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Tam PK, Oey NE, Tang N, Ramamurthy G, Chew E. Facilitating Corticomotor Excitability of the Contralesional Hemisphere Using Non-Invasive Brain Stimulation to Improve Upper Limb Motor Recovery from Stroke-A Scoping Review. J Clin Med 2024; 13:4420. [PMID: 39124687 PMCID: PMC11313572 DOI: 10.3390/jcm13154420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2024] [Revised: 07/18/2024] [Accepted: 07/25/2024] [Indexed: 08/12/2024] Open
Abstract
Upper limb weakness following stroke poses a significant global psychosocial and economic burden. Non-invasive brain stimulation (NIBS) is a potential adjunctive treatment in rehabilitation. However, traditional approaches to rebalance interhemispheric inhibition may not be effective for all patients. The supportive role of the contralesional hemisphere in recovery of upper limb motor function has been supported by animal and clinical studies, particularly for those with severe strokes. This review aims to provide an overview of the facilitation role of the contralesional hemisphere for post-stroke motor recovery. While more studies are required to predict responses and inform the choice of NIBS approach, contralesional facilitation may offer new hope for patients in whom traditional rehabilitation and NIBS approaches have failed.
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Affiliation(s)
- Pui Kit Tam
- Division of Rehabilitation Medicine, Department of Medicine, National University Hospital, Singapore 119228, Singapore; (P.K.T.); (N.E.O.); (N.T.)
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117549, Singapore
| | - Nicodemus Edrick Oey
- Division of Rehabilitation Medicine, Department of Medicine, National University Hospital, Singapore 119228, Singapore; (P.K.T.); (N.E.O.); (N.T.)
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117549, Singapore
| | - Ning Tang
- Division of Rehabilitation Medicine, Department of Medicine, National University Hospital, Singapore 119228, Singapore; (P.K.T.); (N.E.O.); (N.T.)
| | - Guhan Ramamurthy
- BG Institute of Neurosciences, BG Hospital, Tiruchendur, Tuticorin 628216, Tamil Nadu, India;
| | - Effie Chew
- Division of Rehabilitation Medicine, Department of Medicine, National University Hospital, Singapore 119228, Singapore; (P.K.T.); (N.E.O.); (N.T.)
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117549, Singapore
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2
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Tan S, Faull RLM, Curtis MA. The tracts, cytoarchitecture, and neurochemistry of the spinal cord. Anat Rec (Hoboken) 2023; 306:777-819. [PMID: 36099279 DOI: 10.1002/ar.25079] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 08/01/2022] [Accepted: 09/11/2022] [Indexed: 11/06/2022]
Abstract
The human spinal cord can be described using a range of nomenclatures with each providing insight into its structure and function. Here we have comprehensively reviewed the key literature detailing the general structure, configuration of tracts, the cytoarchitecture of Rexed's laminae, and the neurochemistry at the spinal segmental level. The purpose of this review is to detail current anatomical understanding of how the spinal cord is structured and to aid researchers in identifying gaps in the literature that need to be studied to improve our knowledge of the spinal cord which in turn will improve the potential of therapeutic intervention for disorders of the spinal cord.
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Affiliation(s)
- Sheryl Tan
- Centre for Brain Research and Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
| | - Richard L M Faull
- Centre for Brain Research and Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
| | - Maurice A Curtis
- Centre for Brain Research and Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
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3
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Razak RA, Hannanu FF, Naegele B, Hommel MJG, Detante O, Jaillard A. Ipsilateral hand impairment predicts long-term outcome in patients with subacute stroke. Eur J Neurol 2022; 29:1983-1993. [PMID: 35276028 DOI: 10.1111/ene.15323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 02/24/2022] [Accepted: 02/25/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND Ipsilateral hand (ILH) impairment is documented following motor stroke, but its impact on long-term outcome remains unknown. We assessed ILH impairment in subacute stroke and tested whether ILH impairment predicted long-term outcome. METHODS We performed a longitudinal study in 209 consecutive patients with unilateral stroke and sensorimotor deficit at admission. ILH impairment was evaluated using Purdue Pegboard Test (PPT) and handgrip strength and defined as mild (z-score <-1) or moderate (z-score <-1.65). We used logistic regression (LR) to predict outcome assessed 9 (7-12) months post-stroke with the modified Rankin scale (mRS) categorized into good (mRS≤1) and poor outcome (mRS≥2). For internal validation, LR-bootstrapping, and cross-validation with Lasso and Random-Forest were performed. RESULTS ILH impairment assessed at 89.04 ±45.82 days post-stroke was moderate in 10.53% (95% CI, 6.7, 14.83) for PPT and 17.22% (95% CI, 11.96, 22.49) for grip, and mild in 21.05% (95% CI, 15.78, 26.79) for PPT and 35.89 (95% CI, 29.67, 42.58) for grip. Good outcome was predicted by ILH-PPT (B=1.03 [95% CI, 0.39, 3.31]), ILH-grip (B=1.16 [95% CI, 0.54, 3.53]), low NIHSS-discharge (B=-1.57, [95% CI, -4.0, -1.19]), and no depression (B=-0.62, [95% CI, -1.63, -0.43]), accounting for stroke delay (B=-0.011, [95% CI, -0.06, 0.01]). Model efficiency was 91.6% (AUC=0.977, 95%CI, 0.959, 0.996). Lasso and Random-Forest methods provided similar results, confirming the LR model robustness. CONCLUSIONS ILH impairment is frequent after motor stroke and predicts long-term outcome. We propose to integrate ILH impairment in rehabilitation programs to improve recovery and serve research interventions such as neuromodulation.
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Affiliation(s)
- Rien Anggraini Razak
- AGEIS, EA 7407, Université Grenoble Alpes (UGA), Grenoble, France.,Unité IRM 3T Recherche - IRMaGe, Inserm-US17-CNRS-UMS-3552, UGA, Centre Hospitalier Universitaire de Grenoble Alpes (CHUGA), France.,Medical Faculty of Hasanuddin University, Makassar, Indonesia
| | - Firdaus Fabrice Hannanu
- AGEIS, EA 7407, Université Grenoble Alpes (UGA), Grenoble, France.,Unité IRM 3T Recherche - IRMaGe, Inserm-US17-CNRS-UMS-3552, UGA, Centre Hospitalier Universitaire de Grenoble Alpes (CHUGA), France.,Medical Faculty of Hasanuddin University, Makassar, Indonesia
| | | | - Marc J G Hommel
- AGEIS, EA 7407, Université Grenoble Alpes (UGA), Grenoble, France
| | | | - Assia Jaillard
- AGEIS, EA 7407, Université Grenoble Alpes (UGA), Grenoble, France.,Unité IRM 3T Recherche - IRMaGe, Inserm-US17-CNRS-UMS-3552, UGA, Centre Hospitalier Universitaire de Grenoble Alpes (CHUGA), France.,Pôle Recherche, CHUGA
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4
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Tavazzi E, Bergsland N, Pirastru A, Cazzoli M, Blasi V, Baglio F. MRI markers of functional connectivity and tissue microstructure in stroke-related motor rehabilitation: A systematic review. Neuroimage Clin 2021; 33:102931. [PMID: 34995869 PMCID: PMC8741615 DOI: 10.1016/j.nicl.2021.102931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 12/27/2021] [Accepted: 12/28/2021] [Indexed: 12/18/2022]
Abstract
BACKGROUND Stroke-related disability is a major problem at individual and socio-economic levels. Neuromotor rehabilitation has a key role for its dual action on affected body segment and brain reorganization. Despite its known efficacy in clinical practice, the extent and type of effect at a brain level, mediated by neuroplasticity, are still under question. OBJECTIVE To analyze studies applying MRI markers of functional and structural connectivity in patients affected with stroke undergoing motor rehabilitation, and to evaluate the effect of rehabilitation on brain reorganization. METHODS Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria were applied to select studies applying quantitative non-conventional MRI techniques on patients undergoing motor rehabilitation, both physical and virtual (virtual reality, mental imagery). Literature search was conducted using MEDLINE (via PubMed), Cochrane Central Register of Controlled Trials (CENTRAL), and EMBASE from inception to 30th June 2020. RESULTS Forty-one out of 6983 papers were included in the current review. Selected studies are heterogeneous in terms of patient characteristics as well as type, duration and frequency of rehabilitative approach. Neuromotor rehabilitation promotes neuroplasticity, favoring functional recovery of the ipsilesional hemisphere and activation of anatomically and functionally related brain areas in both hemispheres, to compensate for damaged tissue. CONCLUSIONS The evidence derived from the analyzed studies supports the positive impact of rehabilitation on brain reorganization, despite the high data heterogeneity. Advanced MRI techniques provide reliable markers of structural and functional connectivity that may potentially aid in helping to implement the most appropriate rehabilitation intervention.
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Affiliation(s)
- E Tavazzi
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy; Department of Neurology, Buffalo Neuroimaging Analysis Center, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - N Bergsland
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy; Department of Neurology, Buffalo Neuroimaging Analysis Center, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States.
| | - A Pirastru
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
| | - M Cazzoli
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
| | - V Blasi
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
| | - F Baglio
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
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5
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Calvert GHM, Carson RG. Neural mechanisms mediating cross education: With additional considerations for the ageing brain. Neurosci Biobehav Rev 2021; 132:260-288. [PMID: 34801578 DOI: 10.1016/j.neubiorev.2021.11.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 11/03/2021] [Accepted: 11/16/2021] [Indexed: 12/14/2022]
Abstract
CALVERT, G.H.M., and CARSON, R.G. Neural mechanisms mediating cross education: With additional considerations for the ageing brain. NEUROSCI BIOBEHAV REV 21(1) XXX-XXX, 2021. - Cross education (CE) is the process whereby a regimen of unilateral limb training engenders bilateral improvements in motor function. The contralateral gains thus derived may impart therapeutic benefits for patients with unilateral deficits arising from orthopaedic injury or stroke. Despite this prospective therapeutic utility, there is little consensus concerning its mechanistic basis. The precise means through which the neuroanatomical structures and cellular processes that mediate CE may be influenced by age-related neurodegeneration are also almost entirely unknown. Notwithstanding the increased incidence of unilateral impairment in later life, age-related variations in the expression of CE have been examined only infrequently. In this narrative review, we consider several mechanisms which may mediate the expression of CE with specific reference to the ageing CNS. We focus on the adaptive potential of cellular processes that are subserved by a specific set of neuroanatomical pathways including: the corticospinal tract, corticoreticulospinal projections, transcallosal fibres, and thalamocortical radiations. This analysis may inform the development of interventions that exploit the therapeutic utility of CE training in older persons.
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Affiliation(s)
- Glenn H M Calvert
- Trinity College Institute of Neuroscience and School of Psychology, Trinity College Dublin, Dublin, Ireland
| | - Richard G Carson
- Trinity College Institute of Neuroscience and School of Psychology, Trinity College Dublin, Dublin, Ireland; School of Psychology, Queen's University Belfast, Belfast, Northern Ireland, UK; School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Australia.
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6
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Hu D, Wang S, Li B, Liu H, He J. Spinal Cord Injury-Induced Changes in Encoding and Decoding of Bipedal Walking by Motor Cortical Ensembles. Brain Sci 2021; 11:brainsci11091193. [PMID: 34573213 PMCID: PMC8469283 DOI: 10.3390/brainsci11091193] [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: 07/09/2021] [Revised: 08/30/2021] [Accepted: 09/07/2021] [Indexed: 11/24/2022] Open
Abstract
Recent studies have shown that motor recovery following spinal cord injury (SCI) is task-specific. However, most consequential conclusions about locomotor functional recovery from SCI have been derived from quadrupedal locomotion paradigms. In this study, two monkeys were trained to perform a bipedal walking task, mimicking human walking, before and after T8 spinal cord hemisection. Importantly, there is no pharmacological therapy with nerve growth factor for monkeys after SCI; thus, in this study, the changes that occurred in the brain were spontaneous. The impairment of locomotion on the ipsilateral side was more severe than that on the contralateral side. We used information theory to analyze single-cell activity from the left primary motor cortex (M1), and results show that neuronal populations in the unilateral primary motor cortex gradually conveyed more information about the bilateral hindlimb muscle activities during the training of bipedal walking after SCI. We further demonstrated that, after SCI, progressively expanded information from the neuronal population reconstructed more accurate control of muscle activity. These results suggest that, after SCI, the unilateral primary motor cortex could gradually regain control of bilateral coordination and motor recovery and in turn enhance the performance of brain–machine interfaces.
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Affiliation(s)
- Dingyin Hu
- School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China; (B.L.); (H.L.); (J.H.)
- Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing 100081, China;
- Correspondence:
| | - Shirong Wang
- Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing 100081, China;
| | - Bo Li
- School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China; (B.L.); (H.L.); (J.H.)
| | - Honghao Liu
- School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China; (B.L.); (H.L.); (J.H.)
| | - Jiping He
- School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China; (B.L.); (H.L.); (J.H.)
- Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing 100081, China;
- Center for Neural Interface Design, School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ 86287, USA
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7
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Taga M, Charalambous CC, Raju S, Lin J, Zhang Y, Stern E, Schambra HM. Corticoreticulospinal tract neurophysiology in an arm and hand muscle in healthy and stroke subjects. J Physiol 2021; 599:3955-3971. [PMID: 34229359 DOI: 10.1113/jp281681] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 06/30/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The corticoreticulospinal tract (CReST) is a descending motor pathway that reorganizes after corticospinal tract (CST) injury in animals. In humans, the pattern of CReST innervation to upper limb muscles has not been carefully examined in healthy individuals or individuals with CST injury. In the present study, we assessed CReST projections to an arm and hand muscle on the same side of the body in healthy and chronic stoke subjects using transcranial magnetic stimulation. We show that CReST connection strength to the muscles differs between healthy and stroke subjects, with stronger connections to the hand than arm in healthy subjects, and stronger connections to the arm than hand in stroke subjects. These results help us better understand CReST innervation patterns in the upper limb, and may point to its role in normal motor function and motor recovery in humans. ABSTRACT The corticoreticulospinal tract (CReST) is a major descending motor pathway in many animals, but little is known about its innervation patterns in proximal and distal upper extremity muscles in humans. The contralesional CReST furthermore reorganizes after corticospinal tract (CST) injury in animals, but it is less clear whether CReST innervation changes after stroke in humans. We thus examined CReST functional connectivity, connection strength, and modulation in an arm and hand muscle of healthy (n = 15) and chronic stroke (n = 16) subjects. We delivered transcranial magnetic stimulation to the contralesional hemisphere (assigned in healthy subjects) to elicit ipsilateral motor evoked potentials (iMEPs) from the paretic biceps (BIC) and first dorsal interosseous (FDI) muscle. We operationalized CReST functional connectivity as iMEP presence/absence, CReST projection strength as iMEP size and CReST modulation as change in iMEP size by head rotation. We found comparable CReST functional connectivity to the BICs and FDIs in both subject groups. However, the pattern of CReST connection strength to the muscles diverged between groups, with stronger connections to FDIs than BICs in healthy subjects and stronger connections to BICs than FDIs in stroke subjects. Head rotation modulated only FDI iMEPs of healthy subjects. Our findings indicate that the healthy CReST does not have a proximal innervation bias, and its strong FDI connections may have functional relevance to finger individuation. The reversed CReST innervation pattern in stroke subjects confirms its reorganization after CST injury, and its strong BIC connections may indicate upregulation for particular upper extremity muscles or their functional actions.
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Affiliation(s)
- Myriam Taga
- Department of Neurology, School of Medicine, NYU Langone, New York, NY, USA
| | - Charalambos C Charalambous
- Department of Neurology, School of Medicine, NYU Langone, New York, NY, USA.,Department of Basic and Clinical Sciences, University of Nicosia Medical School, Nicosia, Cyprus.,Center for Neuroscience and Integrative Brain Research (CENIBRE), University of Nicosia Medical School, Nicosia, Cyprus
| | - Sharmila Raju
- Department of Neurology, School of Medicine, NYU Langone, New York, NY, USA
| | - Jing Lin
- Department of Neurology, School of Medicine, NYU Langone, New York, NY, USA
| | - Yian Zhang
- Division of Biostatistics, Department of Population Health, School of Medicine, New York University, New York, NY, USA
| | - Elisa Stern
- Department of Neurology, School of Medicine, NYU Langone, New York, NY, USA
| | - Heidi M Schambra
- Department of Neurology, School of Medicine, NYU Langone, New York, NY, USA
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Cleland BT, Sisel E, Madhavan S. Motor evoked potential latency and duration from tibialis anterior in individuals with chronic stroke. Exp Brain Res 2021; 239:2251-2260. [PMID: 34059935 DOI: 10.1007/s00221-021-06144-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 05/26/2021] [Indexed: 11/26/2022]
Abstract
Ipsilateral motor pathways from the contralesional hemisphere to the paretic limbs may be upregulated to compensate for impaired function after stroke. Onset latency and duration of motor evoked potentials (MEPs) evoked by transcranial magnetic stimulation (TMS) provide insight into compensatory pathways but have been understudied in the lower limb. This study assessed MEP onset latency and duration in the lower limb after stroke, and compared ipsilateral and contralateral MEPs in the paretic and non-paretic limb. We hypothesized that: (1) onset latency would be longer for ipsilateral than contralateral MEPs and longer for the paretic than the non-paretic limb, and (2) duration would be shorter for ipsilateral than contralateral MEPs and longer for the paretic than the non-paretic limb. Data were collected as a part of a pre-test of a randomized controlled trial. TMS was applied to the ipsilateral and contralateral hemisphere of the paretic and non-paretic limb. MEP onset latency and duration were calculated from the tibialis anterior. Thirty-five participants with chronic stroke were included in the final analysis. Onset latency was longer in the paretic than the non-paretic limb (~ 6.0 ms) and longer after ipsilateral than contralateral stimulation (~ 1.8 ms). Duration was longer in the paretic than the non-paretic limb (~ 9.2 ms) and longer after contralateral than ipsilateral stimulation (~ 5.2 ms). Ipsilateral MEPs may be elicited through ipsilateral pathways with fewer fibers with a higher activation threshold and/or greater spinal branching. MEPs from the paretic limb may reflect slower central motor conduction, peripheral changes, or changes in motor pathway.
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Affiliation(s)
- Brice T Cleland
- Brain Plasticity Lab, Department of Physical Therapy, College of Applied Health Sciences, University of Illinois at Chicago, 1919 W. Taylor St., Chicago, IL, 60612, USA
| | - Emily Sisel
- College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Sangeetha Madhavan
- Brain Plasticity Lab, Department of Physical Therapy, College of Applied Health Sciences, University of Illinois at Chicago, 1919 W. Taylor St., Chicago, IL, 60612, USA.
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9
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Berger P. A review of physical modalities and the potential to expand the treatment of patients with traumatic brain injury. Acupunct Med 2019; 37:365-369. [PMID: 31032621 DOI: 10.1177/0964528419844264] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Traumatic brain injuries (TBIs) and hemiplegia often involve alterations in cortical function that are often widespread and may not be confined to the peri-infarct regions. Rehabilitation of these injuries may therefore require extensive and innovative physical modalities and exercise activities that enhance mobility. Disuse in limbs can occur in any brain injury derived from different etiologies and advances in rehabilitation indicate that neuromuscular stimulation of both the nerve supply and muscle groups involved impacts plasticity and prepares the limbs for stronger muscle responses during functional activities. Combined therapies are apparently more productive than monotherapies and this may include electroacupuncture and functional electrical stimulation to expedite recovery. The combination of mixed physiotherapeutic interventions also encourages biokinetics, hydrotherapy and robotic rehabilitation over a prolonged period to enable the patient to achieve functional goals. Recovery may not be achieved within a period of 6 months post injury as has previously been accepted and may even require lifelong participation.
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Affiliation(s)
- Phyllis Berger
- Department of Physiotherapy, School of Therapeutic Sciences, University of the Witwatersrand, Johannesburg, South Africa
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10
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Non-invasive brain stimulation in the modulation of cerebral blood flow after stroke: A systematic review of Transcranial Doppler studies. Clin Neurophysiol 2018; 129:2544-2551. [PMID: 30384025 DOI: 10.1016/j.clinph.2018.09.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 09/13/2018] [Accepted: 09/18/2018] [Indexed: 11/21/2022]
Abstract
OBJECTIVE Non-invasive brain stimulation (NIBS), such as repetitive TMS (rTMS) and transcranial direct current stimulation (tDCS), are promising neuromodulatory priming techniques to promote task-specific functional recovery after stroke. Despite promising results, clinical application of NIBS has been limited by high inter-individual variability. We propose that there is a possible influence of neuromodulation on cerebral blood flow (CBF), as neurons are spatially and temporally related to blood vessels. Transcranial Doppler (TCD), a clinically available non-invasive diagnostic tool, allows for evaluation of CBF velocity (CBFv). However, little is known about the role of neuromodulation on CBFv. METHODS A systematic review of literature to understand the effects of NIBS on CBFv using TCD in stroke was conducted. RESULTS Twelve studies fit our inclusion criteria and are included in this review. Our review suggested that CBFv and/or vasomotor reactivity maybe influenced by rTMS dosage (intensity and frequency) and the type of tDCS electrode montage. CONCLUSION There is limited evidence regarding the effects of NIBS on cerebral hemodynamics using TCD and the usefulness of TCD to capture changes in CBFv after NIBS is not evident from this review. We highlight the variability in the experimental protocols, differences in the applied neurostimulation protocols and discuss open questions that remain regarding CBF and neuromodulation. SIGNIFICANCE TCD, a clinically accessible tool, may potentially be useful to understand the interaction between cortical neuromodulation and CBFv.
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11
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Simon JJ, Welfringer A, Leifert-Fiebach G, Brandt T. Motor imagery in chronic neglect: An fMRI pilot study. J Clin Exp Neuropsychol 2018; 41:58-68. [PMID: 30080434 DOI: 10.1080/13803395.2018.1500527] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
AIM Previous studies indicate the effectiveness of motor imagery training in stroke patients. To determine whether patients showing chronic visuospatial neglect symptoms may profit from motor imagery training, it is important to assess how the brain implements motor imagery when cortical systems involved in attentional control are impaired. METHOD Therefore, in this pilot study, nine chronic neglect patients with right-hemispheric stroke performed motor imagery of a finger opposition task during functional magnetic resonance imaging (fMRI). RESULTS Imagery of unaffected hand movements was related to activations in the left primary somatosensory and premotor cortices as well as in the left supplementary motor area. During the imagery of the affected hand, patients displayed activations in the left premotor cortex and supplementary motor area as well as left dorsolateral prefrontal cortex. Furthermore, time since onset and visual imagery capacity were negatively related to activation in the supplementary motor area during the imagery of the affected hand. CONCLUSIONS These initial results demonstrate motor imagery capacity in patients with chronic neglect via compensatory neural processing during motor imagery of the affected hand in ipsilateral brain regions, since we found that the supplementary motor area appears to be specifically related to neglect severity. Although our results must be treated with caution due to the small sample size and missing control group, they indicate that neglect is not necessarily an exclusion criterion for motor imagery training per se.
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Affiliation(s)
- Joe J Simon
- a Department of General Internal Medicine and Psychosomatics, Centre for Psychosocial Medicine , University Hospital Heidelberg , Heidelberg , Germany.,b Department of Psychosomatic Medicine and Psychotherapy, Medical Faculty , Heinrich-Heine-University Düsseldorf , Düsseldorf , Germany
| | | | | | - Tobias Brandt
- d Department of Neurology , University of Heidelberg , Heidelberg , Germany.,e Suva, Insurance Medicine , Luzern , Switzerland
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12
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Winstein C, Varghese R. Been there, done that, so what’s next for arm and hand rehabilitation in stroke? NeuroRehabilitation 2018; 43:3-18. [DOI: 10.3233/nre-172412] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Carolee Winstein
- Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, USA
| | - Rini Varghese
- Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, USA
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13
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Gould L, Kelly ME, Mickleborough MJS, Ekstrand C, Brymer K, Ellchuk T, Borowsky R. Reorganized neural activation in motor cortex following subdural fluid collection: an fMRI and DTI study. Neurocase 2017; 23:292-303. [PMID: 29063812 DOI: 10.1080/13554794.2017.1395056] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We report a patient with a cavernous malformation involving the right lentiform nucleus. Pre-surgical planning included fMRI localization of language, motor, and sensory processing, and DTI of white matter tracts. fMRI results revealed no activation near the planned resection zone. However, post-surgery the patient developed a subdural fluid collection, which applied pressure to the primary motor cortex (M1). Follow-up scans revealed that motor activation had shifted due to pressure, and then shifted to a new location after the fluid collection subsided. This case report suggests that long-term neural reorganization can occur in response to short term compression in the cortex.
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Affiliation(s)
- Layla Gould
- a Department of Surgery, Division of Neurosurgery , Saskatoon , SK , Canada.,b College of Kinesiology , University of Saskatchewan , Saskatoon , SK , Canada
| | - Michael E Kelly
- a Department of Surgery, Division of Neurosurgery , Saskatoon , SK , Canada
| | | | - Chelsea Ekstrand
- c Department of Psychology , University of Saskatchewan , Saskatoon , SK , Canada
| | - Kyle Brymer
- c Department of Psychology , University of Saskatchewan , Saskatoon , SK , Canada
| | - Tasha Ellchuk
- d Department of Medical Imaging , Royal University Hospital , SK , Canada
| | - Ron Borowsky
- a Department of Surgery, Division of Neurosurgery , Saskatoon , SK , Canada.,c Department of Psychology , University of Saskatchewan , Saskatoon , SK , Canada
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McDonnell MN, Stinear CM. TMS measures of motor cortex function after stroke: A meta-analysis. Brain Stimul 2017; 10:721-734. [DOI: 10.1016/j.brs.2017.03.008] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 01/27/2017] [Accepted: 03/20/2017] [Indexed: 01/05/2023] Open
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Chen CC, Lee SH, Wang WJ, Lin YC, Su MC. EEG-based motor network biomarkers for identifying target patients with stroke for upper limb rehabilitation and its construct validity. PLoS One 2017; 12:e0178822. [PMID: 28614395 PMCID: PMC5470671 DOI: 10.1371/journal.pone.0178822] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 05/21/2017] [Indexed: 01/30/2023] Open
Abstract
Rehabilitation is the main therapeutic approach for reducing poststroke functional deficits in the affected upper limb; however, significant between-patient variability in rehabilitation efficacy indicates the need to target patients who are likely to have clinically significant improvement after treatment. Many studies have determined robust predictors of recovery and treatment gains and yielded many great results using linear approachs. Evidence has emerged that the nonlinearity is a crucial aspect to study the inter-areal communication in human brains and abnormality of oscillatory activities in the motor system is linked to the pathological states. In this study, we hypothesized that combinations of linear and nonlinear (cross-frequency) network connectivity parameters are favourable biomarkers for stratifying patients for upper limb rehabilitation with increased accuracy. We identified the biomarkers by using 37 prerehabilitation electroencephalogram (EEG) datasets during a movement task through effective connectivity and logistic regression analyses. The predictive power of these biomarkers was then tested by using 16 independent datasets (i.e. construct validation). In addition, 14 right handed healthy subjects were also enrolled for comparisons. The result shows that the beta plus gamma or theta network features provided the best classification accuracy of 92%. The predictive value and the sensitivity of these biomarkers were 81.3% and 90.9%, respectively. Subcortical lesion, the time poststroke and initial Wolf Motor Function Test (WMFT) score were identified as the most significant clinical variables affecting the classification accuracy of this predictive model. Moreover, 12 of 14 normal controls were classified as having favourable recovery. In conclusion, EEG-based linear and nonlinear motor network biomarkers are robust and can help clinical decision making.
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Affiliation(s)
- Chun-Chuan Chen
- Department of Biomedical Sciences and Engineering, National Central University, Taoyuan, Taiwan, R. O. C
- * E-mail:
| | - Si-Huei Lee
- Department of Physical medicine and Rehabilitation, Taipei Veterans General Hospital, Taiepi, Taiwan, R. O. C
- Department of Medicine, College of Medicine, National Yang Ming University, Taipei, Taiwan, R. O. C
| | - Wei-Jen Wang
- Department of Computer Science and Information Engineering, National Central University, Taoyuan, Taiwan, R. O. C
| | - Yu-Chen Lin
- Department of Biomedical Sciences and Engineering, National Central University, Taoyuan, Taiwan, R. O. C
| | - Mu-Chun Su
- Department of Computer Science and Information Engineering, National Central University, Taoyuan, Taiwan, R. O. C
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Evidence-based guidelines on the therapeutic use of transcranial direct current stimulation (tDCS). Clin Neurophysiol 2016; 128:56-92. [PMID: 27866120 DOI: 10.1016/j.clinph.2016.10.087] [Citation(s) in RCA: 1049] [Impact Index Per Article: 131.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 10/18/2016] [Accepted: 10/20/2016] [Indexed: 12/19/2022]
Abstract
A group of European experts was commissioned by the European Chapter of the International Federation of Clinical Neurophysiology to gather knowledge about the state of the art of the therapeutic use of transcranial direct current stimulation (tDCS) from studies published up until September 2016, regarding pain, Parkinson's disease, other movement disorders, motor stroke, poststroke aphasia, multiple sclerosis, epilepsy, consciousness disorders, Alzheimer's disease, tinnitus, depression, schizophrenia, and craving/addiction. The evidence-based analysis included only studies based on repeated tDCS sessions with sham tDCS control procedure; 25 patients or more having received active treatment was required for Class I, while a lower number of 10-24 patients was accepted for Class II studies. Current evidence does not allow making any recommendation of Level A (definite efficacy) for any indication. Level B recommendation (probable efficacy) is proposed for: (i) anodal tDCS of the left primary motor cortex (M1) (with right orbitofrontal cathode) in fibromyalgia; (ii) anodal tDCS of the left dorsolateral prefrontal cortex (DLPFC) (with right orbitofrontal cathode) in major depressive episode without drug resistance; (iii) anodal tDCS of the right DLPFC (with left DLPFC cathode) in addiction/craving. Level C recommendation (possible efficacy) is proposed for anodal tDCS of the left M1 (or contralateral to pain side, with right orbitofrontal cathode) in chronic lower limb neuropathic pain secondary to spinal cord lesion. Conversely, Level B recommendation (probable inefficacy) is conferred on the absence of clinical effects of: (i) anodal tDCS of the left temporal cortex (with right orbitofrontal cathode) in tinnitus; (ii) anodal tDCS of the left DLPFC (with right orbitofrontal cathode) in drug-resistant major depressive episode. It remains to be clarified whether the probable or possible therapeutic effects of tDCS are clinically meaningful and how to optimally perform tDCS in a therapeutic setting. In addition, the easy management and low cost of tDCS devices allow at home use by the patient, but this might raise ethical and legal concerns with regard to potential misuse or overuse. We must be careful to avoid inappropriate applications of this technique by ensuring rigorous training of the professionals and education of the patients.
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Pruitt DT, Schmid AN, Danaphongse TT, Flanagan KE, Morrison RA, Kilgard MP, Rennaker RL, Hays SA. Forelimb training drives transient map reorganization in ipsilateral motor cortex. Behav Brain Res 2016; 313:10-16. [PMID: 27392641 DOI: 10.1016/j.bbr.2016.07.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 06/06/2016] [Accepted: 07/04/2016] [Indexed: 01/01/2023]
Abstract
Skilled motor training results in reorganization of contralateral motor cortex movement representations. The ipsilateral motor cortex is believed to play a role in skilled motor control, but little is known about how training influences reorganization of ipsilateral motor representations of the trained limb. To determine whether training results in reorganization of ipsilateral motor cortex maps, rats were trained to perform the isometric pull task, an automated motor task that requires skilled forelimb use. After either 3 or 6 months of training, intracortical microstimulation (ICMS) mapping was performed to document motor representations of the trained forelimb in the hemisphere ipsilateral to that limb. Motor training for 3 months resulted in a robust expansion of right forelimb representation in the right motor cortex, demonstrating that skilled motor training drives map plasticity ipsilateral to the trained limb. After 6 months of training, the right forelimb representation in the right motor cortex was significantly smaller than the representation observed in rats trained for 3 months and similar to untrained controls, consistent with a normalization of motor cortex maps. Forelimb map area was not correlated with performance on the trained task, suggesting that task performance is maintained despite normalization of cortical maps. This study provides new insights into how the ipsilateral cortex changes in response to skilled learning and may inform rehabilitative strategies to enhance cortical plasticity to support recovery after brain injury.
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Affiliation(s)
- David T Pruitt
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States.
| | - Ariel N Schmid
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Tanya T Danaphongse
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Kate E Flanagan
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Robert A Morrison
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Michael P Kilgard
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Robert L Rennaker
- The University of Texas at Dallas, School of Behavioral Brain Sciences, 800 West Campbell Road, GR41, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
| | - Seth A Hays
- The University of Texas at Dallas, Erik Jonsson School of Engineering and Computer Science, 800 West Campbell Road, Richardson, TX 75080-3021, United States; The University of Texas at Dallas, Texas Biomedical Device Center, 800 West Campbell Road, Richardson, TX 75080-3021, United States
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18
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The value of preoperative functional cortical mapping using navigated TMS. Neurophysiol Clin 2016; 46:125-33. [PMID: 27229765 DOI: 10.1016/j.neucli.2016.05.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Accepted: 05/02/2016] [Indexed: 01/29/2023] Open
Abstract
The surgical removal of brain tumours in so-called eloquent regions is frequently associated with a high risk of causing disabling postoperative deficits. Among the preoperative techniques proposed to help neurosurgical planning and procedure, navigated transcranial magnetic stimulation (nTMS) is increasingly performed. A high level of evidence is now available in the literature regarding the anatomical and functional accuracy of this mapping technique. This article presents the principles and facts demonstrating the value of using nTMS in clinical practice to preserve motor or language functions from deleterious lesions secondary to brain tumour resection or epilepsy surgery.
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Zhang X, Ji W, Li L, Yu C, Wang W, Liu S, Gao C, Qiu L, Tong X, Wang J, Wu J. The Predictive Value of Motor-Evoked Potentials and the Silent Period on Patient Outcome after Acute Cerebral Infarction. J Stroke Cerebrovasc Dis 2016; 25:1713-1720. [PMID: 27083069 DOI: 10.1016/j.jstrokecerebrovasdis.2016.03.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 02/04/2016] [Accepted: 03/15/2016] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND The predictive value of neurophysiologic assessment on patients' outcome after acute cerebral infarction is poorly understood. The aim of this study was to investigate the prognostic value of motor-evoked potentials (MEPs) and the silent period (SP) on clinical outcome. METHODS A total of 202 patients with acute cerebral infarction were prospectively recruited. MEP and SP were recorded from the abductor pollicis brevis of the affected side within 10 days after stroke onset. Patient outcome was measured as the dependency rate. RESULTS Cortical MEP was induced in 78 patients whereas it was absent in 82 patients. The initial NIHSS (National Institutes of Health Stroke Scale) score was significantly lower in patients with MEP than in those without MEP (P < .001). Regression analysis demonstrated that a left-sided lesion (OR = .391, 95% CI .178-.858, P = .019), NIHSS at admission (OR = .826, 95% CI .744-.917, P < .001), and presence of MEP (OR = 3.918, 95% CI 1.770-8.672, P < .001) were independent predictors of outcome 3 months after stroke. Among patients with MEP, only the contralateral cortical SP value was significantly shorter in the good outcome subgroup (t = 2.541, P = .013). Receiver operating characteristic curve analysis demonstrated that SP was able to predict patients at higher risk of unfavorable outcome 3 months after stroke onset (area under the curve .721, 95% CI .58-.86, P = .008). CONCLUSIONS These data suggested that MEP and SP were useful tools to predict patients' acute outcomes following cerebral infarction.
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Affiliation(s)
- Xueqing Zhang
- Department of Electrophysiology, Tianjin Huanhu Hospital, Tianjin, China
| | - Wenzhen Ji
- Department of Electrophysiology, Tianjin Huanhu Hospital, Tianjin, China
| | - Lancui Li
- Department of Medical Insurance, Tianjin Huanhu Hospital, Tianjin, China
| | - Changshen Yu
- Department of Neurology, Tianjin Huanhu Hospital, Tianjin Key Laboratory of Cerebrovascular and Neurodegenerative Diseases, Tianjin, China
| | - Wanjun Wang
- Department of Neurology, Tianjin Huanhu Hospital, Tianjin Key Laboratory of Cerebrovascular and Neurodegenerative Diseases, Tianjin, China
| | - Shoufeng Liu
- Department of Neurology, Tianjin Huanhu Hospital, Tianjin Key Laboratory of Cerebrovascular and Neurodegenerative Diseases, Tianjin, China
| | - Chunlin Gao
- Department of Neurology, Tianjin Huanhu Hospital, Tianjin Key Laboratory of Cerebrovascular and Neurodegenerative Diseases, Tianjin, China
| | - Lina Qiu
- Department of Neurology, Tianjin Huanhu Hospital, Tianjin Key Laboratory of Cerebrovascular and Neurodegenerative Diseases, Tianjin, China
| | - Xiaoguang Tong
- Department of Neurosurgery, Tianjin Huanhu Hospital, Tianjin Key Laboratory of Cerebrovascular and Neurodegenerative Diseases, Tianjin, China
| | - Jinhuan Wang
- Department of Neurosurgery, Tianjin Huanhu Hospital, Tianjin Key Laboratory of Cerebrovascular and Neurodegenerative Diseases, Tianjin, China
| | - Jialing Wu
- Department of Neurology, Tianjin Huanhu Hospital, Tianjin Key Laboratory of Cerebrovascular and Neurodegenerative Diseases, Tianjin, China.
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20
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Models to Tailor Brain Stimulation Therapies in Stroke. Neural Plast 2016; 2016:4071620. [PMID: 27006833 PMCID: PMC4781989 DOI: 10.1155/2016/4071620] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 12/30/2015] [Accepted: 01/04/2016] [Indexed: 11/18/2022] Open
Abstract
A great challenge facing stroke rehabilitation is the lack of information on how to derive targeted therapies. As such, techniques once considered promising, such as brain stimulation, have demonstrated mixed efficacy across heterogeneous samples in clinical studies. Here, we explain reasons, citing its one-type-suits-all approach as the primary cause of variable efficacy. We present evidence supporting the role of alternate substrates, which can be targeted instead in patients with greater damage and deficit. Building on this groundwork, this review will also discuss different frameworks on how to tailor brain stimulation therapies. To the best of our knowledge, our report is the first instance that enumerates and compares across theoretical models from upper limb recovery and conditions like aphasia and depression. Here, we explain how different models capture heterogeneity across patients and how they can be used to predict which patients would best respond to what treatments to develop targeted, individualized brain stimulation therapies. Our intent is to weigh pros and cons of testing each type of model so brain stimulation is successfully tailored to maximize upper limb recovery in stroke.
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21
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Tan AQ, Shemmell J, Dhaher YY. Downregulating Aberrant Motor Evoked Potential Synergies of the Lower Extremity Post Stroke During TMS of the Contralesional Hemisphere. Brain Stimul 2016; 9:396-405. [PMID: 26927733 DOI: 10.1016/j.brs.2015.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 12/14/2015] [Accepted: 12/15/2015] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Growing evidence demonstrates unique synergistic signatures in the lower limb (LL) post-stroke, with specific across-plane and across-joint representations. While the inhibitory role of the ipsilateral hemisphere in the upper limb (UL) has been widely reported, examination of the contralesional hemisphere (CON-H) in modulating LL expressions of synergies following stroke is lacking. OBJECTIVE We hypothesize that stimulation of lesioned and contralesional motor cortices will differentially regulate paretic LL motor outflow. We propose a novel TMS paradigm to identify synergistic motor evoked potential (MEP) patterns across multiple muscles. METHODS Amplitude and background activation matched adductor MEPs were elicited using single pulse TMS of L-H and CON-H (control ipsilateral) during an adductor torque matching task from 11 stroke and 10 control participants. Associated MEPs of key synergistic muscles were simultaneously observed. RESULTS By quantifying CON-H/L-H MEP ratios, we characterized a significant targeted inhibition of aberrant MEP coupling between ADD and VM (p = 0.0078) and VL (p = 0.047) exclusive to the stroke group (p = 0.028) that was muscle dependent (p = 0.039). We find TA inhibition in both groups following ipsilateral hemisphere stimulation (p = 0.0014; p = 0.015). CONCLUSION We argue that ipsilaterally mediated attenuation of abnormal synergistic activations post stroke may reflect an adaptive intracortical inhibition. The predominance of sub 3ms interhemispheric MEP latency differences implicates LL ipsilateral corticomotor projections. These findings provide insight into the association between CON-H reorganization and post-stroke LL recovery. While a prevailing view of driving L-H disinhibition for UL recovery seems expedient, presuming analogous LL neuromodulation may require further examination for rehabilitation. This study provides a step toward this goal.
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Affiliation(s)
- Andrew Q Tan
- Northwestern University Interdepartmental Neuroscience, Northwestern University, Chicago, IL, USA; Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, USA.
| | - Jon Shemmell
- School of Physical Education, Sport and Exercise Science, University of Otago, Dunedin, New Zealand
| | - Yasin Y Dhaher
- Northwestern University Interdepartmental Neuroscience, Northwestern University, Chicago, IL, USA; Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, USA; Department of Biomedical Engineering, Northwestern University, Chicago, IL, USA
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22
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McCambridge AB, Stinear JW, Byblow WD. Are ipsilateral motor evoked potentials subject to intracortical inhibition? J Neurophysiol 2016; 115:1735-9. [PMID: 26792890 DOI: 10.1152/jn.01139.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 01/13/2016] [Indexed: 11/22/2022] Open
Abstract
Paired-pulse transcranial magnetic stimulation (TMS) can be used to examine intracortical inhibition in primary motor cortex (M1), termed short-interval intracortical inhibition (SICI). To our knowledge, SICI has only been demonstrated in contralateral motor evoked potentials (MEPs). Ipsilateral MEPs (iMEPs) are assumed to reflect excitability of an uncrossed oligosynaptic pathway, and can sometimes be evoked in proximal upper-limb muscles using high-intensity TMS. We examined whether iMEPs in the biceps brachii (BB) would be suppressed by subthreshold conditioning, therefore demonstrating SICI of iMEPs. TMS was delivered to the dominant M1 to evoke conditioned (C) and nonconditioned (NC) iMEPs in the nondominant BB of healthy participants during weak bilateral elbow flexion. The conditioning stimulus intensities tested were 85%, 100%, and 115% of active motor threshold (AMT), at 2 ms and 4 ms interstimulus intervals (ISI). The iMEP ratio (C/NC) was calculated for each condition to assess the amount of inhibition. Inhibition of iMEPs was present at 2 ms ISI with 100% and 115% AMT (bothP< 0.03), mediated by a reduction in persistence and size (allP< 0.05). To our knowledge, this is the first demonstration of SICI of iMEPs. This technique may be useful as a tool to better understand the role of ipsilateral M1 during functional motor tasks.
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Affiliation(s)
- Alana B McCambridge
- Movement Neuroscience Laboratory, Department of Exercise Sciences, Centre for Brain Research, The University of Auckland, Auckland, New Zealand
| | - James W Stinear
- Movement Neuroscience Laboratory, Department of Exercise Sciences, Centre for Brain Research, The University of Auckland, Auckland, New Zealand
| | - Winston D Byblow
- Movement Neuroscience Laboratory, Department of Exercise Sciences, Centre for Brain Research, The University of Auckland, Auckland, New Zealand
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23
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Messamore WG, Van Acker GM, Hudson HM, Zhang HY, Kovac A, Nazzaro J, Cheney PD. Cortical Effects on Ipsilateral Hindlimb Muscles Revealed with Stimulus-Triggered Averaging of EMG Activity. Cereb Cortex 2015; 26:3036-51. [PMID: 26088970 DOI: 10.1093/cercor/bhv122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
While a large body of evidence supports the view that ipsilateral motor cortex may make an important contribution to normal movements and to recovery of function following cortical injury (Chollet et al. 1991; Fisher 1992; Caramia et al. 2000; Feydy et al. 2002), relatively little is known about the properties of output from motor cortex to ipsilateral muscles. Our aim in this study was to characterize the organization of output effects on hindlimb muscles from ipsilateral motor cortex using stimulus-triggered averaging of EMG activity. Stimulus-triggered averages of EMG activity were computed from microstimuli applied at 60-120 μA to sites in both contralateral and ipsilateral M1 of macaque monkeys during the performance of a hindlimb push-pull task. Although the poststimulus effects (PStEs) from ipsilateral M1 were fewer in number and substantially weaker, clear and consistent effects were obtained at an intensity of 120 μA. The mean onset latency of ipsilateral poststimulus facilitation was longer than contralateral effects by an average of 0.7 ms. However, the shortest latency effects in ipsilateral muscles were as short as the shortest latency effects in the corresponding contralateral muscles suggesting a minimal synaptic linkage that is equally direct in both cases.
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Affiliation(s)
| | | | | | | | | | - Jules Nazzaro
- Department of Neurosurgery, University of Kansas Medical Center, Kansas City, KS 66160, USA
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Lewis GN, Signal N, Taylor D. Reliability of lower limb motor evoked potentials in stroke and healthy populations: How many responses are needed? Clin Neurophysiol 2014; 125:748-754. [DOI: 10.1016/j.clinph.2013.07.029] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 07/08/2013] [Accepted: 07/11/2013] [Indexed: 10/26/2022]
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25
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Málly J, Stone TW. New advances in the rehabilitation of CNS diseases applying rTMS. Expert Rev Neurother 2014. [DOI: 10.1586/14737175.7.2.165\] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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26
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Uehara K, Funase K. Contribution of ipsilateral primary motor cortex activity to the execution of voluntary movements in humans: A review of recent studies. JOURNAL OF PHYSICAL FITNESS AND SPORTS MEDICINE 2014. [DOI: 10.7600/jpfsm.3.297] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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27
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Amengual JL, Marco-Pallarés J, Richter L, Oung S, Schweikard A, Mohammadi B, Rodríguez-Fornells A, Münte TF. Tracking post-error adaptation in the motor system by transcranial magnetic stimulation. Neuroscience 2013; 250:342-51. [PMID: 23876325 DOI: 10.1016/j.neuroscience.2013.07.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 07/09/2013] [Accepted: 07/11/2013] [Indexed: 11/15/2022]
Abstract
The commission of an error triggers cognitive control processes dedicated to error correction and prevention. Post-error adjustments leading to response slowing following an error ("post-error slowing"; PES) might be driven by changes in excitability of the motor regions and the corticospinal tract (CST). The time-course of such excitability modulations of the CST leading to PES is largely unknown. To track these presumed excitability changes after an error, single pulse transcranial magnetic stimulation (TMS) was applied to the motor cortex ipsilateral to the responding hand, while participants were performing an Eriksen flanker task. A robotic arm with a movement compensation system was used to maintain the TMS coil in the correct position during the experiment. Magnetic pulses were delivered over the primary motor cortex ipsilateral to the active hand at different intervals (150, 300, 450 ms) after correct and erroneous responses, and the motor-evoked potentials (MEP) of the first dorsal interosseous muscle (FDI) contralateral to the stimulated hemisphere were recorded. MEP amplitude was increased 450 ms after the error. Two additional experiments showed that this increase was neither associated to the correction of the erroneous responses nor to the characteristics of the motor command. To the extent to which the excitability of the motor cortex ipsi- and contralateral to the response hand are inversely related, these results suggest a decrease in the excitability of the active motor cortex after an erroneous response. This modulation of the activity of the CST serves to prevent further premature and erroneous responses. At a more general level, the study shows the power of the TMS technique for the exploration of the temporal evolution of post-error adjustments within the motor system.
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Affiliation(s)
- J L Amengual
- Department of Basic Psychology, University of Barcelona, 08035 Barcelona, Spain.
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28
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Bradnam LV, Stinear CM, Byblow WD. Ipsilateral motor pathways after stroke: implications for non-invasive brain stimulation. Front Hum Neurosci 2013; 7:184. [PMID: 23658541 PMCID: PMC3647244 DOI: 10.3389/fnhum.2013.00184] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 04/23/2013] [Indexed: 12/17/2022] Open
Abstract
In humans the two cerebral hemispheres have essential roles in controlling the upper limb. The purpose of this article is to draw attention to the potential importance of ipsilateral descending pathways for functional recovery after stroke, and the use of non-invasive brain stimulation (NBS) protocols of the contralesional primary motor cortex (M1). Conventionally NBS is used to suppress contralesional M1, and to attenuate transcallosal inhibition onto the ipsilesional M1. There has been little consideration of the fact that contralesional M1 suppression may also reduce excitability of ipsilateral descending pathways that may be important for paretic upper limb control for some patients. One such ipsilateral pathway is the cortico-reticulo-propriospinal pathway (CRPP). In this review we outline a neurophysiological model to explain how contralesional M1 may gain control of the paretic arm via the CRPP. We conclude that the relative importance of the CRPP for motor control in individual patients must be considered before using NBS to suppress contralesional M1. Neurophysiological, neuroimaging, and clinical assessments can assist this decision making and facilitate the translation of NBS into the clinical setting.
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Affiliation(s)
- Lynley V Bradnam
- Brain Research Laboratory, Centre for Neuroscience, School of Medicine, Flinders University Adelaide, SA, Australia ; Effectiveness of Therapy Group, Centre for Clinical Change and Healthcare Research, School of Medicine, Flinders University Adelaide, SA, Australia
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Salinet ASM, Robinson TG, Panerai RB. Active, passive, and motor imagery paradigms: component analysis to assess neurovascular coupling. J Appl Physiol (1985) 2013; 114:1406-12. [PMID: 23449939 DOI: 10.1152/japplphysiol.01448.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The association between neural activity and cerebral blood flow (CBF) has been used to assess neurovascular coupling (NVC) in health and diseases states, but little attention has been given to the contribution of simultaneous changes in peripheral covariates. We used an innovative approach to assess the contributions of arterial blood pressure (BP), PaCO2, and the stimulus itself to changes in CBF velocities (CBFv) during active (MA), passive (MP), and motor imagery (MI) paradigms. Continuous recordings of CBFv, beat-to-beat BP, heart rate, and breath-by-breath end-tidal CO2 (EtCO2) were performed in 17 right-handed subjects before, during, and after motor-cognitive paradigms performed with the right arm. A multivariate autoregressive-moving average model was used to calculate the separate contributions of BP, EtCO2, and the neural activation stimulus (represented by a metronome on-off signal) to the CBFv response during paradigms. Differences were found in the bilateral CBFv responses to MI compared with MA and MP, due to the contributions of stimulation (P < 0.05). BP was the dominant contributor to the initial peaked CBFv response in all paradigms with no significant differences between paradigms, while the contribution of the stimulus explained the plateau phase and extended duration of the CBFv responses. Separating the neural activation contribution from the influences of other covariates, it was possible to detect differences between three paradigms often used to assess disease-related NVC. Apparently similar CBFv responses to different motor-cognitive paradigms can be misleading due to the contributions from peripheral covariates and could lead to inaccurate assessment of NVC, particularly during MI.
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Affiliation(s)
- Angela S M Salinet
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom.
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Salinet ASM, Haunton VJ, Panerai RB, Robinson TG. A systematic review of cerebral hemodynamic responses to neural activation following stroke. J Neurol 2013; 260:2715-21. [DOI: 10.1007/s00415-013-6836-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 01/04/2013] [Indexed: 10/27/2022]
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Liu M, Fujiwara T, Shindo K, Kasashima Y, Otaka Y, Tsuji T, Ushiba J. Newer challenges to restore hemiparetic upper extremity after stroke: HANDS therapy and BMI neurorehabilitation. Hong Kong Physiother J 2012. [DOI: 10.1016/j.hkpj.2012.05.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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Dean PJA, Seiss E, Sterr A. Motor planning in chronic upper-limb hemiparesis: evidence from movement-related potentials. PLoS One 2012; 7:e44558. [PMID: 23049676 PMCID: PMC3462178 DOI: 10.1371/journal.pone.0044558] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 08/06/2012] [Indexed: 11/17/2022] Open
Abstract
Background Chronic hemiplegia is a common long-term consequence of stroke, and subsequent motor recovery is often incomplete. Neurophysiological studies have focused on motor execution deficits in relatively high functioning patients. Much less is known about the influence exerted by processes related to motor preparation, particularly in patients with poor motor recovery. Methodology/Principal Findings The current study investigates motor preparation using a modified response-priming experiment in a large sample of patients (n = 50) with moderate-to-severe chronic hemiparesis. The behavioural results revealed that hemiparetic patients had an increased response-priming effect compared to controls, but that their response times were markedly slower for both hands. Patients also demonstrated significantly enhanced midline late contingent negative variation (CNV) during paretic hand preparation, despite the absence of overall group differences when compared to controls. Furthermore, increased amplitude of the midline CNV correlated with a greater response-priming effect. We propose that these changes might reflect greater anticipated effort to respond in patients, and consequently that advance cueing of motor responses may be of benefit in these individuals. We further observed significantly reduced CNV amplitudes over the lesioned hemisphere in hemiparetic patients compared to controls during non-paretic hand preparation, preparation of both hands and no hand preparation. Two potential explanations for these CNV reductions are discussed: alterations in anticipatory attention or state changes in motor processing, for example an imbalance in inter-hemispheric inhibition. Conclusions/Significance Overall, this study provides evidence that movement preparation could play a crucial role in hemiparetic motor deficits, and that advance motor cueing may be of benefit in future therapeutic interventions. In addition, it demonstrates the importance of monitoring both the non-paretic and paretic hand after stroke and during therapeutic intervention.
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Honaga K, Fujiwara T, Tsuji T, Hase K, Ushiba J, Liu M. State of intracortical inhibitory interneuron activity in patients with chronic stroke. Clin Neurophysiol 2012; 124:364-70. [PMID: 22955029 DOI: 10.1016/j.clinph.2012.08.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 07/22/2012] [Accepted: 08/09/2012] [Indexed: 10/27/2022]
Abstract
OBJECTIVES Few studies have assessed short intracortical inhibition (SICI) in the affected hemisphere (AH) in a large number of patients with chronic stroke. In this study, SICI was assessed in chronic stroke patients with severe hemiparesis, and its relationship to clinical parameters was examined. METHODS The participants were 72 patients with chronic hemiparetic stroke. SICI of both the AH and the unaffected hemisphere (UH) was assessed. The relationships between SICI and the location of lesion, time from onset, and finger function were studied. Motor function of the paretic finger was assessed with the Stroke Impairment Assessment Set (SIAS) and the Fugl-Meyer test upper extremity motor score. To compare the results with those of healthy subjects, SICI was assessed in seven age-matched control subjects. RESULTS MEPs of the UH were evoked in all 72 subjects, and MEPs of the AH were evoked in 24 subjects. SICI of the AH was inversely correlated with paretic finger motor function and time from stroke onset. SICI of the UH was not correlated with either one. SICI of the UH was higher in the cortical lesion group than in the control group. CONCLUSIONS The state of intracortical inhibitory neuron activity depends on the state of motor function and lesion site even in chronic stroke patients with severe hemiparesis. SIGNIFICANCE The inhibitory system of the AH is involved in functional recovery of the paretic hand even in the chronic stage of stroke.
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Affiliation(s)
- Kaoru Honaga
- Department of Rehabilitation Medicine, Keio University School of Medicine, Tokyo, Japan
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Abstract
Acute transverse myelitis (ATM) has many potential etiologies, but a significant proportion of cases are categorized as idiopathic despite thorough evaluation. Clinical presentation of ATM typically includes some combination of motor weakness, sensory symptoms, and bowel and bladder dysfunction. Prompt recognition, even before a final etiologic diagnosis is reached, is critical to initiating early therapeutic intervention to reduce the harmful effects of inflammation. Acute therapeutic options for ATM include corticosteroids, plasma exchange, IV immunoglobulin, and chemotherapeutic agents such as cyclophosphamide. In some instances, combinations of these therapies are used. This article examines the therapeutic approach to ATM and its various acute clinical manifestations.
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Responses of the Less Affected Arm to Bilateral Upper Limb Task Training in Early Rehabilitation After Stroke: A Randomized Controlled Trial. Arch Phys Med Rehabil 2012; 93:1129-37. [DOI: 10.1016/j.apmr.2012.02.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 02/23/2012] [Indexed: 11/19/2022]
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Jayaram G, Stagg CJ, Esser P, Kischka U, Stinear J, Johansen-Berg H. Relationships between functional and structural corticospinal tract integrity and walking post stroke. Clin Neurophysiol 2012; 123:2422-8. [PMID: 22717679 PMCID: PMC3778984 DOI: 10.1016/j.clinph.2012.04.026] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 04/12/2012] [Accepted: 04/30/2012] [Indexed: 11/02/2022]
Abstract
OBJECTIVE Studies on upper limb recovery following stroke have highlighted the importance of the structural and functional integrity of the corticospinal tract (CST) in determining clinical outcomes. However, such relationships have not been fully explored for the lower limb. We aimed to test whether variation in walking impairment was associated with variation in the structural or functional integrity of the CST. METHODS Transcranial magnetic stimulation was used to stimulate each motor cortex while EMG recordings were taken from the vastus lateralis (VL) bilaterally; these EMG measures were used to calculate both ipsilateral and contralateral recruitment curves for each lower limb. The slope of these recruitment curves was used to examine the strength of functional connectivity from the motor cortex in each hemisphere to the lower limbs in chronic stroke patients and to calculate a ratio between ipsilateral and contralateral outputs referred to as the functional connectivity ratio (FCR). The structural integrity of the CST was assessed using diffusion tensor MRI to measure the asymmetry in fractional anisotropy (FA) of the internal capsule. Lower limb impairment and walking speed were also measured. RESULTS The FCR for the paretic leg correlated with walking impairment, such that greater relative ipsilateral connectivity was associated with slower walking speeds. Asymmetrical FA values, reflecting reduced structural integrity of the lesioned CST, were associated with greater walking impairment. FCR and FA asymmetry were strongly positively correlated with each other. CONCLUSIONS Patients with relatively greater ipsilateral connectivity between the contralesional motor cortex and the paretic lower limb were more behaviorally impaired and had more structural damage to their ipsilesional hemisphere CST. SIGNIFICANCE Measures of structural and functional damage may be useful in the selection of therapeutic strategies, allowing for more tailored and potentially more beneficial treatments.
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Affiliation(s)
- Gowri Jayaram
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD 21205, USA.
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Poujois A, Schneider FC, Faillenot I, Camdessanché JP, Vandenberghe N, Thomas-Antérion C, Antoine JC. Brain plasticity in the motor network is correlated with disease progression in amyotrophic lateral sclerosis. Hum Brain Mapp 2012; 34:2391-401. [PMID: 22461315 DOI: 10.1002/hbm.22070] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Revised: 12/21/2011] [Accepted: 02/13/2012] [Indexed: 11/11/2022] Open
Abstract
OBJECTIVE To test the influence of functional cerebral reorganization in amyotrophic lateral sclerosis (ALS) on disease progression. METHODS Nineteen predominantly right-handed ALS patients and 21 controls underwent clinical evaluation, functional Magnetic Resonance Imaging (fMRI), and diffusion tensor imaging. Patients were clinically re-evaluated 1 year later and followed until death. For fMRI, subjects executed and imagined a simple hand-motor task. Between-group comparisons were performed, and correlations were searched with motor deficit arm Medical Research Council (MRC) score, disease progression ALS Functional Rating Scale (ALSFRS), and survival time. RESULTS By the MRC score, the hand strength was lowered by 12% in the ALS group predominating on the right side in accordance with an abnormal fractional anisotropy (FA) limited to the left corticospinal tract (37.3% reduction vs. controls P < 0.01). Compared to controls, patients displayed overactivations in the controlateral parietal (P < 0.004) and somatosensory (P < 0.004) cortex and in the ipsilateral parietal (P < 0.01) and somatosensory (P < 0.01) cortex to right-hand movement. Movement imagination gave similar results while no difference occurred with left-hand tasks. Stepwise regression analysis corrected for multiple comparisons showed that controlateral parietal activity was inversely correlated with disease progression (R(2) = 0.43, P = 0.001) and ipsilateral somatosensory activations with the severity of the right-arm deficit (R(2) = 0.48, P = 0.001). CONCLUSIONS Cortical Blood Oxygen Level Dependent (BOLD) signal changes occur in the brain of ALS patients during a simple hand-motor task when the motor deficit is still moderate. It is correlated with the rate of disease progression suggesting that brain functional rearrangement in ALS may have prognostic implications.
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Affiliation(s)
- Aurélia Poujois
- INSERM U1028, Centre de Recherche en Neurosciences de Lyon, Université de Lyon, F-42023, Saint-Etienne, France; Service de Neurologie, Centre SLA, Centre Hospitalier Universitaire, Saint-Etienne, France
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Shafi MM, Westover MB, Fox MD, Pascual-Leone A. Exploration and modulation of brain network interactions with noninvasive brain stimulation in combination with neuroimaging. Eur J Neurosci 2012; 35:805-25. [PMID: 22429242 PMCID: PMC3313459 DOI: 10.1111/j.1460-9568.2012.08035.x] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Much recent work in systems neuroscience has focused on how dynamic interactions between different cortical regions underlie complex brain functions such as motor coordination, language and emotional regulation. Various studies using neuroimaging and neurophysiologic techniques have suggested that in many neuropsychiatric disorders, these dynamic brain networks are dysregulated. Here we review the utility of combined noninvasive brain stimulation and neuroimaging approaches towards greater understanding of dynamic brain networks in health and disease. Brain stimulation techniques, such as transcranial magnetic stimulation and transcranial direct current stimulation, use electromagnetic principles to alter brain activity noninvasively, and induce focal but also network effects beyond the stimulation site. When combined with brain imaging techniques such as functional magnetic resonance imaging, positron emission tomography and electroencephalography, these brain stimulation techniques enable a causal assessment of the interaction between different network components, and their respective functional roles. The same techniques can also be applied to explore hypotheses regarding the changes in functional connectivity that occur during task performance and in various disease states such as stroke, depression and schizophrenia. Finally, in diseases characterized by pathologic alterations in either the excitability within a single region or in the activity of distributed networks, such techniques provide a potential mechanism to alter cortical network function and architectures in a beneficial manner.
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Affiliation(s)
- Mouhsin M. Shafi
- Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - M. Brandon Westover
- Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Michael D. Fox
- Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Alvaro Pascual-Leone
- Berenson-Allen Center for Noninvasive Brain Stimulation, Division of Cognitive Neurology, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
- Institut Universitari de Neurorehabilitació Guttmann, Universidad Autónoma de Barcelona, Badalona, Spain
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Bradnam LV, Stinear CM, Barber PA, Byblow WD. Contralesional hemisphere control of the proximal paretic upper limb following stroke. Cereb Cortex 2011; 22:2662-71. [PMID: 22139791 DOI: 10.1093/cercor/bhr344] [Citation(s) in RCA: 174] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cathodal transcranial direct current stimulation (c-tDCS) can reduce excitability of neurons in primary motor cortex (M1) and may facilitate motor recovery after stroke. However, little is known about the neurophysiological effects of tDCS on proximal upper limb function. We hypothesized that suppression of contralesional M1 (cM1) excitability would produce neurophysiological effects that depended on the severity of upper limb impairment. Twelve patients with varying upper limb impairment after subcortical stroke were assessed on clinical scales of upper limb spasticity, impairment, and function. Magnetic resonance imaging was used to determine lesion size and fractional anisotropy (FA) within the posterior limbs of the internal capsules indicative of corticospinal tract integrity. Excitability within paretic M1 biceps brachii representation was determined from motor-evoked potentials during selective isometric tasks, after cM1 sham stimulation and after c-tDCS. These neurophysiological data indicate that c-tDCS improved selective proximal upper limb control for mildly impaired patients and worsened it for moderate to severely impaired patients. The direction of the neurophysiological after effects of c-tDCS was strongly related to upper limb spasticity, impairment, function, and FA asymmetry between the posterior limbs of the internal capsules. These results indicate systematic variation of cM1 for proximal upper limb control after stroke and that suppression of cM1 excitability is not a "one size fits all" approach.
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Affiliation(s)
- Lynley V Bradnam
- Movement Neuroscience Laboratory, Department of Sport & Exercise Science, The University of Auckland, Auckland, New Zealand 1142
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Hillebrand A, Barnes GR, Bosboom JL, Berendse HW, Stam CJ. Frequency-dependent functional connectivity within resting-state networks: an atlas-based MEG beamformer solution. Neuroimage 2011; 59:3909-21. [PMID: 22122866 PMCID: PMC3382730 DOI: 10.1016/j.neuroimage.2011.11.005] [Citation(s) in RCA: 297] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 10/27/2011] [Accepted: 11/02/2011] [Indexed: 11/08/2022] Open
Abstract
The brain consists of functional units with more-or-less specific information processing capabilities, yet cognitive functions require the co-ordinated activity of these spatially separated units. Magnetoencephalography (MEG) has the temporal resolution to capture these frequency-dependent interactions, although, due to volume conduction and field spread, spurious estimates may be obtained when functional connectivity is estimated on the basis of the extra-cranial recordings directly. Connectivity estimates on the basis of reconstructed sources may similarly be affected by biases introduced by the source reconstruction approach. Here we propose an analysis framework to reliably determine functional connectivity that is based around two main ideas: (i) functional connectivity is computed for a set of atlas-based ROIs in anatomical space that covers almost the entire brain, aiding the interpretation of MEG functional connectivity/network studies, as well as the comparison with other modalities; (ii) volume conduction and similar bias effects are removed by using a functional connectivity estimator that is insensitive to these effects, namely the Phase Lag Index (PLI). Our analysis approach was applied to eyes-closed resting-state MEG data for thirteen healthy participants. We first demonstrate that functional connectivity estimates based on phase coherence, even at the source-level, are biased due to the effects of volume conduction and field spread. In contrast, functional connectivity estimates based on PLI are not affected by these biases. We then looked at mean PLI, or weighted degree, over areas and subjects and found significant mean connectivity in three (alpha, beta, gamma) of the five (including theta and delta) classical frequency bands tested. These frequency-band dependent patterns of resting-state functional connectivity were distinctive; with the alpha and beta band connectivity confined to posterior and sensorimotor areas respectively, and with a generally more dispersed pattern for the gamma band. Generally, these patterns corresponded closely to patterns of relative source power, suggesting that the most active brain regions are also the ones that are most-densely connected. Our results reveal for the first time, using an analysis framework that enables the reliable characterisation of resting-state dynamics in the human brain, how resting-state networks of functionally connected regions vary in a frequency-dependent manner across the cortex.
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Affiliation(s)
- Arjan Hillebrand
- Department of Clinical Neurophysiology and Magnetoencephalography Center, VU University Medical Center, Amsterdam, The Netherlands.
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Rogers LM, Stinear JW, Lewis GN, Brown DA. Descending control to the nonparetic limb degrades the cyclic activity of paretic leg muscles. Hum Mov Sci 2011; 30:1225-44. [PMID: 21601300 DOI: 10.1016/j.humov.2011.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 03/25/2011] [Accepted: 03/29/2011] [Indexed: 11/30/2022]
Abstract
During anti-phased locomotor tasks such as cycling or walking, hemiparetic phasing of muscle activity is characterized by inappropriate early onset of activity for some paretic muscles and prolonged activity in others. Pedaling with the paretic limb alone reduces inappropriate prolonged activity, suggesting a combined influence of contralesional voluntary commands and movement-related sensory feedback. Five different non-target leg movement state conditions were performed by 15 subjects post-stroke and 15 nonimpaired controls while they pedaled with the target leg and EMG was recorded bilaterally. Voluntary engagement of the non-lesioned motor system increased prolonged paretic vastus medialis (VM) activity and increased phase-advanced rectus femoris (RF) activity. We suggest bilateral descending commands are primarily responsible for the inappropriate activity in the paretic VM during anti-phase pedaling, and contribute to the dysfunctional motor output in the paretic RF. Findings from controls suggest that even an undamaged motor system can contribute to this phenomenon.
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Affiliation(s)
- Lynn M Rogers
- Department of Biomedical Engineering, Northwestern University McCormick School of Engineering and Applied Science, Evanston, IL, USA.
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Meairs S, Hennerici M, Mohr J. Ultrasonography. Stroke 2011. [DOI: 10.1016/b978-1-4160-5478-8.10044-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Excitability changes in the ipsilateral primary motor cortex during rhythmic contraction of finger muscles. Neurosci Lett 2010; 488:22-5. [PMID: 21056628 DOI: 10.1016/j.neulet.2010.10.073] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 10/26/2010] [Accepted: 10/29/2010] [Indexed: 11/22/2022]
Abstract
The aim of this study was to determine whether the excitatory ipsilateral primary motor cortex (ipsi-M1) is affected by changes in the frequency of rhythmic voluntary contraction of the left first dorsal interosseous (FDI) induced by repetitive abduction of the left index-finger. Transcranial magnetic stimulations were delivered to the left M1 during repetitive left index-finger abduction at 1, 2, and 3Hz, and motor evoked potentials (MEPs) were simultaneously evoked in the resting right (Rt)-FDI, Rt-abductor pollicis brevis, and Rt-abductor digiti minimi. The stimulus-response (S-R) curve of the MEP at each frequency was recorded. In addition, F-waves were recorded from the Rt-FDI during these rhythmic contraction tasks in order to examine the changes in spinal motoneuron excitability. MEPs were markedly increased under the 3Hz conditions compared with the other conditions. However, F-waves were hardly changed under these conditions. The S-R curve of the MEP induced under the 3Hz conditions was significantly steeper than the curves produced under other conditions. Our results indicate that the excitability of ipsi-M1 is affected by the frequency of rhythmic voluntary contraction of unilateral finger movement, which may be caused by neural inputs delivered via a transcallosal pathway.
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Kaeser M, Wyss AF, Bashir S, Hamadjida A, Liu Y, Bloch J, Brunet JF, Belhaj-Saif A, Rouiller EM. Effects of Unilateral Motor Cortex Lesion on Ipsilesional Hand's Reach and Grasp Performance in Monkeys: Relationship With Recovery in the Contralesional Hand. J Neurophysiol 2010; 103:1630-45. [DOI: 10.1152/jn.00459.2009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Manual dexterity, a prerogative of primates, is under the control of the corticospinal (CS) tract. Because 90–95% of CS axons decussate, it is assumed that this control is exerted essentially on the contralateral hand. Consistently, unilateral lesion of the hand representation in the motor cortex is followed by a complete loss of dexterity of the contralesional hand. During the months following lesion, spontaneous recovery of manual dexterity takes place to a highly variable extent across subjects, although largely incomplete. In the present study, we tested the hypothesis that after a significant postlesion period, manual performance in the ipsilesional hand is correlated with the extent of functional recovery in the contralesional hand. To this aim, ten adult macaque monkeys were subjected to permanent unilateral motor cortex lesion. Monkeys' manual performance was assessed for each hand during several months postlesion, using our standard behavioral test (modified Brinkman board task) that provides a quantitative measure of reach and grasp ability. The ipsilesional hand's performance was found to be significantly enhanced over the long term (100–300 days postlesion) in six of ten monkeys, with the six exhibiting the best, though incomplete, recovery of the contralesional hand. There was a statistically significant correlation ( r = 0.932; P < 0.001) between performance in the ipsilesional hand after significant postlesion period and the extent of recovery of the contralesional hand. This observation is interpreted in terms of different possible mechanisms of recovery, dependent on the recruitment of motor areas in the lesioned and/or intact hemispheres.
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Affiliation(s)
- Mélanie Kaeser
- Unit of Physiology and Program in Neurosciences, Department of Medicine, Faculty of Sciences, University of Fribourg, Fribourg; and
- Department of Neurosurgery, Neurosurgery Clinic, University Hospital of Lausanne, Lausanne, Switzerland
| | - Alexander F. Wyss
- Unit of Physiology and Program in Neurosciences, Department of Medicine, Faculty of Sciences, University of Fribourg, Fribourg; and
| | - Shahid Bashir
- Unit of Physiology and Program in Neurosciences, Department of Medicine, Faculty of Sciences, University of Fribourg, Fribourg; and
| | - Adjia Hamadjida
- Unit of Physiology and Program in Neurosciences, Department of Medicine, Faculty of Sciences, University of Fribourg, Fribourg; and
| | - Yu Liu
- Unit of Physiology and Program in Neurosciences, Department of Medicine, Faculty of Sciences, University of Fribourg, Fribourg; and
| | - Jocelyne Bloch
- Department of Neurosurgery, Neurosurgery Clinic, University Hospital of Lausanne, Lausanne, Switzerland
| | - Jean-François Brunet
- Department of Neurosurgery, Neurosurgery Clinic, University Hospital of Lausanne, Lausanne, Switzerland
| | - Abderaouf Belhaj-Saif
- Unit of Physiology and Program in Neurosciences, Department of Medicine, Faculty of Sciences, University of Fribourg, Fribourg; and
| | - Eric M. Rouiller
- Unit of Physiology and Program in Neurosciences, Department of Medicine, Faculty of Sciences, University of Fribourg, Fribourg; and
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Schaechter JD, Fricker ZP, Perdue KL, Helmer KG, Vangel MG, Greve DN, Makris N. Microstructural status of ipsilesional and contralesional corticospinal tract correlates with motor skill in chronic stroke patients. Hum Brain Mapp 2010; 30:3461-74. [PMID: 19370766 DOI: 10.1002/hbm.20770] [Citation(s) in RCA: 219] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Greater loss in structural integrity of the ipsilesional corticospinal tract (CST) is associated with poorer motor outcome in patients with hemiparetic stroke. Animal models of stroke have demonstrated that structural remodeling of white matter in the ipsilesional and contralesional hemispheres is associated with improved motor recovery. Accordingly, motor recovery in patients with stroke may relate to the relative strength of CST degeneration and remodeling. This study examined the relationship between microstructural status of brain white matter tracts, indexed by the fractional anisotropy (FA) metric derived from diffusion tensor imaging (DTI) data, and motor skill of the stroke-affected hand in patients with chronic stroke. Voxelwise analysis revealed that motor skill significantly and positively correlated with FA of the ipsilesional and contralesional CST in the patients. Additional voxelwise analyses showed that patients with poorer motor skill had reduced FA of bilateral CST compared to normal control subjects, whereas patients with better motor skill had elevated FA of bilateral CST compared to controls. These findings were confirmed using a DTI-tractography method applied to the CST in both hemispheres. The results of this study suggest that the level of motor skill recovery achieved in patients with hemiparetic stroke relates to microstructural status of the CST in both the ipsilesional and contralesional hemispheres, which may reflect the net effect of degeneration and remodeling of bilateral CST.
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Affiliation(s)
- Judith D Schaechter
- MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts 02129, USA.
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Caramia F, Francia A, Mainero C, Tinelli E, Palmieri MG, Colonnese C, Bozzao L, Caramia MD. Neurophysiological and functional MRI evidence of reorganization of cortical motor areas in cerebral arteriovenous malformation. Magn Reson Imaging 2009; 27:1360-9. [DOI: 10.1016/j.mri.2009.05.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 04/03/2009] [Accepted: 05/07/2009] [Indexed: 10/20/2022]
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Goldstein LB. Stroke recovery and rehabilitation. HANDBOOK OF CLINICAL NEUROLOGY 2009; 94:1327-1337. [PMID: 18793903 DOI: 10.1016/s0072-9752(08)94066-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Affiliation(s)
- Larry B Goldstein
- Duke Center for Cerebrovascular Disease and Durham VA Medical Center, Durham, NC 27710, USA.
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Chen C, Hsieh J, Wu Y, Lee P, Chen S, Niddam DM, Yeh T, Wu Y. Mutual-information-based approach for neural connectivity during self-paced finger lifting task. Hum Brain Mapp 2008; 29:265-80. [PMID: 17394211 PMCID: PMC6871222 DOI: 10.1002/hbm.20386] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Frequency-dependent modulation between neuronal assemblies may provide insightful mechanisms of functional organization in the context of neural connectivity. We present a conjoined time-frequency cross mutual information (TFCMI) method to explore the subtle brain neural connectivity by magnetoencephalography (MEG) during a self-paced finger lifting task. Surface electromyogram (sEMG) was obtained from the extensor digitorum communis. Both within-modality (MEG-MEG) and between-modality studies (sEMG-MEG) were conducted. The TFCMI method measures both the linear and nonlinear dependencies of the temporal dynamics of signal power within a pre-specified frequency band. Each single trial of MEG across channels and sEMG signals was transformed into time-frequency domain with use of the Morlet wavelet to obtain better temporal spectral (power) information. As compared to coherence approach (linear dependency only) in broadband analysis, the TFCMI method demonstrated advantages in encompassing detection for the mesial frontocentral cortex and bilateral primary sensorimotor areas, clear demarcation of event- and non-event-related regions, and robustness for sEMG - MEG between-modality study, i.e., corticomuscular communication. We conclude that this novel TFCMI method promises a possibility to better unravel the intricate functional organizations of brain in the context of oscillation-coded communication.
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Affiliation(s)
- Chun‐Chuan Chen
- Laboratory of Integrated Brain Research, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan
- Center for Neuroscience, National Yang‐Ming University, Taipei, Taiwan
| | - Jen‐Chuen Hsieh
- Laboratory of Integrated Brain Research, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan
- Institute of Brain Science, National Yang‐Ming University, Taipei, Taiwan
- Institute of Neuroscience, School of Life Science, National Yang‐Ming University, Taipei, Taiwan
- Center for Neuroscience, National Yang‐Ming University, Taipei, Taiwan
| | - Yu‐Zu Wu
- Laboratory of Integrated Brain Research, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan
- Institute of Neuroscience, School of Life Science, National Yang‐Ming University, Taipei, Taiwan
- Department of Physical Therapy, Tzu‐Chi College of Technology, Hualien, Taiwan
| | - Po‐Lei Lee
- Laboratory of Integrated Brain Research, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan
- Department of Electrical Engineering, Nation Central University, Jhongli, Taiwan
| | - Shyan‐Shiou Chen
- Laboratory of Integrated Brain Research, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan
| | - David M. Niddam
- Laboratory of Integrated Brain Research, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan
- Center for Neuroscience, National Yang‐Ming University, Taipei, Taiwan
| | - Tzu‐Chen Yeh
- Laboratory of Integrated Brain Research, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan
- Institute of Brain Science, National Yang‐Ming University, Taipei, Taiwan
- Faculty of Medicine, School of Medicine, National Yang‐Ming University, Taipei, Taiwan
| | - Yu‐Te Wu
- Laboratory of Integrated Brain Research, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan
- Institute of Brain Science, National Yang‐Ming University, Taipei, Taiwan
- Department of Biomedical Imaging and Radiological Sciences, National Yang‐Ming University, Taipei, Taiwan
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Darbar A, Stevens RT, Siddiqui AH, McCasland JS, Hodge CJ. Pharmacological modulation of cortical plasticity following kainic acid lesion in rat barrel cortex. J Neurosurg 2008; 109:108-16. [PMID: 18590439 DOI: 10.3171/jns/2008/109/7/0108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The brain shows remarkable capacity for plasticity in response to injury. To maximize the benefits of current neurological treatment and to minimize the impact of injury, the authors examined the ability of commonly administered drugs, dextroamphetamine (D-amphetamine) and phenytoin, to positively or negatively affect the functional recovery of the cerebral cortex following excitotoxic injury. METHODS Previous work from the same laboratory has demonstrated reorganization of whisker functional responses (WFRs) in the rat barrel cortex after excitotoxic lesions were created with kainic acid (KA). In the present study, WFRs were mapped using intrinsic optical signal imaging before and 9 days after creation of the KA lesions. During the post-lesion survival period, animals were either treated with intraperitoneal D-amphetamine, phenytoin, or saline or received no treatment. Following the survival period, WFRs were again measured and compared with prelesion data. RESULTS The findings suggest that KA lesions cause increases in WFR areas when compared with controls. Treatment with D-amphetamine further increased the WFR area (p < 0.05) while phenytoin-treated rats showed decreases in WFR areas. There was also a statistically significant difference (p < 0.05) between the D-amphetamine and phenytoin groups. CONCLUSIONS These results show that 2 commonly used drugs, D-amphetamine and phenytoin, have opposite effects in the functional recovery/plasticity of injured cerebral cortex. The authors' findings emphasize the complex nature of the cortical response to injury and have implications for understanding the biology of the effects of different medications on eventual functional brain recovery.
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Affiliation(s)
- Aneela Darbar
- Department of Neurosurgery, State University of New York Upstate Medical University, Syracuse, New York 13210, USA.
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Misawa S, Kuwabara S, Matsuda S, Honma K, Ono J, Hattori T. The ipsilateral cortico-spinal tract is activated after hemiparetic stroke. Eur J Neurol 2008; 15:706-11. [PMID: 18484986 DOI: 10.1111/j.1468-1331.2008.02168.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND AND PURPOSE The presence of a projection from the primary motor cortex to the ipsilateral muscles has been established in human, but whether this pathway contributes to functional recovery after stroke is unclear. We investigated whether the ipsilateral tract is activated in hemiparetic stroke. METHODS Motor-evoked potentials (MEPs) were simultaneously recorded from the bilateral trapezius or abductor digiti minimi (ADM) muscles after magnetic stimulation to the motor cortex in 40 acute stroke patients. RESULTS At rest, ipsilateral trapezius MEPs were recordable in none of the 24 normal controls, and in 38% of the patients after stimulation to the non-affected hemisphere (P < 0.001). With voluntary contraction, ipsilateral trapezius MEPs were elicited in 21% of the normal controls and 73% of the patients (P < 0.001). Ipsilateral ADM MEPs were rarely recordable in both controls (0%) and patients (3%). The presence of ipsilateral trapezius MEPs was associated with less severe paresis in the trapezius (P = 0.04) and deltoid (P = 0.07), but not in the more distal muscles. CONCLUSIONS The ipsilateral cortico-spinal tract is acutely facilitated after stroke in the trunk or proximal muscles, but not in the hand muscles. Activation of such pathway appears to partly compensate motor dysfunction of the trunk/proximal muscles.
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Affiliation(s)
- S Misawa
- Department of Neurology, Chiba University School of Medicine, Chiba, Japan
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