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Hagen AC, Acosta JS, Swanson CW, Fling BW. Interhemispheric inhibition and gait adaptation associations in people with multiple sclerosis. Exp Brain Res 2024; 242:1761-1772. [PMID: 38822825 DOI: 10.1007/s00221-024-06860-5] [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: 02/13/2024] [Accepted: 05/20/2024] [Indexed: 06/03/2024]
Abstract
BACKGROUND Multiple sclerosis is a neurodegenerative disease that damages the myelin sheath within the central nervous system. Axonal demyelination, particularly in the corpus callosum, impacts communication between the brain's hemispheres in persons with multiple sclerosis (PwMS). Changes in interhemispheric communication may impair gait coordination which is modulated by communication across the corpus callosum to excite and inhibit specific muscle groups. To further evaluate the functional role of interhemispheric communication in gait and mobility, this study assessed the ipsilateral silent period (iSP), an indirect marker of interhemispheric inhibition and how it relates to gait adaptation in PwMS. METHODS Using transcranial magnetic stimulation (TMS), we assessed interhemispheric inhibition differences between the more affected and less affected hemisphere in the primary motor cortices in 29 PwMS. In addition, these same PwMS underwent a split-belt treadmill walking paradigm, with the faster paced belt moving under their more affected limb. Step length asymmetry (SLA) was the primary outcome measure used to assess gait adaptability during split-belt treadmill walking. We hypothesized that PwMS would exhibit differences in iSP inhibitory metrics between the more affected and less affected hemispheres and that increased interhemispheric inhibition would be associated with greater gait adaptability in PwMS. RESULTS No statistically significant differences in interhemispheric inhibition or conduction time were found between the more affected and less affected hemisphere. Furthermore, SLA aftereffect was negatively correlated with both average percent depth of silent period (dSP%AVE) (r = -0.40, p = 0.07) and max percent depth of silent period (dSP%MAX) r = -0.40, p = 0.07), indicating that reduced interhemispheric inhibition was associated with greater gait adaptability in PwMS. CONCLUSION The lack of differences between the more affected and less affected hemisphere indicates that PwMS have similar interhemispheric inhibitory capacity irrespective of the more affected hemisphere. Additionally, we identified a moderate correlation between reduced interhemispheric inhibition and greater gait adaptability. These findings may indicate that interhemispheric inhibition may in part influence responsiveness to motor adaptation paradigms and the need for further research evaluating the neural mechanisms underlying the relationship between interhemispheric inhibition and motor adaptability.
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Affiliation(s)
- Andrew C Hagen
- Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80523, USA
| | - Jordan S Acosta
- Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80523, USA
| | - Clayton W Swanson
- Brain Rehabilitation Research Center, Malcom Randall VA Medical Center, Gainesville, FL, USA
- Department of Neurology, University of Florida, Gainesville, FL, USA
| | - Brett W Fling
- Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80523, USA.
- Molecular, Cellular, & Integrative Neuroscience Program, Colorado State University, Fort Collins, CO, USA.
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Jacques FH, Apedaile BE, Danis I, Sikati-Foko V, Lecompte M, Fortin J. Motor Evoked Potential-A Pilot Study Looking at Reliability and Clinical Correlations in Multiple Sclerosis. J Clin Neurophysiol 2024; 41:357-364. [PMID: 36943437 PMCID: PMC11060055 DOI: 10.1097/wnp.0000000000001003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023] Open
Abstract
PURPOSE Multiple sclerosis (MS) is a clinically heterogeneous disease. Biomarkers that can assess pathological processes that are unseen with conventional imaging remain an unmet need in MS disease management. Motor evoked potentials (MEPs) could be such a biomarker. To determine and follow longitudinal MEP reliability and correlations with clinical measures in MS patients. METHODS This is a single-center study in alemtuzumab-treated MS patients to evaluate temporal reliability of MEPs, identify MEP minimum detectible differences, and explore correlations with existing clinical scales. Ten MS patients recently treated with alemtuzumab were evaluated every 6 months over 3 years. Clinical evaluations consisted of expanded disability status scale, timed 25-foot walk, 6-minute walk, and nine-hole peg test. MEPs were measured twice, 2 weeks apart, every 6 months. RESULTS Eight patients completed all 3 years of study. The intraclass correlation coefficient for MEP parameters ranged from 0.76 to 0.98. TA latency and amplitude with facilitation significantly and strongly correlated with all clinical measures, whereas the MEP duration modestly correlated. Biceps latency with facilitation significantly and moderately correlated with 9-hole peg test. Longitudinal correlations demonstrated good predictive values for either clinical deterioration or improvement. CONCLUSIONS MEPs have excellent intrapatient and intrarater reliability, and TA MEPs significantly and strongly correlated with expanded disability status scale, 6-minute walk, and timed 25-foot walk, whereas biceps MEPs significantly and moderately correlated with nine-hole peg test. Further studies using larger cohorts of MS patients are indicated. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov, Identifier: NCT02623946.
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Affiliation(s)
- F H Jacques
- Clinique Neuro-Outaouais, Gatineau, Quebec, Canada
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Snow NJ, Murphy HM, Chaves AR, Moore CS, Ploughman M. Transcranial magnetic stimulation enhances the specificity of multiple sclerosis diagnostic criteria: a critical narrative review. PeerJ 2024; 12:e17155. [PMID: 38563011 PMCID: PMC10984191 DOI: 10.7717/peerj.17155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 03/04/2024] [Indexed: 04/04/2024] Open
Abstract
Background Multiple sclerosis (MS) is an immune-mediated neurodegenerative disease that involves attacks of inflammatory demyelination and axonal damage, with variable but continuous disability accumulation. Transcranial magnetic stimulation (TMS) is a noninvasive method to characterize conduction loss and axonal damage in the corticospinal tract. TMS as a technique provides indices of corticospinal tract function that may serve as putative MS biomarkers. To date, no reviews have directly addressed the diagnostic performance of TMS in MS. The authors aimed to conduct a critical narrative review on the diagnostic performance of TMS in MS. Methods The authors searched the Embase, PubMed, Scopus, and Web of Science databases for studies that reported the sensitivity and/or specificity of any reported TMS technique compared to established clinical MS diagnostic criteria. Studies were summarized and critically appraised for their quality and validity. Results Seventeen of 1,073 records were included for data extraction and critical appraisal. Markers of demyelination and axonal damage-most notably, central motor conduction time (CMCT)-were specific, but not sensitive, for MS. Thirteen (76%), two (12%), and two (12%) studies exhibited high, unclear, and low risk of bias, respectively. No study demonstrated validity for TMS techniques as diagnostic biomarkers in MS. Conclusions CMCT has the potential to: (1) enhance the specificity of clinical MS diagnostic criteria by "ruling in" true-positives, or (2) revise a diagnosis from relapsing to progressive forms of MS. However, there is presently insufficient high-quality evidence to recommend any TMS technique in the diagnostic algorithm for MS.
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Affiliation(s)
- Nicholas J. Snow
- Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Hannah M. Murphy
- Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Arthur R. Chaves
- Faculty of Health Sciences, Interdisciplinary School of Health Sciences, University of Ottawa, Ottawa, ON, Canada
- Neuromodulation Research Clinic, The Royal’s Institute of Mental Health Research, Ottawa, ON, Canada
- Département de Psychoéducation et de Psychologie, Université du Québec en Outaouais, Gatineau, QC, Canada
| | - Craig S. Moore
- Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Michelle Ploughman
- Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL, Canada
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4
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Snow NJ, Landine J, Chaves AR, Ploughman M. Age and asymmetry of corticospinal excitability, but not cardiorespiratory fitness, predict cognitive impairments in multiple sclerosis. IBRO Neurosci Rep 2023; 15:131-142. [PMID: 37577407 PMCID: PMC10412844 DOI: 10.1016/j.ibneur.2023.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 07/11/2023] [Accepted: 07/15/2023] [Indexed: 08/15/2023] Open
Abstract
Background Cognitive impairment is a disabling and underestimated consequence of multiple sclerosis (MS), with multiple determinants that are poorly understood. Objectives We explored predictors of MS-related processing speed impairment (PSI) and age-related mild cognitive impairment (MCI) and hypothesized that cardiorespiratory fitness and corticospinal excitability would predict these impairments. Methods We screened 73 adults with MS (53 females; median [range]: Age 48 [21-70] years, EDSS 2.0 [0.0-6.5]) for PSI and MCI using the Symbol Digit Modalities Test and Montréal Cognitive Assessment, respectively. We identified six persons with PSI (No PSI, n = 67) and 13 with MCI (No MCI, n = 60). We obtained clinical data from medical records and self-reports; used transcranial magnetic stimulation to test corticospinal excitability; and assessed cardiorespiratory fitness using a graded maximal exercise test. We used receiver operator characteristic (ROC) curves to discern predictors of PSI and MCI. Results Interhemispheric asymmetry of corticospinal excitability was specific for PSI, while age was both sensitive and specific for MCI. MS-related PSI was also associated with statin prescriptions, while age-related MCI was related to progressive MS and GABA agonist prescriptions. Cardiorespiratory fitness was associated with neither PSI nor MCI. Discussion Corticospinal excitability is a potential marker of neurodegeneration in MS-related PSI, independent of age-related effects on global cognitive function. Age is a key predictor of mild global cognitive impairment. Cardiorespiratory fitness did not predict cognitive impairments in this clinic-based sample of persons with MS.
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Affiliation(s)
- Nicholas J. Snow
- Recovery and Performance Laboratory, Faculty of Medicine, Memorial University of Newfoundland and Labrador, St. John's, Newfoundland and Labrador, Canada
| | - Josef Landine
- Recovery and Performance Laboratory, Faculty of Medicine, Memorial University of Newfoundland and Labrador, St. John's, Newfoundland and Labrador, Canada
| | - Arthur R. Chaves
- Recovery and Performance Laboratory, Faculty of Medicine, Memorial University of Newfoundland and Labrador, St. John's, Newfoundland and Labrador, Canada
| | - Michelle Ploughman
- Recovery and Performance Laboratory, Faculty of Medicine, Memorial University of Newfoundland and Labrador, St. John's, Newfoundland and Labrador, Canada
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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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Pearce AJ, King D, Kidgell DJ, Frazer AK, Tommerdahl M, Suter CM. Assessment of Somatosensory and Motor Processing Time in Retired Athletes with a History of Repeated Head Trauma. J Funct Morphol Kinesiol 2022; 7:jfmk7040109. [PMID: 36547655 PMCID: PMC9782447 DOI: 10.3390/jfmk7040109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 11/27/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
Measurement of the adverse outcomes of repeated head trauma in athletes is often achieved using tests where the comparator is ‘accuracy’. While it is expected that ex-athletes would perform worse than controls, previous studies have shown inconsistent results. Here we have attempted to address these inconsistencies from a different perspective by quantifying not only accuracy, but also motor response times. Age-matched control subjects who have never experienced head trauma (n = 20; 41.8 ± 14.4 years) where compared to two cohorts of retired contact sport athletes with a history of head trauma/concussions; one with self-reported concerns (n = 36; 45.4 ± 12.6 years), and another with no ongoing concerns (n = 19; 43.1 ± 13.5 years). Participants performed cognitive (Cogstate) and somatosensory (Cortical Metrics) testing with accuracy and motor times recorded. Transcranial magnetic stimulation (TMS) investigated corticospinal conduction and excitability. Results showed that there was little difference between groups in accuracy scores. Conversely, motor times in all but one test revealed that ex-athletes with self-reported concerns were significantly slower compared to other groups (p ranges 0.031 to <0.001). TMS latency showed significantly increased time (p = 0.008) in the group with ongoing concerns. These findings suggest that incorporating motor times is more informative than considering accuracy scores alone.
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Affiliation(s)
- Alan J. Pearce
- College of Science, Health and Engineering, La Trobe University, Melbourne 3016, Australia
- Correspondence:
| | - Doug King
- Sports Performance Research Institute New Zealand (SPRINZ), Faculty of Health and Environmental Science, Auckland University of Technology, Auckland 1142, New Zealand
- Wolfson Research Institute for Health and Wellbeing, Department of Sport and Exercise Sciences, Durham University, Durham DH1 3LE, UK
| | - Dawson J. Kidgell
- Faculty of Medicine Nursing and Health Science, Monash University, Melbourne 3800, Australia
| | - Ashlyn K. Frazer
- Faculty of Medicine Nursing and Health Science, Monash University, Melbourne 3800, Australia
| | - Mark Tommerdahl
- Cortical Metrics, Carrboro, NC 27510, USA
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27510, USA
| | - Catherine M. Suter
- Department of Neuropathology, Royal Prince Alfred Hospital, Sydney 2050, Australia
- Brain and Mind Centre, University Sydney, Camperdown 2050, Australia
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Royer N, Coates K, Aboodarda SJ, Camdessanché JP, Millet GY. How is neuromuscular fatigability affected by perceived fatigue and disability in people with multiple sclerosis? Front Neurol 2022; 13:983643. [DOI: 10.3389/fneur.2022.983643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 09/23/2022] [Indexed: 11/13/2022] Open
Abstract
Whereas fatigue is recognized to be the main complaint of patients with multiple sclerosis (PwMS), its etiology, and particularly the role of resistance to fatigability and its interplay with disability level, remains unclear. The purposes of this review were to (i) clarify the relationship between fatigue/disability and neuromuscular performance in PwMS and (ii) review the corticospinal and muscular mechanisms of voluntary muscle contraction that are altered by multiple sclerosis, and how they may be influenced by disability level or fatigue. Neuromuscular function at rest and during exercise are more susceptible to impairement, due to deficits in voluntary activation, when the disability is greater. Fatigue level is related to resistance to fatigability but not to neuromuscular function at rest. Neurophysiological parameters related to signal transmission such as central motor conduction time, motor evoked potentials amplitude and latency are affected by disability and fatigue levels but their relative role in the impaired production of torque remain unclear. Nonetheless, cortical reorganization represents the most likely explanation for the heightened fatigability during exercise for highly fatigued and/or disabled PwMS. Further research is needed to decipher how the fatigue and disability could influence fatigability for an ecological task, especially at the corticospinal level.
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Schmidt J, Brown KE, Feldman SJ, Babul S, Zwicker JG, Boyd LA. Evidence of altered interhemispheric communication after pediatric concussion. Brain Inj 2021; 35:1143-1161. [PMID: 34384288 DOI: 10.1080/02699052.2021.1929485] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVES: To investigate neurophysiological alterations within the typical symptomatic period after concussion (1-month) and throughout recovery (6-months) in adolescents; and (2) to examine relationships between neurophysiological and upper limb kinematic outcomes.METHODS: 18 adolescents with concussion were compared to 17 healthy controls. Transcranial magnetic stimulation (TMS) was used to assess neurophysiological differences between groups including: short- and long-interval intracortical inhibition, intracortical facilitation, short- and long-latency afferent inhibition, afferent facilitation, and transcallosal inhibition (TCI). Behavioral measures of upper limb kinematics were assessed with a robotic device.RESULTS: Mixed model analysis of neurophysiological data identified two key findings. First, participants with concussion demonstrated delayed onset of interhemispheric inhibition, as indexed by TCI, compared to healthy controls. Second, our exploratory analysis indicated that the magnitude of TCI onset delay in adolescents with concussion was related to upper limb kinematics.CONCLUSIONS: Our findings indicate that concussion in adolescence alters interhemispheric communication. We note relationships between neurophysiological and kinematic data, suggesting an affinity for individuals with less concussion-related physiological change to improve their motor behavior over time. These data serve as an important step in future development of assessments (neurobiological and clinical) and interventions for concussion.
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Affiliation(s)
- Julia Schmidt
- Department of Occupational Science and Occupational Therapy, University of British Columbia, Vancouver, British Columbia, Canada
| | - Katlyn E Brown
- Sobell Department of Motor Neuroscience and Movement Disorders, University College London, London, UK.,Graduate Program in Rehabilitation Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Samantha J Feldman
- Graduate Program in Neuroscience, University of British Columbia, Vancouver, British Columbia, Canada
| | - Shelina Babul
- BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Emergency Medicine, BC Children's Hospital, Vancouver, British Columbia, Canada.,Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jill G Zwicker
- Department of Occupational Science and Occupational Therapy, University of British Columbia, Vancouver, British Columbia, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada.,Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada.,Sunny Hill Health Centre at BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Lara A Boyd
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Physical Therapy, University of British Columbia, Vancouver, British Columbia, Canada
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Chaves AR, Snow NJ, Alcock LR, Ploughman M. Probing the Brain-Body Connection Using Transcranial Magnetic Stimulation (TMS): Validating a Promising Tool to Provide Biomarkers of Neuroplasticity and Central Nervous System Function. Brain Sci 2021; 11:384. [PMID: 33803028 PMCID: PMC8002717 DOI: 10.3390/brainsci11030384] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/09/2021] [Accepted: 03/12/2021] [Indexed: 01/18/2023] Open
Abstract
Transcranial magnetic stimulation (TMS) is a non-invasive method used to investigate neurophysiological integrity of the human neuromotor system. We describe in detail, the methodology of a single pulse TMS protocol that was performed in a large cohort of people (n = 110) with multiple sclerosis (MS). The aim was to establish and validate a core-set of TMS variables that predicted typical MS clinical outcomes: walking speed, hand dexterity, fatigue, and cognitive processing speed. We provide a brief and simple methodological pipeline to examine excitatory and inhibitory corticospinal mechanisms in MS that map to clinical status. Delayed and longer ipsilateral silent period (a measure of transcallosal inhibition; the influence of one brain hemisphere's activity over the other), longer cortical silent period (suggestive of greater corticospinal inhibition via GABA) and higher resting motor threshold (lower corticospinal excitability) most strongly related to clinical outcomes, especially when measured in the hemisphere corresponding to the weaker hand. Greater interhemispheric asymmetry (imbalance between hemispheres) correlated with poorer performance in the greatest number of clinical outcomes. We also show, not surprisingly, that TMS variables related more strongly to motor outcomes than non-motor outcomes. As it was validated in a large sample of patients with varying severities of central nervous system dysfunction, the protocol described herein can be used by investigators and clinicians alike to investigate the role of TMS as a biomarker in MS and other central nervous system disorders.
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Affiliation(s)
| | | | | | - Michelle Ploughman
- L.A. Miller Centre, Recovery and Performance Laboratory, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL A1A 1E5, Canada; (A.R.C.); (N.J.S.); (L.R.A.)
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Mamoei S, Hvid LG, Boye Jensen H, Zijdewind I, Stenager E, Dalgas U. Neurophysiological impairments in multiple sclerosis-Central and peripheral motor pathways. Acta Neurol Scand 2020; 142:401-417. [PMID: 32474916 DOI: 10.1111/ane.13289] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 05/09/2020] [Accepted: 05/24/2020] [Indexed: 12/27/2022]
Abstract
A systematic review of the literature was conducted comparing neurophysiological outcomes in persons with multiple sclerosis (PwMS) to healthy controls (HC), in studies of the central nervous system (CNS) function comprising motor evoked potentials (MEP) elicited by transcranial magnetic stimulation (TMS) and in studies of the peripheral nervous system (PNS) function comprising electroneuronography (ENG) outcomes elicited by peripheral nerve stimulation. Studies comparing neuromuscular function, assessed during maximal voluntary contraction (MVC) of muscle, were included if they reported muscle strength along with muscle activation by use of electromyography (EMG) and/or interpolated twitch technique (ITT). Studies investigating CNS function showed prolonged central motor conduction times, asymmetry of nerve conduction motor pathways, and prolonged latencies in PwMS when compared to HC. Resting motor threshold, amplitude, and cortical silent periods showed conflicting results. CNS findings generally correlated with disabilities. Studies of PNS function showed near significant prolongation in motor latency of the median nerve, reduced nerve conduction velocities in the tibial and peroneal nerves, and decreased compound muscle action potential amplitudes of the tibial nerve in PwMS. ENG findings did not correlate with clinical severity of disabilities. Studies of neuromuscular function showed lower voluntary muscle activation and increased central fatigue in PwMS, whereas EMG showed divergent muscle activation (ie, EMG amplitude) during MVC. When comparing the existing literature on neurophysiological motor examinations in PwMS and HC, consistent and substantial impairments of CNS function were seen in PwMS, whereas impairments of the PNS were less pronounced and inconsistent. In addition, impairments in muscle activation were observed in PwMS.
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Affiliation(s)
- Sepehr Mamoei
- Department of Regional Health Research University of Southern Denmark Odense Denmark
- Denmark/MS‐Clinic of Southern Jutland (Sønderborg, Kolding, Esbjerg) Department of Neurology University Hospital of Southern Jutland Sønderborg Denmark
| | - Lars G. Hvid
- Exercise Biology Department of Public Health Aarhus University Aarhus C Denmark
| | - Henrik Boye Jensen
- Department of Regional Health Research University of Southern Denmark Odense Denmark
- Department of Neurology Kolding Sygehus Kolding Denmark
| | - Inge Zijdewind
- Department of Biomedical Sciences of Cells and Systems UMCG University of Groningen Groningen The Netherlands
| | - Egon Stenager
- Department of Regional Health Research University of Southern Denmark Odense Denmark
- Denmark/MS‐Clinic of Southern Jutland (Sønderborg, Kolding, Esbjerg) Department of Neurology University Hospital of Southern Jutland Sønderborg Denmark
| | - Ulrik Dalgas
- Exercise Biology Department of Public Health Aarhus University Aarhus C Denmark
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11
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Thompson AK, Sinkjær T. Can Operant Conditioning of EMG-Evoked Responses Help to Target Corticospinal Plasticity for Improving Motor Function in People With Multiple Sclerosis? Front Neurol 2020; 11:552. [PMID: 32765389 PMCID: PMC7381136 DOI: 10.3389/fneur.2020.00552] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 05/15/2020] [Indexed: 11/25/2022] Open
Abstract
Corticospinal pathway and its function are essential in motor control and motor rehabilitation. Multiple sclerosis (MS) causes damage to the brain and descending connections, and often diminishes corticospinal function. In people with MS, neural plasticity is available, although it does not necessarily remain stable over the course of disease progress. Thus, inducing plasticity to the corticospinal pathway so as to improve its function may lead to motor control improvements, which impact one's mobility, health, and wellness. In order to harness plasticity in people with MS, over the past two decades, non-invasive brain stimulation techniques have been examined for addressing common symptoms, such as cognitive deficits, fatigue, and spasticity. While these methods appear promising, when it comes to motor rehabilitation, just inducing plasticity or having a capacity for it does not guarantee generation of better motor functions. Targeting plasticity to a key pathway, such as the corticospinal pathway, could change what limits one's motor control and improve function. One of such neural training methods is operant conditioning of the motor-evoked potential that aims to train the behavior of the corticospinal-motoneuron pathway. Through up-conditioning training, the person learns to produce the rewarded neuronal behavior/state of increased corticospinal excitability, and through iterative training, the rewarded behavior/state becomes one's habitual, daily motor behavior. This minireview introduces operant conditioning approach for people with MS. Guiding beneficial CNS plasticity on top of continuous disease progress may help to prolong the duration of maintained motor function and quality of life in people living with MS.
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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, SC, United States
| | - Thomas Sinkjær
- Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.,Lundbeck Foundation, Copenhagen, Denmark
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12
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Stampanoni Bassi M, Buttari F, Gilio L, De Paolis N, Fresegna D, Centonze D, Iezzi E. Inflammation and Corticospinal Functioning in Multiple Sclerosis: A TMS Perspective. Front Neurol 2020; 11:566. [PMID: 32733354 PMCID: PMC7358546 DOI: 10.3389/fneur.2020.00566] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 05/19/2020] [Indexed: 12/13/2022] Open
Abstract
Transcranial magnetic stimulation (TMS) has been employed in multiple sclerosis (MS) to assess the integrity of the corticospinal tract and the corpus callosum and to explore some physiological properties of the motor cortex. Specific alterations of TMS measures have been strongly associated to different pathophysiological mechanisms, particularly to demyelination and neuronal loss. Moreover, TMS has contributed to investigate the neurophysiological basis of MS symptoms, particularly those not completely explained by conventional structural damage, such as fatigue. However, variability existing between studies suggests that alternative mechanisms should be involved. Knowledge of MS pathophysiology has been enriched by experimental studies in animal models (i.e., experimental autoimmune encephalomyelitis) demonstrating that inflammation alters synaptic transmission, promoting hyperexcitability and neuronal damage. Accordingly, TMS studies have demonstrated an imbalance between cortical excitation and inhibition in MS. In particular, cerebrospinal fluid concentrations of different proinflammatory and anti-inflammatory molecules have been associated to corticospinal hyperexcitability, highlighting that inflammatory synaptopathy may represent a key pathophysiological mechanism in MS. In this perspective article, we discuss whether corticospinal excitability alterations assessed with TMS in MS patients could be useful to explain the pathophysiological correlates and their relationships with specific MS clinical characteristics and symptoms. Furthermore, we discuss evidence indicating that, in MS patients, inflammatory synaptopathy could be present since the early phases, could specifically characterize relapses, and could progressively increase during the disease course.
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Affiliation(s)
| | - Fabio Buttari
- Unit of Neurology & Neurorehabilitation, IRCCS Neuromed, Pozzilli, Italy
| | - Luana Gilio
- Unit of Neurology & Neurorehabilitation, IRCCS Neuromed, Pozzilli, Italy
| | - Nicla De Paolis
- Unit of Neurology & Neurorehabilitation, IRCCS Neuromed, Pozzilli, Italy
| | - Diego Fresegna
- Laboratory of Synaptic Immunopathology, IRCCS San Raffaele Pisana, Rome, Italy
| | - Diego Centonze
- Unit of Neurology & Neurorehabilitation, IRCCS Neuromed, Pozzilli, Italy.,Laboratory of Synaptic Immunopathology, Department of Systems Medicine, Tor Vergata University, Rome, Italy
| | - Ennio Iezzi
- Unit of Neurology & Neurorehabilitation, IRCCS Neuromed, Pozzilli, Italy
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13
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Abstract
The corpus callosum is an important neural structure for controlling and coordinating bilateral movements of the upper limbs; however, there remains a substantial lack of knowledge regarding its association with lower limb control. We argue that transcallosal structure is an integral neural mechanism underlying control of the lower limbs and callosal degradation is a key contributor to mobility declines.
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Affiliation(s)
| | - Brett W Fling
- Department of Health and Exercise Science.,Molecular, Cellular, and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO
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14
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Snow NJ, Wadden KP, Chaves AR, Ploughman M. Transcranial Magnetic Stimulation as a Potential Biomarker in Multiple Sclerosis: A Systematic Review with Recommendations for Future Research. Neural Plast 2019; 2019:6430596. [PMID: 31636661 PMCID: PMC6766108 DOI: 10.1155/2019/6430596] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 08/31/2019] [Indexed: 12/23/2022] Open
Abstract
Multiple sclerosis (MS) is a demyelinating disorder of the central nervous system. Disease progression is variable and unpredictable, warranting the development of biomarkers of disease status. Transcranial magnetic stimulation (TMS) is a noninvasive method used to study the human motor system, which has shown potential in MS research. However, few reviews have summarized the use of TMS combined with clinical measures of MS and no work has comprehensively assessed study quality. This review explored the viability of TMS as a biomarker in studies of MS examining disease severity, cognitive impairment, motor impairment, or fatigue. Methodological quality and risk of bias were evaluated in studies meeting selection criteria. After screening 1603 records, 30 were included for review. All studies showed high risk of bias, attributed largely to issues surrounding sample size justification, experimenter blinding, and failure to account for key potential confounding variables. Central motor conduction time and motor-evoked potentials were the most commonly used TMS techniques and showed relationships with disease severity, motor impairment, and fatigue. Short-latency afferent inhibition was the only outcome related to cognitive impairment. Although there is insufficient evidence for TMS in clinical assessments of MS, this review serves as a template to inform future research.
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Affiliation(s)
- Nicholas J. Snow
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Katie P. Wadden
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Arthur R. Chaves
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Michelle Ploughman
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
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15
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Giffroy X, Dive D, Kaux JF, Maes N, Albert A, Göbels C, Wang F. Is the triple stimulation technique a better quantification tool of motor dysfunction than motor evoked potentials in multiple sclerosis? Acta Neurol Belg 2019; 119:47-54. [PMID: 30136146 DOI: 10.1007/s13760-018-1001-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 08/13/2018] [Indexed: 01/07/2023]
Abstract
The triple stimulation technique (TST) was rarely used in multiple sclerosis (MS). This study aimed to compare TST and motor evoked potentials (MEP) for the quantification of motor dysfunction. Central motor conduction based on MEP (four limbs) and TST (upper limbs) was assessed in 28 MS patients with a median Expanded Disability Status Scale (EDSS) of 4. EDSS, timed 25-foot walk (T25FW), grasping strength and motor components of the MS functional composite were evaluated. Regression analysis was used to assess the relationship between MEP, TST and clinical findings. TST was negatively correlated with EDSS (r = - 0.74, p < 0.0001) and to a lesser extent with T25FW (r = - 0.47, p < 0.05), and grasping strength (r = - 0.43, p < 0.05). A multiple regression analysis underlined the better correlation between clinical data and TST (R2 = 0.56, p < 0.0005) than with MEP (0.03 < R2 < 0.22, p > 0.05). This study evidenced the value of TST as a quantification tool of motor dysfunction. TST appeared to reflect a global disability since it was correlated not only to hand function but also to walking capacity.
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16
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Chaves AR, Wallack EM, Kelly LP, Pretty RW, Wiseman HD, Chen A, Moore CS, Stefanelli M, Ploughman M. Asymmetry of Brain Excitability: A New Biomarker that Predicts Objective and Subjective Symptoms in Multiple Sclerosis. Behav Brain Res 2019; 359:281-291. [DOI: 10.1016/j.bbr.2018.11.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 10/24/2018] [Accepted: 11/05/2018] [Indexed: 12/13/2022]
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17
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Operant Up-Conditioning of the Tibialis Anterior Motor-Evoked Potential in Multiple Sclerosis: Feasibility Case Studies. Neural Plast 2018; 2018:4725393. [PMID: 30123249 PMCID: PMC6079394 DOI: 10.1155/2018/4725393] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Accepted: 04/12/2018] [Indexed: 11/18/2022] Open
Abstract
Damage to the corticospinal pathway often results in weak dorsiflexion of the ankle, thereby limiting the mobility of people with multiple sclerosis (MS). Thus, strengthening corticospinal connectivity may improve locomotion. Here, we investigated the feasibility of tibialis anterior (TA) motor-evoked potential (MEP) operant conditioning and whether it can enhance corticospinal excitability and alleviate locomotor problems in people with chronic stable MS. The protocol consisted of 6 baseline and 24 up-conditioning sessions over 10 weeks. In all sessions, TA MEPs were elicited at 10% above active threshold while the sitting subject provided 30–35% maximum voluntary contraction (MVC) level of TA background EMG. During baseline sessions, MEPs were simply measured. During conditioning trials of the conditioning sessions, the subject was encouraged to increase MEP and was given immediate feedback indicating whether MEP size was above a criterion. In 3/4 subjects, TA MEP increased 32–75%, MVC increased 28–52%, locomotor EMG modulation improved in multiple leg muscles, and foot drop became less severe. In one of them, MEP and MVC increases were maintained throughout 3 years of extensive follow-up sessions. These initial results support a therapeutic possibility of MEP operant conditioning for improving locomotion in people with MS or other CNS disorders, such as spinal cord injury and stroke.
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18
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Zhong J, Chen DQ, Nantes JC, Holmes SA, Hodaie M, Koski L. Combined structural and functional patterns discriminating upper limb motor disability in multiple sclerosis using multivariate approaches. Brain Imaging Behav 2018; 11:754-768. [PMID: 27146291 DOI: 10.1007/s11682-016-9551-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A structural or functional pattern of neuroplasticity that could systematically discriminate between people with impaired and preserved motor performance could help us to understand the brain networks contributing to preservation or compensation of behavior in multiple sclerosis (MS). This study aimed to (1) investigate whether a machine learning-based technique could accurately classify MS participants into groups defined by upper extremity function (i.e. motor function preserved (MP) vs. motor function impaired (MI)) based on their regional grey matter measures (GMM, cortical thickness and deep grey matter volume) and inter-regional functional connection (FC), (2) investigate which features (GMM, FC, or GMM + FC) could classify groups more accurately, and (3) identify the multivariate patterns of GMM and FCs that are most discriminative between MP and MI participants, and between each of these groups and the healthy controls (HCs). With 26 MP, 25 MI, and 21 HCs (age and sex matched) underwent T1-weighted and resting-state functional MRI at 3 T, we applied support vector machine (SVM) based classification to learn discriminant functions indicating regions in which GMM or between which FCs were most discriminative between groups. This study demonstrates that there exist structural and FC patterns sufficient for correct classification of upper limb motor ability of people with MS. The classifier with GMM + FC features yielded the highest accuracy of 85.61 % (p < 0.001) to distinguish between the MS groups using leave-one-out cross-validation. It suggests that a machine-learning approach combining structural and functional features is useful for identifying the specific neural substrates that are necessary and sufficient to preserve motor function among people with MS.
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Affiliation(s)
- Jidan Zhong
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada. .,Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada. .,Toronto Western Hospital, 399 Bathurst Street, Toronto, ON, M5T 2S8, Canada.
| | - David Qixiang Chen
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Division of Brain, Imaging and Behaviour-Systems, Neuroscience, Krembil Research Institute, University Health Network, Toronto, ON, Canada
| | - Julia C Nantes
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada.,Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
| | - Scott A Holmes
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada.,Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
| | - Mojgan Hodaie
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Division of Brain, Imaging and Behaviour-Systems, Neuroscience, Krembil Research Institute, University Health Network, Toronto, ON, Canada.,Division of Neurosurgery, Toronto Western Hospital & University of Toronto, Toronto, ON, Canada
| | - Lisa Koski
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada.,Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada.,Department of Psychology, McGill University, Montreal, QC, Canada
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19
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Stampanoni Bassi M, Gilio L, Buttari F, Maffei P, Marfia GA, Restivo DA, Centonze D, Iezzi E. Remodeling Functional Connectivity in Multiple Sclerosis: A Challenging Therapeutic Approach. Front Neurosci 2017; 11:710. [PMID: 29321723 PMCID: PMC5733539 DOI: 10.3389/fnins.2017.00710] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 12/04/2017] [Indexed: 11/13/2022] Open
Abstract
Neurons in the central nervous system are organized in functional units interconnected to form complex networks. Acute and chronic brain damage disrupts brain connectivity producing neurological signs and/or symptoms. In several neurological diseases, particularly in Multiple Sclerosis (MS), structural imaging studies cannot always demonstrate a clear association between lesion site and clinical disability, originating the "clinico-radiological paradox." The discrepancy between structural damage and disability can be explained by a complex network perspective. Both brain networks architecture and synaptic plasticity may play important roles in modulating brain networks efficiency after brain damage. In particular, long-term potentiation (LTP) may occur in surviving neurons to compensate network disconnection. In MS, inflammatory cytokines dramatically interfere with synaptic transmission and plasticity. Importantly, in addition to acute and chronic structural damage, inflammation could contribute to reduce brain networks efficiency in MS leading to worse clinical recovery after a relapse and worse disease progression. These evidence suggest that removing inflammation should represent the main therapeutic target in MS; moreover, as synaptic plasticity is particularly altered by inflammation, specific strategies aimed at promoting LTP mechanisms could be effective for enhancing clinical recovery. Modulation of plasticity with different non-invasive brain stimulation (NIBS) techniques has been used to promote recovery of MS symptoms. Better knowledge of features inducing brain disconnection in MS is crucial to design specific strategies to promote recovery and use NIBS with an increasingly tailored approach.
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Affiliation(s)
- Mario Stampanoni Bassi
- Unit of Neurology & Unit of Neurorehabilitation, IRCCS Istituto Neurologico Mediterraneo Neuromed, Pozzilli, Italy.,Multiple Sclerosis Research Unit, Department of Systems Medicine, Tor Vergata University, Rome, Italy
| | - Luana Gilio
- Unit of Neurology & Unit of Neurorehabilitation, IRCCS Istituto Neurologico Mediterraneo Neuromed, Pozzilli, Italy.,Multiple Sclerosis Research Unit, Department of Systems Medicine, Tor Vergata University, Rome, Italy
| | - Fabio Buttari
- Unit of Neurology & Unit of Neurorehabilitation, IRCCS Istituto Neurologico Mediterraneo Neuromed, Pozzilli, Italy.,Multiple Sclerosis Research Unit, Department of Systems Medicine, Tor Vergata University, Rome, Italy
| | - Pierpaolo Maffei
- Unit of Neurology & Unit of Neurorehabilitation, IRCCS Istituto Neurologico Mediterraneo Neuromed, Pozzilli, Italy
| | - Girolama A Marfia
- Multiple Sclerosis Research Unit, Department of Systems Medicine, Tor Vergata University, Rome, Italy
| | | | - Diego Centonze
- Unit of Neurology & Unit of Neurorehabilitation, IRCCS Istituto Neurologico Mediterraneo Neuromed, Pozzilli, Italy.,Multiple Sclerosis Research Unit, Department of Systems Medicine, Tor Vergata University, Rome, Italy
| | - Ennio Iezzi
- Unit of Neurology & Unit of Neurorehabilitation, IRCCS Istituto Neurologico Mediterraneo Neuromed, Pozzilli, Italy
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20
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Peterson DS, Fling BW. How changes in brain activity and connectivity are associated with motor performance in people with MS. Neuroimage Clin 2017; 17:153-162. [PMID: 29071209 PMCID: PMC5651557 DOI: 10.1016/j.nicl.2017.09.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 09/22/2017] [Accepted: 09/25/2017] [Indexed: 01/18/2023]
Abstract
People with multiple sclerosis (MS) exhibit pronounced changes in brain structure, activity, and connectivity. While considerable work has begun to elucidate how these neural changes contribute to behavior, the heterogeneity of symptoms and diagnoses makes interpretation of findings and application to clinical practice challenging. In particular, whether MS related changes in brain activity or brain connectivity protect against or contribute to worsening motor symptoms is unclear. With the recent emergence of neuromodulatory techniques that can alter neural activity in specific brain regions, it is critical to establish whether localized brain activation patterns are contributing to (i.e. maladaptive) or protecting against (i.e. adaptive) progression of motor symptoms. In this manuscript, we consolidate recent findings regarding changes in supraspinal structure and activity in people with MS and how these changes may contribute to motor performance. Furthermore, we discuss a hypothesis suggesting that increased neural activity during movement may be either adaptive or maladaptive depending on where in the brain this increase is observed. Specifically, we outline preliminary evidence suggesting sensorimotor cortex activity in the ipsilateral cortices may be maladaptive in people with MS. We also discuss future work that could supply data to support or refute this hypothesis, thus improving our understanding of this important topic.
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Affiliation(s)
- Daniel S Peterson
- Arizona State University, Tempe, AZ, USA; Veterans Affairs Phoenix Medical Center Phoenix, AZ, USA.
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21
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Hameed MQ, Dhamne SC, Gersner R, Kaye HL, Oberman LM, Pascual-Leone A, Rotenberg A. Transcranial Magnetic and Direct Current Stimulation in Children. Curr Neurol Neurosci Rep 2017; 17:11. [PMID: 28229395 PMCID: PMC5962296 DOI: 10.1007/s11910-017-0719-0] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Promising results in adult neurologic and psychiatric disorders are driving active research into transcranial brain stimulation techniques, particularly transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), in childhood and adolescent syndromes. TMS has realistic utility as an experimental tool tested in a range of pediatric neuropathologies such as perinatal stroke, depression, Tourette syndrome, and autism spectrum disorder (ASD). tDCS has also been tested as a treatment for a number of pediatric neurologic conditions, including ASD, attention-deficit/hyperactivity disorder, epilepsy, and cerebral palsy. Here, we complement recent reviews with an update of published TMS and tDCS results in children, and discuss developmental neuroscience considerations that should inform pediatric transcranial stimulation.
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Affiliation(s)
- Mustafa Q Hameed
- Neuromodulation Program, Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA
- Department of Neurosurgery, Boston Children's Hospital Harvard Medical School, Boston, MA, 02115, USA
| | - Sameer C Dhamne
- Neuromodulation Program, Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - Roman Gersner
- Neuromodulation Program, Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - Harper L Kaye
- Neuromodulation Program, Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - Lindsay M Oberman
- Neuroplasticity and Autism Spectrum Disorder Program and Department of Psychiatry and Human Behavior, E.P. Bradley Hospital and Warren Alpert Medical School, Brown University, Providence, RI, USA
| | - Alvaro Pascual-Leone
- Berenson-Allen Center for Noninvasive Brain Stimulation and Division for Cognitive Neurology, Beth Israel Deaconness Medical Center Harvard Medical School, Boston, MA, USA
- Institut Guttmann, Universitat Autonoma, Barcelona, Spain
| | - Alexander Rotenberg
- Neuromodulation Program, Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA.
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital Harvard Medical School, 300 Longwood Avenue, Boston, MA, 02115, USA.
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22
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Evidence of alterations in transcallosal motor inhibition as a possible long-term consequence of concussions in sports: A transcranial magnetic stimulation study. Clin Neurophysiol 2016; 127:3364-75. [DOI: 10.1016/j.clinph.2016.07.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 06/03/2016] [Accepted: 07/23/2016] [Indexed: 01/14/2023]
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23
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Liepert J, Mingers D, Heesen C, Bäumer T, Weiller C. Motor cortex excitability and fatigue in multiple sclerosis: a transcranial magnetic stimulation study. Mult Scler 2016; 11:316-21. [PMID: 15957514 DOI: 10.1191/1352458505ms1163oa] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We investigated electrophysiological correlates of fatigue in patients with multiple sclerosis (MS). Transcranial magnetic stimulation (TMS) was used to explore motor excitability in three groups of subjects: MS patients with fatigue (MS-F), MS patients without fatigue (MS-NF) and healthy control subjects. All participants had to perform a fatiguing hand-grip exercise. TMS was performed prior to and after the exercise. Prior to the motor task, MS-F patients had less inhibition in the primary motor cortex compared to both other groups. Postexercise, intracortical inhibition was still reduced in the MS-F patients compared to the MS-NF patients. In MS-F patients the postexercise time interval for normalization of the motor threshold was correlated with the fatigue severity. We conclude that MS patients with fatigue have an impairment of inhibitory circuits in their primary motor cortex. The results also indicate that fatigue severity is associated with an exercise-induced reduction of membrane excitability.
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Affiliation(s)
- J Liepert
- Department of Neurology, University Hospital Eppendorf, Hamburg, Germany.
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24
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MEG evaluation of pico-Tesla external TMS on multiple sclerosis patients. Mult Scler Relat Disord 2016; 8:45-53. [DOI: 10.1016/j.msard.2016.04.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 04/11/2016] [Accepted: 04/25/2016] [Indexed: 12/15/2022]
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25
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Neva JL, Lakhani B, Brown KE, Wadden KP, Mang CS, Ledwell NHM, Borich MR, Vavasour IM, Laule C, Traboulsee AL, MacKay AL, Boyd LA. Multiple measures of corticospinal excitability are associated with clinical features of multiple sclerosis. Behav Brain Res 2016; 297:187-95. [PMID: 26467603 PMCID: PMC4904787 DOI: 10.1016/j.bbr.2015.10.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 09/04/2015] [Accepted: 10/05/2015] [Indexed: 10/22/2022]
Abstract
In individuals with multiple sclerosis (MS), transcranial magnetic stimulation (TMS) may be employed to assess the integrity of corticospinal system and provides a potential surrogate biomarker of disability. The purpose of this study was to provide a comprehensive examination of the relationship between multiple measures corticospinal excitability and clinical disability in MS (expanded disability status scale (EDSS)). Bilateral corticospinal excitability was assessed using motor evoked potential (MEP) input-output (IO) curves, cortical silent period (CSP), short-interval intracortical inhibition (SICI), intracortical facilitation (ICF) and transcallosal inhibition (TCI) in 26 individuals with MS and 11 healthy controls. Measures of corticospinal excitability were compared between individuals with MS and controls. We evaluated the relationship(s) between age and clinical demographics such as age at MS onset (AO), disease duration (DD) and clinical disability (EDSS) with measures of corticospinal excitability. Corticospinal excitability thresholds were higher, MEP latency and CSP onset delayed and MEP durations prolonged in individuals with MS compared to controls. Age, DD and EDSS correlated with corticospinal excitability thresholds. Also, TCI duration and the linear slope of the MEP amplitude IO curve correlated with EDSS. Hierarchical regression modeling demonstrated that combining multiple TMS-based measures of corticospinal excitability accounted for unique variance in clinical disability (EDSS) beyond that of clinical demographics (AO, DD). Our results indicate that multiple TMS-based measures of corticospinal and interhemispheric excitability provide insights into the potential neural mechanisms associated with clinical disability in MS. These findings may aid in the clinical evaluation, disease monitoring and prediction of disability in MS.
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Affiliation(s)
- J L Neva
- Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
| | - B Lakhani
- Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - K E Brown
- Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - K P Wadden
- Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - C S Mang
- Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - N H M Ledwell
- Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - M R Borich
- Division of Physical Therapy, Department of Rehabilitation Medicine, School of Medicine, Emory University, Atlanta, GA, USA
| | - I M Vavasour
- Department of Radiology, The University of British Columbia, Vancouver, BC, Canada
| | - C Laule
- Department of Radiology, The University of British Columbia, Vancouver, BC, Canada; Department of Pathology & Laboratory Medicine, The University of British Columbia, Vancouver, BC, Canada
| | - A L Traboulsee
- Division of Neurology, Department of Medicine, Faculty of Medicine, The University of British Columbia, Vancouver, BC, Canada
| | - A L MacKay
- Department of Radiology, The University of British Columbia, Vancouver, BC, Canada; Department of Physics & Astronomy, The University of British Columbia, Vancouver, BC, Canada
| | - L A Boyd
- Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
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Mandolesi G, Gentile A, Musella A, Fresegna D, De Vito F, Bullitta S, Sepman H, Marfia GA, Centonze D. Synaptopathy connects inflammation and neurodegeneration in multiple sclerosis. Nat Rev Neurol 2015; 11:711-24. [PMID: 26585978 DOI: 10.1038/nrneurol.2015.222] [Citation(s) in RCA: 181] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Multiple sclerosis (MS) has long been regarded as a chronic inflammatory disease of the white matter that leads to demyelination and eventually to neurodegeneration. In the past decade, several aspects of MS pathogenesis have been challenged, and degenerative changes of the grey matter, which are independent of demyelination, have become a topic of interest. CNS inflammation in MS and experimental autoimmune encephalomyelitis (EAE; a disease model used to study MS in rodents) causes a marked imbalance between GABAergic and glutamatergic transmission, and a loss of synapses, all of which leads to a diffuse 'synaptopathy'. Altered synaptic transmission can occur early in MS and EAE, independently of demyelination and axonal loss, and subsequently causes excitotoxic damage. Inflammation-driven synaptic abnormalities are emerging as a prominent pathogenic mechanism in MS-importantly, they are potentially reversible and, therefore, represent attractive therapeutic targets. In this Review, we focus on the connection between inflammation and synaptopathy in MS and EAE, which sheds light not only on the pathophysiology of MS but also on that of primary neurodegenerative disorders in which inflammatory processes contribute to disease progression.
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Affiliation(s)
- Georgia Mandolesi
- IRCCS Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), Via del Fosso di Fiorano 64, 00143 Rome, Italy
| | - Antonietta Gentile
- Dipartimento di Medicina dei Sistemi, Università Tor Vergata, Via Montpellier 1, 00133 Rome, Italy
| | - Alessandra Musella
- IRCCS Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), Via del Fosso di Fiorano 64, 00143 Rome, Italy
| | - Diego Fresegna
- IRCCS Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), Via del Fosso di Fiorano 64, 00143 Rome, Italy
| | - Francesca De Vito
- Dipartimento di Medicina dei Sistemi, Università Tor Vergata, Via Montpellier 1, 00133 Rome, Italy
| | - Silvia Bullitta
- IRCCS Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), Via del Fosso di Fiorano 64, 00143 Rome, Italy
| | - Helena Sepman
- IRCCS Fondazione Santa Lucia/Centro Europeo per la Ricerca sul Cervello (CERC), Via del Fosso di Fiorano 64, 00143 Rome, Italy.,Dipartimento di Medicina dei Sistemi, Università Tor Vergata, Via Montpellier 1, 00133 Rome, Italy
| | - Girolama A Marfia
- Dipartimento di Medicina dei Sistemi, Università Tor Vergata, Via Montpellier 1, 00133 Rome, Italy
| | - Diego Centonze
- IRCCS Istituto Neurologico Mediterraneo (INM) Neuromed, Via Atinense 18, 86077 Pozzilli, Italy
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Consistency of evoked responses to dual-stimulator, single-pulse transcranial magnetic stimulation in the lower limb of people with multiple sclerosis. J Clin Neurosci 2015; 22:1434-7. [DOI: 10.1016/j.jocn.2015.02.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 02/21/2015] [Indexed: 11/21/2022]
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Cabib C, Llufriu S, Casanova-Molla J, Saiz A, Valls-Solé J. Defective sensorimotor integration in preparation for reaction time tasks in patients with multiple sclerosis. J Neurophysiol 2015; 113:1462-9. [DOI: 10.1152/jn.00591.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Slowness of voluntary movements in patients with multiple sclerosis (MS) may be due to various factors, including attentional and cognitive deficits, delays in motor conduction time, and impairment of specific central nervous system circuits. In 13 healthy volunteers and 20 mildly disabled, relapsing-remitting MS patients, we examined simple reaction time (SRT) tasks requiring sensorimotor integration in circuits involving the corpus callosum and the brain stem. A somatosensory stimulus was used as the imperative signal (IS), and subjects were requested to react with either the ipsilateral or the contralateral hand (uncrossed vs. crossed SRT). In 33% of trials, a startling auditory stimulus was presented together with the IS, and the percentage reaction time change with respect to baseline SRT trials was measured (StartReact effect). The difference between crossed and uncrossed SRT, which requires interhemispheric conduction, was significantly larger in patients than in healthy subjects ( P = 0.021). The StartReact effect, which involves activation of brain stem motor pathways, was reduced significantly in patients with respect to healthy subjects (uncrossed trials: P = 0.015; crossed trials: P = 0.005). In patients, a barely significant correlation was found between SRT delay and conduction abnormalities in motor and sensory pathways ( P = 0.02 and P = 0.04, respectively). The abnormalities found specifically in trials reflecting interhemispheric transfer of information, as well as the evidence for reduced subcortical motor preparation, indicate that a delay in reaction time execution in MS patients cannot be explained solely by conduction slowing in motor and sensory pathways but suggest, instead, defective sensorimotor integration mechanisms in at least the two circuits examined.
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Affiliation(s)
- Christopher Cabib
- EMG Unit, Neurology Department, Hospital Clinic, and Institut d'Investigació Augustí Pi i Sunyer, Facultat de Medicina, University of Barcelona, Barcelona, Spain; and
| | - Sara Llufriu
- Center for Neuroimmunology, Neurology Department, Hospital Clínic, and Institut d'Investigació August Pi i Sunyer, Universitat de Barcelona, Barcelona, Spain
| | - Jordi Casanova-Molla
- EMG Unit, Neurology Department, Hospital Clinic, and Institut d'Investigació Augustí Pi i Sunyer, Facultat de Medicina, University of Barcelona, Barcelona, Spain; and
| | - Albert Saiz
- Center for Neuroimmunology, Neurology Department, Hospital Clínic, and Institut d'Investigació August Pi i Sunyer, Universitat de Barcelona, Barcelona, Spain
| | - Josep Valls-Solé
- EMG Unit, Neurology Department, Hospital Clinic, and Institut d'Investigació Augustí Pi i Sunyer, Facultat de Medicina, University of Barcelona, Barcelona, Spain; and
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Brown KE, Neva JL, Ledwell NM, Boyd LA. Use of transcranial magnetic stimulation in the treatment of selected movement disorders. Degener Neurol Neuromuscul Dis 2014; 4:133-151. [PMID: 32669907 PMCID: PMC7337234 DOI: 10.2147/dnnd.s70079] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 04/23/2014] [Indexed: 11/23/2022] Open
Abstract
Transcranial magnetic stimulation (TMS) is a valuable technique for assessing the underlying neurophysiology associated with various neuropathologies, and is a unique tool for establishing potential neural mechanisms responsible for disease progression. Recently, repetitive TMS (rTMS) has been advanced as a potential therapeutic technique to treat selected neurologic disorders. In healthy individuals, rTMS can induce changes in cortical excitability. Therefore, targeting specific cortical areas affected by movement disorders theoretically may alter symptomology. This review discusses the evidence for the efficacy of rTMS in Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis, and multiple sclerosis. It is hoped that gaining a more thorough understanding of the timing and parameters of rTMS in individuals with neurodegenerative disorders may advance both clinical care and research into the most effective uses of this technology.
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Affiliation(s)
| | - Jason L Neva
- Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | | | - Lara A Boyd
- Graduate Program in Rehabilitation Science.,Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
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Iglesias-Bregna D, Hanak S, Ji Z, Petty M, Liu L, Zhang D, McMonagle-Strucko K. Effects of prophylactic and therapeutic teriflunomide in transcranial magnetic stimulation-induced motor-evoked potentials in the dark agouti rat model of experimental autoimmune encephalomyelitis. J Pharmacol Exp Ther 2013; 347:203-11. [PMID: 23892570 DOI: 10.1124/jpet.113.205146] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Teriflunomide is a once-daily oral immunomodulatory agent recently approved in the United States for the treatment of relapsing multiple sclerosis (RMS). This study investigated neurophysiological deficits in descending spinal cord motor tracts during experimental autoimmune encephalomyelitis (EAE; a model of multiple sclerosis) and the functional effectiveness of prophylactic or therapeutic teriflunomide treatment in preventing the debilitating paralysis observed in this model. Relapsing-remitting EAE was induced in Dark Agouti rats using rat spinal cord homogenate. Animals were treated with oral teriflunomide (10 mg/kg daily) prophylactically, therapeutically, or with vehicle (control). Transcranial magnetic motor-evoked potentials were measured throughout the disease to provide quantitative assessment of the neurophysiological status of descending motor tracts. Axonal damage was quantified histologically by silver staining. Both prophylactic and therapeutic teriflunomide treatment significantly reduced maximum EAE disease scores (P < 0.0001 and P = 0.0001, respectively) compared with vehicle-treated rats. Electrophysiological recordings demonstrated that both teriflunomide treatment regimens prevented a delay in wave-form latency and a decrease in wave-form amplitude compared with that observed in vehicle-treated animals. A significant reduction in axonal loss was observed with both teriflunomide treatment regimens compared with vehicle (P < 0.0001 and P = 0.0014, respectively). The results of this study suggest that therapeutic teriflunomide can prevent the deficits observed in this animal model in descending spinal cord motor tracts. The mechanism behind reduced axonal loss and improved motor function may be primarily the reduced inflammation and consequent demyelination observed in these animals through the known effects of teriflunomide on impairing proliferation of stimulated T cells. These findings may have significant implications for patients with RMS.
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Yusuf A, Koski L. A qualitative review of the neurophysiological underpinnings of fatigue in multiple sclerosis. J Neurol Sci 2013; 330:4-9. [PMID: 23651867 DOI: 10.1016/j.jns.2013.04.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 04/09/2013] [Accepted: 04/11/2013] [Indexed: 11/19/2022]
Abstract
Fatigue is debilitating in multiple sclerosis (MS) and may have multiple causes. Recent investigations into objectively measurable correlates of fatigue have used transcranial magnetic stimulation (TMS) to examine a range of neurophysiological measures of neural excitability that may be altered in patients with MS. This qualitative review was conducted to test the hypothesis that changes in neural excitability are a contributing factor in MS-related fatigue. A search of the English language literature led to the compilation and synthesis of original research papers in which various aspects of neural excitability and neural transmission were measured using TMS in patients with MS. The resulting papers were classified into three categories of study relevant to fatigue: abnormalities in excitability and their correlation with self-reported fatigue; effects of exercise-induced fatigue on neural excitability; and effects of fatigue medications on neural excitability. Evidence of an association between fatigue and intracortical inhibition is both limited and conflicting, and no evidence suggests associations of fatigue with corticomotor excitability or neuronal conduction. Pharmacologically-induced changes in fatigue were found to correlate with changes in intracortical excitability. No conclusions could be drawn regarding neural excitability and exercise-induced fatigue, due to variability in study populations, outcome measures, and exercise protocols across different studies. Suggestions for future studies in this area are proposed with a view to identifying potentially modifiable factors contributing to fatigue in MS.
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Affiliation(s)
- Afiqah Yusuf
- Integrated Program in Neuroscience, McGill University, Montreal, QC H3A 1A1, Canada.
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Schlaeger R, Hardmeier M, Fuhr P. Superficial brain stimulation in multiple sclerosis. HANDBOOK OF CLINICAL NEUROLOGY 2013; 116:577-84. [PMID: 24112925 DOI: 10.1016/b978-0-444-53497-2.00046-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Central motor conduction time (CMCT) is the most frequently studied measure derived from transcranial magnetic stimulation (TMS) in multiple sclerosis (MS); it is abnormal in 57-93% of patients. Addition of the triple stimulation technique and combining motor with other evoked potentials (EPs) increases sensitivity. Cross-sectional correlations of TMS measures with clinical assessments of motor dysfunction or global disability are high. Longitudinally, CMCT is sensitive to both worsening and improvement of motor function, showing its potential to detect therapeutic responses. Moreover, combined multimodal EPs are valid quantitative predictors of the clinical course over periods ranging from 2 to 14 years. Measures of transcallosal connectivity (ipsilateral silent period and interhemispheric inhibition) are altered even in early MS, and yield complementary information on subclinical changes. Pathological brain plasticity in MS has been demonstrated by paired associative stimulation studies revealing a compensatory role of the ipsilateral motor and premotor areas. Central motor fatigue is associated with reduced motor EP amplitudes and increased cortical silent periods in normal controls, whereas patients with MS suffering from subjective fatigue show various abnormalities in cortical modulation of the motor system.
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Affiliation(s)
- Regina Schlaeger
- Department of Neurology, Hospitals of the University of Basel, Basel, Switzerland
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Short interval intracortical facilitation correlates with the degree of disability in multiple sclerosis. Brain Stimul 2013; 6:67-71. [DOI: 10.1016/j.brs.2012.02.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 01/23/2012] [Accepted: 02/06/2012] [Indexed: 11/19/2022] Open
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Llufriu S, Blanco Y, Martinez-Heras E, Casanova-Molla J, Gabilondo I, Sepulveda M, Falcon C, Berenguer J, Bargallo N, Villoslada P, Graus F, Valls-Sole J, Saiz A. Influence of corpus callosum damage on cognition and physical disability in multiple sclerosis: a multimodal study. PLoS One 2012; 7:e37167. [PMID: 22606347 PMCID: PMC3351399 DOI: 10.1371/journal.pone.0037167] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 04/16/2012] [Indexed: 12/21/2022] Open
Abstract
Background Corpus callosum (CC) is a common target for multiple sclerosis (MS) pathology. We investigated the influence of CC damage on physical disability and cognitive dysfunction using a multimodal approach. Methods Twenty-one relapsing-remitting MS patients and 13 healthy controls underwent structural MRI and diffusion tensor of the CC (fractional anisotropy; mean diffusivity, MD; radial diffusivity, RD; axial diffusivity). Interhemisferic transfer of motor inhibition was assessed by recording the ipsilateral silent period (iSP) to transcranial magnetic stimulation. We evaluated cognitive function using the Brief Repeatable Battery and physical disability using the Expanded Disability Status Scale (EDSS) and the MS Functional Composite (MSFC) z-score. Results The iSP latency correlated with physical disability scores (r ranged from 0.596 to 0.657, P values from 0.004 to 0.001), and with results of visual memory (r = −0.645, P = 0.002), processing speed (r = −0.51, P = 0.018) and executive cognitive domain tests (r = −0.452, P = 0.039). The area of the rostrum correlated with the EDSS (r = −0.442, P = 0.045). MD and RD correlated with cognitive performance, mainly with results of visual and verbal memory tests (r ranged from −0.446 to −0.546, P values from 0.048 to 0.011). The iSP latency correlated with CC area (r = −0.345, P = 0.049), volume (r = −0.401, P = 0.002), MD (r = 0.404, P = 0.002) and RD (r = 0.415, P = 0.016). Conclusions We found evidence for structural and microstructural CC abnormalities associated with impairment of motor callosal inhibitory conduction in MS. CC damage may contribute to cognitive dysfunction and in less extent to physical disability likely through a disconnection mechanism.
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Affiliation(s)
- Sara Llufriu
- Center for Neuroimmunology, Service of Neurology, Hospital Clinic and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Yolanda Blanco
- Center for Neuroimmunology, Service of Neurology, Hospital Clinic and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Eloy Martinez-Heras
- Center for Neuroimmunology, Service of Neurology, Hospital Clinic and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | | | - Iñigo Gabilondo
- Center for Neuroimmunology, Service of Neurology, Hospital Clinic and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Maria Sepulveda
- Center for Neuroimmunology, Service of Neurology, Hospital Clinic and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Carles Falcon
- Medical Imaging Platform, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Centros de Investigación Biomédica en Red (CIBER-BBN), Barcelona, Spain
| | - Joan Berenguer
- Service of Radiology and Imaging Diagnostic Center, Hospital Clinic and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Nuria Bargallo
- Medical Imaging Platform, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Service of Radiology and Imaging Diagnostic Center, Hospital Clinic and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Pablo Villoslada
- Center for Neuroimmunology, Service of Neurology, Hospital Clinic and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Francesc Graus
- Center for Neuroimmunology, Service of Neurology, Hospital Clinic and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | | | - Albert Saiz
- Center for Neuroimmunology, Service of Neurology, Hospital Clinic and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- * E-mail:
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Ziemann U, Wahl M, Hattingen E, Tumani H. Development of biomarkers for multiple sclerosis as a neurodegenerative disorder. Prog Neurobiol 2011; 95:670-85. [DOI: 10.1016/j.pneurobio.2011.04.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Revised: 04/07/2011] [Accepted: 04/10/2011] [Indexed: 01/24/2023]
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Pearce AJ, Rowe GS, Whyte DG. Neural conduction and excitability following a simple warm up. J Sci Med Sport 2011; 15:164-8. [PMID: 22018523 DOI: 10.1016/j.jsams.2011.09.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 08/18/2011] [Accepted: 09/17/2011] [Indexed: 10/16/2022]
Abstract
OBJECTIVE This study examined the effect of a generic, active warm up on neural and muscular conduction time. DESIGN Single group, pre-post design. METHODS Central and peripheral neuromuscular conduction time was quantified in the abductor pollicis brevis (APB) and gastrocnemius muscles of 18 healthy participants (mean age 25.9±5.8 years, 12 males) using transcranial magnetic stimulation (TMS) and M-wave techniques, prior to and immediately following an active warm up consisting of 5 min running at 65% of maximum heart rate. Neural conduction time, for both TMS and M-wave, was quantified as the time between stimulus artefact and deflection of the wave form, whilst muscle conduction time for TMS and M-wave, was quantified from the stimulus artefact to the absolute peak twitch response. RESULTS Following the warm up protocol, a significant reduction in muscle conduction time was found in both TMS and M-wave of 0.43 ms (P=0.02) and 0.30 ms (P=0.001) for the APB; and 0.29 ms (P<0.001) and 0.87 ms (P=0.003) for the gastrocnemius, respectively. No change was found in neural conduction using either TMS or M-wave techniques. CONCLUSIONS These findings support previous data which demonstrate an improvement in muscular conduction time and subsequent improvement in athletic performance post warm up. The data also make evident that changes in muscular conduction time are a global response to warm up and are not directly related to muscular activity. In contrast, neural conduction time did not change and should not be confused with changes in muscular conduction time in the literature.
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Affiliation(s)
- Alan J Pearce
- Motor Control TMS Laboratory, School of Sport and Exercise Science, Victoria University, Australia.
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Codecà C, Mori F, Kusayanagi H, Monteleone F, Boffa L, Paolillo A, Bernardi G, Koch G, Centonze D. Differential patterns of interhemispheric functional disconnection in mild and advanced multiple sclerosis. Mult Scler 2010; 16:1308-16. [PMID: 20702503 DOI: 10.1177/1352458510376957] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Patients with multiple sclerosis may present altered patterns of connectivity between the two brain hemispheres. To date, only transcallosal connectivity between the two primary motor cortices (M1) has been investigated functionally in patients with multiple sclerosis. OBJECTIVES The aim of this study was to investigate whether connectivity between the dorsal premotor cortex and the contralateral M1 was altered in patients with multiple sclerosis, and to see whether clinical progression is accompanied by exacerbated dorsal premotor cortex-M1 disconnectivity. METHODS A twin-coil transcranial magnetic stimulation approach was used to investigate both excitatory and inhibitory interhemispheric connections between the left dorsal premotor cortex and the contralateral M1 in 18 multiple sclerosis patients without disability, in 18 multiple sclerosis patients with advanced disease and in 12 age-matched healthy subjects. To activate distinct inhibitory and facilitatory transcallosal pathways, the intensity of dorsal premotor cortex stimulation was adjusted to be either suprathreshold (110% of resting motor threshold) or subthreshold (80% of active motor threshold). RESULTS Our sample of patients with multiple sclerosis showed altered patterns of interhemispheric dorsal premotor cortex-M1 functional connectivity even in the absence of clinical deficits. Facilitatory connections originating from dorsal premotor cortex were reduced in multiple sclerosis patients with or without disability, while inhibitory dorsal premotor cortex-M1 connections were altered only in disabled patients. CONCLUSIONS The current study demonstrates that functional excitatory connectivity originating from non-primary motor areas is compromised in multiple sclerosis patients even in the absence of clinical disability. Clinical disease progression leads to an impairment of both excitatory and inhibitory transcallosal connections.
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Affiliation(s)
- Claudia Codecà
- Clinica Neurologica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy
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Langan J, Peltier SJ, Bo J, Fling BW, Welsh RC, Seidler RD. Functional implications of age differences in motor system connectivity. Front Syst Neurosci 2010; 4:17. [PMID: 20589101 PMCID: PMC2893009 DOI: 10.3389/fnsys.2010.00017] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 05/11/2010] [Indexed: 12/13/2022] Open
Abstract
Older adults show less lateralized task-related brain activity than young adults. One potential mechanism of this increased activation is that age-related degeneration of the corpus callosum (CC) may alter the balance of inhibition between the two hemispheres. To determine whether age differences in interhemispheric connectivity affect functional brain activity in older adults, we used magnetic resonance imaging (MRI) to assess resting functional connectivity and functional activation during a simple motor task. We found that older adults had smaller CC area compared to young adults. Older adults exhibited greater recruitment of ipsilateral primary motor cortex (M1), which was associated with longer reaction times. Additionally, recruitment of ipsilateral M1 in older adults was correlated with reduced resting interhemispheric connectivity and a larger CC. We suggest that reduced interhemispheric connectivity reflects a loss of the ability to inhibit the non-dominant hemisphere during motor task performance for older adults, which has a negative impact on performance.
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Affiliation(s)
- Jeanne Langan
- School of Kinesiology, University of Michigan Ann Arbor, MI, USA
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Conte A, Lenzi D, Frasca V, Gilio F, Giacomelli E, Gabriele M, Marini Bettolo C, Iacovelli E, Pantano P, Pozzilli C, Inghilleri M. Intracortical excitability in patients with relapsing–remitting and secondary progressive multiple sclerosis. J Neurol 2009; 256:933-8. [DOI: 10.1007/s00415-009-5047-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Revised: 01/15/2009] [Accepted: 01/20/2009] [Indexed: 11/30/2022]
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Thickbroom GW, Sacco P, Faulkner DL, Kermode AG, Mastaglia FL. Enhanced corticomotor excitability with dynamic fatiguing exercise of the lower limb in multiple sclerosis. J Neurol 2008; 255:1001-5. [DOI: 10.1007/s00415-008-0818-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 03/15/2007] [Accepted: 05/03/2007] [Indexed: 10/22/2022]
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Oulad Ben Taib N, Manto M. Reinstating the ability of the motor cortex to modulate cutaneomuscular reflexes in hemicerebellectomized rats. Brain Res 2008; 1204:59-68. [PMID: 18339362 DOI: 10.1016/j.brainres.2008.02.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2007] [Revised: 02/05/2008] [Accepted: 02/05/2008] [Indexed: 02/05/2023]
Abstract
The pathways passing through the cerebellum calibrate cutaneomuscular responses. Indeed, the enhancement of cutaneomuscular responses associated with subthreshold high-frequency trains of stimulation applied on motor cortex following a period of peripheral repetitive stimulation (PRS) is prevented by hemicerebellectomy. We analysed the effects of low-frequency repetitive stimulation of motor cortex (LFRSM1) on interhemispheric inhibition (IHI) and on the modulation of cutaneomuscular reflexes in rats with left hemicerebellar ablation. IHI was assessed by paired-pulse method with a conditioning stimulus (CS) to M1 followed by a test stimulus (TS) to the opposite M1. LFRSM1 reduced IHI. Combination of LFRSM1 with PRS increased significantly the magnitudes of cutaneomuscular responses evoked ipsilaterally to the hemicerebellar ablation. The increase of the intensity of cutaneomuscular responses was correlated with the reduction of IHI. Excitability of anterior horn motoneurons pool, assessed by F-wave, remained unchanged. Conjunction of LFRSM1 with PRS can be used to restore the ability of the motor cortex to modulate the intensity of cutaneomuscular responses in case of extensive unilateral cerebellar lesion. This study underlines for the first time the potential role of callosal pathways in the deficits of corticomotor tuning of cutaneomuscular responses contralaterally to acute extensive cerebellar lesion.
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Chen R, Cros D, Curra A, Di Lazzaro V, Lefaucheur JP, Magistris MR, Mills K, Rösler KM, Triggs WJ, Ugawa Y, Ziemann U. The clinical diagnostic utility of transcranial magnetic stimulation: Report of an IFCN committee. Clin Neurophysiol 2008; 119:504-532. [DOI: 10.1016/j.clinph.2007.10.014] [Citation(s) in RCA: 348] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 10/12/2007] [Accepted: 10/18/2007] [Indexed: 12/11/2022]
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Frye RE, Rotenberg A, Ousley M, Pascual-Leone A. Transcranial magnetic stimulation in child neurology: current and future directions. J Child Neurol 2008; 23:79-96. [PMID: 18056688 PMCID: PMC2539109 DOI: 10.1177/0883073807307972] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Transcranial magnetic stimulation (TMS) is a method for focal brain stimulation based on the principle of electromagnetic induction, where small intracranial electric currents are generated by a powerful, rapidly changing extracranial magnetic field. Over the past 2 decades TMS has shown promise in the diagnosis, monitoring, and treatment of neurological and psychiatric disease in adults, but has been used on a more limited basis in children. We reviewed the literature to identify potential diagnostic and therapeutic applications of TMS in child neurology and also its safety in pediatrics. Although TMS has not been associated with any serious side effects in children and appears to be well tolerated, general safety guidelines should be established. The potential for applications of TMS in child neurology and psychiatry is significant. Given its excellent safety profile and possible therapeutic effect, this technique should develop as an important tool in pediatric neurology over the next decade.
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Affiliation(s)
- Richard E. Frye
- Department of Pediatrics, Division of Child Neurology, University of Texas Health Science Center at Houston
| | - Alexander Rotenberg
- Department of Neurology, Children's Hospital Boston, Boston, Massachusetts, Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, Harvard Medical School, Boston, Massachusetts
| | | | - Alvaro Pascual-Leone
- Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, Harvard Medical School, Boston, Massachusetts, Institut Guttmann de Neurorehabilitació, Universitat Autónoma de Barcelona, Spain
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Lenzi D, Conte A, Mainero C, Frasca V, Fubelli F, Totaro P, Caramia F, Inghilleri M, Pozzilli C, Pantano P. Effect of corpus callosum damage on ipsilateral motor activation in patients with multiple sclerosis: a functional and anatomical study. Hum Brain Mapp 2007; 28:636-44. [PMID: 17080438 PMCID: PMC6871400 DOI: 10.1002/hbm.20305] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Functional MRI (fMRI) studies have shown increased activation of ipsilateral motor areas during hand movement in patients with multiple sclerosis (MS). We hypothesized that these changes could be due to disruption of transcallosal inhibitory pathways. We studied 18 patients with relapsing-remitting MS. Conventional T1- and T2-weighted images were acquired and lesion load (LL) measured. Diffusion tensor imaging (DTI) was performed to estimate fractional anisotropy (FA) and mean diffusivity (MD) in the body of the corpus callosum (CC). fMRI was obtained during a right-hand motor task. Patients were studied to evaluate transcallosal inhibition (TCI, latency and duration) and central conduction time (CCT). Eighteen normal subjects were studied with the same techniques. Patients showed increased MD (P < 0.0005) and reduced FA (P < 0.0005) in the body of the CC. Mean latency and duration of TCI were altered in 12 patients and absent in the others. Between-group analysis showed greater activation in patients in bilateral premotor, primary motor (M1), and middle cingulate cortices and in the ipsilateral supplementary motor area, insula, and thalamus. A multivariate analysis between activation patterns, structural MRI, and neurophysiological findings demonstrated positive correlations between T1-LL, MD in the body of CC, and activation of the ipsilateral motor cortex (iM1) in patients. Duration of TCI was negatively correlated with activation in the iM1. Our data suggest that functional changes in iM1 in patients with MS during a motor task partially represents a consequence of loss of transcallosal inhibitory fibers.
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Affiliation(s)
- Delia Lenzi
- Department of Neurological Sciences, University of Rome La Sapienza, Rome, Italy.
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Boërio D, Créange A, Hogrel JY, Lefaucheur JP. Alteration of motor nerve recovery cycle in multiple sclerosis. Clin Neurophysiol 2007; 118:1753-8. [PMID: 17573238 DOI: 10.1016/j.clinph.2007.04.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Revised: 04/04/2007] [Accepted: 04/30/2007] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To study peripheral motor nerve excitability in patients with multiple sclerosis (MS). METHODS Twenty MS patients with normal nerve conduction parameters and no predisposing factors for peripheral neuropathy were included. Compound muscle action potentials were recorded from the abductor digiti minimi muscle to paired-pulse stimulation of the ulnar nerve at the wrist, with various interstimuli intervals (ISIs) ranging from 1 to 7 ms. The motor nerve recovery cycle was studied using a subtraction method. We measured the durations of the absolute and relative refractory periods (ARP, RRP) and the percentages of refractoriness and supernormality at 2.6 and 7 ms ISIs. The results obtained in MS patients were compared to normative values established in 20 age-matched healthy subjects. Correlations were made between excitability parameters and MS type (relapsing-remitting or progressive), EDSS score, disease duration, and motor evoked potential (MEP) abnormalities. RESULTS Supernormality was extremely reduced, refractoriness was increased and both ARP and RRP were prolonged in MS patients vs. healthy controls. These alterations did not correlate to clinical features or to the presence of MEP abnormalities. CONCLUSIONS Changes in motor nerve recovery cycle revealed the existence of subtle impairment in the peripheral nervous system of MS patients, mainly characterized by a reduced supernormality. SIGNIFICANCE Peripheral nerve excitability alterations in MS may be due to axoglial paranodal dysjunction or juxtaparanodal dysfunction.
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Affiliation(s)
- Delphine Boërio
- Service de Physiologie, Explorations Fonctionnelles, Hôpital Henri Mondor, AP-HP, 51 avenue de Lattre de Tassigny, 94010 Créteil cedex, France
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Takeuchi N, Ikoma K, Chuma T, Matsuo Y. Measurement of transcallosal inhibition in traumatic brain injury by transcranial magnetic stimulation. Brain Inj 2007; 20:991-6. [PMID: 17046801 DOI: 10.1080/02699050600909771] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PRIMARY OBJECTIVE To study whether transcallosal inhibition (TCI) can evaluate the severity of traumatic brain injury (TBI). RESEARCH DESIGN Case-control study. METHODS AND PROCEDURES Twenty patients with a chronic TBI and 20 control subjects were studied. The following transcranial magnetic stimulation parameters were checked; resting motor threshold, central motor latency times, onset latency of TCI, duration of TCI, transcallosal conduction times and amount of TCI. The severity of TBI was evaluated using the Glasgow Coma Scale (GCS). MAIN OUTCOME AND RESULTS The amount of TCI was significantly lower in the patients than the control subjects (p < 0.001). The amount of TCI was highly correlated with the GCS (r = 0.787, p < 0.001). CONCLUSION An assessment of TCI was found to be a more sensitive and useful method for an evaluation of the severity of TBI.
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Affiliation(s)
- Naoyuki Takeuchi
- Department of Rehabilitation Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
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Schäfer R, Popp K, Jörgens S, Lindenberg R, Franz M, Seitz RJ. Alexithymia-like disorder in right anterior cingulate infarction. Neurocase 2007; 13:201-8. [PMID: 17786780 DOI: 10.1080/13554790701494964] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The frontal midline structures have been demonstrated by functional neuroimaging to be involved in the affective control of human behavior. However, due to the rareness of diseases affecting this part of the brain little is known about behavioral abnormalities following damage to these brain areas. We present a patient with a right anterior cingulate infarct who presented with an alexithymia-like disorder. Event-related potentials revealed an abnormality of emotional face perception in the right cerebral hemisphere. We suggest that the anterior cingulate lesion induced a deficit of emotion processing including emotional face perception probably due to an interference in a critical node of a large-scale network subserving affective control of behavior.
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Affiliation(s)
- Ralf Schäfer
- Institute of Psychosomatic Medicine and Psychotherapy, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
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Harris-Love ML, Cohen LG. Noninvasive cortical stimulation in neurorehabilitation: a review. Arch Phys Med Rehabil 2007; 87:S84-93. [PMID: 17140884 DOI: 10.1016/j.apmr.2006.08.330] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 08/02/2006] [Accepted: 08/02/2006] [Indexed: 12/13/2022]
Abstract
The purpose of this special communication is to provide an overview of noninvasive cortical stimulation techniques, the types of mechanistic information they can provide, and the ways their use is contributing to our understanding of current models of neurorehabilitation. The focus is primarily on studies using noninvasive cortical stimulation techniques in the human motor system. Noninvasive cortical stimulation techniques are useful tools in the field of neurorehabilitation that are being actively used to test proposed models of functional recovery after neurologic injury. They can provide insight into the physiologic mechanisms of functional recovery and are under investigation as a possible auxiliary intervention to modulate cortical excitability and enhance training effects.
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Affiliation(s)
- Michelle L Harris-Love
- Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
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Gagliardo A, Galli F, Grippo A, Amantini A, Martinelli C, Amato MP, Borsini W. Motor evoked potentials in multiple sclerosis patients without walking limitation: amplitude vs. conduction time abnormalities. J Neurol 2007; 254:220-7. [PMID: 17308868 DOI: 10.1007/s00415-006-0334-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2005] [Accepted: 04/05/2006] [Indexed: 10/23/2022]
Abstract
We used Motor Evoked Potentials (MEPs), elicited by transcranial magnetic stimulation, for assessing a motor pathways dysfunction in a selected group of Multiple Sclerosis (MS) patients, without limitation in walking. We selected 32 Relapsing Remitting MS patients, in remission phase, with EDSS < or = 3.5 and 20 healthy individuals with similar height and age distribution. We measured the following MEP parameters: motor thresholds; central motor conduction time (CMCT); amplitude and area, both expressed as MEP/CMAP ratio. Patients were divided into two groups according to the EDSS score: non-disabled group (ND; EDSS 0-1.5) and disabled group (D; EDSS 2-3.5). Mean average MEP values were significantly different in the patients compared with the controls. Even in MS patients with no or minor neurological signs (ND group), MEP parameters showed differences from controls and furthermore all MEP parameters were significantly different in the D group compared with the ND group. The 75% of the patients had an amplitude or area alteration; this percentage was significantly higher than the percentage of patients with a CMCT alteration (56.2%). In addition, CMCT increase was always associated with reduced amplitude and area, but amplitude and area alterations were present also in patients with normal CMCT. In early stages of MS, the higher percentage shown in alteration of MEP amplitudes and areas as opposed to CMCTs has not previously been highlighted in the literature. Independently of its pathogenesis (demyelination or axonal loss), the amplitude or area decrease should be considered in clinical trials and in follow-up studies, as a marker of the motor pathways dysfunction, at least as much as CMCT increase.
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Affiliation(s)
- Andrea Gagliardo
- Clinical Neurophysiology Unit, Department of Neurological and Psychiatric Sciences, Careggi Hospital, University of Florence, Viale Morgagni 85, 50100 Florence, Italy.
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Feuillet L, Pelletier J, Suchet L, Rico A, Ali Cherif A, Pouget J, Attarian S. Prospective clinical and electrophysiological follow-up on a multiple sclerosis population treated with interferon beta-1 a. Mult Scler 2007; 13:348-56. [PMID: 17439904 DOI: 10.1177/1352458506070235] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Objective To analyse transcranial magnetic stimulation (TMS) variables in a prospective six-month follow-up pilot study on patients suffering from relapsing-remitting multiple sclerosis (RRMS), satisfying inclusion criteria for interferon (IFN) beta-1a treatment. Background So far, no predictive factors are available as to the course of RRMS treated with IFN beta-1 a. Design/methods Fifteen RRMS patients were studied before (month 0 (M0)) and after IFN beta-1a onset (M3, M6). The parameters analysed were motor functional score (mFS), Expanded Disability Status Scale (EDSS), and TMS variables - central motor conduction time (CMCT) and amplitude ratio (AR). Results Four of the six patients with no motor signs at inclusion, subsequently showed signs of pyramidal dysfunction. All had abnormal M0_TMS variables. The number of M0_TMS abnormalities per patient was greatest in the group that showed mFS worsening, and was significantly correlated with M6_EDSS. The M0_CMCT was significantly correlated with M6_EDSS. During follow-up, the number of patients with abnormal TMS variables decreased from 12/15 to 4/15, and the total number of abnormalities decreased from 33.3 to 16.7%. Conclusions TMS variables might be predictive of disease progression. The improvement observed here in the TMS variables may reflect an improvement in MS patients undergoing IFN beta treatment. Multiple Sclerosis 2007; 13: 348-356. http://msj.sagepub.com
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Affiliation(s)
- L Feuillet
- Department of Neurology, Faculté de Médecine de Marseille, Université de la Méditerranée, Hôpital de La Timone, Marseille, France.
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