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Carroll AS, Howells J, Lin CS, Park SB, Simon N, Reilly MM, Vucic S, Kiernan MC. Differences in nerve excitability properties across upper limb sensory and motor axons. Clin Neurophysiol 2021; 136:138-149. [DOI: 10.1016/j.clinph.2021.12.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 11/16/2021] [Accepted: 12/07/2021] [Indexed: 11/24/2022]
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Miyazawa H, Kimura M, Yonezawa H, Maeda T. Sporadic Triple A (Allgrove) Syndrome with Novel Tandem Mutations. Intern Med 2021; 60:799-802. [PMID: 33087664 PMCID: PMC7990642 DOI: 10.2169/internalmedicine.5201-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 09/06/2020] [Indexed: 12/11/2022] Open
Abstract
In triple A (Allgrove) syndrome, motor neuron disease is a co-morbid condition. We herein report a 38-year-old Japanese man with triple A (Allgrove) syndrome and novel tandem mutations: a novel c.881delT deletion mutation and c.835C>T localized to the AAAS gene. A nerve conduction study revealed marked axonal damage in several motor nerves. Tandem mutations in the AAAS gene may be involved in co-morbid motor neuron disease and aberrant electrophysiological findings.
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Affiliation(s)
- Haruna Miyazawa
- Division of Neurology and Gerontology, Department of Internal Medicine, School of Medicine, Iwate Medical University, Japan
| | - Manami Kimura
- Division of Neurology and Gerontology, Department of Internal Medicine, School of Medicine, Iwate Medical University, Japan
| | - Hisashi Yonezawa
- Division of Neurology and Gerontology, Department of Internal Medicine, School of Medicine, Iwate Medical University, Japan
| | - Tetsuya Maeda
- Division of Neurology and Gerontology, Department of Internal Medicine, School of Medicine, Iwate Medical University, Japan
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Koźmiński W, Pera J. Involvement of the Peripheral Nervous System in Episodic Ataxias. Biomedicines 2020; 8:biomedicines8110448. [PMID: 33105744 PMCID: PMC7690566 DOI: 10.3390/biomedicines8110448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 12/04/2022] Open
Abstract
Episodic ataxias comprise a group of inherited disorders, which have a common hallmark—transient attacks of ataxia. The genetic background is heterogeneous and the causative genes are not always identified. Furthermore, the clinical presentation, including intraictal and interictal symptoms, as well as the retention and progression of neurological deficits, is heterogeneous. Spells of ataxia can be accompanied by other symptoms—mostly from the central nervous system. However, in some of episodic ataxias involvement of peripheral nervous system is a part of typical clinical picture. This review intends to provide an insight into involvement of peripheral nervous system in episodic ataxias.
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Affiliation(s)
- Wojciech Koźmiński
- Department of Neurology, University Hospital, ul. Jakubowskiego 2, 30-688 Krakow, Poland;
| | - Joanna Pera
- Department of Neurology, Jagiellonian University Medical College, ul. Botaniczna 3, 31-503 Krakow, Poland
- Correspondence:
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Excitability of motor and sensory axons in multifocal motor neuropathy. Clin Neurophysiol 2020; 131:2641-2650. [PMID: 32947198 DOI: 10.1016/j.clinph.2020.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Revised: 07/18/2020] [Accepted: 08/14/2020] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To assess excitability differences between motor and sensory axons of affected nerves in patients with multifocal motor neuropathy (MMN). METHODS We performed motor and sensory excitability tests in affected median nerves of 20 MMN patients and in 20 age-matched normal subjects. CMAPs were recorded from the thenar and SNAPs from the 3rd digit. Clinical tests included assessment of muscle strength, two-point discrimination and joint position. RESULTS All MMN patients had weakness of the thenar muscle and normal sensory tests. Motor excitability testing in MMN showed an increased threshold for a 50% CMAP, increased rheobase, decreased stimulus-response slope, fanning-out of threshold electrotonus, decreased resting I/V slope, shortened refractory period, and more pronounced superexcitability. Sensory excitability testing in MMN revealed decreased accommodation half-time and S2-accommodation and less pronounced subexcitability. Mathematical modeling indicated increased Barrett-Barrett conductance for motor fibers and increase in internodal fast potassium conductance for sensory fibers. CONCLUSIONS Excitability findings in MMN suggest myelin sheath or paranodal seal involvement in motor fibers and, possibly, paranodal detachment in sensory fibers. SIGNIFICANCE Excitability properties of affected nerves in MMN differ between motor and sensory nerve fibers.
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Kiernan MC, Bostock H, Park SB, Kaji R, Krarup C, Krishnan AV, Kuwabara S, Lin CSY, Misawa S, Moldovan M, Sung J, Vucic S, Wainger BJ, Waxman S, Burke D. Measurement of axonal excitability: Consensus guidelines. Clin Neurophysiol 2019; 131:308-323. [PMID: 31471200 DOI: 10.1016/j.clinph.2019.07.023] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 07/17/2019] [Accepted: 07/24/2019] [Indexed: 12/12/2022]
Abstract
Measurement of axonal excitability provides an in vivo indication of the properties of the nerve membrane and of the ion channels expressed on these axons. Axonal excitability techniques have been utilised to investigate the pathophysiological mechanisms underlying neurological diseases. This document presents guidelines derived for such studies, based on a consensus of international experts, and highlights the potential difficulties when interpreting abnormalities in diseased axons. The present manuscript provides a state-of-the-art review of the findings of axonal excitability studies and their interpretation, in addition to suggesting guidelines for the optimal performance of excitability studies.
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Affiliation(s)
- Matthew C Kiernan
- Brain and Mind Centre, University of Sydney and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney 2006, Australia.
| | - Hugh Bostock
- UCL Queen Square Institute of Neurology, London WC1N 3BG, United Kingdom
| | - Susanna B Park
- Brain and Mind Centre, University of Sydney and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney 2006, Australia
| | - Ryuji Kaji
- National Utano Hospital, 8-Narutaki Ondoyamacho, Ukyoku, Kyoto 616-8255, Japan
| | - Christian Krarup
- Department of Neuroscience, University of Copenhagen and Department of Clinical Neurophysiology, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Arun V Krishnan
- Prince of Wales Clinical School, University of New South Wales, Sydney, Australia
| | - Satoshi Kuwabara
- Department of Neurology, Graduate School of Medicine, Chiba University, Japan
| | - Cindy Shin-Yi Lin
- Brain and Mind Centre, University of Sydney and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney 2006, Australia
| | - Sonoko Misawa
- Department of Neurology, Graduate School of Medicine, Chiba University, Japan
| | - Mihai Moldovan
- Department of Neuroscience, University of Copenhagen and Department of Clinical Neurophysiology, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Jiaying Sung
- Taipei Medical University, Wanfang Hospital, Taipei, Taiwan
| | - Steve Vucic
- Department of Neurology, Westmead Hospital, Western Clinical School, University of Sydney, Australia
| | - Brian J Wainger
- Department of Neurology and Anesthesiology, Critical Care & Pain Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Stephen Waxman
- Department of Neurology, Yale Medical School, New Haven, CT 06510, USA; Neurorehabilitation Research Center, Veterans Affairs Hospital, West Haven, CT 06516, USA
| | - David Burke
- Brain and Mind Centre, University of Sydney and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney 2006, Australia
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Orsucci D, Raglione LM, Mazzoni M, Vista M. Therapy of episodic ataxias: case report and review of the literature. Drugs Context 2019; 8:212576. [PMID: 30891074 PMCID: PMC6415777 DOI: 10.7573/dic.212576] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 02/15/2019] [Accepted: 02/18/2019] [Indexed: 11/21/2022] Open
Abstract
Episodic ataxias (EAs) are characterized by recurrent, discrete episodes of vertigo and ataxia. EA1 and EA2 are the two most common forms. In the interictal interval, myokymia is typically present in EA1, whereas EA2 patients present with interictal nystagmus. Specific pharmacological therapies are available for EA1 and especially EA2. We briefly discuss the case of an Italian young man with EA2, with a novel de novo CACNA1A mutation, who in our opinion is particularly illustrative for introducing the therapeutic approach. Acetazolamide could fully suppress EA episodes in our patient. We also provide a perspective review of the topic. 4-Aminopyridine is another valid treatment option. For EA1 (and for rarer EAs), the therapeutic possibilities are more limited. Carbamazepine is probably the treatment of choice for EA1, but the optimal treatment plan is unknown. A better understanding of the molecular processes involved in the mediation of EAs will lead to more specific and efficacious therapies for this still elusive group of disorders.
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Affiliation(s)
| | | | | | - Marco Vista
- Unit of Neurology, San Luca Hospital, Lucca, Italy
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Abstract
The familial episodic ataxias (EAs) are prototypical channelopathies in the central nervous system clinically characterized by attacks of imbalance and incoordination variably associated with progressive ataxia and variable interictal features. EA1, EA2, and EA6 are caused by mutations in ion channel- and transporter-encoding genes that regulate neuronal excitability and neurotransmission.
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Affiliation(s)
- Joanna C Jen
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA, United States; Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, CA, United States.
| | - Jijun Wan
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA, United States
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Gueguen A, Jardel C, Polivka M, Tan SV, Gray F, Vignal C, Lombès A, Gout O, Bostock H. Nerve excitability changes related to muscle weakness in chronic progressive external ophthalmoplegia. Clin Neurophysiol 2017; 128:1258-1263. [PMID: 28535487 DOI: 10.1016/j.clinph.2017.04.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Revised: 03/25/2017] [Accepted: 04/14/2017] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To explore potential spreading to peripheral nerves of the mitochondrial dysfunction in chronic progressive external ophthalmoplegia (CPEO) by assessing axonal excitability. METHODS CPEO patients (n=13) with large size deletion of mitochondrial DNA and matching healthy controls (n=22) were included in a case-control study. Muscle strength was quantified using MRC sum-score and used to define two groups of patients: CPEO-weak and CPEO-normal (normal strength). Nerve excitability properties of median motor axons were assessed with the TROND protocol and changes interpreted with the aid of a model. RESULTS Alterations of nerve excitability strongly correlated with scores of muscle strength. CPEO-weak displayed abnormal nerve excitability compared to CPEO-normal and healthy controls, with increased superexcitability and responses to hyperpolarizing current. Modeling indicated that the CPEO-weak recordings were best explained by an increase in the 'Barrett-Barrett' conductance across the myelin sheath. CONCLUSION CPEO patients with skeletal weakness presented sub-clinical nerve excitability changes, which were not consistent with axonal membrane depolarization, but suggested Schwann cell involvement. SIGNIFICANCE This study provides new insights into the spreading of large size deletion of mitochondrial DNA to Schwann cells in CPEO patients.
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Affiliation(s)
- Antoine Gueguen
- Department of Neurology, Fondation Ophtalmologique A. de Rothschild, Paris, France
| | - Claude Jardel
- INSERM U1016, Institut Cochin, Paris F-75014, France; Department of Metabolic Biochemistry, AP/HP, Hôpital Pitié-Salpêtrière, Paris F-75651, France
| | - Marc Polivka
- Department of Anatomical Pathology, AP/HP, Hôpital Lariboisière, Paris, France
| | - S Veronica Tan
- Institute of Neurology, University College London, London, United Kingdom
| | - Françoise Gray
- Department of Anatomical Pathology, AP/HP, Hôpital Lariboisière, Paris, France
| | - Catherine Vignal
- Department of Neuro-Ophthalmology, Fondation Ophtalmologique A. de Rothschild, Paris, France
| | - Anne Lombès
- INSERM U1016, Institut Cochin, Paris F-75014, France; Department of Metabolic Biochemistry, AP/HP, Hôpital Pitié-Salpêtrière, Paris F-75651, France
| | - Olivier Gout
- Department of Neurology, Fondation Ophtalmologique A. de Rothschild, Paris, France
| | - Hugh Bostock
- Institute of Neurology, University College London, London, United Kingdom.
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Tomlinson SE, Howells J, Burke D. In vivo assessment of neurological channelopathies: Application of peripheral nerve excitability studies. Neuropharmacology 2017; 132:98-107. [PMID: 28476643 DOI: 10.1016/j.neuropharm.2017.04.045] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/19/2017] [Accepted: 04/29/2017] [Indexed: 12/14/2022]
Abstract
With the rapid evolution of understanding of neurological channelopathies comes a need for sensitive tools to evaluate patients in clinical practice. Neurological channelopathies with a single-gene basis can manifest as seizures, headache, ataxia, vertigo, confusion, weakness and neuropathic pain and it is likely that other genetic factors contribute to the phenotype of many of these disorders. Ion channel dysfunction can result in abnormal cell membrane excitability but utilisation of advanced neurophysiology techniques has lagged behind developments in clinical, genetic and imaging evaluation of channelopathies. However, momentum in the application of in vivo axonal excitability testing sees these tests emerging as valuable tools, with the capacity to provide sensitive and specific insights into the mechanism of disease. While single-channel function cannot be directly measured in vivo, evaluation of subjects with single-gene channelopathies has provided insights into the effects of mutation-related alterations of membrane excitability, as well as compensatory adaptive changes. By showing how ion channel dysfunction can affect axonal excitability in vivo, studies of the excitability of peripheral nerve axons complement in vitro analysis of single channel activity. The interpretation of results is enhanced by mathematical modelling of axonal function and insights provided by in vitro work. This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- Susan E Tomlinson
- Sydney Medical School, University of Sydney, Sydney, Australia; Department of Neurology, St Vincent's Hospital, Sydney, Australia.
| | - James Howells
- Brain and Mind Centre, University of Sydney, Sydney, Australia
| | - David Burke
- Sydney Medical School, University of Sydney, Sydney, Australia; Department of Neurology, Royal Prince Alfred Hospital, Sydney, Australia
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