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Verma S, Khurana S, Vats A, Sahu B, Ganguly NK, Chakraborti P, Gourie-Devi M, Taneja V. Neuromuscular Junction Dysfunction in Amyotrophic Lateral Sclerosis. Mol Neurobiol 2022; 59:1502-1527. [PMID: 34997540 DOI: 10.1007/s12035-021-02658-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 11/18/2021] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurological disorder characterized by progressive degeneration of motor neurons leading to skeletal muscle denervation. Earlier studies have shown that motor neuron degeneration begins in motor cortex and descends to the neuromuscular junction (NMJ) in a dying forward fashion. However, accumulating evidences support that ALS is a distal axonopathy where early pathological changes occur at the NMJ, prior to onset of clinical symptoms and propagates towards the motor neuron cell body supporting "dying back" hypothesis. Despite several evidences, series of events triggering NMJ disassembly in ALS are still obscure. Neuromuscular junction is a specialized tripartite chemical synapse which involves a well-coordinated communication among the presynaptic motor neuron, postsynaptic skeletal muscle, and terminal Schwann cells. This review provides comprehensive insight into the role of NMJ in ALS pathogenesis. We have emphasized the molecular alterations in cellular components of NMJ leading to loss of effective neuromuscular transmission in ALS. Further, we provide a preview into research involved in exploring NMJ as potential target for designing effective therapies for ALS.
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Affiliation(s)
- Sagar Verma
- Department of Research, Sir Ganga Ram Hospital, Delhi, India.,Department of Biotechnology, Jamia Hamdard, Delhi, India
| | - Shiffali Khurana
- Department of Research, Sir Ganga Ram Hospital, Delhi, India.,Department of Biomedical Science, Bhaskaracharya College of Applied Sciences, University of Delhi, Delhi, India
| | - Abhishek Vats
- Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Bandana Sahu
- Department of Research, Sir Ganga Ram Hospital, Delhi, India
| | | | | | | | - Vibha Taneja
- Department of Research, Sir Ganga Ram Hospital, Delhi, India.
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Fogarty MJ, Mu EWH, Lavidis NA, Noakes PG, Bellingham MC. Size‐dependent dendritic maladaptations of hypoglossal motor neurons in SOD1
G93A
mice. Anat Rec (Hoboken) 2020; 304:1562-1581. [DOI: 10.1002/ar.24542] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 09/14/2020] [Accepted: 09/22/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Matthew J. Fogarty
- School of Biomedical Sciences The University of Queensland St Lucia Australia
- Department of Physiology and Biomedical Engineering, Mayo Clinic Rochester Minnesota USA
| | - Erica W. H. Mu
- School of Biomedical Sciences The University of Queensland St Lucia Australia
| | - Nickolas A. Lavidis
- School of Biomedical Sciences The University of Queensland St Lucia Australia
| | - Peter G. Noakes
- School of Biomedical Sciences The University of Queensland St Lucia Australia
- Queensland Brain Institute The University of Queensland St Lucia Australia
| | - Mark C. Bellingham
- School of Biomedical Sciences The University of Queensland St Lucia Australia
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Fogarty MJ, Mu EWH, Lavidis NA, Noakes PG, Bellingham MC. Size-Dependent Vulnerability of Lumbar Motor Neuron Dendritic Degeneration in SOD1 G93A Mice. Anat Rec (Hoboken) 2019; 303:1455-1471. [PMID: 31509351 DOI: 10.1002/ar.24255] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 05/22/2019] [Accepted: 06/29/2019] [Indexed: 12/14/2022]
Abstract
The motor neuron (MN) soma surface area is correlated with motor unit type. Larger MNs innervate fast fatigue-intermediate (FInt) or fast-fatiguable (FF) muscle fibers in type FInt and FF motor units, respectively. Smaller MNs innervate slow-twitch fatigue-resistant (S) or fast fatigue-resistant (FR) muscle fibers in type S and FR motor units, respectively. In amyotrophic lateral sclerosis (ALS), FInt and FF motor units are more vulnerable, with denervation and MN death occurring for these units before the more resilient S and FR units. Abnormal MN dendritic arbors have been observed in ALS in humans and rodent models. We used a Golgi-Cox impregnation protocol to examine soma size-dependent changes in the dendritic morphology of lumbar MNs in SOD1G93A mice, a model of ALS, at pre-symptomatic, onset and mid-disease stages. In wildtype control mice, the relationship between MN soma surface area and dendritic length or dendritic spine number was highly linear (i.e., increased MN soma size correlated with increased dendritic length and spines). By contrast, in SOD1G93A mice, this linear relationship was lost and dendritic length reduction and spine loss were observed in larger MNs, from pre-symptomatic stages onward. These changes correlated with the neuromotor symptoms of ALS in rodent models. At presymptomatic ages, changes were restricted to the larger MNs, likely to comprise vulnerable FInt and FF motor units. Our results suggest morphological changes of MN dendrites and dendritic spines are likely to contribute ALS pathogenesis, not compensate for it. Anat Rec, 303:1455-1471, 2020. © 2019 American Association for Anatomy.
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Affiliation(s)
- Matthew J Fogarty
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Erica W H Mu
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Nickolas A Lavidis
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | - Peter G Noakes
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia.,Queensland Brain Institute, The University of Queensland, St Lucia, Queensland, Australia
| | - Mark C Bellingham
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia
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Abstract
Although we currently have two, approved, disease-modifying drugs for the treatment of amyotrophic lateral sclerosis (ALS), we are in disperate need for more efficacious treatment. To aggressively test for newer therapies, we must develop reliable objective biomarkers to supplement clinical outcome measures. Many biomarker candidates have been actively and vigorously investigated. Among neurophysiological biomarkers, transcranial magnetic stimulation (TMS)-based biomarkers show potential in exploring disease mechanisms. Neuroimaging biomarkers have high specificity in diagnosing ALS but are an expensive endeavor and are not sensitive enough to detect changes over time of the disease. Among fluid-based biochemical biomarkers, creatinine (Crn) and uric acids (UA), which have been known for decades, may prove to be highly promising biomarkers that can predict disease progression. They can be easily tested in any clinical trials because the costs are minimal. Although known for some time, neurofilaments (NF), either phosphorylated-NF heavy subunit (pNFH) or NF light subunit (NFL), have emerged as "new" biomarkers using specific antibodies. They appear to be highly specific and sensitive in diagnosing ALS, yet they may be insensitive to assess changes in disease over time. These two NF biomarkers along with Crn and UA should be explored extensively in future clinical trials and any other clinical studies in ALS. Yet, we still need newer, more innovative, and reliable biomarkers for future ALS research. Fortunatley, aggressive investigations appear to be currently underway.
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Affiliation(s)
- Hiroshi Mitsumoto
- Wesley J Howe Professor of Neurology (at CUMC), Eleanor and Lou Gehrig ALS Center, Department of Neurology, Columbia University Medical Center (CUMC)
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Van den Bos MA, Higashihara M, Geevasinga N, Menon P, Kiernan MC, Vucic S. Imbalance of cortical facilitatory and inhibitory circuits underlies hyperexcitability in ALS. Neurology 2018; 91:e1669-e1676. [DOI: 10.1212/wnl.0000000000006438] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 07/18/2018] [Indexed: 12/14/2022] Open
Abstract
ObjectiveTo determine the relative contribution of inhibitory and facilitatory circuits in the development of cortical hyperexcitability in amyotrophic lateral sclerosis (ALS).MethodsIn this cross-sectional study, cortical excitability was assessed in 27 patients with ALS, and results compared to 25 healthy controls. In addition, a novel neurophysiologic measure of cortical function, short-interval intracortical facilitation (SICF), was assessed reflecting activity of the facilitatory circuits.ResultsThere was a significant increase in SICF (ALS −18.51 ± 1.56%, controls −8.52 ± 1.21%, p < 0.001) in patients with ALS that was accompanied by a reduction of short-interval intracortical inhibition (ALS 3.94 ± 1.29%, controls 14.23 ± 1.18%, p < 0.001) and cortical silent period duration (p = 0.034). The index of excitation, a biomarker reflecting the contribution of inhibitory and facilitatory circuit activity, was significantly increased in patients with ALS (82.79 ± 6.01%) compared to controls (36.15 ± 3.44, p < 0.001), suggesting a shift toward cortical excitation. Increased excitation correlated with upper motor neuron signs (R2 = 0.235, p = 0.016) and greater functional disability as reflected by a correlation with the Amyotrophic Lateral Sclerosis Functional Rating Scale–Revised score (R2 = 0.335, p = 0.002).ConclusionsThe present study established that cortical hyperexcitability is a key contributor to ALS pathophysiology, mediated through dysfunction of inhibitory and facilitatory intracortical circuits. Therapies aimed at restoring the cortical inhibitory imbalance provide novel avenues for future therapeutic targets.
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Driven to decay: Excitability and synaptic abnormalities in amyotrophic lateral sclerosis. Brain Res Bull 2018; 140:318-333. [PMID: 29870780 DOI: 10.1016/j.brainresbull.2018.05.023] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/26/2018] [Accepted: 05/31/2018] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is the most common motor neuron (MN) disease and is clinically characterised by the death of corticospinal motor neurons (CSMNs), spinal and brainstem MNs and the degeneration of the corticospinal tract. Degeneration of CSMNs and MNs leads inexorably to muscle wastage and weakness, progressing to eventual death within 3-5 years of diagnosis. The CSMNs, located within layer V of the primary motor cortex, project axons constituting the corticospinal tract, forming synaptic connections with brainstem and spinal cord interneurons and MNs. Clinical ALS may be divided into familial (∼10% of cases) or sporadic (∼90% of cases), based on apparent random incidence. The emergence of transgenic murine models, expressing different ALS-associated mutations has accelerated our understanding of ALS pathogenesis, although precise mechanisms remain elusive. Multiple avenues of investigation suggest that cortical electrical abnormalities have pre-eminence in the pathophysiology of ALS. In addition, glutamate-mediated functional and structural alterations in both CSMNs and MNs are present in both sporadic and familial forms of ALS. This review aims to promulgate debate in the field with regard to the common aetiology of sporadic and familial ALS. A specific focus on a nexus point in ALS pathogenesis, namely, the synaptic and intrinsic hyperexcitability of CSMNs and MNs and alterations to their structure are comprehensively detailed. The association of extramotor dysfunction with neuronal structural/functional alterations will be discussed. Finally, the implications of the latest research on the dying-forward and dying-back controversy are considered.
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Sangari S, Giron A, Marrelec G, Pradat PF, Marchand-Pauvert V. Abnormal cortical brain integration of somatosensory afferents in ALS. Clin Neurophysiol 2017; 129:874-884. [PMID: 29317192 DOI: 10.1016/j.clinph.2017.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 11/25/2017] [Accepted: 12/11/2017] [Indexed: 12/12/2022]
Abstract
OBJECTIVES Infraclinical sensory alterations have been reported at early stages of amyotrophic lateral sclerosis (ALS). While previous studies mainly focused on early somatosensory evoked potentials (SEPs), late SEPs, which reflect on cortical pathways involved in cognitive-motor functions, are relatively underinvestigated. Early and late SEPs were compared to assess their alterations in ALS. METHODS Median and ulnar nerves were electrically stimulated at the wrist, at 9 times the perceptual threshold, in 21 ALS patients without clinical evidence of sensory deficits, and 21 age- and gender-matched controls. SEPs were recorded at the Erb point using surface electrodes and using a needle inserted in the scalp, in front of the primary somatosensory area (with reference electrode on the ear lobe). RESULTS Compared to controls, ALS patients showed comparable peripheral (N9) and early cortical component (N20, P25, N30) reductions, while the late cortical components (N60, P100) were more depressed than the early ones. CONCLUSIONS The peripheral sensory alteration likely contributed to late SEP depression to a lesser extent than that of early SEPs. SIGNIFICANCE Late SEPs may provide new insights on abnormal cortical excitability affecting brain areas involved in cognitive-motor functions.
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Affiliation(s)
- Sina Sangari
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Inserm, Laboratoire d'Imagerie Biomédicale, F-75013 Paris, France
| | - Alain Giron
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Inserm, Laboratoire d'Imagerie Biomédicale, F-75013 Paris, France
| | - Guillaume Marrelec
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Inserm, Laboratoire d'Imagerie Biomédicale, F-75013 Paris, France
| | - Pierre-François Pradat
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Inserm, Laboratoire d'Imagerie Biomédicale, F-75013 Paris, France; Département de Neurologie, AP-HP, Hôpital Pitié-Salpêtrière, F-75013 Paris, France
| | - Véronique Marchand-Pauvert
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Inserm, Laboratoire d'Imagerie Biomédicale, F-75013 Paris, France.
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Yalinay Dikmen P, Kocasoy Orhan E, Baslo MB. Analysis of motor unit firing characteristics in patients with motor neuron diseases. Somatosens Mot Res 2016; 33:16-9. [PMID: 26911921 DOI: 10.3109/08990220.2016.1142437] [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]
Abstract
This study was designed to evaluate firing rate variability in patients with upper/lower motor neuron disorders. Twenty healthy subjects and 19 patients with motor neuron disorders participated in the study. Consecutive motor unit action potential pairs from extensor digitorum communis (EDC) muscle were recorded from each subject with trigger-delay line mode. Patients with motor neuron disorders (17.7 ± 10.8 ms) showed significantly higher mean time variability of interpotential interval value than healthy volunteers (10.3 ± 0.1 ms) (p < 0.001).
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Affiliation(s)
- Pınar Yalinay Dikmen
- a Department of Neurology, Acibadem University School of Medicine , Istanbul , Turkey
| | - Elif Kocasoy Orhan
- b Department of Neurology, Istanbul University, Istanbul Faculty of Medicine , Istanbul , Turkey
| | - M Barış Baslo
- b Department of Neurology, Istanbul University, Istanbul Faculty of Medicine , Istanbul , Turkey
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Vucic S, Ziemann U, Eisen A, Hallett M, Kiernan MC. Transcranial magnetic stimulation and amyotrophic lateral sclerosis: pathophysiological insights. J Neurol Neurosurg Psychiatry 2013; 84:1161-70. [PMID: 23264687 PMCID: PMC3786661 DOI: 10.1136/jnnp-2012-304019] [Citation(s) in RCA: 189] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder of the motor neurons in the motor cortex, brainstem and spinal cord. A combination of upper and lower motor neuron dysfunction comprises the clinical ALS phenotype. Although the ALS phenotype was first observed by Charcot over 100 years ago, the site of ALS onset and the pathophysiological mechanisms underlying the development of motor neuron degeneration remain to be elucidated. Transcranial magnetic stimulation (TMS) enables non-invasive assessment of the functional integrity of the motor cortex and its corticomotoneuronal projections. To date, TMS studies have established motor cortical and corticospinal dysfunction in ALS, with cortical hyperexcitability being an early feature in sporadic forms of ALS and preceding the clinical onset of familial ALS. Taken together, a central origin of ALS is supported by TMS studies, with an anterograde transsynaptic mechanism implicated in ALS pathogenesis. Of further relevance, TMS techniques reliably distinguish ALS from mimic disorders, despite a compatible peripheral disease burden, thereby suggesting a potential diagnostic utility of TMS in ALS. This review will focus on the mechanisms underlying the generation of TMS measures used in assessment of cortical excitability, the contribution of TMS in enhancing the understanding of ALS pathophysiology and the potential diagnostic utility of TMS techniques in ALS.
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Affiliation(s)
- Steve Vucic
- Sydney Medical School Westmead, University of Sydney, Sydney, New South Wales, Australia.
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Vucic S, Kiernan MC. Utility of transcranial magnetic stimulation in delineating amyotrophic lateral sclerosis pathophysiology. HANDBOOK OF CLINICAL NEUROLOGY 2013; 116:561-575. [PMID: 24112924 DOI: 10.1016/b978-0-444-53497-2.00045-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder of the motor neurons in the motor cortex, brainstem, and spinal cord. The clinical phenotype of ALS is underscored by a combination of upper and lower motor neuron dysfunction. Although this phenotype was observed over 100 years ago, the site of ALS onset and the pathophysiological mechanisms underlying the development of motor neuron degeneration remain to be elucidated. Transcranial magnetic stimulation (TMS) enables noninvasive assessment of the functional integrity of the motor cortex and its corticomotoneuronal projections. To date, TMS studies have established cortical dysfunction in ALS, with cortical hyperexcitability being an early feature in sporadic forms of ALS and preceding the clinical onset of familial ALS. Taken together, a central origin of ALS is supported by TMS studies, with an anterograde dying-forward mechanism implicated in ALS pathogenesis. Of further relevance, TMS techniques reliably distinguish ALS from mimic disorders, despite a compatible peripheral disease burden, thereby suggesting a potential diagnostic utility of TMS in ALS. This chapter reviews the mechanisms underlying the generation of TMS parameters utilized in assessment of cortical excitability, the contribution of TMS in enhancing the understanding of ALS pathophysiology, and the potential diagnostic utility of TMS techniques in ALS.
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Affiliation(s)
- Steve Vucic
- Sydney Medical School Westmead, University of Sydney, Sydney, Australia; Neuroscience Research Australia, Sydney, Australia
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de Carvalho M. Why is ALS so excited? Clin Neurophysiol 2011; 122:1689-90. [PMID: 21377922 DOI: 10.1016/j.clinph.2011.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2011] [Revised: 02/03/2011] [Accepted: 02/05/2011] [Indexed: 12/13/2022]
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Attarian S, Pouget J, Schmied A. Changes in cortically induced inhibition in amyotrophic lateral sclerosis with time. Muscle Nerve 2009; 39:310-7. [PMID: 19208411 DOI: 10.1002/mus.21137] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Changes in intracortical inhibition have been detected by means of paired-pulse transcranial magnetic stimulation (TMS) based on electromyographic recordings in many neurological or psychiatric disorders, including amyotrophic lateral sclerosis (ALS). By contrast, inhibitory responses have been generally overlooked in single motor unit (MU) studies in patients with ALS. The aim of this study was to investigate the TMS-induced inhibitory responses of single MUs in peristimulus time histograms and the changes observed with time. For this purpose, 263 MUs were tested in 10 ALS patients in two to four recording sessions. Upon subdividing the data into epochs corresponding to mean disease durations of 12, 20, 32, 43, and 168 months, we found that inhibitory responses occurred more frequently than normal throughout the course of the disease and were stronger than normal during the first year after disease onset. This finding argues against the hypothesis that loss of inhibition may be part of the pathogenic process in ALS.
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Affiliation(s)
- Shahram Attarian
- Department of Neurology and Neuromuscular Diseases, CHU La Timone, 264 rue Saint-Pierre, 13385 Marseille, France.
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Attarian S, Vedel JP, Pouget J, Schmied A. Progression of cortical and spinal dysfunctions over time in amyotrophic lateral sclerosis. Muscle Nerve 2008; 37:364-75. [PMID: 18080998 DOI: 10.1002/mus.20942] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In view of the conflicting results about the links between lower and upper motor neuron (LMN, UMN) dysfunction in amyotrophic lateral sclerosis (ALS), we undertook this study to correlate their changes over time. Single motor units (MUs) were characterized by their macro-MU potentials, twitch amplitude, and excitatory responses to transcranial magnetic stimulation (TMS). Ten ALS patients were studied 2 to 4 times and their data were subdivided into epochs corresponding to mean disease duration of 12 (58 MUs), 20 (60 MUs), 32 (50 MUs), 43 (40 MUs), and 168 months (55 MUs). The MU size increased and the contractile effectiveness and the excitatory response rates decreased significantly with time. The contractile effectiveness of MUs producing normal excitatory responses decreased with time, whereas a gradual loss of excitatory responses was observed among MUs with normal electromechanical properties. Since no correlation was found between UMN and LMN dysfunction, we conclude that UMN and LMN probably degenerate independently in ALS.
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Affiliation(s)
- Shahram Attarian
- Department of Neurology and Neuromuscular Diseases CHU La Timone, 264 rue Saint-Pierre, 13385 Marseille, France.
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Attarian S, Vedel JP, Pouget J, Schmied A. Cortical versus spinal dysfunction in amyotrophic lateral sclerosis. Muscle Nerve 2006; 33:677-90. [PMID: 16506152 DOI: 10.1002/mus.20519] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Little is known about the possible link between cortical and spinal motor neuron dysfunction in amyotrophic lateral sclerosis (ALS). We correlated the characteristics of the responses to transcranial magnetic stimulation (TMS) with the electromechanical properties and firing pattern of single motor units (MUs) tested in nine ALS patients, three patients with Kennedy's disease, and 15 healthy subjects. In Kennedy's disease, 19 of 22 MUs were markedly enlarged with good electromechanical coupling and discharged with great variability. Their excitatory responses increased with MU size. In ALS, 17 of 34 MUs with excitatory responses behaved as in Kennedy's disease. By contrast, 28 MUs with nonsignificant responses showed poor electromechanical coupling and high firing rates, whereas 28 MUs with inhibitory responses showed moderate functional alterations. This result indicates that in ALS as in Kennedy's disease, sprouting of corticospinal axons may occur on surviving motoneurons. A clear relationship exists between the responsiveness of MUs to TMS and their functional state.
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Affiliation(s)
- Shahram Attarian
- Department of Neurology and Neuromuscular Diseases, CHU La Timone, 264 rue Saint-Pierre, 13385 Marseille, France. sattarian@@ap-hm.fr
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Attarian S, Azulay JP, Lardillier D, Verschueren A, Pouget J. Transcranial magnetic stimulation in lower motor neuron diseases. Clin Neurophysiol 2005; 116:35-42. [PMID: 15589181 DOI: 10.1016/j.clinph.2004.07.020] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/18/2004] [Indexed: 12/01/2022]
Abstract
OBJECTIVE To study the diagnostic value of transcranial magnetic stimulation (TMS) in a group of patients with lower motor neuron disease (LMND). Among LMND, several chronic immune mediate motor neuropathies may simulate amyotrophic lateral sclerosis (ALS). METHODS Forty patients with LMND were included TMS was performed at the first visit. The patients were seen prospectively every 3 months for a period of 1-4 years. RESULTS Three different groups were distinguished at the end of follow-up: (1) ALS group with 7 patients, (2) Pure motor neuropathy with 14 patients and (3) Other LMND including 12 patients with hereditary spinal amyotrophy, 3 patients with Kennedy's disease and 4 patients with post-poliomyelitis. On the basis of the results of TMS variables, 6 out of 7 ALS patients had abnormality of silent period (SP) associated or not with abnormality of excitatory threshold or amplitude ratio. Patients with pure motor neuropathy had normal SP and amplitude ratio. Four out of 14 patients had increased central motor conduction time (CMCT), one had increased CMCT and excitatory threshold, and one patient had a slightly increased excitatory threshold. Considering the abnormality of TMS variables in the groups, SP, excitatory threshold, and amplitude ratio were chosen in a post-hoc attempt to select variables yielding high sensitivity and specificity. The overall sensitivity of TMS for diagnosis of ALS among LMND was 85.7%, its specificity was 93.9%. When only the abnormality of SP was taken into account, the sensitivity was unchanged. But the specificity was improved to 100%. CONCLUSIONS TMS helped to distinguish suspected ALS from pure motor neuropathy.
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Affiliation(s)
- S Attarian
- Department of Neurology and Neuromuscular Diseases, CHU La Timone, 264 rue Saint-Pierre, 13385 Marseilles, France.
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16
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Emeryk-Szajewska B. Electrophysiologic diagnostics of very early stages of ALS. SUPPLEMENTS TO CLINICAL NEUROPHYSIOLOGY 2003; 53:116-25. [PMID: 12740985 DOI: 10.1016/s1567-424x(09)70146-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- B Emeryk-Szajewska
- Department of Neurology, Warsaw Medical School, Banacha 1a, 02-097 Warsaw, Poland.
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Weber M, Stewart H, Hirota N, Eisen A. Corticomotoneuronal connections in primary lateral sclerosis (PLS). AMYOTROPHIC LATERAL SCLEROSIS AND OTHER MOTOR NEURON DISORDERS : OFFICIAL PUBLICATION OF THE WORLD FEDERATION OF NEUROLOGY, RESEARCH GROUP ON MOTOR NEURON DISEASES 2002; 3:190-8. [PMID: 12710508 DOI: 10.1080/146608202760839004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND The relationship between primary lateral sclerosis (PLS) and amyotrophic lateral sclerosis (ALS) is uncertain. The slow progression and dominant upper motor neuron features of PLS are associated with a high threshold to cortical magnetic stimulation and sometimes slow central motor conduction. In ALS the cortical threshold may be reduced early in the disease and central conduction is usually normal. Corticomotoneuronal function appears to be impaired differently in PLS and ALS. SUBJECTS AND METHODS We assessed corticomotoneuronal function by analyzing the primary peak in the peristimulus time histograms (PSTHs) in 12 PLS and 12 ALS patients. Surface recorded motor evoked potentials (MEPs) and central motor conduction time (CMCT) were determined. PSTHs were constructed from 4-5 different, voluntarily recruited motor units in each patient and the onset latency, number of excess bins, duration and synchrony of the primary peak were measured. RESULTS The mean cortical threshold of single motor units in PLS was 73.6%, significantly higher than in ALS (60.3%; p < 2.2 x 10(-5)). Profoundly delayed primary peaks occurred in both PLS and ALS. Onset latency and desynchronization of the primary peak were similar in PLS and ALS, but the duration of the primary peak was significantly longer in PLS (p < 0.04). CONCLUSIONS Desynchronized primary peaks indicate dysfunction or demise of corticomotoneurones. Higher threshold and longer duration of the primary peak in PLS probably reflect different excitability and greater loss of corticomotoneuronal connections than in ALS.
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Affiliation(s)
- Markus Weber
- Neuromuscular Diseases Unit, Vancouver Hospital, University of British Columbia, Canada.
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Pohl C, Block W, Träber F, Schmidt S, Pels H, Grothe C, Schild HH, Klockgether T. Proton magnetic resonance spectroscopy and transcranial magnetic stimulation for the detection of upper motor neuron degeneration in ALS patients. J Neurol Sci 2001; 190:21-7. [PMID: 11574102 DOI: 10.1016/s0022-510x(01)00568-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Transcranial magnetic stimulation (TMS) was compared to proton magnetic resonance spectroscopy (1H-MRS) for the detection of upper motor neuron loss or dysfunction in 49 ALS patients classified according to the El Escorial criteria. Abnormal NAA/Cho ratios were detected in 53% of ALS patients. Abnormal TMS results (i.e. cortical inexcitability or prolonged CMCT's) were obtained in 63% of ALS patients. If one or both methods were considered for diagnosis of upper motor neuron degeneration/dysfunction, the percentage of abnormal findings was 77%, whilst in 39% of all patients both methods produced abnormal results. Compared to TMS, 1H-MRS detected more patients with upper motor neuron involvement in the suspected El Escorial subgroup (42% versus 25%), whereas TMS detected more patients with upper motor neuron involvement in the possible (81% versus 50%), probable (71% versus 57%) and definite El Escorial subgroup (71% versus 64%). We conclude that the combined use of 1H-MRS and TMS increases diagnostic accuracy for the detection of upper motor neuron involvement in ALS patients.
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Affiliation(s)
- C Pohl
- Department of Neurology, University of Bonn, Sigmund-Freud-Str. 25, D-53105, Bonn, Germany.
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Abstract
On theoretical grounds, abnormalities of the motor cortex in patients with amyotrophic lateral sclerosis (ALS) could lead to anterograde ("dying-forward") transneuronal degeneration of the anterior horn cells as suggested by Charcot. Conversely, retrograde ("dying-back") degeneration of the corticospinal tracts could affect the motor cortex. Evidence derived from clinical, neuropathological, static, and functional imaging, and physiological studies, favors the occurrence of anterograde degeneration. It is hypothesized that transneuronal degeneration in ALS is an active excitotoxic process in which live but dysfunctional corticomotoneurons, originating in the primary motor cortex, drive the anterior horn cell into metabolic deficit. When this is marked, it will result in more rapid and widespread loss of lower motor neurons. In contrast, slow loss of corticomotoneurons, as occurs in primary lateral sclerosis (PLS), precludes excitotoxic drive and is incompatible with anterograde degeneration. Preservation of slow-conducting non-M1 direct pathways in PLS is not associated with excitotoxicity, and anterior horn cells survive for long periods of time.
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Affiliation(s)
- A Eisen
- Neuromuscular Diseases Unit, First Floor Willow Pavilion, Vancouver General Hospital, 855 West 12th Avenue, Vancouver, British Columbia V5Z 1M9, Canada.
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Rösler KM, Truffert A, Hess CW, Magistris MR. Quantification of upper motor neuron loss in amyotrophic lateral sclerosis. Clin Neurophysiol 2000; 111:2208-18. [PMID: 11090774 DOI: 10.1016/s1388-2457(00)00481-8] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To quantitatively estimate upper motor neuron (UMN) loss in ALS. METHODS We used the recently developed triple stimulation technique (TST) to study corticospinal conduction to 86 abductor digiti minimi muscles of 48 ALS patients. This method employs a collision technique to estimate the proportion of motor units activated by a transcranial magnetic stimulus. At the same time, it yields an estimate of lower motor neuron (LMN) integrity. RESULTS The TST disclosed and quantified central conduction failures attributable to UMN loss in 38 sides of 24 patients (subclinical in 15 sides), whereas conventional motor evoked potentials detected abnormalities in only 18 sides of 12 patients (subclinical in two sides). The increased sensitivity of the TST to detect UMN dysfunction was particularly observed in early cases. Increased central motor conduction times (CMCT) occurred exclusively in sides with conduction failure. In sides with clinical UMN syndromes, the TST response size (but not the CMCT) correlated with the muscle weakness. In sides with clinical LMN syndromes, the size of the peripherally evoked compound muscle action potentials correlated with the muscle weakness. CONCLUSION The TST is a sensitive method to detect UMN dysfunction in ALS. It allows a quantitative estimate of the UMN loss, which is related to the functional deficit. Therefore, the TST has a considerable impact on diagnostic certainty in many patients. It will be suited to follow the disease progression and therapeutic trials.
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Affiliation(s)
- K M Rösler
- Department of Neurology, University of Berne, Inselspital, CH-3010, Bern, Switzerland.
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Weber M, Eisen A, Nakajima M. Corticomotoneuronal activity in ALS: changes in the peristimulus time histogram over time. Clin Neurophysiol 2000; 111:169-77. [PMID: 10656525 DOI: 10.1016/s1388-2457(99)00190-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The primary peak in the peristimulus time histogram (PSTH) reflects the initial rising phase of the excitatory post-synaptic potential (EPSP) evoked at the anterior horn cell. In ALS the primary peak is delayed in onset. increased in duration and desynchronized. abnormalities reflecting dysfunction of the corticomotoneurons. It is not known whether these abnormalities change over time in amyotrophic lateral sclerosis (ALS). METHODS PSTHs were constructed from changes in the firing probability of single, voluntarily activated motor units subjected to subthreshold transcranial magnetic stimuli. We studied 58 motor units in 12 patients with ALS on two separate occasions (mean time interval of 10.6 +/- 1.6 months). Results were compared with 49 motor units in 11 age matched controls. RESULTS All the parameters except the amplitude differed significantly between normals and patients. In general the primary peak in ALS was complex, desynchronized and occasionally consisted of a double peak. The abnormalities persisted or were accentuated at tile follow up visit. This was reflected by an increase in the number of excess bins, longer duration and latency and decrease of synchrony. CONCLUSIONS Increasing desynchronization of the primary peak over time in ALS reflects dysfunction of the monosynaptic corticomotoneuronal pathway and may also reflect activation of additional slow conducting and/or polysynaptic corticomotoneuronal connections.
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Affiliation(s)
- M Weber
- Neuromuscular Diseases Unit, Vancouver Hospital, BC, Canada
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