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Pavey N, Hannaford A, van den Bos M, Kiernan MC, Menon P, Vucic S. Distinct neuronal circuits mediate cortical hyperexcitability in amyotrophic lateral sclerosis. Brain 2024; 147:2344-2356. [PMID: 38374770 DOI: 10.1093/brain/awae049] [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: 10/11/2023] [Revised: 01/16/2024] [Accepted: 01/27/2024] [Indexed: 02/21/2024] Open
Abstract
Cortical hyperexcitability is an important pathophysiological mechanism in amyotrophic lateral sclerosis (ALS), reflecting a complex interaction of inhibitory and facilitatory interneuronal processes that evolves in the degenerating brain. The advances in physiological techniques have made it possible to interrogate progressive changes in the motor cortex. Specifically, the direction of transcranial magnetic stimulation (TMS) stimulus within the primary motor cortex can be utilized to influence descending corticospinal volleys and to thereby provide information about distinct interneuronal circuits. Cortical motor function and cognition was assessed in 29 ALS patients with results compared to healthy volunteers. Cortical dysfunction was assessed using threshold-tracking TMS to explore alterations in short interval intracortical inhibition (SICI), short interval intracortical facilitation (SICF), the index of excitation and stimulus response curves using a figure-of-eight coil with the coil oriented relative to the primary motor cortex in a posterior-anterior, lateral-medial and anterior-posterior direction. Mean SICI, between interstimulus interval of 1-7 ms, was significantly reduced in ALS patients compared to healthy controls when assessed with the coil oriented in posterior-anterior (P = 0.044) and lateral-medial (P = 0.005) but not the anterior-posterior (P = 0.08) directions. A significant correlation between mean SICI oriented in a posterior-anterior direction and the total Edinburgh Cognitive and Behavioural ALS Screen score (Rho = 0.389, P = 0.037) was evident. In addition, the mean SICF, between interstimulus interval 1-5 ms, was significantly increased in ALS patients when recorded with TMS coil oriented in posterior-anterior (P = 0.035) and lateral-medial (P < 0.001) directions. In contrast, SICF recorded with TMS coil oriented in the anterior-posterior direction was comparable between ALS and controls (P = 0.482). The index of excitation was significantly increased in ALS patients when recorded with the TMS coil oriented in posterior-anterior (P = 0.041) and lateral-medial (P = 0.003) directions. In ALS patients, a significant increase in the stimulus response curve gradient was evident compared to controls when recorded with TMS coil oriented in posterior-anterior (P < 0.001), lateral-medial (P < 0.001) and anterior-posterior (P = 0.002) directions. The present study has established that dysfunction of distinct interneuronal circuits mediates the development of cortical hyperexcitability in ALS. Specifically, complex interplay between inhibitory circuits and facilitatory interneuronal populations, that are preferentially activated by stimulation in posterior-to-anterior or lateral-to-medial directions, promotes cortical hyperexcitability in ALS. Mechanisms that underlie dysfunction of these specific cortical neuronal circuits will enhance understanding of the pathophysiological processes in ALS, with the potential to uncover focussed therapeutic targets.
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Affiliation(s)
- Nathan Pavey
- Brain and Nerve Research Centre, Concord Clinical School, The University of Sydney, Concord Hospital, Sydney, NSW 2139, Australia
| | - Andrew Hannaford
- Brain and Nerve Research Centre, Concord Clinical School, The University of Sydney, Concord Hospital, Sydney, NSW 2139, Australia
| | - Mehdi van den Bos
- Brain and Nerve Research Centre, Concord Clinical School, The University of Sydney, Concord Hospital, Sydney, NSW 2139, Australia
| | - Matthew C Kiernan
- Brain and Mind Centre, The University of Sydney, Sydney, NSW 2139, Australia
- Department of Neurology, Royal Prince Alfred Hospital, Sydney, NSW 2139, Australia
| | - Parvathi Menon
- Brain and Nerve Research Centre, Concord Clinical School, The University of Sydney, Concord Hospital, Sydney, NSW 2139, Australia
| | - Steve Vucic
- Brain and Nerve Research Centre, Concord Clinical School, The University of Sydney, Concord Hospital, Sydney, NSW 2139, Australia
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Higashihara M, Pavey N, Menon P, van den Bos M, Shibuya K, Kuwabara S, Kiernan MC, Koinuma M, Vucic S. Reduction in short interval intracortical inhibition from the early stage reflects the pathophysiology in amyotrophic lateral sclerosis: A meta-analysis study. Eur J Neurol 2024; 31:e16281. [PMID: 38504632 DOI: 10.1111/ene.16281] [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: 10/29/2023] [Revised: 02/13/2024] [Accepted: 03/05/2024] [Indexed: 03/21/2024]
Abstract
BACKGROUND AND PURPOSE Cortical hyperexcitability has been identified as a diagnostic and pathogenic biomarker of amyotrophic lateral sclerosis (ALS). Cortical excitability is assessed by transcranial magnetic stimulation (TMS), a non-invasive neurophysiological technique. The TMS biomarkers exhibiting highest sensitivity for cortical hyperexcitability in ALS remain to be elucidated. A meta-analysis was performed to determine the TMS biomarkers exhibiting the highest sensitivity for cortical hyperexcitability in ALS. METHODS A systematic literature review was conducted of all relevant studies published in the English language by searching PubMed, MEDLINE, Embase and Scopus electronic databases from 1 January 2006 to 28 February 2023. Inclusion criteria included studies reporting the utility of threshold tracking TMS (serial ascending method) in ALS and controls. RESULTS In total, more than 2500 participants, incorporating 1530 ALS patients and 1102 controls (healthy, 907; neuromuscular, 195) were assessed with threshold tracking TMS across 25 studies. Significant reduction of mean short interval intracortical inhibition (interstimulus interval 1-7 ms) exhibited the highest standardized mean difference with moderate heterogeneity (-0.994, 95% confidence interval -1.12 to -0.873, p < 0.001; Q = 38.61, p < 0.05; I2 = 40%). The reduction of cortical silent period duration along with an increase in motor evoked potential amplitude and intracortical facilitation also exhibited significant, albeit smaller, standardized mean differences. CONCLUSION This large meta-analysis study disclosed that mean short interval intracortical inhibition reduction exhibited the highest sensitivity for cortical hyperexcitability in ALS. Combined findings from this meta-analysis suggest that research strategies aimed at understanding the cause of inhibitory interneuronal circuit dysfunction could enhance understanding of ALS pathogenesis.
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Affiliation(s)
- Mana Higashihara
- Department of Neurology, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan
| | - Nathan Pavey
- Brain and Nerve Research Center, University of Sydney, Sydney, New South Wales, Australia
| | - Parvathi Menon
- Brain and Nerve Research Center, University of Sydney, Sydney, New South Wales, Australia
| | - Mehdi van den Bos
- Brain and Nerve Research Center, University of Sydney, Sydney, New South Wales, Australia
| | - Kazumoto Shibuya
- Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Satoshi Kuwabara
- Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Matthew C Kiernan
- Neuroscience Resarch Australia, University of New South Wales, Sydney, New South Wales, Australia
- Department of Neurology, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
| | - Masayoshi Koinuma
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Tokyo, Japan
- Healthy Aging Innovation Center, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan
| | - Steve Vucic
- Brain and Nerve Research Center, University of Sydney, Sydney, New South Wales, Australia
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Corcia P, Bede P, Pradat PF, Couratier P, Vucic S, de Carvalho M. Split-hand and split-limb phenomena in amyotrophic lateral sclerosis: pathophysiology, electrophysiology and clinical manifestations. J Neurol Neurosurg Psychiatry 2021; 92:1126-1130. [PMID: 34285065 DOI: 10.1136/jnnp-2021-326266] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 07/05/2021] [Indexed: 11/03/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting the upper and lower motor neurons. A key clinical feature of ALS is the absence of accurate, early-stage diagnostic indicators. 'Split-hand syndrome' was first described in ALS at the end of the last century and a considerable body of literature suggests that the split-hand phenomenon may be an important clinical feature of ALS. Considering the published investigations, it is conceivable that the 'split-hand syndrome' results from the associated upper and lower motor neuron degeneration, whose interaction remains to be fully clarified. Additionally, other split syndromes have been described in ALS involving upper or lower limbs, with a nuanced description of clinical and neurophysiological manifestations that may further aid ALS diagnosis. In this review, we endeavour to systematically present the spectrum of the 'split syndromes' in ALS from a clinical and neurophysiology perspective and discuss their diagnostic and pathogenic utility.
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Affiliation(s)
- Philippe Corcia
- Centre Constitutif de Référence SLA, CHU Bretonneau, Tours, France
| | - Peter Bede
- Computational Neuroimaging Group, Trinity College Dublin, Ireland.,Pitié-Salpêtrière University Hospital, Sorbonne University, Paris, France
| | - Pierre-François Pradat
- Neurology, Hopital Pitie-Salpetriere, Paris, France.,LIB, Université Pierre et Marie Curie Faculté de Médecine, Paris, Île-de-France, France
| | | | - Steve Vucic
- Westmead Clinical School, Westmead Hospital, University of Sydney, Sydney, New South Wales, Australia.,Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
| | - Mamede de Carvalho
- Instituto de Fisiologia, Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisbon, Lisbon, Portugal.,Department of Neurosciences and Mental Health, Hospital de Santa Maria, Lisboa, Portugal
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Demystifying the spontaneous phenomena of motor hyperexcitability. Clin Neurophysiol 2021; 132:1830-1844. [PMID: 34130251 DOI: 10.1016/j.clinph.2021.03.053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 03/18/2021] [Accepted: 03/29/2021] [Indexed: 10/21/2022]
Abstract
Possessing a discrete functional repertoire, the anterior horn cell can be in one of two electrophysiological states: on or off. Usually under tight regulatory control by the central nervous system, a hierarchical network of these specialist neurons ensures muscular strength is coordinated, gradated and adaptable. However, spontaneous activation of these cells and their axons can result in abnormal muscular twitching. The muscular twitch is the common building block of several distinct clinical patterns, namely fasciculation, myokymia and neuromyotonia. When attempting to distinguish these entities electromyographically, their unique temporal and morphological profiles must be appreciated. Detection and quantification of burst duration, firing frequency, multiplet patterns and amplitude are informative. A common feature is their persistence during sleep. In this review, we explain the accepted terminology used to describe the spontaneous phenomena of motor hyperexcitability, highlighting potential pitfalls amidst a bemusing and complex collection of overlapping terms. We outline the relevance of these findings within the context of disease, principally amyotrophic lateral sclerosis, Isaacs syndrome and Morvan syndrome. In addition, we highlight the use of high-density surface electromyography, suggesting that more widespread use of this non-invasive technique is likely to provide an enhanced understanding of these motor hyperexcitability syndromes.
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Park SB, Thurbon R, Kiernan MC. Isaacs syndrome: the frontier of neurology, psychiatry, immunology and cancer. J Neurol Neurosurg Psychiatry 2020; 91:1243-1244. [PMID: 32878974 DOI: 10.1136/jnnp-2020-324675] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 08/05/2020] [Indexed: 12/13/2022]
Affiliation(s)
- Susanna B Park
- Brain and Mind Centre, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Rick Thurbon
- Patient Editorial Board, Journal of Neurology, Neurosurgery and Psychiatry, Tavistock Square, London, UK
| | - Matthew C Kiernan
- Bushell Chair of Neurology, Brain and Mind Centre, University of Sydney, Sydney, New South Wales, Australia.,Neurology, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia
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Vincent A, Pettingill P, Pettingill R, Lang B, Birch R, Waters P, Irani SR, Buckley C, Watanabe O, Arimura K, Kiernan MC. Association of Leucine-Rich Glioma Inactivated Protein 1, Contactin-Associated Protein 2, and Contactin 2 Antibodies With Clinical Features and Patient-Reported Pain in Acquired Neuromyotonia. JAMA Neurol 2019; 75:1519-1527. [PMID: 30242309 PMCID: PMC6583195 DOI: 10.1001/jamaneurol.2018.2681] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Questions Which specific targets of voltage-gated potassium channel–complex antibodies are found in acquired neuromyotonia, and are these antibodies associated with additional clinical features of tumors, pain, or autonomic or central disorders? Findings This cohort study combined with a patient-led survey found that antibodies to the extracellular aspects of leucine-rich glioma inactivated protein, contactin-associated protein 2, and contactin 2 were variably present in 45% of patients with neuromyotonia. Paresthesia and various pain manifestations were common in neuromyotonia, and the type and severity of pain were found to exert a substantial influence on quality of life. Meaning Antibodies to voltage-gated potassium channel–complex proteins are not found in all patients with neuromyotonia and do not individually relate to specific clinical features, but the presence of pain and its effects on quality of life need greater recognition. Importance Although acquired autoimmune neuromyotonia (NMT) is associated with voltage-gated potassium channel (VGKC)–complex antibodies, to date there has been no systematic study of autoantibodies to the specific antigens leucine-rich glioma inactivated protein 1 (LGI1), contactin-associated protein 2 (CASPR2), and contactin 2 together with the full clinical syndrome, particularly pain and autonomic and central nervous system involvement. Objectives To study the full spectrum of clinical features and serum autoantibodies in patients with NMT, including the effects of pain on quality of life. Design, Setting, and Participants A cohort study of clinical features and serologic testing in 38 patients with electrophysiologically-confirmed NMT, reviewed clinically between February 2007 and August 2009, in the Universities of Sydney and Kagoshima and followed up across 2 to 4 years. Association of NMT with quality of life was researched in an independent, patient-led, online pain survey conducted from April 2012 to May 2012. Serologic analyses were performed in 2012, and final data analysis was performed in 2016. Main Outcomes and Measures Clinical data and scores on the modified Rankin Scale (mRS), which measures disability on a range of 0 to 6, with 0 indicating normal and 6 indicating death, before and after treatments were combined with CASPR2, LGI1, and contactin 2 antibody status. Results Among the 38-person NMT cohort, 25 (65.8%) were male and the median (range) age was 55 (12-85) years. Twenty-three (60.5%) were Japanese and 15 (39.5%) were of white race/ethnicity. Symptomatic treatments (mainly antiepileptic drugs) were used in most patients with mild disease (12 patients with mRS <3), whereas immunotherapies were successful in most patients with mRS scores greater than 2. Autoantibodies to VGKC-complex antigens (17 patients [45%]), bound to CASPR2 (5 [13%]), contactin 2 (5 patients, 1 with CASPR2 [13%]), LGI1 (2 [5%]), or both LGI1 and CASPR2 (6 [16%]). The last group of 6 patients had high mRS scores (mean [SD], 3.8 [1.7]), thymoma (4 patients), pain (5 patients), autonomic (6 patients) and sleep (5 patients) disturbance, suggesting Morvan syndrome. The 56 responders to the independent patient-led survey reported pain that could be severe, anatomically widespread, and that often resulted in unemployment, domestic problems, and poor quality of life. Conclusions and Relevance The cohort study detailed underrecognized aspects of the clinical and serologic spectrum of NMT. The heterogeneity of clinical features and of specific antibodies limit associations, but the common existence of thymoma, pain, and autonomic and central nervous system features, often with both LGI1 and CASPR2 antibodies, should be better recognized to more completely address the range of comorbidities and consequences of the disease regarding quality of life.
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Affiliation(s)
- Angela Vincent
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Philippa Pettingill
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Rosie Pettingill
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Bethan Lang
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Ron Birch
- Patient representative, Highland Park, Gold Coast, Australia
| | - Patrick Waters
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Sarosh R Irani
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Camilla Buckley
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Osamu Watanabe
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Kimiyoshi Arimura
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Matthew C Kiernan
- Brain and Mind Centre, University of Sydney, Sydney, Australia.,Department of Neurology, Royal Prince Alfred Hospital, Sydney, Australia
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Abstract
PURPOSE OF REVIEW Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder of the motor neurons, characterized by upper motor neuron (UMN) and lower motor neuron (LMN) dysfunction. There have been significant technological advances in the development of neurophysiological biomarkers of UMN and LMN dysfunction in ALS. In this review, we discuss major advances in development of neurophysiological biomarkers in ALS, critiquing their potential in diagnosis and prognosis of ALS, as well as utility in monitoring treatment effects. RECENT FINDINGS The threshold tracking transcranial magnetic stimulation (TMS) technique has established cortical hyperexcitability as an early and specific biomarker of UMN dysfunction in ALS, and associated with neurodegeneration. In addition to establishing cortical hyperexcitability as a pathophysiological mechanism, threshold tracking TMS has enabled an earlier diagnosis of ALS and provided a means of monitoring effects of therapeutic agents. Biomarkers of LMN dysfunction, including motor unit number estimation, the neurophysiological index, electrical impedance myography and axonal excitability techniques, have all exhibited utility in monitoring disease progression. SUMMARY In addition to enhancing ALS diagnosis, the development of novel neurophysiological biomarkers has implications for clinical trials research and drug development, enabling the assessment of biological efficacy of agents in early stages of drug development.
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Huynh W, Dharmadasa T, Vucic S, Kiernan MC. Functional Biomarkers for Amyotrophic Lateral Sclerosis. Front Neurol 2019; 9:1141. [PMID: 30662429 PMCID: PMC6328463 DOI: 10.3389/fneur.2018.01141] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 12/10/2018] [Indexed: 01/06/2023] Open
Abstract
The clinical diagnosis of amyotrophic lateral sclerosis (ALS) relies on determination of progressive dysfunction of both cortical as well as spinal and bulbar motor neurons. However, the variable mix of upper and lower motor neuron signs result in the clinical heterogeneity of patients with ALS, resulting frequently in delay of diagnosis as well as difficulty in monitoring disease progression and treatment outcomes particularly in a clinical trial setting. As such, the present review provides an overview of recently developed novel non-invasive electrophysiological techniques that may serve as biomarkers to assess UMN and LMN dysfunction in ALS patients.
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Affiliation(s)
- William Huynh
- Brain and Mind Centre, University of Sydney, Sydney, NSW, Australia.,Prince of Wales Clinical School, University of New South Wales, Sydney, NSW, Australia
| | | | - Steve Vucic
- Western Clinical School, University of Sydney, Sydney, NSW, Australia
| | - Matthew C Kiernan
- Brain and Mind Centre, University of Sydney, Sydney, NSW, Australia.,Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney, NSW, Australia
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Agarwal S, Koch G, Hillis AE, Huynh W, Ward NS, Vucic S, Kiernan MC. Interrogating cortical function with transcranial magnetic stimulation: insights from neurodegenerative disease and stroke. J Neurol Neurosurg Psychiatry 2019; 90:47-57. [PMID: 29866706 DOI: 10.1136/jnnp-2017-317371] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 05/07/2018] [Accepted: 05/07/2018] [Indexed: 12/11/2022]
Abstract
Transcranial magnetic stimulation (TMS) is an accessible, non-invasive technique to study cortical function in vivo. TMS studies have provided important pathophysiological insights across a range of neurodegenerative disorders and enhanced our understanding of brain reorganisation after stroke. In neurodegenerative disease, TMS has provided novel insights into the function of cortical output cells and the related intracortical interneuronal networks. Characterisation of cortical hyperexcitability in amyotrophic lateral sclerosis and altered motor cortical function in frontotemporal dementia, demonstration of cholinergic deficits in Alzheimer's disease and Parkinson's disease are key examples where TMS has led to advances in understanding of disease pathophysiology and potential mechanisms of propagation, with the potential for diagnostic applications. In stroke, TMS methodology has facilitated the understanding of cortical reorganisation that underlie functional recovery. These insights are critical to the development of effective and targeted rehabilitation strategies in stroke. The present review will provide an overview of cortical function measures obtained using TMS and how such measures may provide insight into brain function. Through an improved understanding of cortical function across a range of neurodegenerative disorders, and identification of changes in neural structure and function associated with stroke that underlie clinical recovery, more targeted therapeutic approaches may now be developed in an evolving era of precision medicine.
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Affiliation(s)
- Smriti Agarwal
- Brain and Mind Centre, University of Sydney, and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
| | - Giacomo Koch
- Non-Invasive Brain Stimulation Unit, Neurologia Clinica e Comportamentale, Fondazione Santa Lucia IRCCS, Rome, Italy.,Stroke Unit, Department of Neuroscience, Policlinico Tor Vergata, Rome, Italy
| | - Argye E Hillis
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Physical Medicine and Rehabilitation, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Cognitive Science, Johns Hopkins University, Baltimore, Maryland, USA
| | - William Huynh
- Brain and Mind Centre, University of Sydney, and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
| | - Nick S Ward
- Sobell Department of Motor Neuroscience, UCL Institute of Neurology, University College London, London, UK.,UCL Partners Centre for Neurorehabilitation, UCL Institute of Neurology, University College London, London, UK.,The National Hospital for Neurology and Neurosurgery, London, UK
| | - Steve Vucic
- Westmead Clinical School, University of Sydney, Sydney, Australia
| | - Matthew C Kiernan
- Brain and Mind Centre, University of Sydney, and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
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Noto YI, Garg N, Li T, Timmins HC, Park SB, Shibuya K, Shahrizaila N, Huynh W, Matamala JM, Dharmadasa T, Yiannikas C, Vucic S, Kiernan MC. Comparison of cross-sectional areas and distal-proximal nerve ratios in amyotrophic lateral sclerosis. Muscle Nerve 2018; 58:777-783. [PMID: 30019401 DOI: 10.1002/mus.26301] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 07/04/2018] [Accepted: 07/08/2018] [Indexed: 12/23/2022]
Abstract
INTRODUCTION This study explored potential diagnostic markers of nerve ultrasound in differentiating amyotrophic lateral sclerosis (ALS) from mimic disorders. METHODS Ultrasound of the median, ulnar, and tibial nerves was conducted in 53 patients with ALS, 32 patients with ALS-mimic disorders, and 30 controls. Nerve cross-sectional area (CSA) and distal-proximal ratios were calculated. RESULTS The median nerve CSA in the upper arm was decreased (7.9 ± 1.3 mm2 vs. 9.0 ± 1.4 mm2 , P < 0.05), and the median nerve wrist-upper arm ratio was increased in ALS patients compared with controls (1.3 ± 0.4 vs. 1.1 ± 0.2; P < 0.01). In differentiating ALS from mimic presentations, assessment of median nerve CSA in the upper arm and comparison of a median and ulnar nerve CSA distal-proximal ratio provide diagnostic potential. DISCUSSION Assessment of nerve CSA combined with calculation of nerve CSA distal-proximal ratio provides a useful marker to aid in the diagnosis of ALS. Muscle Nerve 58:777-783, 2018.
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Affiliation(s)
- Yu-Ichi Noto
- Brain and Mind Centre, Sydney Medical School, University of Sydney, 94 Mallett Street, Camperdown, Sydney, New South Wales, 2040, Australia.,Royal Prince Alfred Hospital Sydney, Sydney, New South Wales, Australia
| | - Nidhi Garg
- Brain and Mind Centre, Sydney Medical School, University of Sydney, 94 Mallett Street, Camperdown, Sydney, New South Wales, 2040, Australia.,Royal Prince Alfred Hospital Sydney, Sydney, New South Wales, Australia
| | - Tiffany Li
- Brain and Mind Centre, Sydney Medical School, University of Sydney, 94 Mallett Street, Camperdown, Sydney, New South Wales, 2040, Australia.,Royal Prince Alfred Hospital Sydney, Sydney, New South Wales, Australia
| | - Hannah C Timmins
- Brain and Mind Centre, Sydney Medical School, University of Sydney, 94 Mallett Street, Camperdown, Sydney, New South Wales, 2040, Australia.,Royal Prince Alfred Hospital Sydney, Sydney, New South Wales, Australia
| | - Susanna B Park
- Brain and Mind Centre, Sydney Medical School, University of Sydney, 94 Mallett Street, Camperdown, Sydney, New South Wales, 2040, Australia.,Royal Prince Alfred Hospital Sydney, Sydney, New South Wales, Australia
| | - Kazumoto Shibuya
- Brain and Mind Centre, Sydney Medical School, University of Sydney, 94 Mallett Street, Camperdown, Sydney, New South Wales, 2040, Australia.,Royal Prince Alfred Hospital Sydney, Sydney, New South Wales, Australia
| | - Nortina Shahrizaila
- Brain and Mind Centre, Sydney Medical School, University of Sydney, 94 Mallett Street, Camperdown, Sydney, New South Wales, 2040, Australia.,Royal Prince Alfred Hospital Sydney, Sydney, New South Wales, Australia
| | - William Huynh
- Brain and Mind Centre, Sydney Medical School, University of Sydney, 94 Mallett Street, Camperdown, Sydney, New South Wales, 2040, Australia.,Royal Prince Alfred Hospital Sydney, Sydney, New South Wales, Australia
| | - José M Matamala
- Brain and Mind Centre, Sydney Medical School, University of Sydney, 94 Mallett Street, Camperdown, Sydney, New South Wales, 2040, Australia.,Royal Prince Alfred Hospital Sydney, Sydney, New South Wales, Australia
| | - Thanuja Dharmadasa
- Brain and Mind Centre, Sydney Medical School, University of Sydney, 94 Mallett Street, Camperdown, Sydney, New South Wales, 2040, Australia.,Royal Prince Alfred Hospital Sydney, Sydney, New South Wales, Australia
| | - Con Yiannikas
- Brain and Mind Centre, Sydney Medical School, University of Sydney, 94 Mallett Street, Camperdown, Sydney, New South Wales, 2040, Australia.,Royal Prince Alfred Hospital Sydney, Sydney, New South Wales, Australia
| | - Steve Vucic
- Western Clinical School, University of Sydney, Sydney, New South Wales, Australia
| | - Matthew C Kiernan
- Brain and Mind Centre, Sydney Medical School, University of Sydney, 94 Mallett Street, Camperdown, Sydney, New South Wales, 2040, Australia.,Royal Prince Alfred Hospital Sydney, Sydney, New South Wales, Australia
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Noto YI, Simon NG, Selby A, Garg N, Shibuya K, Shahrizaila N, Huynh W, Matamala JM, Dharmadasa T, Park SB, Vucic S, Kiernan MC. Ectopic impulse generation in peripheral nerve hyperexcitability syndromes and amyotrophic lateral sclerosis. Clin Neurophysiol 2018; 129:974-980. [DOI: 10.1016/j.clinph.2018.01.061] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 12/15/2017] [Accepted: 01/14/2018] [Indexed: 12/11/2022]
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12
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Parissis D, Ioannidis P, Papadopoulos G, Karacostas D. Neuromyotonia Confined to Faciobulbar Muscles in a Patient with Myasthenia Gravis. Mov Disord Clin Pract 2017; 4:635-636. [PMID: 30713974 PMCID: PMC6353516 DOI: 10.1002/mdc3.12467] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 11/25/2016] [Accepted: 12/01/2016] [Indexed: 10/13/2023] Open
Abstract
View Supplementary Video 1
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Affiliation(s)
- Dimitrios Parissis
- 2nd Neurology DepartmentAHEPA HospitalAristotle University of ThessalonikiThessalonikiGreece
| | - Panagiotis Ioannidis
- 2nd Neurology DepartmentAHEPA HospitalAristotle University of ThessalonikiThessalonikiGreece
| | - Georgios Papadopoulos
- 2nd Neurology DepartmentAHEPA HospitalAristotle University of ThessalonikiThessalonikiGreece
| | - Dimitrios Karacostas
- 2nd Neurology DepartmentAHEPA HospitalAristotle University of ThessalonikiThessalonikiGreece
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Vucic S, Kiernan MC. Transcranial Magnetic Stimulation for the Assessment of Neurodegenerative Disease. Neurotherapeutics 2017; 14:91-106. [PMID: 27830492 PMCID: PMC5233629 DOI: 10.1007/s13311-016-0487-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Transcranial magnetic stimulation (TMS) is a noninvasive technique that has provided important information about cortical function across an array of neurodegenerative disorders, including Alzheimer's disease, frontotemporal dementia, Parkinson's disease, and related extrapyramidal disorders. Application of TMS techniques in neurodegenerative diseases has provided important pathophysiological insights, leading to the development of pathogenic and diagnostic biomarkers that could be used in the clinical setting and therapeutic trials. Abnormalities of TMS outcome measures heralding cortical hyperexcitability, as evidenced by a reduction of short-interval intracortical inhibition and increased in motor-evoked potential amplitude, have been consistently identified as early and intrinsic features of amyotrophic lateral sclerosis (ALS), preceding and correlating with the ensuing neurodegeneration. Cortical hyperexcitability appears to form the pathogenic basis of ALS, mediated by trans-synaptic glutamate-mediated excitotoxic mechanisms. As a consequence of these research findings, TMS has been developed as a potential diagnostic biomarker, capable of identifying upper motor neuronal pathology, at earlier stages of the disease process, and thereby aiding in ALS diagnosis. Of further relevance, marked TMS abnormalities have been reported in other neurodegenerative diseases, which have varied from findings in ALS. With time and greater utilization by clinicians, TMS outcome measures may prove to be of utility in future therapeutic trial settings across the neurodegenerative disease spectrum, including the monitoring of neuroprotective, stem-cell, and genetic-based strategies, thereby enabling assessment of biological effectiveness at early stages of drug development.
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Affiliation(s)
- Steve Vucic
- Westmead Clinical School, University of Sydney, Sydney, Australia
| | - Matthew C Kiernan
- Bushell Chair of Neurology, Brain and Mind Centre, University of Sydney, Camperdown, Australia.
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Extensive Postradiation Ocular and Diffuse Cranial Neuromyotonia Mimicking Myasthenia Gravis. Neurologist 2016; 21:79-82. [PMID: 27564076 DOI: 10.1097/nrl.0000000000000088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Ocular neuromyotonia is a rare, but well-recognized, complication of cranial irradiation. CASE REPORT Using figures and videos, we report a 52-year-old man with extensive ocular, brainstem, and lower cranial nerve neuromyotonia postradiation therapy for a fourth ventricle glioma who, in the context of an apparently positive edrophonium test, was initially misdiagnosed with myasthenia gravis. CONCLUSIONS This is the first case of postirradiation neuromyotonia to be reported with such extensive cranial nerve and brainstem involvement.
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Assessment of the upper motor neuron in amyotrophic lateral sclerosis. Clin Neurophysiol 2016; 127:2643-60. [PMID: 27291884 DOI: 10.1016/j.clinph.2016.04.025] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2015] [Revised: 04/22/2016] [Accepted: 04/27/2016] [Indexed: 02/07/2023]
Abstract
Clinical signs of upper motor neuron (UMN) involvement are an important component in supporting the diagnosis of amyotrophic lateral sclerosis (ALS), but are often not easily appreciated in a limb that is concurrently affected by muscle wasting and lower motor neuron degeneration, particularly in the early symptomatic stages of ALS. Whilst recent criteria have been proposed to facilitate improved detection of lower motor neuron impairment through electrophysiological features that have improved diagnostic sensitivity, assessment of upper motor neuron involvement remains essentially clinical. As a result, there is often a significant diagnostic delay that in turn may impact institution of disease-modifying therapy and access to other optimal patient management. Biomarkers of pathological UMN involvement are also required to ensure patients with suspected ALS have timely access to appropriate therapeutic trials. The present review provides an analysis of current and recently developed assessment techniques, including novel imaging and electrophysiological approaches used to study corticomotoneuronal pathology in ALS.
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Saitoh BY, Hayashi S, Ogata K, Uehara T, Doi H, Watanabe O, Yamasaki R, Murai H, Kira JI. Immune-mediated spastic paraparesis accompanied with high titres of voltage-gated potassium channel complex antibodies and myokymia/fasciculation. J Neurol Sci 2016; 364:133-5. [DOI: 10.1016/j.jns.2016.03.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 03/16/2016] [Accepted: 03/16/2016] [Indexed: 12/13/2022]
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Geevasinga N, Menon P, Nicholson GA, Ng K, Howells J, Kril JJ, Yiannikas C, Kiernan MC, Vucic S. Cortical Function in Asymptomatic Carriers and Patients With C9orf72 Amyotrophic Lateral Sclerosis. JAMA Neurol 2016; 72:1268-74. [PMID: 26348842 DOI: 10.1001/jamaneurol.2015.1872] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
IMPORTANCE The identification of the chromosome 9 open reading frame 72 (c9orf72) gene hexanucleotide repeat expansion represents a major advance in the understanding of amyotrophic lateral sclerosis (ALS) pathogenesis. The pathophysiological mechanism by which the c9orf72 gene expansion leads to neurodegeneration is not yet elucidated. Cortical hyperexcitability is potentially an important pathophysiological process in sporadic ALS and familial ALS (FALS). OBJECTIVE To investigate whether cortical hyperexcitability forms the pathophysiological basis of c9orf72 FALS using the threshold-tracking transcranial magnetic stimulation technique. DESIGN, SETTING, AND PARTICIPANTS Prospective case-control single-center study that took place at hospitals and outpatient clinics from January 1, 2013, to January 1, 2015. Clinical and functional assessments along with transcranial magnetic stimulation studies were taken on 15 patients with c9orf72 FALS and 11 asymptomatic expansion carriers of c9orf72 who were longitudinally followed up for 3 years. Results were compared with 73 patients with sporadic ALS and 74 healthy control participants. MAIN OUTCOMES AND MEASURES Cortical excitability variables, including short-interval intracortical inhibition, were measured in patients with c9orf72 FALS and results were compared with asymptomatic c9orf72 carriers, patients with sporadic ALS, and healthy control participants. RESULTS Mean (SD) short-interval intracortical inhibition was significantly reduced in patients with c9orf72 FALS (1.2% [1.8%]) and sporadic ALS (1.6% [1.2%]) compared with asymptomatic c9orf72 expansion carriers (10.2% [1.8%]; F = 16.1; P < .001) and healthy control participants (11.8% [1.0%]; F = 16.1; P < .001). The reduction of short-interval intracortical inhibition was accompanied by an increase in intracortical facilitation (P < .01) and motor-evoked potential amplitude (P < .05) as well as a reduction in the resting motor threshold (P < .05) and cortical silent period duration (P < .001). CONCLUSIONS AND RELEVANCE This study establishes cortical hyperexcitability as an intrinsic feature of symptomatic c9orf72 expansion-related ALS but not asymptomatic expansion carriers.
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Affiliation(s)
- Nimeshan Geevasinga
- Westmead Clinical School, University of Sydney, Sydney, New South Wales, Australia
| | - Parvathi Menon
- Westmead Clinical School, University of Sydney, Sydney, New South Wales, Australia
| | - Garth A Nicholson
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney, New South Wales, Australia
| | - Karl Ng
- Department of Neurology, Royal North Shore Hospital, Sydney, New South Wales, Australia
| | - James Howells
- Brain and Mind Research Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Jillian J Kril
- Disciplines of Medicine and Pathology, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Con Yiannikas
- Department of Neurology, Royal North Shore Hospital, Sydney, New South Wales, Australia
| | - Matthew C Kiernan
- Brain and Mind Research Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Steve Vucic
- Westmead Clinical School, University of Sydney, Sydney, New South Wales, Australia
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Mantero V, Rigamonti A, Basso F, Stanzani L, Scaioli V, Salmaggi A. When it rains it pours: amyotrophic lateral sclerosis concealed with Isaac’s syndrome. Neurol Sci 2016; 37:1181-3. [DOI: 10.1007/s10072-016-2528-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 02/18/2016] [Indexed: 12/13/2022]
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19
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Axonal dysfunction with voltage gated potassium channel complex antibodies. Exp Neurol 2014; 261:337-42. [DOI: 10.1016/j.expneurol.2014.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 05/29/2014] [Accepted: 06/01/2014] [Indexed: 12/13/2022]
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Geevasinga N, Menon P, Yiannikas C, Kiernan MC, Vucic S. Diagnostic utility of cortical excitability studies in amyotrophic lateral sclerosis. Eur J Neurol 2014; 21:1451-7. [DOI: 10.1111/ene.12422] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Accepted: 02/24/2014] [Indexed: 11/28/2022]
Affiliation(s)
- N. Geevasinga
- Westmead Clinical School; University of Sydney; Sydney NSW Australia
| | - P. Menon
- Westmead Clinical School; University of Sydney; Sydney NSW Australia
| | - C. Yiannikas
- Department of Neurology; Concord Hospital; Sydney NSW Australia
| | - M. C. Kiernan
- Brain and Mind Research Institute; University of Sydney; Sydney NSW Australia
| | - S. Vucic
- Westmead Clinical School; University of Sydney; Sydney NSW Australia
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Bae JS, Menon P, Mioshi E, Kiernan MC, Vucic S. Cortical hyperexcitability and the split-hand plus phenomenon: pathophysiological insights in ALS. Amyotroph Lateral Scler Frontotemporal Degener 2014; 15:250-6. [PMID: 24555863 DOI: 10.3109/21678421.2013.872150] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Preferential involvement of thenar muscles compared to flexor pollicis longus (FPL), termed 'the split-hand plus sign', appears to be a clinical feature of amyotrophic lateral sclerosis (ALS). In an attempt to understand the pathophysiological mechanisms underlying this clinical phenomenon, threshold tracking transcranial magnetic stimulation techniques were utilized to assess whether cortical mechanisms may be a significant contributing influence. Cortical excitability studies were undertaken on 17 ALS patients, with motor evoked potentials (MEP) recorded from thenar muscles and FPL. Split-hand plus index (SHPI) was derived by dividing motor amplitudes recorded over APB with those recorded over FPL. Results showed the SHPI was significantly reduced in ALS (SHPIALS 0.87 ± 0.12; SHPICONTROLS 1.7 ± 0.2, p < 0.001). Cortical studies disclosed significant increases in MEP amplitudes recorded over thenar muscles (p < 0.05) but not FPL (p = 0.11), and were significantly correlated with the SHPI (R = -0.83, p < 0.01). The cortical silent period duration was reduced from thenar muscles (p < 0.01). Although there was a ubiquitous reduction in short-interval intracortical inhibition (APB, p < 0.01; FPL < 0.05), this reduction was more prominent over the thenar muscles. In conclusion, findings from the present study suggest that cortical dysfunction in the form of hyperexcitability contributes to the pathophysiological basis of the split-hand plus sign in ALS.
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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, Lin CSY, Cheah BC, Murray J, Menon P, Krishnan AV, Kiernan MC. Riluzole exerts central and peripheral modulating effects in amyotrophic lateral sclerosis. ACTA ACUST UNITED AC 2013; 136:1361-70. [PMID: 23616585 DOI: 10.1093/brain/awt085] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Riluzole, a benzothiazole derivative, has been shown to be effective in prolonging survival in amyotrophic lateral sclerosis. The mechanisms by which riluzole exerts neuroprotective effects in amyotrophic lateral sclerosis remains to be fully elucidated, although inhibition of glutamatergic transmission and modulation of Na+ channel function have been proposed. In an attempt to determine the mechanisms by which riluzole exerts neuroprotective effects, in particular to dissect the relative contributions of inhibition of glutamatergic transmission and Na+ channel modulation, the present study utilized a combination of cortical and peripheral axonal excitability approaches to monitor changes in excitability and function in patients with amyotrophic lateral sclerosis. Cortical assessment was undertaken by utilising the threshold tracking transcranial magnetic stimulation (TMS) technique and combined with peripheral axonal excitability studies in 25 patients with amyotrophic lateral sclerosis. Studies were performed at baseline and repeated when patients were receiving riluzole 100 mg/day. At the time of second testing all patients were tolerating the medication well. Motor evoked potential and compound muscle action potential responses were recorded over the abductor pollicis brevis muscle. At baseline, features of cortical hyperexcitability were evident in patients with amyotrophic lateral sclerosis, indicated by marked reduction in short interval intracortical inhibition (P < 0.001) and cortical silent period duration (P < 0.001), as well as an increase in the motor evoked potential amplitude (P < 0.01). Riluzole therapy partially normalized cortical excitability by significantly increasing short interval intracortical inhibition (short interval intracortical inhibitionbaseline 0.5 ± 1.8%; short interval intracortical inhibitionON riluzole 7.9 ± 1.7%, P < 0.01). In contrast, riluzole did not exert any modulating effect on cortical silent period duration (P = 0.45) or motor evoked potential amplitude (P = 0.31). In terms of peripheral nerve function, axonal excitability studies established that, relative to control subjects, patients with amyotrophic lateral sclerosis had significant increases in depolarizing threshold electrotonus [amyotrophic lateral sclerosisbaseline TEd (90-100 ms) 49.1 ± 1.8%; controlsTEd (90-100 ms) 45.2 ± 0.6%, P < 0.01] and superexcitability (amyotrophic lateral sclerosisbaseline 30.1 ± 2.3%; control subjects 23.4 ± 1.0%, P < 0.01) at baseline. Following institution of riluzole therapy there was a significant reduction in superexcitability (amyotrophic lateral sclerosisbaseline 30.1 ± 2.3%; amyotrophic lateral sclerosisON riluzole 27.3 ± 2.3%, P < 0.05) and refractoriness at 2 ms (amyotrophic lateral sclerosisbaseline 98.7 ± 10.7%; amyotrophic lateral sclerosisON riluzole 67.8 ± 9.3%, P < 0.001). In conclusion, the present study has established that riluzole exerts effects on both central and peripheral nerve function, interpreted as partial normalization of cortical hyperexcitability and reduction of transient Na+ conductances. Taken together, these findings suggest that the neuroprotective effects of riluzole in amyotrophic lateral sclerosis are complex, with evidence of independent effects across both compartments of the nervous system.
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Affiliation(s)
- Steve Vucic
- Neuroscience Research Australia, Barker Street, Randwick, Sydney, NSW 2031, 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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Cheah BC, Lin CS, Park SB, Vucic S, Krishnan AV, Kiernan MC. Progressive axonal dysfunction and clinical impairment in amyotrophic lateral sclerosis. Clin Neurophysiol 2012; 123:2460-7. [DOI: 10.1016/j.clinph.2012.06.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 05/22/2012] [Accepted: 06/06/2012] [Indexed: 01/01/2023]
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Menon P, Kiernan MC, Vucic S. Appearance, phenomenology and diagnostic utility of the split hand in amyotrophic lateral sclerosis. Neurodegener Dis Manag 2011. [DOI: 10.2217/nmt.11.60] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
SUMMARY The split hand has been increasingly recognized as a clinical feature of amyotrophic lateral sclerosis (ALS), heralded by preferential wasting of the thenar group of muscles and the first dorsal interosseous. Although the mechanisms underlying the development of the split hand in ALS remain to be fully elucidated, a cortical basis has been suggested, thereby supporting the notion of upper motor neuron primacy in ALS pathophysiology. In addition, quantifying the split-hand phenomena through the recent development of a novel split-hand index, appears to robustly differentiate ALS from mimic disorders. Taken together, the split-hand index appears to be a useful neurophysiological parameter that has the potential to aid the diagnostic pathway in ALS. The current review discusses the pathophysiological, diagnostic and prognostic utility of the split-hand index in ALS.
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Affiliation(s)
- Parvathi Menon
- Sydney Medical School Westmead, University of Sydney, NSW, Australia; Department of Neurology, Westmead Hospital, Cnr Hawkesbury and Darcy Roads, Westmead, NSW, 2145, Australia
| | - Matthew C Kiernan
- Neuroscience Research Australia, University of New South Wales, NSW, Australia
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Burrell JR, Yiannikas C, Rowe D, Kiernan MC. Predicting a positive response to intravenous immunoglobulin in isolated lower motor neuron syndromes. PLoS One 2011; 6:e27041. [PMID: 22066029 PMCID: PMC3204999 DOI: 10.1371/journal.pone.0027041] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 10/09/2011] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVE To determine clinically related characteristics in patients with pure lower motor neuron (LMN) syndromes, not fulfilling accepted diagnostic criteria, who were likely to respond to intravenous immunoglobulin (IVIg) treatment. METHODS Demographic, clinical, laboratory and neurophysiological characteristics were prospectively collected from patients with undifferentiated isolated LMN syndromes who were then treated with IVIg. Patients were classified as either responders or non-responders to therapy with IVIg based on clinical data and the two groups were compared. RESULTS From a total cohort of 42 patients (30 males, 12 females, aged 18-83 years), 31 patients responded to IVIg and 11 did not. Compared to patients that developed progressive neurological decline, responders were typically younger (45.8 compared to 56.0 years, P<0.05) and had upper limb (83.9% compared to 63.6%, NS), unilateral (80.6% compared to 45.5%, P<0.05), and isolated distal (54.1% compared to 9.1%, P<0.05) weakness. Patients with predominantly upper limb, asymmetrical, and distal weakness were more likely to respond to IVIg therapy. Of the patients who responded to treatment, only 12.9% had detectable GM(1) antibodies and conduction block (not fulfilling diagnostic criteria) was only identified in 22.6%. CONCLUSIONS More than 70% of patients with pure LMN syndromes from the present series responded to treatment with IVIg therapy, despite a low prevalence of detectable GM(1) antibodies and conduction block. Patients with isolated LMN presentations, not fulfilling accepted diagnostic criteria, may respond to IVIg therapy, irrespective of the presence of conduction block or GM(1) antibodies, and should be given an empirical trial of IVIg to determine treatment responsiveness.
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Affiliation(s)
- James R. Burrell
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- University of New South Wales, Sydney, New South Wales, Australia
- Concord Repatriation General Hospital, Sydney, New South Wales, Australia
| | - Con Yiannikas
- Concord Repatriation General Hospital, Sydney, New South Wales, Australia
| | - Dominic Rowe
- Australian School of Advanced Medicine, Macquarie University, Sydney, New South Wales, Australia
| | - Matthew C. Kiernan
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- University of New South Wales, Sydney, New South Wales, Australia
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Kuwabara S. Excitability testing: from nerve to muscle. Clin Neurophysiol 2010; 122:639-40. [PMID: 21035391 DOI: 10.1016/j.clinph.2010.10.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Accepted: 10/06/2010] [Indexed: 11/19/2022]
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