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Li X, Chen M, Barkhaus PE, Nandedkar SD, Schmit B, Zhou P. F wave analysis based on the compound muscle action potential scan. Muscle Nerve 2024; 70:395-401. [PMID: 38963007 PMCID: PMC11324398 DOI: 10.1002/mus.28197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 06/17/2024] [Accepted: 06/18/2024] [Indexed: 07/05/2024]
Abstract
INTRODUCTION/AIMS Conventional F wave analysis involves a relatively uniform physiological environment induced by supramaximal stimulations. The F wave characteristics in a dynamic physiological condition, however, are rarely investigated. This study aimed to improve understanding of F wave properties in the more dynamic process by introducing a novel method to analyze F waves based on the compound muscle action potential (CMAP) scan technique. METHODS Twenty four healthy subjects participated in the study. The CMAP scan was applied to record muscle responses in the abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles, respectively. F wave characteristics including mean F wave amplitude and latency (F-M latency), persistence and activating threshold were quantified. RESULTS An average of 200 F waves per muscle were obtained from the CMAP scan recording. Weak to moderate correlations between F wave amplitude and stimulating intensity were observed in most of the APB (19 muscles; r = 0.33 ± 0.14, all p < .05) and ADM (23 muscles, r = 0.46 ± 0.16, all p < .05) muscles. Significantly longer mean F latency and lower activating F-threshold were found in the ADM muscles (F-M latency: APB: 25.43 ± 2.39 ms, ADM: 26.15 ± 2.32 ms, p < .05; F-threshold: APB: 7.68 ± 8.96% CMAP, ADM: 2.35 ± 2.42% CMAP, p < .05). DISCUSSION This study introduces new features of F waves using the CMAP scan technique and identifies differences of F wave characteristics between the hand muscles. The CMAP scan based F waves analysis can be combined with the motor unit number estimation to assess functional alterations in motor neurons in neurological disorders.
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Affiliation(s)
- Xiaoyan Li
- Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
- Fischell Department of Bioengineering, University of Maryland at College Park, College Park, Maryland, USA
| | - Maoqi Chen
- School of Rehabilitation Science and Engineering, University of Health and Rehabilitation Sciences, Qingdao, China
| | - Paul E Barkhaus
- Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Sanjeev D Nandedkar
- Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
- Natus Medical, Inc, Middleton, Wisconsin, USA
| | - Brian Schmit
- Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin, USA
| | - Ping Zhou
- School of Rehabilitation Science and Engineering, University of Health and Rehabilitation Sciences, Qingdao, China
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Zhang L, Liu J, Liu M. Transsynaptic degeneration of ventral horn motor neurons exists but plays a minor role in lower motor system dysfunction in acute ischemic rats. PLoS One 2024; 19:e0298006. [PMID: 38669239 PMCID: PMC11051614 DOI: 10.1371/journal.pone.0298006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 01/16/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND As a leading cause of mortality and long-term disability, acute ischemic stroke can produce far-reaching pathophysiological consequences. Accumulating evidence has demonstrated abnormalities in the lower motor system following stroke, while the existence of Transsynaptic degeneration of contralateral spinal cord ventral horn (VH) neurons is still debated. METHODS Using a rat model of acute ischemic stroke, we analyzed spinal cord VH neuron counts contralaterally and ipsilaterally after stroke with immunofluorescence staining. Furthermore, we estimated the overall lower motor unit abnormalities after stroke by simultaneously measuring the modified neurological severity score (mNSS), compound muscle action potential (CMAP) amplitude, repetitive nerve stimulation (RNS), spinal cord VH neuron counts, and the corresponding muscle fiber morphology. The activation status of microglia and extracellular signal-regulated kinase 1/2 (ERK 1/2) in the spinal cord VH was also assessed. RESULTS At 7 days after stroke, the contralateral CMAP amplitudes declined to a nadir indicating lower motor function damage, and significant muscle disuse atrophy was observed on the same side; meanwhile, the VH neurons remained intact. At 14 days after focal stroke, lower motor function recovered with alleviated muscle disuse atrophy, while transsynaptic degeneration occurred on the contralateral side with elevated activation of ERK 1/2, along with the occurrence of neurogenic muscle atrophy. No apparent decrement of CMAP amplitude was observed with RNS during the whole experimental process. CONCLUSIONS This study offered an overview of changes in the lower motor system in experimental ischemic rats. We demonstrated that transsynaptic degeneration of contralateral VH neurons occurred when lower motor function significantly recovered, which indicated the minor role of transsynaptic degeneration in lower motor dysfunction during the acute and subacute phases of focal ischemic stroke.
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Affiliation(s)
- Lei Zhang
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Jingwen Liu
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Mingsheng Liu
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
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Chen M, Lu Z, Li X, Zong Y, Xie Q, Li S, Zhou P. Compound muscle action potential (CMAP) scan examination of paretic and contralateral muscles reveals motor unit alterations after stroke. SCIENCE CHINA. LIFE SCIENCES 2023; 66:2604-2613. [PMID: 37258801 PMCID: PMC11057326 DOI: 10.1007/s11427-022-2308-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 03/19/2023] [Indexed: 06/02/2023]
Abstract
This study presents a novel compound muscle action potential (CMAP) examination of motor unit changes in paretic muscle post stroke. CMAP scan of the first dorsal interosseous (FDI) muscle was performed bilaterally in 16 chronic stroke subjects. Various parameters were derived from the CMAP scan to examine paretic muscle changes, including CMAP amplitude, D50, step index (STEPIX) and amplitude index (AMPIX). A significant decrease in CMAP amplitude and STEPIX was observed in paretic muscles compared with contralateral muscles (CMAP amplitude: paretic (9.0±0.5) mV, contralateral (11.3±0.9) mV, P=0.024; STEPIX: paretic 101.2±7.6, contralateral 121.9±6.5, P=0.020). No significant difference in D50 and AMPIX was observed between the paretic and contralateral sides (P>0.05). The findings revealed complex paretic muscle changes including motor unit degeneration, muscle fiber denervation, reinnervation and atrophy, providing useful insights to help understand neuromuscular mechanisms associated with weakness and other functional deterioration post stroke. The CMAP scan experimental protocols and the applied processing methods are noninvasive, convenient, and automated, offering practical benefits for clinical application.
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Affiliation(s)
- Maoqi Chen
- School of Rehabilitation Science and Engineering, University of Health and Rehabilitation Sciences, Qingdao, 266071, China
| | - Zhiyuan Lu
- School of Rehabilitation Science and Engineering, University of Health and Rehabilitation Sciences, Qingdao, 266071, China.
| | - Xiaoyan Li
- Department of Neurology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
- Fischell Department of Bioengineering, University of Maryland at College Park, College Park, MD, 20742, USA
| | - Ya Zong
- Department of Rehabilitation Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Qing Xie
- Department of Rehabilitation Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Sheng Li
- Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center, Houston, TX, 77030, USA
- TIRR Memorial Hermann Research Center, TIRR Memorial Hermann Hospital, Houston, TX, 77030, USA
| | - Ping Zhou
- School of Rehabilitation Science and Engineering, University of Health and Rehabilitation Sciences, Qingdao, 266071, China
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Artuğ NT. Fully automated F-wave corridor extraction and analysis algorithm for F-wave analyses and MUNE studies. Sci Rep 2023; 13:13822. [PMID: 37620418 PMCID: PMC10449933 DOI: 10.1038/s41598-023-41183-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 08/23/2023] [Indexed: 08/26/2023] Open
Abstract
F-waves are used in motor unit number estimation (MUNE) studies, which require rapid dedicated software to perform calculations. The aim of this study is to define a mathematical method for a fully automated F-wave extraction algorithm to perform F-wave and MUNE studies while performing baseline corrections without distorting traces. Ten recordings from each class, such as healthy controls, polio patients and ALS patients, were included. Submaximal stimuli were applied to the median and ulnar nerves to record 300 traces from the abductor pollicis brevis and abductor digiti minimi muscles. The autocorrelation function and the signal of sum of all traces were used to find the location for the maximum amplitude of the F-waves. F-waves were revealed by using a cutting window. Linear line estimation was preferred for baseline corrections because it did not cause any distortion in the traces. The algorithm automatically revealed F-waves from all 30 recordings in accordance with the locations marked by a neurophysiologist. The execution of the algorithm was less than 2 (usually < 1) minutes when 300 traces were analyzed. Mean sMUP amplitudes and MUNE values are important for differentiating healthy controls from patients. Moreover, F-wave parameters belonging to polio patients on whom there was a relatively low number of studies conducted were also evaluated.
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Affiliation(s)
- N Tuğrul Artuğ
- Department of Electric, Vocational School of Technical Sciences, Istanbul University-Cerrahpasa, Buyukcekmece, Istanbul, Turkey.
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Aze OD, Ojardias E, Akplogan B, Giraux P, Calmels P. Structural and pathophysiological muscle changes up to one year after post-stroke hemiplegia: a systematic review. Eur J Phys Rehabil Med 2023; 59:474-487. [PMID: 37695037 PMCID: PMC10548887 DOI: 10.23736/s1973-9087.23.07844-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 05/31/2023] [Accepted: 07/17/2023] [Indexed: 09/12/2023]
Abstract
INTRODUCTION Muscle changes after stroke cannot be explained solely on the basis of corticospinal bundle damage. Muscle-specific changes contribute to limited functional recovery but have been poorly characterized. EVIDENCE ACQUISITION We conducted a systematic review of muscular changes occurring at the histological, neuromuscular and functional levels during the first year after the onset of post-stroke hemiplegia. A literature search was performed on PubMed, Embase and CINHAL databases up to November 2022 using a keyword combination comprising cerebral stroke, hemiplegic, atrophy, muscle structure, paresis, skeletal muscle fiber type, motor unit, oxidative stress, strength, motor control. EVIDENCE SYNTHESIS Twenty-seven trial reports were included in the review, out of 12,798 articles screened. Structural modifications described on the paretic side include atrophy, transformation of type II fibers into type I fibers, decrease in fiber diameter and apparent myofilament disorganization from the first week post-stroke up to the fourth month. Reported biochemical changes comprise the abnormal presence of lipid droplets and glycogen granules in the subsarcolemmal region during the first month post-stroke. At the neurophysiological level, studies indicate an early decrease in the number and activity of motor units, correlated with the degree of motor impairment. All these modifications were present to a lesser degree on the non-paretic side. Although only sparse data concerning the subacute stage are available, these changes seem to appear during the first two weeks post-stroke and continue up to the third or fourth month. CONCLUSIONS Considering these early pathophysiological changes on both the paretic and non-paretic sides, it seems crucial to promptly stimulate central and also peripheral muscular activation after stroke through specific rehabilitation programs focused on the maintenance of muscle capacities associated with neurological recovery or plasticity.
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Affiliation(s)
- Oscar D Aze
- Interuniversity Lab of Motricity Biology, Savoie Mont-Blanc University, Jean Monnet Saint-Etienne Universities, CHU Saint-Etienne, Lyon1, Saint-Etienne, France
- Impairments, Adapted Physical Activities and Rehabilitation Research Unit (UR-DAPAR), National Institute of Youth, Physical Education, and Sports, Abomey-Calavi University (INJEPS-UAC), Porto-Novo, Benin
- Service of Physical Medicine and Readaptation, CHU Saint-Etienne, Saint-Etienne, France
| | - Etienne Ojardias
- Service of Physical Medicine and Readaptation, CHU Saint-Etienne, Saint-Etienne, France -
- Inserm UMR-S 1028, Lyon Neuroscience Research Center, Lyon1 and Saint-Etienne Universities, Saint-Etienne, France
| | - Barnabé Akplogan
- Impairments, Adapted Physical Activities and Rehabilitation Research Unit (UR-DAPAR), National Institute of Youth, Physical Education, and Sports, Abomey-Calavi University (INJEPS-UAC), Porto-Novo, Benin
| | - Pascal Giraux
- Service of Physical Medicine and Readaptation, CHU Saint-Etienne, Saint-Etienne, France
- Inserm UMR-S 1028, Lyon Neuroscience Research Center, Lyon1 and Saint-Etienne Universities, Saint-Etienne, France
| | - Paul Calmels
- Interuniversity Lab of Motricity Biology, Savoie Mont-Blanc University, Jean Monnet Saint-Etienne Universities, CHU Saint-Etienne, Lyon1, Saint-Etienne, France
- Service of Physical Medicine and Readaptation, CHU Saint-Etienne, Saint-Etienne, France
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Gong Z, Lo WLA, Wang R, Li L. Electrical impedance myography combined with quantitative assessment techniques in paretic muscle of stroke survivors: Insights and challenges. Front Aging Neurosci 2023; 15:1130230. [PMID: 37020859 PMCID: PMC10069712 DOI: 10.3389/fnagi.2023.1130230] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 02/27/2023] [Indexed: 03/18/2023] Open
Abstract
Aging is a non-modifiable risk factor for stroke and the global burden of stroke is continuing to increase due to the aging society. Muscle dysfunction, common sequela of stroke, has long been of research interests. Therefore, how to accurately assess muscle function is particularly important. Electrical impedance myography (EIM) has proven to be feasible to assess muscle impairment in patients with stroke in terms of micro structures, such as muscle membrane integrity, extracellular and intracellular fluids. However, EIM alone is not sufficient to assess muscle function comprehensively given the complex contributors to paretic muscle after an insult. This article discusses the potential to combine EIM and other common quantitative methods as ways to improve the assessment of muscle function in stroke survivors. Clinically, these combined assessments provide not only a distinct advantage for greater accuracy of muscle assessment through cross-validation, but also the physiological explanation on muscle dysfunction at the micro level. Different combinations of assessments are discussed with insights for different purposes. The assessments of morphological, mechanical and contractile properties combined with EIM are focused since changes in muscle structures, tone and strength directly reflect the muscle function of stroke survivors. With advances in computational technology, finite element model and machine learning model that incorporate multi-modal evaluation parameters to enable the establishment of predictive or diagnostic model will be the next step forward to assess muscle function for individual with stroke.
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Affiliation(s)
- Ze Gong
- Research & Development Institute of Northwestern Polytechnical University in Shenzhen, Shenzhen, China
- Institute of Medical Research, Northwestern Polytechnical University, Xi’an, China
| | - Wai Leung Ambrose Lo
- Department of Rehabilitation Medicine, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Ruoli Wang
- KTH MoveAbility Lab, Department of Engineering Mechanics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Le Li
- Research & Development Institute of Northwestern Polytechnical University in Shenzhen, Shenzhen, China
- Institute of Medical Research, Northwestern Polytechnical University, Xi’an, China
- *Correspondence: Le Li,
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Liu Y, Chen YT, Zhang C, Zhou P, Li S, Zhang Y. Motor Unit Number Estimation in Spastic Biceps Brachii Muscles of Chronic Stroke Survivors Before and After BoNT Injection. IEEE Trans Biomed Eng 2023; 70:1045-1052. [PMID: 36126033 PMCID: PMC10676740 DOI: 10.1109/tbme.2022.3208078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The study aims to characterize the motor unit (MU) loss in spastic biceps brachii muscle (BBM) of chronic stroke survivors before and after botulinum neurotoxin (BoNT) injection. METHODS High-density weighted average (HDWA) motor unit number estimation (MUNE) was employed to estimate the number of functioning motor units of BBMs of eight chronic stroke survivors 1-week before (1st visit) and 3-week after (2nd visit) BoNT injection based on the surface electromyography (sEMG) signals recorded during voluntary contraction and supramaximal electrical stimulation. RESULT Significant lower MUNE was estimated from the spastic BBMs compared to the non-spastic MUNEs during two visits. A surprisingly higher MUNE was obtained from the spastic side during the 2nd visit after BoNT injection. CONCLUSIONS The HDWA MUNE technique can be employed to characterize the motor unit loss in spastic muscle caused by upper motor neuro lesions at contraction level up to 30% MVC, but may fail to detect the MU loss caused by the chemodenervation effect of BoNT due to the non-uniform denervation of small and large size MUs. SIGNIFICANCE This study presents the first effort to evaluate the applicability of HDWA MUNE technique to characterize the MU loss in the spastic muscle following stroke and the subsequent BoNT injection for the treatment of post-stroke spasticity. The finding of this study suggests that HDWA MUNE can be a sensitive approach to detect the MU loss in spastic muscles after stroke, but the large inter-subject MUNE variability after the BoNT injection should be interpreted with caution.
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Affiliation(s)
- Yang Liu
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204 USA
| | - Yen-Ting Chen
- (1) Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, Houston, TX 77030, United States; (2) TIRR Memorial Hermann Hospital, Houston, TX 77030, USA; (3) Department of Health and Kinesiology, Northeastern State University, Broken Arrow, OK 74014, USA
| | - Chuan Zhang
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204 USA
| | - Ping Zhou
- Faculty of Rehabilitation Engineering, University of Health and Rehabilitation Sciences, Qingdao 266024, China
| | - Sheng Li
- (1) Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, Houston, TX 77030, United States; (2) TIRR Memorial Hermann Hospital, Houston, TX 77030, USA
| | - Yingchun Zhang
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204 USA
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Chen M, Bashford J, Zhou P. Motor Unit Number Estimation (MUNE) Free of Electrical Stimulation or M Wave Recording: Feasibility and Challenges. Front Aging Neurosci 2022; 14:799676. [PMID: 35221991 PMCID: PMC8873975 DOI: 10.3389/fnagi.2022.799676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 01/10/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- Maoqi Chen
- Faculty of Rehabilitation Engineering, University of Health and Rehabilitation Sciences, Qingdao, China
| | - James Bashford
- Department of Basic and Clinical Neuroscience, UK Dementia Research Institute, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom
| | - Ping Zhou
- Faculty of Rehabilitation Engineering, University of Health and Rehabilitation Sciences, Qingdao, China
- *Correspondence: Ping Zhou
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Oguz-Akarsu E, Sirin NG, Artug T, Erbas B, Orhan EK, Idrisoğlu HA, Ketenci A, Baslo MB, Oge AE. Automatic detection of F-waves and F-MUNE in Two Types of Motor Neuron Diseases. Muscle Nerve 2022; 65:422-432. [PMID: 35020950 DOI: 10.1002/mus.27494] [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: 04/02/2021] [Revised: 01/02/2022] [Accepted: 01/06/2022] [Indexed: 11/09/2022]
Abstract
INTRODUCTION/AIMS Motor unit number estimation by F-waves (F-MUNE) is an uncommonly used MUNE technique. The aim of this study was to analyze the sensitivity of F-MUNE values elicited with newly developed software in motor neuron diseases. METHODS F-waves were recorded by 300 submaximal stimuli from abductor digiti minimi (ADM) and abductor pollicis brevis (APB) muscles of 35 patients with amyotrophic lateral sclerosis, 18 with previous poliomyelitis, and 20 controls. The software extracted the surface motor unit action potentials (sMUAP) and calculated the F-MUNE values. CMAP Scans were also recorded to obtain step% and MScanFit. RESULTS sMUAP amplitudes were higher and F-MUNE values were lower in both muscles of the patients than in controls. F-MUNE values were able to distinguish the patients from controls. Significant correlations were found between F-MUNE and MScanFit in patient groups. DISCUSSION The new F-MUNE software gave promising results in revealing motor unit loss caused by motor neuron diseases.
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Affiliation(s)
- Emel Oguz-Akarsu
- Departments of Neurology and Clinical Neurophysiology, Faculty of Medicine, Istanbul University, Istanbul, Turkey.,Department of Neurology, Faculty of Medicine, Bursa Uludag University, Bursa, Turkey
| | - Nermin Gorkem Sirin
- Departments of Neurology and Clinical Neurophysiology, Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Tugrul Artug
- Department of Electrical and Electronics Engineering, Faculty of Engineering, Izmir Democracy University, Izmir, Turkey
| | - Bahar Erbas
- Departments of Neurology and Clinical Neurophysiology, Faculty of Medicine, Istanbul University, Istanbul, Turkey.,Department of Pharmacology, Faculty of Medicine, Demiroglu Bilim University, Istanbul, Turkey
| | - Elif Kocasoy Orhan
- Departments of Neurology and Clinical Neurophysiology, Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Halil Atilla Idrisoğlu
- Departments of Neurology and Clinical Neurophysiology, Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Aysegul Ketenci
- Department of Physical Medicine and Rehabilitation, Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Mehmet Baris Baslo
- Departments of Neurology and Clinical Neurophysiology, Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Ali Emre Oge
- Departments of Neurology and Clinical Neurophysiology, Faculty of Medicine, Istanbul University, Istanbul, Turkey
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Azzollini V, Dalise S, Chisari C. How Does Stroke Affect Skeletal Muscle? State of the Art and Rehabilitation Perspective. Front Neurol 2022; 12:797559. [PMID: 35002937 PMCID: PMC8733480 DOI: 10.3389/fneur.2021.797559] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 11/29/2021] [Indexed: 12/25/2022] Open
Abstract
Long-term disability caused by stroke is largely due to an impairment of motor function. The functional consequences after stroke are caused by central nervous system adaptations and modifications, but also by the peripheral skeletal muscle changes. The nervous and muscular systems work together and are strictly dependent in their structure and function, through afferent and efferent communication pathways with a reciprocal “modulation.” Knowing how altered interaction between these two important systems can modify the intrinsic properties of muscle tissue is essential in finding the best rehabilitative therapeutic approach. Traditionally, the rehabilitation effort has been oriented toward the treatment of the central nervous system damage with a central approach, overlooking the muscle tissue. However, to ensure greater effectiveness of treatments, it should not be forgotten that muscle can also be a target in the rehabilitation process. The purpose of this review is to summarize the current knowledge about the skeletal muscle changes, directly or indirectly induced by stroke, focusing on the changes induced by the treatments most applied in stroke rehabilitation. The results of this review highlight changes in several muscular features, suggesting specific treatments based on biological knowledge; on the other hand, in standard rehabilitative practice, a realist muscle function evaluation is rarely carried out. We provide some recommendations to improve a comprehensive muscle investigation, a specific rehabilitation approach, and to draw research protocol to solve the remaining conflicting data. Even if a complete multilevel muscular evaluation requires a great effort by a multidisciplinary team to optimize motor recovery after stroke.
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Affiliation(s)
- Valentina Azzollini
- Department of Translational Research and New Technologies in Medicine and Surgery, DS Neurorehabilitation, University of Pisa, Pisa, Italy
| | - Stefania Dalise
- Department of Neurorehabilitation, Pisa University Hospital - Azienda Ospedaliera Universitaria Pisana (AOUP), Pisa, Italy
| | - Carmelo Chisari
- Department of Translational Research and New Technologies in Medicine and Surgery, DS Neurorehabilitation, University of Pisa, Pisa, Italy
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Muscle Fiber Diameter and Density Alterations after Stroke Examined by Single-Fiber EMG. Neural Plast 2021; 2021:3045990. [PMID: 34434227 PMCID: PMC8380495 DOI: 10.1155/2021/3045990] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 07/01/2021] [Accepted: 07/30/2021] [Indexed: 11/18/2022] Open
Abstract
This study presents single-fiber electromyography (EMG) analysis for assessment of paretic muscle changes after stroke. Single-fiber action potentials (SFAPs) were recorded from the first dorsal interosseous (FDI) muscle bilaterally in 12 individuals with hemiparetic stroke. The SFAP parameters, including the negative peak duration and the peak-peak amplitude, were measured and further used to estimate muscle fiber diameter through a model based on the quadratic function. The SFAP parameters, fiber density, and muscle fiber diameter derived from the model were compared between the paretic and contralateral muscles. The results show that SFAPs recorded from the paretic muscle had significantly smaller negative peak duration than that from the contralateral muscle. As a result, the derived muscle fiber diameter of the paretic muscle was significantly smaller than that of the contralateral muscle. The fiber density of the paretic muscle was significantly higher than that of the contralateral muscle. These results provide further evidence of remodeled motor units after stroke and suggest that paretic muscle weakness can be due to both complex central and peripheral neuromuscular alterations.
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12
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Model-Based Analysis of Muscle Strength and EMG-Force Relation with respect to Different Patterns of Motor Unit Loss. Neural Plast 2021; 2021:5513224. [PMID: 34257638 PMCID: PMC8245245 DOI: 10.1155/2021/5513224] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 05/02/2021] [Accepted: 06/01/2021] [Indexed: 01/07/2023] Open
Abstract
This study presents a model-based sensitivity analysis of the strength of voluntary muscle contraction with respect to different patterns of motor unit loss. A motor unit pool model was implemented including simulation of a motor neuron pool, muscle force, and surface electromyogram (EMG) signals. Three different patterns of motor unit loss were simulated, including (1) motor unit loss restricted to the largest ones, (2) motor unit loss restricted to the smallest ones, and (3) motor unit loss without size restriction. The model outputs including muscle force amplitude, variability, and the resultant EMG-force relation were quantified under two different motor neuron firing strategies. It was found that motor unit loss restricted to the largest ones had the most dominant impact on muscle strength and significantly changed the EMG-force relation, while loss restricted to the smallest motor units had a pronounced effect on force variability. These findings provide valuable insight toward our understanding of the neurophysiological mechanisms underlying experimental observations of muscle strength, force control, and EMG-force relation in both normal and pathological conditions.
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Balch MHH, Harris H, Chugh D, Gnyawali S, Rink C, Nimjee SM, Arnold WD. Ischemic stroke-induced polyaxonal innervation at the neuromuscular junction is attenuated by robot-assisted mechanical therapy. Exp Neurol 2021; 343:113767. [PMID: 34044000 DOI: 10.1016/j.expneurol.2021.113767] [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: 02/25/2021] [Revised: 04/30/2021] [Accepted: 05/22/2021] [Indexed: 01/12/2023]
Abstract
Ischemic stroke is a leading cause of disability world-wide. Mounting evidence supports neuromuscular pathology following stroke, yet mechanisms of dysfunction and therapeutic action remain undefined. The objectives of our study were to investigate neuromuscular pathophysiology following ischemic stroke and to evaluate the therapeutic effect of Robot-Assisted Mechanical massage Therapy (RAMT) on neuromuscular junction (NMJ) morphology. Using an ischemic stroke model in male rats, we demonstrated longitudinal losses of muscle contractility and electrophysiological estimates of motor unit number in paretic hindlimb muscles within 21 days of stroke. Histological characterization demonstrated striking pre- and postsynaptic alterations at the NMJ. Stroke prompted enlargement of motor axon terminals, acetylcholine receptor (AChR) area, and motor endplate size. Paretic muscle AChRs were also more homogenously distributed across motor endplates, exhibiting fewer clusters and less fragmentation. Most interestingly, NMJs in paretic muscle exhibited increased frequency of polyaxonal innervation. This finding of increased polyaxonal innervation in stroke-affected skeletal muscle suggests that reduction of motor unit number following stroke may be a spurious artifact due to overlapping of motor units rather than losses. Furthermore, we tested the effects of RAMT - which we recently showed to improve motor function and protect against subacute myokine disturbance - and found significant attenuation of stroke-induced NMJ alterations. RAMT not only normalized the post-stroke presentation of polyaxonal innervation but also mitigated postsynaptic expansion. These findings confirm complex neuromuscular pathophysiology after stroke, provide mechanistic direction for ongoing research, and inform development of future therapeutic strategies. SIGNIFICANCE: Ischemic stroke is a leading contributor to chronic disability, and there is growing evidence that neuromuscular pathology may contribute to the impact of stroke on physical function. Following ischemic stroke in a rat model, there are progressive declines of motor unit number estimates and muscle contractility. These changes are paralleled by striking pre- and postsynaptic maladaptive changes at the neuromuscular junction, including polyaxonal innervation. When administered to paretic hindlimb muscle, Robot-Assisted Mechanical massage Therapy - previously shown to improve motor function and protect against subacute myokine disturbance - prevents stroke-induced neuromuscular junction alterations. These novel observations provide insight into the neuromuscular response to cerebral ischemia, identify peripheral mechanisms of functional disability, and present a therapeutic rehabilitation strategy with clinical relevance.
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Affiliation(s)
- Maria H H Balch
- Department of Biomedical Education and Anatomy, The Ohio State University College of Medicine, Columbus, OH, USA; Department of Neurosurgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Hallie Harris
- Department of Neurosurgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Deepti Chugh
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Surya Gnyawali
- Department of Neurosurgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Cameron Rink
- Department of Neurosurgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Shahid M Nimjee
- Department of Neurosurgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - W David Arnold
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Physical Medicine and Rehabilitation, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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Zhang C, Chen YT, Liu Y, Magat E, Gutierrez-Verduzco M, Francisco GE, Zhou P, Li S, Zhang Y. Improving Botulinum Toxin Efficiency in Treating Post-Stroke Spasticity Using 3D Innervation Zone Imaging. Int J Neural Syst 2021; 31:2150007. [PMID: 33438529 DOI: 10.1142/s0129065721500076] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Spasticity is a common post-stroke syndrome that imposes significant adverse impacts on patients and caregivers. This study aims to improve the efficiency of botulinum toxin (BoNT) in managing spasticity, by utilizing a three-dimensional innervation zone imaging (3DIZI) technique based on high-density surface electromyography (HD-sEMG) recordings. Stroke subjects were randomly assigned to two groups: the control group ([Formula: see text]) which received standard ultrasound-guided injections, and the experimental group ([Formula: see text]) which received 3DIZI-guided injections. The amount of BoNT given was consistent for all subjects. The Modified Ashworth Scale (MAS), compound muscle action potential (CMAP) and muscle activation volume (MAV) from bilateral biceps brachii muscles were obtained at the baseline, 3 weeks, and 3 months after injection. Intra-group and inter-group comparisons of MAS, CMAP amplitude and MAV were performed. An overall improvement in MAS of spastic elbow flexors was observed during the 3-week visit ([Formula: see text]), yet no statistically significant difference found with intra-group or inter-group analysis. Compared to the baseline, a significant reduction of CMAP amplitude and MAV were observed in the spastic biceps muscles of both groups at 3-week post-injection, and returned to approximate baseline value at 12-week post injection. A significantly higher reduction was found in CMAP amplitude ([Formula: see text]% versus [Formula: see text]%, [Formula: see text]) and MAV ([Formula: see text]% versus [Formula: see text]%, [Formula: see text]) in the experimental group compared to the control group. The study has demonstrated preliminary evidence that precisely directing BoNT to the innervation zones (IZs) localized by 3DIZI leads to a significantly higher treatment efficiency improvement in spasticity management. Results have also shown the feasibility of developing a personalized BoNT injection technique for the optimization of clinical treatment for post-stroke spasticity using proposed 3DIZI technique.
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Affiliation(s)
- Chuan Zhang
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Yen-Ting Chen
- Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston and TIRR, Memorial Hermann Hospital, Houston, TX, USA
| | - Yang Liu
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
| | - Elaine Magat
- Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston and TIRR, Memorial Hermann Hospital, Houston, TX, USA
| | - Monica Gutierrez-Verduzco
- Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston and TIRR, Memorial Hermann Hospital, Houston, TX, USA
| | - Gerard E Francisco
- Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston and TIRR, Memorial Hermann Hospital, Houston, TX, USA
| | - Ping Zhou
- Institute of Rehabilitation Engineering, The University of Rehabilitation, Qingdao, P. R. China
| | - Sheng Li
- Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston and TIRR, Memorial Hermann Hospital, Houston, TX, USA
| | - Yingchun Zhang
- Department of Biomedical Engineering, University of Houston, Houston, TX, USA
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15
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Brain and Muscle: How Central Nervous System Disorders Can Modify the Skeletal Muscle. Diagnostics (Basel) 2020; 10:diagnostics10121047. [PMID: 33291835 PMCID: PMC7762031 DOI: 10.3390/diagnostics10121047] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 11/28/2020] [Accepted: 12/02/2020] [Indexed: 12/16/2022] Open
Abstract
It is widely known that nervous and muscular systems work together and that they are strictly dependent in their structure and functions. Consequently, muscles undergo macro and microscopic changes with subsequent alterations after a central nervous system (CNS) disease. Despite this, only a few researchers have addressed the problem of skeletal muscle abnormalities following CNS diseases. The purpose of this review is to summarize the current knowledge on the potential mechanisms responsible for changes in skeletal muscle of patients suffering from some of the most common CSN disorders (Stroke, Multiple Sclerosis, Parkinson’s disease). With this purpose, we analyzed the studies published in the last decade. The published studies show an extreme heterogeneity of the assessment modality and examined population. Furthermore, it is evident that thanks to different evaluation methodologies, it is now possible to implement knowledge on muscle morphology, for a long time limited by the requirement of muscle biopsies. This could be the first step to amplify studies aimed to analyze muscle characteristics in CNS disease and developing rehabilitation protocols to prevent and treat the muscle, often neglected in CNS disease.
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16
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Yang Q, Zheng M, Ye Y, Li L, Yan T, Song R. The Step Response in Isometric Grip Force Tracking: A Model to Characterize Aging- and Stroke-Induced Changes. IEEE Trans Neural Syst Rehabil Eng 2019; 27:673-681. [PMID: 30872233 DOI: 10.1109/tnsre.2019.2904251] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
This paper aimed to construct a model to represent dynamic motor behavior to quantitatively investigate aging- and stroke-induced changes and, thus, to explore the underlying mechanisms of grip control. Grip force tracking tasks were conducted by stroke patients, age-matched healthy controls, and healthy young adults at 25%, 50%, and 75% maximum voluntary contractions (MVC), respectively. Sensorimotor control of the tracking task was modeled as the step response of a second-order system. The results revealed that aging had no significant effect on the parameters of the model, whereas significant differences were found between the age-matched control and stroke groups. Target force level significantly affected the damping ratio and natural frequency in the young group, and significantly affected the damping ratio in the stroke group. Significant correlations were found between the wolf motor function test score and damping ratio, natural frequency, and settling time at 25% MVC. The model could describe the stroke-induced oscillation and slow response in dynamic grip force control and has the potential to be a quantitative evaluation of motor disabilities in clinic.
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17
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Yao B, Klein CS, Hu H, Li S, Zhou P. Motor Unit Properties of the First Dorsal Interosseous in Chronic Stroke Subjects: Concentric Needle and Single Fiber EMG Analysis. Front Physiol 2018; 9:1587. [PMID: 30559674 PMCID: PMC6287192 DOI: 10.3389/fphys.2018.01587] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 10/23/2018] [Indexed: 02/04/2023] Open
Abstract
The purpose of this study was to better understand changes in motor unit electrophysiological properties in people with chronic stroke based on concentric needle electromyography (EMG) and single fiber EMG recordings. The first dorsal interosseous (FDI) muscle was studied bilaterally in eleven hemiparetic stroke subjects. A significant increase in mean fiber density (FD) was found in the paretic muscle compared with the contralateral side based on single fiber EMG (1.6 ± 0.2 vs. 1.3 ± 0.1, respectively, P = 0.003). There was no statistically significant difference between the paretic and contralateral sides in most concentric needle motor unit action potential (MUAP) parameters, such as amplitude (768.7 ± 441.7 vs. 855.0 ± 289.9 μV), duration (8.9 ± 1.8 vs. 8.68 ± 0.9 ms) and size index (1.2 ± 0.5 vs. 1.1 ± 0.3) (P > 0.18), nor was there a significant difference in single fiber EMG recorded jitter (37.0 ± 9.6 vs. 39.9 ± 10.6 μs, P = 0.45). The increase in FD suggests motor units of the paretic FDI have enlarged due to collateral reinnervation. However, sprouting might be insufficient to result in a statistically significant change in the concentric needle MUAP parameters. Single fiber EMG appears more sensitive than concentric needle EMG to reflect electrophysiological changes in motor units after stroke. Both single fiber and concentric needle EMG recordings may be necessary to better understand muscle changes after stroke, which is important for development of appropriate rehabilitation strategies. The results provide further evidence that motor units are remodeled after stroke, possibly in response to a loss of motoneurons.
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Affiliation(s)
- Bo Yao
- Institute of Biomedical Engineering, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, China.,Department of Physical Medicine & Rehabilitation, The University of Texas Health Science Center at Houston, Houston, TX, United States.,TIRR Memorial Hermann Research Center, Houston, TX, United States
| | - Cliff S Klein
- Guangdong Work Injury Rehabilitation Center, Guangzhou, China
| | - Huijing Hu
- Department of Physical Medicine & Rehabilitation, The University of Texas Health Science Center at Houston, Houston, TX, United States.,TIRR Memorial Hermann Research Center, Houston, TX, United States.,Guangdong Work Injury Rehabilitation Center, Guangzhou, China
| | - Sheng Li
- Department of Physical Medicine & Rehabilitation, The University of Texas Health Science Center at Houston, Houston, TX, United States.,TIRR Memorial Hermann Research Center, Houston, TX, United States
| | - Ping Zhou
- Department of Physical Medicine & Rehabilitation, The University of Texas Health Science Center at Houston, Houston, TX, United States.,TIRR Memorial Hermann Research Center, Houston, TX, United States
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18
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Hamdi O, Mighri F, Rodrigue D. Piezoelectric property improvement of polyethylene ferroelectrets using postprocessing thermal-pressure treatment. POLYM ADVAN TECHNOL 2018. [DOI: 10.1002/pat.4453] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Ouassim Hamdi
- Department of Chemical Engineering; Université Laval; Quebec G1V0A6 Canada
| | - Frej Mighri
- Department of Chemical Engineering; Université Laval; Quebec G1V0A6 Canada
| | - Denis Rodrigue
- Department of Chemical Engineering; Université Laval; Quebec G1V0A6 Canada
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19
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Zong Y, Shin HH, Wang YC, Li S, Zhou P, Li X. Assessing Hand Muscle Structural Modifications in Chronic Stroke. Front Neurol 2018; 9:296. [PMID: 29867714 PMCID: PMC5953342 DOI: 10.3389/fneur.2018.00296] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 04/17/2018] [Indexed: 12/14/2022] Open
Abstract
The purpose of the study is to assess poststroke muscle structural alterations by examining muscular electrical conductivity and inherent electrophysiological properties. In particular, muscle impedance and compound muscle action potentials (CMAP) were measured from the hypothenar muscle bilaterally using the electrical impedance myography and the electrophysiological techniques, respectively. Significant changes of muscle impedance were observed in the paretic muscle compared with the contralateral side (resistance: paretic: 27.54 ± 0.97 Ω, contralateral: 25.46 ± 0.91 Ω, p < 0.05; phase angle: paretic: 8.81 ± 0.61°, contralateral: 10.79 ± 0.69°, p < 0.05). In addition, impedance changes correlated moderately with the CMAP amplitude in the paretic hand (phase angle: r = 0.66, p < 0.05; reactance: r = 0.58, p < 0.05). The study discloses significant muscle rearrangements as a result of fiber loss or atrophy, fat infiltration or impaired membrane integrity in chronic stroke.
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Affiliation(s)
- Ya Zong
- Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.,Guangdong Work Injury Rehabilitation Center, Guangzhou, China.,Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, TIRR Memorial Hermann Research Center, Houston, TX, United States
| | - Henry H Shin
- Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, TIRR Memorial Hermann Research Center, Houston, TX, United States
| | - Ying-Chih Wang
- Department of Occupational Science and Technology, University of Wisconsin-Milwaukee, Milwaukee, WI, United States
| | - Sheng Li
- Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, TIRR Memorial Hermann Research Center, Houston, TX, United States
| | - Ping Zhou
- Guangdong Work Injury Rehabilitation Center, Guangzhou, China.,Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, TIRR Memorial Hermann Research Center, Houston, TX, United States
| | - Xiaoyan Li
- Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, TIRR Memorial Hermann Research Center, Houston, TX, United States
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20
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Li X, Li L, Shin H, Li S, Zhou P. Electrical Impedance Myography for Evaluating Paretic Muscle Changes After Stroke. IEEE Trans Neural Syst Rehabil Eng 2017; 25:2113-2121. [PMID: 28574361 DOI: 10.1109/tnsre.2017.2707403] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Electrical impedance myography (EIM) was used to assess the paretic muscle intrinsic electrical properties post stroke. Twenty-seven subjects with chronic hemiparesis participated in this study. Muscle impedance was measured by applying high-frequency, low-intensity alternating current to biceps brachii muscles. Major EIM parameters, resistance ( ), reactance ( ), phase angle ( ), and electrical anisotropy ratios (AR) of the three parameters, were examined at 50 kHz. Statistical analysis demonstrated significant reduction of reactance, phase angle, AR of resistance, and AR of reactance in the paretic muscle compared with the contralateral side (Paretic X: , contralateral X: , and p < 0.001; Paretic : , contralateral : 14.5 ± 0.82°, and p < 0.001; Paretic AR of R: 0.969 ± 0.013, contralateral AR of R: 1.008 ± 0.011, and p < 0.02; and Paretic AR of X: 0.981 ± 0.066, contralateral AR of X: 1.114 ± 0.041, and p < 0.02). Correlation analysis, however, did not show any significant relationship between EIM parameters and clinical assessments. Findings of this paper indicated significant changes in the muscular intrinsic electrical properties after stroke, possibly related to structural modifications induced by loss of muscle fibers or fat infiltration as well as changes in the quality of cell membranes post stroke.
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