treatment, an increase in the late facilitatory phase of HRC was recorded in patients compared to the control group, that normalised post treatment. At central level, SICI and LICI were significantly higher in patients compared to healthy subjects. After therapy, a significant strengthening of inhibition (e.g. reduced LICI) and a non-significant facilitation (e.g. marginally increased ICF) occurred, suggesting a modulatory effect of Sativex® on different pathways, predominantly of inhibitory type. Sativex® treatment was well tolerated, with only 3 patients complaining about dizziness and bitter taste in their mouth. DISCUSSION Our results confirm the clinical benefit of Sativex® on spastic hypertonia and demonstrate that it might modulate both cortical and spinal circuits, arguably in terms of both excitation and inhibition. We suggest that the clinical benefit was likely related to a net increase of inhibition at cortical level that, in turn, might have influenced spinal excitability.
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Affiliation(s)
- Giovanna Squintani
- Neuroscience Department, Azienda Ospedaliera Universitaria Integrata, Verona, Italy.
| | - Francesco Donato
- Neuroscience Department, Azienda Ospedaliera Universitaria Integrata, Verona, Italy
| | - Mara Turri
- Neurology Unit, Ospedale Centrale di Bolzano, Italy
| | - Luciano Deotto
- Neuroscience Department, Azienda Ospedaliera Universitaria Integrata, Verona, Italy
| | | | - Giuseppe Moretto
- Neuroscience Department, Azienda Ospedaliera Universitaria Integrata, Verona, Italy
| | - Roberto Erro
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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Reliability of TMS metrics in patients with chronic incomplete spinal cord injury. Spinal Cord 2016; 54:980-990. [DOI: 10.1038/sc.2016.47] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 02/18/2016] [Accepted: 02/28/2016] [Indexed: 12/26/2022]
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Potter-Baker KA, Bonnett CE, Chabra P, Roelle S, Varnerin N, Cunningham DA, Sankarasubramanian V, Pundik S, Conforto AB, Machado AG, Plow EB. Challenges in Recruitment for the Study of Noninvasive Brain Stimulation in Stroke: Lessons from Deep Brain Stimulation. J Stroke Cerebrovasc Dis 2016; 25:927-37. [PMID: 26851211 DOI: 10.1016/j.jstrokecerebrovasdis.2015.12.044] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 11/06/2015] [Accepted: 12/30/2015] [Indexed: 12/27/2022] Open
Abstract
OBJECTIVE Noninvasive brain stimulation (NIBS) can augment functional recovery following stroke; however, the technique lacks regulatory approval. Low enrollment in NIBS clinical trials is a key roadblock. Here, we pursued evidence to support the prevailing opinion that enrollment in trials of NIBS is even lower than enrollment in trials of invasive, deep brain stimulation (DBS). METHODS We compared 2 clinical trials in stroke conducted within a single urban hospital system, one employing NIBS and the other using DBS, (1) to identify specific criteria that generate low enrollment rates for NIBS and (2) to devise strategies to increase recruitment with guidance from DBS. RESULTS Notably, we found that enrollment in the NIBS case study was 5 times lower (2.8%) than the DBS trial (14.5%) (χ(2) = 20.815, P < .0001). Although the number of candidates who met the inclusion criteria was not different (χ(2) = .04, P < .841), exclusion rates differed significantly between the 2 studies (χ(2) = 21.354, P < .0001). Beyond lack of interest, higher exclusion rates in the NIBS study were largely due to exclusion criteria that were not present in the DBS study, including restrictions for recurrent strokes, seizures, and medications. CONCLUSIONS Based on our findings, we conclude and suggest that by (1) establishing criteria specific to each NIBS modality, (2) adjusting exclusion criteria based on guidance from DBS, and (3) including patients with common contraindications based on a probability of risk, we may increase enrollment and hence significantly impact the feasibility and generalizability of NIBS paradigms, particularly in stroke.
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Affiliation(s)
- Kelsey A Potter-Baker
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Corin E Bonnett
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Patrick Chabra
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Sarah Roelle
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Nicole Varnerin
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | - David A Cunningham
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | | | - Svetlana Pundik
- Department of Neurology, Case Western Reserve University, Cleveland, Ohio; Department of Neurology, Louis Stokes Department of Veterans Affairs Medical Center, Cleveland, Ohio
| | - Adriana B Conforto
- Neurology Clinical Division, Neurology Department, Hospital das Clinicas, São Paulo University, São Paulo, Brazil; Hospital Israelita Albert Einstein, Department of Neurology, São Paulo, Brazil
| | - Andre G Machado
- Center for Neurological Restoration, Neurosurgery, Neurological Institute, Cleveland Clinic Foundation, Cleveland Clinic, Cleveland, Ohio
| | - Ela B Plow
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio; Department of Physical Medicine and Rehabilitation, Neurological Institute, Cleveland Clinic Foundation, Cleveland, Ohio.
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Abstract
BACKGROUND Short- (SICI) and long-interval intracortical inhibition (LICI) are involved in the control of movement and movement initiation. Alterations to the two circuits can result in direct alterations to the physiology of the muscles and can be used to explain the physiological changes to individuals with spinal cord injury (SCI). OBJECTIVE To probe changes in GABAergic function by characterizing the recruitment curves of SICI and LICI interval intracortical inhibition in an upper limb muscle in chronic SCI participants with injury between C3 and C7. METHODS Recruitment curves were elicited with conditioning stimulus intensities determined as a percentage of active motor threshold (AMT) (SICI, 60% to 110% AMT; LICI, 90% to 130% AMT) and recorded from the flexor carpi radialis muscle during an isometric contraction equal to 15% to 20% of maximum voluntary contraction. RESULTS AMT was greater and motor-evoked potential sizes were lower in SCI compared with uninjured controls. SICI magnitude was not different between groups, although the range of conditioning stimulus intensities to evoke SICI was unique to each group. LICI was reduced in the control group during active contraction and remained present in SCI. DISCUSSION LICI was increased in the actively contracted flexor carpi radialis muscle in individuals with SCI compared with age-matched controls. These findings indicate that GABAB function mediating LICI is different in SCI versus controls. CONCLUSIONS Increased LICI in SCI may be attributed to the medication baclofen or to changes in the neural mechanisms controlling contraction-related modulation of the LICI circuit.
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Yavari F, Shahbabaie A, Leite J, Carvalho S, Ekhtiari H, Fregni F. Noninvasive brain stimulation for addiction medicine: From monitoring to modulation. PROGRESS IN BRAIN RESEARCH 2015; 224:371-99. [PMID: 26822367 DOI: 10.1016/bs.pbr.2015.08.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Addiction is a chronic relapsing brain disease with significant economical and medical burden on the societies but with limited effectiveness in the available treatment options. Better understanding of the chemical, neuronal, regional, and network alterations of the brain due to drug abuse can ultimately lead to tailoring individualized and more effective interventions. To this end, employing new assessment and intervention procedures seems crucial. Noninvasive brain stimulation (NIBS) techniques including transcranial electrical and magnetic stimulations (tES and TMS) have provided promising opportunities for the addiction medicine in two main domains: (1) providing new insights into neurochemical and neural circuit changes in the human brain cortex and (2) understanding the role of different brain regions by using NIBS and modulating cognitive functions, such as drug craving, risky decision making, inhibitory control and executive functions to obtain specific treatment outcomes. In spite of preliminary positive results, there are several open questions, which need to be addressed before routine clinical utilization of NIBS techniques in addiction to medicine, such as how to account for interindividual differences, define optimal cognitive and neural targets, optimize stimulation protocols, and integrate NIBS with other therapeutic methods. Therefore, in this chapter we revise the available literature on the use of NIBS (TMS and tES) in the diagnostic, prognostic, and therapeutic aspects of the addiction medicine.
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Affiliation(s)
- Fatemeh Yavari
- Neurocognitive Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical Sciences, Tehran, Iran
| | - Alireza Shahbabaie
- Neurocognitive Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical Sciences, Tehran, Iran; Translational Neuroscience Program, Institute for Cognitive Science Studies (ICSS), Tehran, Iran; Neuroimaging and Analysis Group, Research Center for Molecular and Cellular Imaging (RCMCI), Tehran University of Medical Sciences, Tehran, Iran
| | - Jorge Leite
- Department of Physical Medicine and Rehabilitation, Laboratory of Neuromodulation, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Neuropsychophysiology Laboratory, CIPsi, School of Psychology (EPsi), University of Minho, Braga, Portugal
| | - Sandra Carvalho
- Department of Physical Medicine and Rehabilitation, Laboratory of Neuromodulation, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Neuropsychophysiology Laboratory, CIPsi, School of Psychology (EPsi), University of Minho, Braga, Portugal
| | - Hamed Ekhtiari
- Neurocognitive Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical Sciences, Tehran, Iran; Translational Neuroscience Program, Institute for Cognitive Science Studies (ICSS), Tehran, Iran; Neuroimaging and Analysis Group, Research Center for Molecular and Cellular Imaging (RCMCI), Tehran University of Medical Sciences, Tehran, Iran.
| | - Felipe Fregni
- Department of Physical Medicine and Rehabilitation, Laboratory of Neuromodulation, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
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Cirillo J, Calabro FJ, Perez MA. Impaired Organization of Paired-Pulse TMS-Induced I-Waves After Human Spinal Cord Injury. Cereb Cortex 2015; 26:2167-77. [PMID: 25814508 DOI: 10.1093/cercor/bhv048] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Paired-pulse transcranial magnetic stimulation (TMS) of the human motor cortex results in consecutive facilitatory motor-evoked potential (MEP) peaks in surface electromyography in intact humans. Here, we tested the effect of an incomplete cervical spinal cord injury (SCI) on early (first) and late (second and third) MEP peaks in a resting intrinsic finger muscle. We found that all peaks had decreased amplitude in SCI subjects compared with controls. The second and third peaks were delayed with the third peak also showing an increased duration. The delay of the third peak was smaller than that seen in controls at lower stimulation intensity, suggesting lesser influence of decreased corticospinal inputs. A mathematical model showed that after SCI the third peak aberrantly contributed to spinal motoneurone recruitment, regardless on the motor unit threshold tested. Temporal and spatial aspects of the late peaks correlated with MEP size and hand motor output. Thus, early and late TMS-induced MEP peaks undergo distinct modulation after SCI, with the third peak likely reflecting a decreased ability to summate descending volleys at the spinal level. We argue that the later corticospinal inputs on the spinal cord might be crucial for recruitment of motoneurones after human SCI.
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Affiliation(s)
- John Cirillo
- Department of Physical Medicine and Rehabilitation, Center for the Neural Basis of Cognition, Systems Neuroscience Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Finnegan J Calabro
- Department of Physical Medicine and Rehabilitation, Center for the Neural Basis of Cognition, Systems Neuroscience Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Monica A Perez
- Department of Physical Medicine and Rehabilitation, Center for the Neural Basis of Cognition, Systems Neuroscience Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
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26
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Fakhoury M. Spinal cord injury: overview of experimental approaches used to restore locomotor activity. Rev Neurosci 2015; 26:397-405. [DOI: 10.1515/revneuro-2015-0001] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 01/26/2015] [Indexed: 01/16/2023]
Abstract
AbstractSpinal cord injury affects more than 2.5 million people worldwide and can lead to paraplegia and quadriplegia. Anatomical discontinuity in the spinal cord results in disruption of the impulse conduction that causes temporary or permanent changes in the cord’s normal functions. Although axonal regeneration is limited, damage to the spinal cord is often accompanied by spontaneous plasticity and axon regeneration that help improve sensory and motor skills. The recovery process depends mainly on synaptic plasticity in the preexisting circuits and on the formation of new pathways through collateral sprouting into neighboring denervated territories. However, spontaneous recovery after spinal cord injury can go on for several years, and the degree of recovery is very limited. Therefore, the development of new approaches that could accelerate the gain of motor function is of high priority to patients with damaged spinal cord. Although there are no fully restorative treatments for spinal injury, various rehabilitative approaches have been tested in animal models and have reached clinical trials. In this paper, a closer look will be given at the potential therapies that could facilitate axonal regeneration and improve locomotor recovery after injury to the spinal cord. This article highlights the application of several interventions including locomotor training, molecular and cellular treatments, and spinal cord stimulation in the field of rehabilitation research. Studies investigating therapeutic approaches in both animal models and individuals with injured spinal cords will be presented.
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27
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Tazoe T, Perez MA. Effects of repetitive transcranial magnetic stimulation on recovery of function after spinal cord injury. Arch Phys Med Rehabil 2014; 96:S145-55. [PMID: 25175159 DOI: 10.1016/j.apmr.2014.07.418] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 06/02/2014] [Accepted: 07/08/2014] [Indexed: 11/30/2022]
Abstract
A major goal of rehabilitation strategies after spinal cord injury (SCI) is to enhance the recovery of function. One possible avenue to achieve this goal is to strengthen the efficacy of the residual neuronal pathways. Noninvasive repetitive transcranial magnetic stimulation (rTMS) has been used in patients with motor disorders as a tool to modulate activity of corticospinal, cortical, and subcortical pathways to promote functional recovery. This article reviews a series of studies published during the last decade that used rTMS in the acute and chronic stages of paraplegia and tetraplegia in humans with complete and incomplete SCI. In the studies, rTMS has been applied over the arm and leg representations of the primary motor cortex to target 3 main consequences of SCI: sensory and motor function impairments, spasticity, and neuropathic pain. Although some studies demonstrated that consecutive sessions of rTMS improve aspects of particular functions, other studies did not show similar effects. We discuss how rTMS parameters and postinjury reorganization in the corticospinal tract, motor cortical, and spinal cord circuits might be critical factors in understanding the advantages and disadvantages of using rTMS in patients with SCI. The available data highlight the limited information on the use of rTMS after SCI and the need to further understand the pathophysiology of neuronal structures affected by rTMS to maximize the potential beneficial effects of this technique in humans with SCI.
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Affiliation(s)
- Toshiki Tazoe
- Department of Physical Medicine and Rehabilitation, Center for the Neural Basis of Cognition, Systems Neuroscience Institute, University of Pittsburgh, Pittsburgh, PA; Japanese Society for the Promotion of Science, Tokyo, Japan
| | - Monica A Perez
- Department of Physical Medicine and Rehabilitation, Center for the Neural Basis of Cognition, Systems Neuroscience Institute, University of Pittsburgh, Pittsburgh, PA.
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28
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Abstract
The motor cortex and the corticospinal system contribute to the control of a precision grip between the thumb and index finger. The involvement of subcortical pathways during human precision grip remains unclear. Using noninvasive cortical and cervicomedullary stimulation, we examined motor evoked potentials (MEPs) and the activity in intracortical and subcortical pathways targeting an intrinsic hand muscle when grasping a small (6 mm) cylinder between the thumb and index finger and during index finger abduction in uninjured humans and in patients with subcortical damage due to incomplete cervical spinal cord injury (SCI). We demonstrate that cortical and cervicomedullary MEP size was reduced during precision grip compared with index finger abduction in uninjured humans, but was unchanged in SCI patients. Regardless of whether cortical and cervicomedullary stimulation was used, suppression of the MEP was only evident 1-3 ms after its onset. Long-term (∼5 years) use of the GABAb receptor agonist baclofen by SCI patients reduced MEP size during precision grip to similar levels as uninjured humans. Index finger sensory function correlated with MEP size during precision grip in SCI patients. Intracortical inhibition decreased during precision grip and spinal motoneuron excitability remained unchanged in all groups. Our results demonstrate that the control of precision grip in humans involves premotoneuronal subcortical mechanisms, likely disynaptic or polysynaptic spinal pathways that are lacking after SCI and restored by long-term use of baclofen. We propose that spinal GABAb-ergic interneuronal circuits, which are sensitive to baclofen, are part of the subcortical premotoneuronal network shaping corticospinal output during human precision grip.
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