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Beecher G, Gavrilova RH, Mandrekar J, Naddaf E. Mitochondrial myopathies diagnosed in adulthood: clinico-genetic spectrum and long-term outcomes. Brain Commun 2024; 6:fcae041. [PMID: 38434220 PMCID: PMC10906953 DOI: 10.1093/braincomms/fcae041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 12/14/2023] [Accepted: 02/12/2024] [Indexed: 03/05/2024] Open
Abstract
Mitochondrial myopathies are frequently recognized in childhood as part of a broader multisystem disorder and often overlooked in adulthood. Herein, we describe the phenotypic and genotypic spectrum and long-term outcomes of mitochondrial myopathies diagnosed in adulthood, focusing on neuromuscular features, electrodiagnostic and myopathological findings and survival. We performed a retrospective chart review of adult patients diagnosed with mitochondrial myopathy at Mayo Clinic (2005-21). We identified 94 patients. Median time from symptom onset to diagnosis was 11 years (interquartile range 4-21 years). Median age at diagnosis was 48 years (32-63 years). Primary genetic defects were identified in mitochondrial DNA in 48 patients (10 with single large deletion, 38 with point mutations) and nuclear DNA in 29. Five patients had multiple mitochondrial DNA deletions or depletion without nuclear DNA variants. Twelve patients had histopathological features of mitochondrial myopathy without molecular diagnosis. The most common phenotypes included multisystem disorder (n = 30); mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (14); limb myopathy (13); chronic progressive external ophthalmoplegia (12); and chronic progressive external ophthalmoplegia-plus (12). Isolated skeletal muscle manifestations occurred in 27%. Sixty-nine per cent had CNS and 21% had cardiac involvement. Mutations most frequently involved MT-TL1 (27) and POLG (17); however, a wide spectrum of established and novel molecular defects, with overlapping phenotypes, was identified. Electrodiagnostic studies identified myopathy (77%), fibrillation potentials (27%) and axonal peripheral neuropathy (42%, most common with nuclear DNA variants). Among 42 muscle biopsies available, median percentage counts were highest for cytochrome C oxidase negative fibres (5.1%) then ragged blue (1.4%) and ragged red fibres (0.5%). Skeletal muscle weakness was mild and slowly progressive (decline in strength summated score of 0.01/year). Median time to gait assistance was 5.5 years from diagnosis and 17 years from symptom onset. Thirty patients died, with median survival of 33.4 years from symptom onset and 10.9 years from diagnosis. Median age at death was 55 years. Cardiac involvement was associated with increased mortality [hazard ratio 2.36 (1.05, 5.29)]. There was no difference in survival based on genotype or phenotype. Despite the wide phenotypic and genotypic spectrum, mitochondrial myopathies in adults share similar features with slowly progressive limb weakness, contrasting with common multiorgan involvement and high mortality.
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Affiliation(s)
- Grayson Beecher
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
- Division of Neurology, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada T6G 2G3
| | - Ralitza H Gavrilova
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
- Department of Clinical Genomics, Mayo Clinic, Rochester, MN 55905, USA
| | - Jay Mandrekar
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | - Elie Naddaf
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
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O'Connor K, Spendiff S, Lochmüller H, Horvath R. Mitochondrial Mutations Can Alter Neuromuscular Transmission in Congenital Myasthenic Syndrome and Mitochondrial Disease. Int J Mol Sci 2023; 24:ijms24108505. [PMID: 37239850 DOI: 10.3390/ijms24108505] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 04/28/2023] [Accepted: 05/02/2023] [Indexed: 05/28/2023] Open
Abstract
Congenital myasthenic syndromes (CMS) are a group of rare, neuromuscular disorders that usually present in childhood or infancy. While the phenotypic presentation of these disorders is diverse, the unifying feature is a pathomechanism that disrupts neuromuscular transmission. Recently, two mitochondrial genes-SLC25A1 and TEFM-have been reported in patients with suspected CMS, prompting a discussion about the role of mitochondria at the neuromuscular junction (NMJ). Mitochondrial disease and CMS can present with similar symptoms, and potentially one in four patients with mitochondrial myopathy exhibit NMJ defects. This review highlights research indicating the prominent roles of mitochondria at both the pre- and postsynapse, demonstrating the potential for mitochondrial involvement in neuromuscular transmission defects. We propose the establishment of a novel subcategorization for CMS-mitochondrial CMS, due to unifying clinical features and the potential for mitochondrial defects to impede transmission at the pre- and postsynapse. Finally, we highlight the potential of targeting the neuromuscular transmission in mitochondrial disease to improve patient outcomes.
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Affiliation(s)
- Kaela O'Connor
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Centre for Neuromuscular Disease, University of Ottawa Brain and Mind Research Institute, Ottawa, ON K1H 8M5, Canada
| | - Sally Spendiff
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
| | - Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON K1H 8L1, Canada
- Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, ON K1H 8L6, Canada
- Brain and Mind Research Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, Medical Center-University of Freiburg, 79104 Freiburg, Germany
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Catalonia, Spain
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge CB3 0FD, UK
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Estephan EP, Zambon AA, Thompson R, Polavarapu K, Jomaa D, Töpf A, Helito PVP, Heise CO, Moreno CAM, Silva AMS, Kouyoumdjian JA, Morita MDP, Reed UC, Lochmüller H, Zanoteli E. Congenital myasthenic syndrome: Correlation between clinical features and molecular diagnosis. Eur J Neurol 2021; 29:833-842. [PMID: 34749429 DOI: 10.1111/ene.15173] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/01/2021] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To present phenotype features of a large cohort of congenital myasthenic syndromes (CMS) and correlate them with their molecular diagnosis. METHODS Suspected CMS patients were divided into three groups: group A (limb, bulbar or axial weakness, with or without ocular impairment, and all the following: clinical fatigability, electrophysiology compatible with neuromuscular junction involvement and anticholinesterase agents response), group B (limb, bulbar or axial weakness, with or without ocular impairment, and at least one of additional characteristics noted in group A) and group C (pure ocular syndrome). Individual clinical findings and the clinical groups were compared between the group with a confirmed molecular diagnosis of CMS and the group without molecular diagnosis or with a non-CMS molecular diagnosis. RESULTS Seventy-nine patients (68 families) were included in the cohort: 48 in group A, 23 in group B and 8 in group C. Fifty-one were considered confirmed CMS (30 CHRNE, 5 RAPSN, 4 COL13A1, 3 DOK7, 3 COLQ, 2 GFPT1, 1 CHAT, 1 SCN4A, 1 GMPPB, 1 CHRNA1), 7 probable CMS, 5 non-CMS and 16 unsolved. The chance of a confirmed molecular diagnosis of CMS was significantly higher for group A and lower for group C. Some individual clinical features, alterations on biopsy and electrophysiology enhanced specificity for CMS. Muscle imaging showed at least mild alterations in the majority of confirmed cases, with preferential involvement of soleus, especially in CHRNE CMS. CONCLUSIONS Stricter clinical criteria increase the chance of confirming a CMS diagnosis, but may lose sensitivity, especially for some specific genes.
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Affiliation(s)
- Eduardo P Estephan
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil.,Department of Neurology, Hospital Santa Marcelina, Sao Paulo, Brazil.,Department of Medical Clinic, Faculdade de Medicina Santa Marcelina (FASM), Sao Paulo, Brazil
| | - Antonio A Zambon
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
| | - Rachel Thompson
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Kiran Polavarapu
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Danny Jomaa
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.,Queen's University School of Medicine, Kingston, ON, Canada
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, University of Newcastle, Newcastle upon Tyne, UK
| | - Paulo V P Helito
- Department of Radiology, Hospital das Clínicas (HCFMUSP), Instituto de Ortopedia (IOT), Sao Paulo, Brazil
| | - Carlos O Heise
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
| | - Cristiane A M Moreno
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil.,Department of Neurology, Hospital Santa Marcelina, Sao Paulo, Brazil.,Department of Medical Clinic, Faculdade de Medicina Santa Marcelina (FASM), Sao Paulo, Brazil
| | - André M S Silva
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
| | - Joao A Kouyoumdjian
- Faculdade Estadual de Medicina de Sao Jose do Rio Preto (FAMERP), Sao Jose do Rio Preto, Brazil
| | - Maria da Penha Morita
- Faculdade Estadual de Medicina de Sao Jose do Rio Preto (FAMERP), Sao Jose do Rio Preto, Brazil
| | - Umbertina C Reed
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
| | - Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.,Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada.,Department of Medicine, Ottawa Research Institute, Ottawa, ON, Canada.,Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, University Medical Center Freiburg, Freiburg, Germany.,Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Edmar Zanoteli
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Sao Paulo, Brazil
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Lu JQ, Tarnopolsky MA. Mitochondrial neuropathy and neurogenic features in mitochondrial myopathy. Mitochondrion 2020; 56:52-61. [PMID: 33220502 DOI: 10.1016/j.mito.2020.11.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 10/25/2020] [Accepted: 11/02/2020] [Indexed: 01/21/2023]
Abstract
Mitochondrial diseases (MIDs) involve multiple organs including peripheral nerves and skeletal muscle. Mitochondrial neuropathy (MN) and mitochondrial myopathy (MM) are commonly associated and linked at the neuromuscular junction (NMJ). Herein we review MN in connection with neurogenic features of MM, and pathological evidence for the involvement of the peripheral nerve and NMJ in MID patients traditionally assumed to have predominantly MM. MN is not uncommon, but still likely under-reported, and muscle biopsies of MM commonly exhibit neurogenic features. Pathological examination remains the gold standard to assess the nerve and muscle changes in patients with MIDs. Ultrastructural studies by electron microscopy are often necessary to fully characterize the pathology of mitochondrial cytopathy in MN and MM.
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Affiliation(s)
- Jian-Qiang Lu
- Department of Pathology and Molecular Medicine/Neuropathology, McMaster University, Hamilton, Ontario, Canada.
| | - Mark A Tarnopolsky
- Department of Medicine/Neurology, McMaster University, Hamilton, Ontario, Canada; Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
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Caldas VM, Heise CO, Kouyoumdjian JA, Zambon AA, Silva AMS, Estephan EDP, Zanoteli E. Electrophysiological study of neuromuscular junction in congenital myasthenic syndromes, congenital myopathies, and chronic progressive external ophthalmoplegia. Neuromuscul Disord 2020; 30:897-903. [PMID: 33121830 DOI: 10.1016/j.nmd.2020.10.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 10/05/2020] [Accepted: 10/07/2020] [Indexed: 11/19/2022]
Abstract
This study was designed to analyze the sensitivity, specificity, and accuracy of jitter parameters combined with repetitive nerve stimulation (RNS) in congenital myasthenic syndrome (CMS), chronic progressive external ophthalmoplegia (CPEO), and congenital myopathies (CM). Jitter was obtained with a concentric needle electrode during voluntary activation of the Orbicularis Oculi muscle in CMS (n = 21), CPEO (n = 20), and CM (n = 18) patients and in controls (n = 14). RNS (3 Hz) was performed in six different muscles for all patients (Abductor Digiti Minimi, Tibialis Anterior, upper Trapezius, Deltoideus, Orbicularis Oculi, and Nasalis). RNS was abnormal in 90.5% of CMS patients and in only one CM patient. Jitter was abnormal in 95.2% of CMS, 20% of CPEO, and 11.1% of CM patients. No patient with CPEO or CM presented a mean jitter higher than 53.6 µs or more than 30% abnormal individual jitter (> 45 µs). No patient with CPEO or CM and mild abnormal jitter values presented an abnormal decrement. Jitter and RNS assessment are valuable tools for diagnosing neuromuscular transmission abnormalities in CMS patients. A mean jitter value above 53.6 µs or the presence of more than 30% abnormal individual jitter (> 45 µs) strongly suggests CMS compared with CPEO and CM.
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Affiliation(s)
- Vitor Marques Caldas
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Av. Dr. Enéas Carvalho Aguiar 255, 05403-900 São Paulo SP, Brazil
| | - Carlos Otto Heise
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Av. Dr. Enéas Carvalho Aguiar 255, 05403-900 São Paulo SP, Brazil
| | - João Aris Kouyoumdjian
- Laboratório de Investigação Neuromuscular, Faculdade Estadual de Medicina de São Jose do Rio Preto (FAMERP), São Jose do Rio Preto, SP, Brazil
| | - Antônio Alberto Zambon
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Av. Dr. Enéas Carvalho Aguiar 255, 05403-900 São Paulo SP, Brazil
| | - André Macedo Serafim Silva
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Av. Dr. Enéas Carvalho Aguiar 255, 05403-900 São Paulo SP, Brazil
| | - Eduardo de Paula Estephan
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Av. Dr. Enéas Carvalho Aguiar 255, 05403-900 São Paulo SP, Brazil; Department of Medicine, Faculdade Santa Marcelina, São Paulo, Brazil
| | - Edmar Zanoteli
- Department of Neurology, Faculdade de Medicina da Universidade de São Paulo (FMUSP), Av. Dr. Enéas Carvalho Aguiar 255, 05403-900 São Paulo SP, Brazil.
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6
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Musa AMM, Ahmed AEM. Reference Jitter Values for Concentric Needle Electrode of Orbicularis Oculi and Frontalis Muscles Using Voluntary Activation Method in Sudanese Population. Sci Rep 2020; 10:1031. [PMID: 31974444 PMCID: PMC6978519 DOI: 10.1038/s41598-020-58037-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 01/09/2020] [Indexed: 11/18/2022] Open
Abstract
Single fibre electromyography is the most sensitive neurophysiological test for the diagnosis of neuromuscular junction disorders, particularly myasthenia gravis. The study aimed at establishing concentric needle (CN) normal jitter values for voluntarily activated orbicularis-oculi (V-OOc) & Frontalis (V-FRO) muscles in Sudanese population. 57 healthy volunteers (20 males & 37 females) were included in the study (mean Age 43.6 ± 14.2 years, range 18–70 years). V-OOc and V-FRO were tested in the same individual using CN. Jitter values were expressed as the mean consecutive difference (MCD) of 30 potential pairs in microseconds. The mean jitter, mean individual fibre pairs jitter & mean outliers jitter values with (upper 95% Confidence Limit-CL) for [OOc] were [26.9 ± 3.3 (31.97), 26.1 ± 8.9 (41.8) & 38.5 ± 5.7 (49.0) µs] & for [FRO] were [27.1 ± 3.0 (31.32), 26.4 ± 9.4 (42.9) & 39.9 ± 5 (49.2) µs] respectively. The suggested practical upper limits for mean jitter & for outliers were (32, 49 µs) for OOc & (31, 49 µs) for FRO. Our CN-jitter values were within the range of the few published studies. The study was unique in that it established and compared between CN reference jitter values of two voluntarily activated facial muscles (V-OOc & V-FRO) in the same individual in large number of healthy subjects.
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Affiliation(s)
- Afraa M M Musa
- Department of Physiology, Faculty of Medicine, University of Khartoum, El Qasr Street, Khartoum, P.O. BOX 102, Sudan.
| | - Ammar E M Ahmed
- Department of Physiology, Faculty of Medicine, University of Khartoum, El Qasr Street, Khartoum, P.O. BOX 102, Sudan
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Braz LP, Ng YS, Gorman GS, Schaefer AM, McFarland R, Taylor RW, Turnbull DM, Whittaker RG. Neuromuscular Junction Abnormalities in Mitochondrial Disease: An Observational Cohort Study. Neurol Clin Pract 2019; 11:97-104. [PMID: 33842062 PMCID: PMC8032443 DOI: 10.1212/cpj.0000000000000795] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Objective To determine the prevalence of neuromuscular junction (NMJ) abnormalities in patients with mitochondrial disease. Methods Eighty patients with genetically proven mitochondrial disease were recruited from a national center for mitochondrial disease in the United Kingdom. Participants underwent detailed clinical and neurophysiologic testing including single-fiber electromyography. Results The overall prevalence of neuromuscular transmission defects was 25.6%. The highest prevalence was in patients with pathogenic dominant RRM2B variants (50%), but abnormalities were found in a wide range of mitochondrial genotypes. The presence of NMJ abnormalities was strongly associated with coexistent myopathy, but not with neuropathy. Furthermore, 15% of patients with NMJ abnormality had no evidence of either myopathy or neuropathy. Conclusions NMJ transmission defects are common in mitochondrial disease. In some patients, NMJ dysfunction occurs in the absence of obvious pre- or post-synaptic pathology, suggesting that the NMJ may be specifically affected.
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Affiliation(s)
- Luis P Braz
- Department of Neurology (LPB), Centro Hospitalar Universitário de São João, Porto, Portugal; and Wellcome Centre for Mitochondrial Research (YSN, GSG, AMS, RM, RWT, DMT), Translational and Clinical Research Institute (RGW), Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Yi Shiau Ng
- Department of Neurology (LPB), Centro Hospitalar Universitário de São João, Porto, Portugal; and Wellcome Centre for Mitochondrial Research (YSN, GSG, AMS, RM, RWT, DMT), Translational and Clinical Research Institute (RGW), Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Gráinne S Gorman
- Department of Neurology (LPB), Centro Hospitalar Universitário de São João, Porto, Portugal; and Wellcome Centre for Mitochondrial Research (YSN, GSG, AMS, RM, RWT, DMT), Translational and Clinical Research Institute (RGW), Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Andrew M Schaefer
- Department of Neurology (LPB), Centro Hospitalar Universitário de São João, Porto, Portugal; and Wellcome Centre for Mitochondrial Research (YSN, GSG, AMS, RM, RWT, DMT), Translational and Clinical Research Institute (RGW), Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Robert McFarland
- Department of Neurology (LPB), Centro Hospitalar Universitário de São João, Porto, Portugal; and Wellcome Centre for Mitochondrial Research (YSN, GSG, AMS, RM, RWT, DMT), Translational and Clinical Research Institute (RGW), Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Robert W Taylor
- Department of Neurology (LPB), Centro Hospitalar Universitário de São João, Porto, Portugal; and Wellcome Centre for Mitochondrial Research (YSN, GSG, AMS, RM, RWT, DMT), Translational and Clinical Research Institute (RGW), Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Doug M Turnbull
- Department of Neurology (LPB), Centro Hospitalar Universitário de São João, Porto, Portugal; and Wellcome Centre for Mitochondrial Research (YSN, GSG, AMS, RM, RWT, DMT), Translational and Clinical Research Institute (RGW), Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Roger G Whittaker
- Department of Neurology (LPB), Centro Hospitalar Universitário de São João, Porto, Portugal; and Wellcome Centre for Mitochondrial Research (YSN, GSG, AMS, RM, RWT, DMT), Translational and Clinical Research Institute (RGW), Newcastle University, Newcastle upon Tyne, United Kingdom
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8
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Myasthenia graves-like symptoms associated with rare mitochondrial mutation (m.5728T>C). Mitochondrion 2019; 47:139-140. [DOI: 10.1016/j.mito.2019.04.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 02/15/2019] [Accepted: 04/17/2019] [Indexed: 11/21/2022]
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9
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Sanders DB, Arimura K, Cui L, Ertaş M, Farrugia ME, Gilchrist J, Kouyoumdjian JA, Padua L, Pitt M, Stålberg E. Guidelines for single fiber EMG. Clin Neurophysiol 2019; 130:1417-1439. [PMID: 31080019 DOI: 10.1016/j.clinph.2019.04.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 03/30/2019] [Accepted: 04/06/2019] [Indexed: 12/13/2022]
Abstract
This document is the consensus of international experts on the current status of Single Fiber EMG (SFEMG) and the measurement of neuromuscular jitter with concentric needle electrodes (CNE - CN-jitter). The panel of authors was chosen based on their particular interests and previous publications within a specific area of SFEMG or CN-jitter. Each member of the panel was asked to submit a section on their particular area of interest and these submissions were circulated among the panel members for edits and comments. This process continued until a consensus was reached. Donald Sanders and Erik Stålberg then edited the final document.
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Affiliation(s)
| | - Kimiyoshi Arimura
- Department of Neurology and Geriatrics, Kagoshima University, Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
| | - LiYing Cui
- Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
| | | | | | - James Gilchrist
- Southern Illinois University School of Medicine, Springfield, IL USA.
| | | | - Luca Padua
- Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Department of Geriatrics, Neurosciences and Orthopaedics, Università Cattolica del Sacro Cuore, Rome, Italy.
| | - Matthew Pitt
- Department of Clinical Neurophysiology, Great Ormond Street Hospital, London, UK.
| | - Erik Stålberg
- Department of Clinical Neurophysiology, Uppsala University, Uppsala, Sweden.
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10
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Lu JQ, Mubaraki A, Yan C, Provias J, Tarnopolsky MA. Neurogenic Muscle Biopsy Findings Are Common in Mitochondrial Myopathy. J Neuropathol Exp Neurol 2019; 78:508-514. [DOI: 10.1093/jnen/nlz029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Jian-Qiang Lu
- Department of Pathology and Molecular Medicine/Neuropathology
| | | | - Chuanzhu Yan
- Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada
- Neuromuscular Center; and Mitochondrial Medicine Laboratory, Qilu Hospital, Shandong University, Shandong, China
| | - John Provias
- Department of Pathology and Molecular Medicine/Neuropathology
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11
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Constantinides VC, Papahatzaki MM, Papadimas GK, Karandreas N, Zambelis T, Kokotis P, Manda P. Diagnostic Accuracy of Muscle Biopsy and Electromyography in 123 Patients with Neuromuscular Disorders. In Vivo 2019; 32:1647-1652. [PMID: 30348729 DOI: 10.21873/invivo.11427] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 07/12/2018] [Accepted: 07/13/2018] [Indexed: 11/10/2022]
Abstract
BACKGROUND/AIM Diagnostic accuracy of muscle biopsy and electromyography (EMG) in patients with myopathy varies widely among studies. The goal of this study was to examine the diagnostic accuracy of each method in the diagnosis of patients with suspected myopathy, and determine the level of agreement between the two methods. PATIENTS AND METHODS The files of all patients with a presumed myopathy were retrospectively reviewed. All patients with detailed muscle biopsy and EMG data were included. RESULTS A total of 123 patients were included. Accuracy of biopsy was 80.4% compared to 70.7% for EMG. Biopsy was sensitive and specific in all neuromuscular disorders. EMG was accurate in neurogenic disorders. Biopsy and EMG agreement was 70.7%. CONCLUSION Muscle biopsy is more accurate than EMG in patients with myopathy. Muscle biopsy-EMG discordance can be attributed to different muscle sampling and to disorders with both neurogenic and myopathic features, such as acquired and mitochondrial myopathies.
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Affiliation(s)
- Vasilios C Constantinides
- First Department of Neurology, National and Kapodistrian University of Athens, School of Medicine, Eginition Hospital, Athens, Greece
| | - Maria Martha Papahatzaki
- First Department of Neurology, National and Kapodistrian University of Athens, School of Medicine, Eginition Hospital, Athens, Greece
| | - Georgios K Papadimas
- First Department of Neurology, National and Kapodistrian University of Athens, School of Medicine, Eginition Hospital, Athens, Greece
| | - Nikos Karandreas
- First Department of Neurology, National and Kapodistrian University of Athens, School of Medicine, Eginition Hospital, Athens, Greece
| | - Thomas Zambelis
- First Department of Neurology, National and Kapodistrian University of Athens, School of Medicine, Eginition Hospital, Athens, Greece
| | - Panagiotis Kokotis
- First Department of Neurology, National and Kapodistrian University of Athens, School of Medicine, Eginition Hospital, Athens, Greece
| | - Panagiota Manda
- First Department of Neurology, National and Kapodistrian University of Athens, School of Medicine, Eginition Hospital, Athens, Greece
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12
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Parikh S, Goldstein A, Karaa A, Koenig MK, Anselm I, Brunel-Guitton C, Christodoulou J, Cohen BH, Dimmock D, Enns GM, Falk MJ, Feigenbaum A, Frye RE, Ganesh J, Griesemer D, Haas R, Horvath R, Korson M, Kruer MC, Mancuso M, McCormack S, Raboisson MJ, Reimschisel T, Salvarinova R, Saneto RP, Scaglia F, Shoffner J, Stacpoole PW, Sue CM, Tarnopolsky M, Van Karnebeek C, Wolfe LA, Cunningham ZZ, Rahman S, Chinnery PF. Patient care standards for primary mitochondrial disease: a consensus statement from the Mitochondrial Medicine Society. Genet Med 2017; 19:S1098-3600(21)04766-3. [PMID: 28749475 PMCID: PMC7804217 DOI: 10.1038/gim.2017.107] [Citation(s) in RCA: 153] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 05/25/2017] [Indexed: 02/07/2023] Open
Abstract
The purpose of this statement is to provide consensus-based recommendations for optimal management and care for patients with primary mitochondrial disease. This statement is intended for physicians who are engaged in the diagnosis and management of these patients. Working group members were appointed by the Mitochondrial Medicine Society. The panel included members with several different areas of expertise. The panel members utilized surveys and the Delphi method to reach consensus. We anticipate that this statement will need to be updated as the field continues to evolve. Consensus-based recommendations are provided for the routine care and management of patients with primary genetic mitochondrial disease.
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Affiliation(s)
- Sumit Parikh
- Center for Child Neurology, Cleveland Clinic Children’s Hospital, Cleveland, Ohio, USA
| | - Amy Goldstein
- Division of Child Neurology, Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Amel Karaa
- Division of Genetics, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Mary Kay Koenig
- Division of Child and Adolescent Neurology, University of Texas Medical School at Houston, Houston, Texas, USA
| | - Irina Anselm
- Department of Neurology, Boston Children’s Hospital, Boston, Massachusetts, USA
| | | | - John Christodoulou
- Neurodevelopmental Genomics Research Group, Murdoch Childrens Research Institute, and Department of Paediatrics, Melbourne Medical School, University of Melbourne, Melbourne, Australia
| | - Bruce H. Cohen
- Neurodevelopmental Science Center, Children’s Hospital Medical Center of Akron, Akron, Ohio, USA
| | - David Dimmock
- Rady Children’s Institute for Genomic Medicine, San Diego, California, USA
| | - Gregory M. Enns
- Division of Medical Genetics, Department of Pediatrics, Stanford University Lucile Packard Children’s Hospital, Palo Alto, California, USA
| | - Marni J. Falk
- Division of Human Genetics, Department of Pediatrics, The Children’s Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Annette Feigenbaum
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada
- Department of Pediatrics, University of California San Diego and Rady Childrens Hospital, San Diego, California, USA
| | - Richard E. Frye
- Department of Pediatrics, University of Arkansas Medical Sciences, Little Rock, Arkansas, USA
| | - Jaya Ganesh
- Division of Genetics, Department of Pediatrics, Cooper Medical School at Rowan University, Camden, New Jersey, USA
| | - David Griesemer
- Division of Neurology, Levine Children’s Hospital, Charlotte, North Carolina, USA
| | - Richard Haas
- Departments of Neurosciences and Pediatrics, University of California San Diego, La Jolla, California, USA
- Department of Neurosciences, Rady Children’s Hospital, San Diego, California, USA
| | - Rita Horvath
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Mark Korson
- Genetic Metabolic Center for Education, Salem, Massachusetts, USA
| | - Michael C. Kruer
- Department of Pediatric Neurology, University of Arizona College of Medicine, Phoenix, Arizona, USA
| | - Michelangelo Mancuso
- Department of Experimental and Clinical Medicine, Neurological Clinic, University of Pisa, Pisa, Italy
| | - Shana McCormack
- Division of Endocrinology and Diabetes, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | | | - Tyler Reimschisel
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Ramona Salvarinova
- Division of Biochemical Diseases, BC Children’s Hospital, British Columbia, Canada
| | - Russell P. Saneto
- Department of Neurology, Seattle Children’s Hospital/University of Washington, Seattle, Washington, USA
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas, USA
| | - John Shoffner
- Neurology, Biochemical & Molecular Genetics, Atlanta, Georgia, USA
| | - Peter W. Stacpoole
- Department of Medicine, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Carolyn M. Sue
- Department of Neurology and Kolling Institute, Royal North Shore Hospital, St Leonards, Australia
| | - Mark Tarnopolsky
- Division of Neurology, McMaster University, Hamilton, Ontario, Canada
| | - Clara Van Karnebeek
- Department of Pediatrics, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
- Department of Pediatrics, Centre for Molecular Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Lynne A. Wolfe
- Undiagnosed Diseases Network, National Institutes of Health, Bethesda, Maryland, USA
| | | | - Shamima Rahman
- Mitochondrial Research Group, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Patrick F. Chinnery
- Department of Clinical Neurosciences & MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
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Lehmann D, Kornhuber ME, Clajus C, Alston CL, Wienke A, Deschauer M, Taylor RW, Zierz S. Peripheral neuropathy in patients with CPEO associated with single and multiple mtDNA deletions. NEUROLOGY-GENETICS 2016; 2:e113. [PMID: 27822509 PMCID: PMC5089902 DOI: 10.1212/nxg.0000000000000113] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 09/07/2016] [Indexed: 11/15/2022]
Abstract
Objective: To characterize peripheral nerve involvement in patients with chronic progressive external ophthalmoplegia (CPEO) with single and multiple mitochondrial DNA (mtDNA) deletions, based on clinical scores and detailed nerve conduction studies. Methods: Peripheral nerve involvement was prospectively investigated in 33 participants with CPEO (single deletions n = 18 and multiple deletions n = 15). Clinically, a modified Total Neuropathy Score (mTNS) and a modified International Cooperative Ataxia Rating Scale (mICARS) were used. Nerve conduction studies included Nn. suralis, superficialis radialis, tibialis, and peroneus mot. Early somatosensory evoked potentials were obtained by N. tibialis stimulation. Results: Participants with multiple deletions had higher mTNS and mICARS scores than those with single deletions. Electrophysiologically in both sensory nerves (N. suralis and N. radialis superficialis), compound action potential (CAP) amplitudes and nerve conduction velocities were lower and mostly abnormal in multiple deletions than those in single deletions. Early somatosensory evoked potentials of N. tibialis revealed increased P40 latencies and decreased N35-P40 amplitudes in multiple deletions. Both sensory nerves had higher areas under the receiver operating characteristic curves for the decreased CAP amplitudes than the 2 motor nerves. The N. suralis had the best Youden index, indicating a sensitivity of 93.3% and a specificity of 72.2% to detect multiple deletions. Conclusions: Peripheral nerve involvement in participants with multiple mtDNA deletions is an axonal type of predominant sensory neuropathy. This is clinically consistent with higher mTNS and mICARS scores. Sensory nerve involvement in participants with multiple deletions was not correlated with age at onset and duration of disease.
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Affiliation(s)
- Diana Lehmann
- Form the Department of Neurology (D.L., M.E.K., C.C., S.Z.), Institute of Medical Epidemiology, Biometrics and Informatics (A.W.), University of Halle-Wittenberg, Halle/Saale, Germany; Wellcome Trust Centre for Mitochondrial Research (C.L.A., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, UK; and Department of Neurology (M.D.), Technical University Munich, Germany
| | - Malte E Kornhuber
- Form the Department of Neurology (D.L., M.E.K., C.C., S.Z.), Institute of Medical Epidemiology, Biometrics and Informatics (A.W.), University of Halle-Wittenberg, Halle/Saale, Germany; Wellcome Trust Centre for Mitochondrial Research (C.L.A., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, UK; and Department of Neurology (M.D.), Technical University Munich, Germany
| | - Carolina Clajus
- Form the Department of Neurology (D.L., M.E.K., C.C., S.Z.), Institute of Medical Epidemiology, Biometrics and Informatics (A.W.), University of Halle-Wittenberg, Halle/Saale, Germany; Wellcome Trust Centre for Mitochondrial Research (C.L.A., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, UK; and Department of Neurology (M.D.), Technical University Munich, Germany
| | - Charlotte L Alston
- Form the Department of Neurology (D.L., M.E.K., C.C., S.Z.), Institute of Medical Epidemiology, Biometrics and Informatics (A.W.), University of Halle-Wittenberg, Halle/Saale, Germany; Wellcome Trust Centre for Mitochondrial Research (C.L.A., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, UK; and Department of Neurology (M.D.), Technical University Munich, Germany
| | - Andreas Wienke
- Form the Department of Neurology (D.L., M.E.K., C.C., S.Z.), Institute of Medical Epidemiology, Biometrics and Informatics (A.W.), University of Halle-Wittenberg, Halle/Saale, Germany; Wellcome Trust Centre for Mitochondrial Research (C.L.A., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, UK; and Department of Neurology (M.D.), Technical University Munich, Germany
| | - Marcus Deschauer
- Form the Department of Neurology (D.L., M.E.K., C.C., S.Z.), Institute of Medical Epidemiology, Biometrics and Informatics (A.W.), University of Halle-Wittenberg, Halle/Saale, Germany; Wellcome Trust Centre for Mitochondrial Research (C.L.A., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, UK; and Department of Neurology (M.D.), Technical University Munich, Germany
| | - Robert W Taylor
- Form the Department of Neurology (D.L., M.E.K., C.C., S.Z.), Institute of Medical Epidemiology, Biometrics and Informatics (A.W.), University of Halle-Wittenberg, Halle/Saale, Germany; Wellcome Trust Centre for Mitochondrial Research (C.L.A., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, UK; and Department of Neurology (M.D.), Technical University Munich, Germany
| | - Stephan Zierz
- Form the Department of Neurology (D.L., M.E.K., C.C., S.Z.), Institute of Medical Epidemiology, Biometrics and Informatics (A.W.), University of Halle-Wittenberg, Halle/Saale, Germany; Wellcome Trust Centre for Mitochondrial Research (C.L.A., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, UK; and Department of Neurology (M.D.), Technical University Munich, Germany
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14
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"Mitochondrial neuropathies": A survey from the large cohort of the Italian Network. Neuromuscul Disord 2016; 26:272-6. [PMID: 27020842 DOI: 10.1016/j.nmd.2016.02.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 02/10/2016] [Accepted: 02/15/2016] [Indexed: 11/21/2022]
Abstract
Involvement of the peripheral nervous system in mitochondrial disorders has been previously reported. However, the prevalence of peripheral neuropathy in mitochondrial disorders is still unclear. Based on the large database of the "Nation-wide Italian Collaborative Network of Mitochondrial Diseases", we reviewed the clinical data of 1200 patients, with special regard to peripheral neuropathy (mean age at onset 24.3 ± 20.1 years; age at last evaluation 39.8 ± 22.3 years; females 52.7%; childhood onset [before age 16 years] 43.1%). Peripheral neuropathy was present in 143/1156 patients (12.4%), being one of the ten most common signs and symptoms. POLG mutations cause a potentially painful, axonal/mixed, mainly sensory polyneuropathy; TYMP mutations lead to a demyelinating sensory-motor polyneuropathy; SURF1 mutations are associated with a demyelinating/mixed sensory-motor polyneuropathy. The only mtDNA mutation consistently associated with peripheral neuropathy (although less severely than in the above-considered nuclear genes) was the m.8993T > G (or the rarer T > C) changes, which lead to an axonal, mainly sensory polyneuropathy. In conclusion, peripheral neuropathy is one of the most common features of a mitochondrial disorder, and may negatively impact on the quality of life of these patients. Furthermore, the presence or absence of peripheral neuropathy, as well as its specific forms and the association with neuropathic pain (indicative of a POLG-associated disease) can guide the molecular analysis.
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15
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Rodríguez Cruz PM, Sewry C, Beeson D, Jayawant S, Squier W, McWilliam R, Palace J. Congenital myopathies with secondary neuromuscular transmission defects; A case report and review of the literature. Neuromuscul Disord 2014; 24:1103-10. [DOI: 10.1016/j.nmd.2014.07.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 06/27/2014] [Accepted: 07/18/2014] [Indexed: 01/14/2023]
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16
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Mancuso M, Piazza S, Volpi L, Orsucci D, Calsolaro V, Caldarazzo Ienco E, Carlesi C, Rocchi A, Petrozzi L, Calabrese R, Siciliano G. Nerve and muscle involvement in mitochondrial disorders: an electrophysiological study. Neurol Sci 2011; 33:449-52. [PMID: 21751099 DOI: 10.1007/s10072-011-0703-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Accepted: 07/01/2011] [Indexed: 11/27/2022]
Abstract
Involvement of the peripheral nervous system in mitochondrial disorders (MD) has been previously reported. However, the exact prevalence of peripheral neuropathy and/or myopathy in MD is still unclear. In order to evaluate the prevalence of neuropathy and myopathy in MD, we performed sensory and motor nerve conduction studies (NCS) and concentric needle electromyography (EMG) in 44 unselected MD patients. NCS were abnormal in 36.4% of cases, and were consistent with a sensori-motor axonal multineuropathy (multifocal neuropathy), mainly affecting the lower limbs. EMG evidence of myopathy was present in 54.5% of patients, again mainly affecting the lower limbs. Nerve and muscle involvement was frequently subclinical. Peripheral nerve and muscle involvement is common in MD patients. Our study supports the variability of the clinical expression of MD. Further studies are needed to better understand the molecular basis underlying the phenotypic variability among MD patients.
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Affiliation(s)
- Michelangelo Mancuso
- Department of Neuroscience, Neurological Clinic, University of Pisa, Via Roma 67, 56126 Pisa, Italy.
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17
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Pinto S, de Carvalho M. Amyotrophic lateral sclerosis patients and ocular ptosis. Clin Neurol Neurosurg 2008; 110:168-70. [DOI: 10.1016/j.clineuro.2007.08.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 08/24/2007] [Accepted: 08/27/2007] [Indexed: 11/24/2022]
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18
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Abstract
The diagnosis of mitochondrial myopathy depends upon a constellation of findings, family history, type of muscle involvement, specific laboratory abnormalities, and the results of histological, pathobiochemical and genetic analysis. In the present paper, the authors describe the diagnostic approach to mitochondrial myopathies manifesting as extraocular muscle disease. The most common ocular manifestation of mitochondrial myopathy is progressive external ophthalmoplegia (PEO). To exclude myasthenia gravis, ocular myositis, thyroid associated orbitopathy, oculopharyngeal muscular dystrophy, and congenital fibrosis of the extraocular muscles in patients with an early onset or long-lasting very slowly progressive ptosis and external ophthalmoplegia, almost without any diplopia, and normal to mildly elevated serum creatine kinase and lactate, electromyography, nerve conduction studies and MRI of the orbits should be performed. A PEO phenotype forces one to look comprehensively for other multisystemic mitochondrial features (e.g., exercise induced weakness, encephalopathy, polyneuropathy, diabetes, heart disease). Thereafter, and presently even in familiar PEO, a diagnostic muscle biopsy should be taken. Histological and ultrastructural hallmarks are mitochondrial proliferations and structural abnormalities, lipid storage, ragged-red fibers, or cytochrome-C negative myofibers. In addition, Southern blotting may reveal the common deletion, or molecular analysis may verify specific mutations of distinct mitochondrial or nuclear genes.
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Affiliation(s)
- Benedikt G H Schoser
- Department of Neurology, Friedrich Baur Institute, Ludwig Maximilians University, Munich, Germany.
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19
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Fuglsang-Frederiksen A. The role of different EMG methods in evaluating myopathy. Clin Neurophysiol 2006; 117:1173-89. [PMID: 16516549 DOI: 10.1016/j.clinph.2005.12.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 11/22/2005] [Accepted: 12/17/2005] [Indexed: 10/25/2022]
Abstract
For the diagnosis of myopathy, EMG may have an important role along with blood tests, muscle biopsies and genetic testing. This review evaluates different EMG methods in the diagnosis of myopathy. These include manual analysis of individual motor unit potentials and multi-motor unit potential analysis sampled at weak effort. At high effort, turns-amplitude analyses such as the cloud analysis and the peak ratio analysis have a high diagnostic yield. The EMG can seldom be used to differentiate between different types of myopathy. In the channelopathies, myotonia, exercise test and cooling of the muscle are helpful. Macro-EMG, single-fibre EMG and muscle fibre conduction velocity analysis have a limited role in myopathy, but provide information about the changes seen. Analysis of the firing rate of motor units, power spectrum analysis, as well as multichannel surface EMG may have diagnostic potential in the future. EMG is of great importance in the diagnosing of patients with myopathy, preferably a needle electrode and quantitative analyses should be used. A combination of a method at weak effort as well as a method at stronger effort seems optimal.
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Affiliation(s)
- Anders Fuglsang-Frederiksen
- Department of Clinical Neurophysiology, Aarhus University Hospital, Nørrebrogade 44, DK-8000 Aarhus C, Denmark.
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20
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Abstract
Single-fiber EMG is a technique introduced in 1963 by Stålberg and Ekstedt for recording single muscle fiber action potentials by means of a specially constructed needle with a 25-microm recording surface. The needle is positioned in the muscle to record from two or more time-locked potentials belonging to the same motor unit. Jitter is the variability in the arrival time of action potentials to the recording electrode between consecutive discharges. This variability reflects end-plate conduction and is measured along with fiber density, which is the average number of fibers belonging to the same motor unit that is in the recording area. An abnormal test is one in which more than 10%, or the mean, of 20 fiber pairs has increased jitter when compared with normal reference values. Increased fiber density is seen with reinnervation. Single-fiber EMG is more sensitive than conventional EMG and is the most sensitive, but not specific, test for myasthenia gravis. Lambert-Eaton myasthenic syndrome, and other neuromusculasr junction pathology. It has been useful in the evaluation of some neuropathies and myopathies and has provided valuable information on the motor unit spatial arrangement, territory, microphysiology, and pathophysiology.
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Affiliation(s)
- Justina L Tanhehco
- Department of Physical Medicine and Rehabilitation, Northwestern University, 345 East Superior Street, Chicago, IL 60611, USA.
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21
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Abstract
The interference pattern of the electrical activity of muscle can be quantified by amplitude measurements, different spike counting methods, and power spectrum analyses. Interference pattern analysis (IPA) methods are used to describe the degree of activation of different muscles, muscle fatigue, occupational work, muscles in chronic pain syndromes, disused muscle, and dystonic muscle treated with botulinum toxin. In patients with neuromuscular disorders, the turns/amplitude analysis is useful for diagnosis. High diagnostic yields can be obtained without force measurements, for example, by using the amplitude as an indicator of force (the peak ratio method) or plotting the amplitude against the turns (cloud analysis). The diagnostic possibilities of the power spectrum analysis and the motor unit firing rate obtained by decomposition techniques are still unclear.
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Affiliation(s)
- A Fuglsang-Frederiksen
- Department of Clinical Neurophysiology, Gentofte Hospital, Niels Andersens Vej 65, DK 2900 Hellerup, Denmark.
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