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Voskuil CC, Dudar MD, Carr JC. Exploring the Relationship between Ultrasonographic Measures of the Quadriceps and Knee Extensor Muscle Fitness in Endurance-Trained Individuals. TRANSLATIONAL SPORTS MEDICINE 2024; 2024:3415740. [PMID: 38654724 PMCID: PMC11023727 DOI: 10.1155/2024/3415740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 03/04/2024] [Accepted: 03/20/2024] [Indexed: 04/26/2024]
Abstract
Background B-mode ultrasonography is an accessible and cost-effective method to assess muscle size and quality through muscle thickness (MT) and echo intensity (EI), respectively. Muscle thickness and EI have demonstrated relationships with maximal strength and local muscle endurance, providing a noninvasive and efficient modality to examine muscle fitness. However, these relationships have not been quantified in the individual quadriceps muscles of habitually endurance-trained populations, which may provide information to practitioners regarding rehabilitation and performance. Methods Twenty-three participants (males: N = 10; females: N = 13) underwent B-mode ultrasonography to assess MT, EI, and adipose tissue thickness-corrected echo intensity (cEI) in the vastus intermedius (VI), vastus lateralis (VL), and rectus femoris (RF). Muscle fitness was evaluated through maximal strength (1RM) and local muscle endurance (4 sets to failure at 50% 1RM) during dynamic knee extension. Relationships between ultrasonography outcomes and muscle fitness were examined through stepwise multiple linear regression. Results The results indicate that VI cEI is the strongest predictor of 1RM strength (r = -0.643), while no ultrasonography-derived measures significantly predicted local muscle endurance. Conclusion The study demonstrates that ultrasonography, specifically measures of cEI in the VI, has the greatest association with maximal strength in endurance-trained individuals. These findings suggest monitoring VI muscle size and quality may benefit practitioners who aim to improve knee extension strength for performance or following injury. In addition, the findings support the use of EI examinations in trained populations.
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Affiliation(s)
- Caleb C. Voskuil
- Texas Christian University, Department of Kinesiology, Fort Worth, TX, USA
| | - Monique D. Dudar
- Texas Christian University, Department of Kinesiology, Fort Worth, TX, USA
| | - Joshua C. Carr
- Texas Christian University, Department of Kinesiology, Fort Worth, TX, USA
- Department of Medical Education, Anne Burnett Marion School of Medicine at Texas Christian University, Fort Worth, TX, USA
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Jacobsen LN, Stemmerik MG, Skriver SV, Pedersen JJ, Løkken N, Vissing J. Contractile properties and magnetic resonance imaging-assessed fat replacement of muscles in myotonia congenita. Eur J Neurol 2024; 31:e16207. [PMID: 38270354 DOI: 10.1111/ene.16207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 12/18/2023] [Accepted: 12/28/2023] [Indexed: 01/26/2024]
Abstract
BACKGROUND AND PURPOSE Myotonia congenita (MC) is a muscle channelopathy in which pathogenic variants in a key sarcolemmal chloride channel Gene (CLCN1) cause myotonia. This study used muscle magnetic resonance imaging (MRI) to quantify contractile properties and fat replacement of muscles in a Danish cohort of MC patients. METHODS Individuals with the Thomsen (dominant) and Becker (recessive) variants of MC were studied. Isometric muscle strength, whole-body MRI, and clinical data were collected. The degree of muscle fat replacement of thigh, calf, and forearm muscles was quantitively calculated on Dixon MRI as fat fractions (FFs). Contractility was evaluated as the muscle strength per contractile muscle cross-sectional area (PT/CCSA). Muscle contractility was compared with clinical data. RESULTS Intramuscular FF was increased and contractility reduced in calf and in forearm muscles compared with controls (FF = 7.0-14.3% vs. 5.3-9.6%, PT/CCSA = 1.1-4.9 Nm/cm2 vs. 1.9-5.8 Nm/cm2 [p < 0.05]). Becker individuals also showed increased intramuscular FF and reduced contractility of thigh muscles (FF = 11.9% vs. 9.2%, PT/CCSA = 1.9 Nm/cm2 vs. 3.2 Nm/cm2 [p < 0.05]). Individual muscle analysis showed that increased FF was limited to seven of 18 examined muscles (p < 0.05). There was a weak correlation between reduced contractility and severity of symptoms. CONCLUSIONS Individuals with MC have increased fat replacement and reduced contractile properties of muscles. Nonetheless, changes were small and likely did not impact clinically on their myotonic symptoms.
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Affiliation(s)
- Laura Nørager Jacobsen
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Mads Godtfeldt Stemmerik
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Sofie Vinther Skriver
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jonas Jalili Pedersen
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Nicoline Løkken
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - John Vissing
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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Vicino A, Brugnoni R, Maggi L. Diagnostics in skeletal muscle channelopathies. Expert Rev Mol Diagn 2023; 23:1175-1193. [PMID: 38009256 DOI: 10.1080/14737159.2023.2288258] [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: 08/23/2023] [Accepted: 11/22/2023] [Indexed: 11/28/2023]
Abstract
INTRODUCTION Skeletal muscle channelopathies (SMCs) are a heterogenous group of disorders, caused by mutations in skeletal ion channels leading to abnormal muscle excitability, resulting in either delayed muscle relaxation (myotonia) which characterizes non-dystrophic myotonias (NDMs), or membrane transient inactivation, causing episodic weakness, typical of periodic paralyses (PPs). AREAS COVERED SMCs include myotonia congenita, paramyotonia congenita, and sodium-channel myotonia among NDMs, and hyper-normokalemic, hypokalemic, or late-onset periodic paralyses among PPs. When suspecting an SMC, a structured diagnostic approach is required. Detailed personal and family history and clinical examination are essential, while neurophysiological tests should confirm myotonia and rule out alternative diagnosis. Moreover, specific electrodiagnostic studies are important to further define the phenotype of de novo cases and drive molecular analyses together with clinical data. Definite diagnosis is achieved through genetic testing, either with Sanger sequencing or multigene next-generation sequencing panel. In still unsolved patients, more advanced techniques, as exome-variant sequencing or whole-genome sequencing, may be considered in expert centers. EXPERT OPINION The diagnostic approach to SMC is still mainly based on clinical data; moreover, definite diagnosis is sometimes complicated by the difficulty to establish a proper genotype-phenotype correlation. Lastly, further studies are needed to allow the genetic characterization of unsolved patients.
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Affiliation(s)
- Alex Vicino
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
- Nerve-Muscle Unit, Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Raffaella Brugnoni
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Lorenzo Maggi
- Neurology IV Unit, Neuroimmunology and Neuromuscular Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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Mañago MM, Seamon BA, Boncella KL, Wallin MT, Maloni H, Hoover B, Blackman MR, Harris-Love MO. Ultrasound measures of muscle morphology in people with multiple sclerosis are associated with muscle performance and functional mobility. Mult Scler Relat Disord 2023; 75:104759. [PMID: 37192587 PMCID: PMC10330594 DOI: 10.1016/j.msard.2023.104759] [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: 03/08/2023] [Revised: 04/27/2023] [Accepted: 05/09/2023] [Indexed: 05/18/2023]
Abstract
BACKGROUND Neurologically-based muscle weakness is a common symptom in people with multiple sclerosis MS (MS), who may also exhibit muscle morphology changes and intrinsic muscle dysfunction. Diagnostic ultrasound (sonography) is a non-invasive, inexpensive, and clinically feasible method to measure muscle morphology. The purpose of this study was to investigate possible asymmetries in lower limb muscle morphology and performance in people with MS, and to assess the relationships of muscle morphology measures with individual patient characteristics, muscle performance, and functional mobility. METHODS This cross-sectional study was conducted at the Washington, DC Veterans Affairs Medical Center. The study participants were 29 Veterans with MS (52% female, 79% African-American, 48.6 ± 11.2 years old, Mean Expanded Disability Status Scale: 3.6 ± 1.4) who completed seated knee extension isokinetic strength and power tests, functional assessments (Timed 25-Foot Walk - T25FW, 5-Times Sit-to-Stand - 5STS), and quantitative B-mode ultrasound image acquisition of the rectus femoris muscle to derive morphology measures (thickness and echogenicity). The limb with weaker knee extension strength was identified as the more-involved limb. Differences between the more and less-involved limb were quantified using a t-test for all muscle morphology and muscle performance measures. Relationships between muscle morphology and patient characteristics, muscle performance, and functional mobility were evaluated using bivariate and multivariate analyses. RESULTS The rectus femoris thickness from the more-involved limb was lower (p<0.001) than that of the less-involved limb, whereas echogenicity was not different between the two limbs (p=0.147). Rectus femoris thickness of the more-involved limb was directly related to age (r=-0.63, p<0.001), muscle strength (r=0.53, p=0.003) and power (r=0.53, p=0.003), and gait speed (r=0.42, p=0.024); whereas its echogenicity was positively associated only with muscle strength (r=-0.46, p=0.013) and power (r=-0.50, p=0.006). Together rectus femoris thickness and echogenicity of the more involved limb explained 44% and 48% of the variance in muscle strength and power, respectively (p<0.001). CONCLUSION This study supports the ability of sonography to measure muscle morphology in people with MS, identify asymmetries, and quantify associations with important clinical correlates. Compared with more invasive and costly alternatives, sonography is a clinically feasible, relatively low-cost tool that can be used to assess muscle morphology in people with MS. Further research is warranted to determine the potential clinical utility of sonographic measures of muscle morphology in evaluating changes due to disease progression or therapeutic interventions in this population.
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Affiliation(s)
- Mark M Mañago
- Department of Physical Medicine and Rehabilitation, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; VA Research Service, Rocky Mountain Regional VA Medical Center, Aurora, CO, USA.
| | - Bryant A Seamon
- Department of Rehabilitation Sciences, Medical University of South Carolina, Charleston, SC, USA; Muscle Morphology, Mechanics and Performance Lab, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Research Service, Washington DC VA Medical Center, Washington, DC, USA
| | - Katie L Boncella
- Muscle Morphology, Mechanics and Performance Lab, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Mitchell T Wallin
- VA Multiple Sclerosis Center of Excellence and Neurology Service, Washington DC VA Medical Center, Washington, DC, USA
| | - Heidi Maloni
- VA Multiple Sclerosis Center of Excellence and Neurology Service, Washington DC VA Medical Center, Washington, DC, USA
| | - Brian Hoover
- Muscle Morphology, Mechanics and Performance Lab, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Research Service, Washington DC VA Medical Center, Washington, DC, USA
| | - Marc R Blackman
- Research Service, Washington DC VA Medical Center, Washington, DC, USA; Departments of Medicine and Rehabilitation Medicine, Georgetown University, Washington, DC, USA; Department of Medicine, George Washington University, Washington, DC, USA
| | - Michael O Harris-Love
- Department of Physical Medicine and Rehabilitation, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; VA Research Service, Rocky Mountain Regional VA Medical Center, Aurora, CO, USA; Muscle Morphology, Mechanics and Performance Lab, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Research Service, Washington DC VA Medical Center, Washington, DC, USA; Geriatric Service, Washington DC VA Medical Center, Washington, DC, USA
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Pedersen JJ, Stemmerik MG, Jacobsen LN, Skriver SV, Wilms GR, Duno M, Vissing J. Muscle fat replacement and contractility in patients with skeletal muscle sodium channel disorders. Sci Rep 2023; 13:2538. [PMID: 36782059 PMCID: PMC9925746 DOI: 10.1038/s41598-023-29759-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 02/09/2023] [Indexed: 02/15/2023] Open
Abstract
Skeletal muscle sodium channel disorders give rise to episodic symptoms such as myotonia and/or periodic paralysis. Chronic symptoms with permanent weakness are not considered characteristic of the phenotypes. Muscle fat replacement represents irreversible damage that inevitably will impact on muscle strength. This study investigates muscle fat replacement and contractility in patients with pathogenic SCN4A variants compared to healthy controls. T1-weighted and 2-point Dixon MRI of the legs were conducted to assess fat replacement. Stationary dynamometry was used to assess muscle strength. Contractility was determined by maximal muscle contraction divided by cross-sectional muscle area. The average cross-sectional intramuscular fat fraction was greater in patients compared with controls by 2.5% in the calves (95% CI 0.74-4.29%, p = 0.007) and by 2.0% in the thighs (95% CI 0.75-3.2%, p = 0.003). Muscle contractility was less in patients vs. controls by 14-27% (p < 0.05). Despite greater fat fraction and less contractility, absolute strength was not significantly less. This study quantitatively documents greater fat fraction and additionally describes difference in muscle contractility in a large cohort of patients with skeletal muscle sodium channel disorders. The clinical impact of these abnormal findings is likely limited as muscle hypertrophy in the patients served to preserve absolute muscle strength. Subgroup analysis indicated significant difference in phenotype by genotype, however these findings lack statistical significance and serve as inspiration for future researchers to probe into the geno- phenotype relationship in these disorders.Trial registration: The study was registered at http://clinicaltrials.gov (identifier: NCT04808388).
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Affiliation(s)
- Jonas Jalili Pedersen
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark.
| | - Mads Godtfeldt Stemmerik
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
| | - Laura Nørager Jacobsen
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
| | - Sofie Vinther Skriver
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
| | - Gustav Rhode Wilms
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
| | - Morten Duno
- Clinical Genetic Laboratory, Department of Biochemical Genetics, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - John Vissing
- Copenhagen Neuromuscular Center, Department of Neurology, Rigshospitalet, University of Copenhagen, Inge Lehmanns Vej 7-9, 2100, Copenhagen, Denmark
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Isaka M, Sugimoto K, Akasaka H, Yasunobe Y, Takahashi T, Xie K, Onishi Y, Yoshida S, Minami T, Yamamoto K, Kamide K, Rakugi H. The Muscle Thickness Assessment Using Ultrasonography is a Useful Alternative to Skeletal Muscle Mass by Bioelectrical Impedance Analysis. Clin Interv Aging 2022; 17:1851-1861. [PMID: 36545348 PMCID: PMC9762259 DOI: 10.2147/cia.s385469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 11/24/2022] [Indexed: 12/23/2022] Open
Abstract
Purpose Muscle mass, a key index for the diagnosis of sarcopenia, is currently assessed using the appendicular skeletal muscle mass index (ASMI) by bioelectrical impedance analysis (BIA). Muscle thickness (MT) assessed by ultrasonography (US) may be a better determinant and/or predictor of muscle condition than ASMI. Thus, we compared it to the ASMI determined by the BIA. Patients and Methods Our study included 165 ambulatory older adults (84 males, 81 females, mean age: 76.82 years). The ASMI by the BIA method, MT by US, and the distribution of body mass index (BMI) and body fat percentage (BFP) were examined using defined values for men and women. These were used as the basis for examining the association of MT and ASMI with handgrip strength (HGS), leg muscle strength (LMS), gait speed (GS), and echo intensity (EI). We compared HGS, LMS, GS, and EI for high and low ASMI among lower BMI or BFP. The same was also done for MT assessed by US. Results MT, as well as ASMI, was strongly associated with HGS and LMS. There was a correlation between MT and GS and EI but not between ASMI and GS and EI. There were significant differences in the prevalence between high ASMI and high MT or low ASMI and low MT in those with lower BMI or BFP. In non-overweight participants, HGS, LMS, GS, and EI were significantly higher in those with high MT than in those with low MT; however, there were no significant differences in them between those with high and low ASMI. Conclusion In the non-overweight group, the MT assessment by US showed a stronger relationship to muscle strength and muscle quality than the ASMI assessment by BIA. The MT assessment using US is a useful alternative to BIA-assessed ASMI, especially in non-overweight participants.
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Affiliation(s)
- Masaaki Isaka
- Department of Geriatric and General Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan,Department of Health Science, Osaka University Graduate School of Medicine, Suita, Osaka, Japan,Physical Therapy, Osaka Yukioka College of Health Science, Ibaraki, Osaka, Japan
| | - Ken Sugimoto
- Department of Geriatric and General Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan,Department of General Geriatric Medicine, Kawasaki Medical School, Okayama, Okayama, Japan,Correspondence: Ken Sugimoto, Department of General Geriatric Medicine, Kawasaki Medical School, 2-6-1, Nakasange, Kita-ku, Okayama, Okayama, 700-8505, Japan, Tel +81 86 225 2111, Fax +81 86 232 8343, Email
| | - Hiroshi Akasaka
- Department of Geriatric and General Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Yukiko Yasunobe
- Department of Geriatric and General Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Toshimasa Takahashi
- Department of Geriatric and General Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Keyu Xie
- Department of Geriatric and General Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Yuri Onishi
- Department of Geriatric and General Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Shino Yoshida
- Department of Geriatric and General Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Tomohiro Minami
- Department of Geriatric and General Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Koichi Yamamoto
- Department of Geriatric and General Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Kei Kamide
- Department of Geriatric and General Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan,Department of Health Science, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Hiromi Rakugi
- Department of Geriatric and General Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
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Hannaford A, Vucic S, van Alfen N, Simon NG. Muscle ultrasound in hereditary muscle disease. Neuromuscul Disord 2022; 32:851-863. [PMID: 36323605 DOI: 10.1016/j.nmd.2022.09.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 09/27/2022] [Accepted: 09/29/2022] [Indexed: 12/31/2022]
Abstract
In this review we summarise the key techniques of muscle ultrasound as they apply to hereditary muscle disease. We review the diagnostic utility of muscle ultrasound including its role in guiding electromyography and muscle biopsy sampling. We summarize the different patterns of sonographic muscle involvement in the major categories of genetic muscle disorders and discuss the limitations of the technique. We hope to encourage others to adopt ultrasound in their care for patients with hereditary muscle diseases.
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Affiliation(s)
- Andrew Hannaford
- Brain and Nerve Research Center, Concord Clinical School, University of Sydney, Sydney, Australia
| | - Steve Vucic
- Brain and Nerve Research Center, Concord Clinical School, University of Sydney, Sydney, Australia
| | - Nens van Alfen
- Department of Neurology and Clinical Neurophysiology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Neil G Simon
- Northern Beaches Clinical School, Macquarie University, Suite 6a, 105 Frenchs Forest Rd W, Frenchs Forest, Sydney, NSW 2086, Australia.
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Taminato T, Mori-Yoshimura M, Miki J, Sasaki R, Sato N, Oya Y, Nishino I, Takahashi Y. Paramyotonia Congenita with Persistent Distal and Facial Muscle Weakness: A Case Report with Literature Review. J Neuromuscul Dis 2020; 7:193-201. [PMID: 32083589 DOI: 10.3233/jnd-190440] [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] [Indexed: 11/15/2022]
Abstract
BACKGROUND Paramyotonia congenita (PC; OMIM 168300) is a non-dystrophic myotonia caused by mutations in the SCN4A gene. Transient muscle stiffness, usually induced by exposure to cold and aggravated by exercise, is the predominant clinical symptom, and interictal persistent weakness is uncommon. CASE REPORT We report a family with a history of PC accompanied by persistent hand muscle weakness with masticatory muscle involvement. Persistent weakness was exacerbated with age, and MR analysis showed marked atrophy of temporal, masseter, and finger flexor muscles with fatty replacement. The PC causative mutation T1313M in the SCN4A gene was prevalent in the family. Administration of acetazolamide chloride improved clinical symptoms and the results of cold and short exercise tests. Phenotypic variation within the family was remarkable, as the two younger affected patients did not present with persistent weakness or muscle atrophy. CONCLUSIONS PC associated with the T1313M mutation is a possible cause of persistent distal hand weakness.
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Affiliation(s)
- Tomoya Taminato
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Madoka Mori-Yoshimura
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Jun Miki
- Department of Neurology, Saku Central Hospital, Nagano Prefectural Federation of Agricultural Cooperatives for Health and Welfare, Nagano, Japan
| | - Ryogen Sasaki
- Department of Neurology, Kuwana City Medical Center, Mie, Japan
| | - Noriko Sato
- Department of Radiology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yasushi Oya
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Ichizo Nishino
- Department of Genome Medicine Development, Medical Genome Center, National Center of Neurology and Psychiatry, Tokyo, Japan.,Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yuji Takahashi
- Department of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
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9
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Stunnenberg BC, LoRusso S, Arnold WD, Barohn RJ, Cannon SC, Fontaine B, Griggs RC, Hanna MG, Matthews E, Meola G, Sansone VA, Trivedi JR, van Engelen BG, Vicart S, Statland JM. Guidelines on clinical presentation and management of nondystrophic myotonias. Muscle Nerve 2020; 62:430-444. [PMID: 32270509 PMCID: PMC8117169 DOI: 10.1002/mus.26887] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 04/01/2020] [Accepted: 04/04/2020] [Indexed: 12/26/2022]
Abstract
The nondystrophic myotonias are rare muscle hyperexcitability disorders caused by gain-of-function mutations in the SCN4A gene or loss-of-function mutations in the CLCN1 gene. Clinically, they are characterized by myotonia, defined as delayed muscle relaxation after voluntary contraction, which leads to symptoms of muscle stiffness, pain, fatigue, and weakness. Diagnosis is based on history and examination findings, the presence of electrical myotonia on electromyography, and genetic confirmation. In the absence of genetic confirmation, the diagnosis is supported by detailed electrophysiological testing, exclusion of other related disorders, and analysis of a variant of uncertain significance if present. Symptomatic treatment with a sodium channel blocker, such as mexiletine, is usually the first step in management, as well as educating patients about potential anesthetic complications.
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Affiliation(s)
- Bas C. Stunnenberg
- Department of Neurology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Samantha LoRusso
- Department of Neurology, Ohio State University Wexner Medical Center, Columbus, Ohio
| | - W. David Arnold
- Department of Neurology, Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Richard J. Barohn
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas
| | - Stephen C. Cannon
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Bertrand Fontaine
- Assistance Publique-Hôpitaix de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Robert C. Griggs
- Department of Neurology, University of Rochester, Rochester, New York
| | - Michael G. Hanna
- MRC Centre for Neuromuscular Diseases, Department of Neuromuscular diseases, UCL Queen Square Institute of Neurology, United Kingdom
| | - Emma Matthews
- MRC Centre for Neuromuscular Diseases, Department of Neuromuscular diseases, UCL Queen Square Institute of Neurology, United Kingdom
| | - Giovanni Meola
- Department of Neurorehabilitation Sciences, Casa Cura Policlinico, Milan, Italy
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Valeria A. Sansone
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
- Neurorehabilitation Unit, University of Milan, NEuroMuscular Omnicentre (NEMO), Fondazione Serena Onlus, Milan, Italy
| | - Jaya R. Trivedi
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, Texas
| | | | - Savine Vicart
- Assistance Publique-Hôpitaix de Paris, Sorbonne Université, INSERM, Service of Neuro-Myology and UMR 974, Institute of Myology, University Hospital Pitié-Salpêtrière, Paris, France
| | - Jeffrey M. Statland
- Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas
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Abstract
Purpose of Review The purpose of this review is to critically discuss the use of ultrasound in the evaluation of muscle disorders with a particular focus on the emerging use in inflammatory myopathies. Recent Findings In myopathies, pathologic muscle shows an increase in echogenicity. Muscle echogenicity can be assessed visually, semi-quantitatively, or quantitatively using grayscale analysis. The involvement of specific muscle groups and the pattern of increase in echogenicity can further point to specific diseases. In pediatric neuromuscular disorders, the value of muscle ultrasound for screening and diagnosis is well-established. It has also been found to be a responsive measure of disease change in muscular dystrophies. In chronic forms of myositis like inclusion body myositis, ultrasound is very suitable for detecting markedly increased echogenicity and atrophy in affected muscles. Acute cases of muscle edema show only a mild increase in echogenicity, which can also reverse with successful treatment. Summary Muscle ultrasound is an important imaging modality that is highly adaptable to study various muscle conditions. Although its diagnostic value for neuromuscular disorders is high, the evidence in myositis has only begun to accrue in earnest. Further systematic studies are needed, especially in its role for detecting muscle edema.
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Nojszewska M, Lusakowska A, Gawel M, Sierdzinski J, Sulek A, Krysa W, Elert-Dobkowska E, Seroka A, Kaminska AM, Kostera-Pruszczyk A. The needle EMG findings in myotonia congenita. J Electromyogr Kinesiol 2019; 49:102362. [PMID: 31610484 DOI: 10.1016/j.jelekin.2019.102362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 09/25/2019] [Accepted: 10/01/2019] [Indexed: 10/25/2022] Open
Abstract
INTRODUCTION Myotonia congenita (MC) is caused by pathogenic variants in the CLCN1 gene coding the chloride channel protein. METHODS To test the hypothesis that needle EMG could be helpful in distinguishing between the recessive and dominant MC, we performed EMG examination in 36 patients (23 men) aged 4-61 years with genetically proven MC: in 30 patients with autosomal recessive MC (Becker MC) and in 6 with autosomal dominant MC (Thomsen MC). RESULTS Myotonic discharges were recorded in 95.8% of examined muscles. For the whole MC group we observed a significant positive correlation between parameters of motor unit activity potentials (MUAPs) in vastus lateralis and tibialis anterior muscles and the duration of the disease. Similar correlation for biceps brachii also was found in Becker MC subgroup only. DISCUSSION EMG could still be helpful in diagnosis of MC and together with provocative tests might be useful in differentiation between recessive and autosomal MC.
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Affiliation(s)
- Monika Nojszewska
- Department of Neurology, Medical University of Warsaw, Warsaw, Poland
| | - Anna Lusakowska
- Department of Neurology, Medical University of Warsaw, Warsaw, Poland
| | - Malgorzata Gawel
- Department of Neurology, Medical University of Warsaw, Warsaw, Poland
| | - Janusz Sierdzinski
- Department of Medical Informatics and Telemedicine, Medical University of Warsaw, Poland.
| | - Anna Sulek
- Department of Genetics, Institute of Psychiatry and Neurology, Warsaw, Poland
| | - Wioletta Krysa
- Department of Genetics, Institute of Psychiatry and Neurology, Warsaw, Poland
| | | | - Andrzej Seroka
- Department of Neurology, Medical University of Warsaw, Warsaw, Poland
| | - Anna M Kaminska
- Department of Neurology, Medical University of Warsaw, Warsaw, Poland
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12
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The Usefulness of an Alternative Diagnostic Method for Sarcopenia Using Thickness and Echo Intensity of Lower Leg Muscles in Older Males. J Am Med Dir Assoc 2019; 20:1185.e1-1185.e8. [DOI: 10.1016/j.jamda.2019.01.152] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 01/26/2019] [Accepted: 01/28/2019] [Indexed: 01/03/2023]
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13
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Abstract
Advances in high-resolution ultrasound have provided clinicians with unique opportunities to study diseases of the peripheral nervous system. Ultrasound complements the clinical and electrophysiology exam by showing the degree of abnormalities in myopathies, as well as spontaneous muscle activities in motor neuron diseases and other disorders. In experienced hands, ultrasound is more sensitive than MRI in detecting peripheral nerve pathologies. It can also guide needle placement for electromyography exam, therapeutic injections, and muscle biopsy. Ultrasound enhances the ability to detect carpal tunnel syndrome and other focal nerve entrapment, as well as pathological nerve enlargements in genetic and acquired neuropathies. Furthermore, ultrasound can potentially be used as a biomarker for muscular dystrophy and spinal muscular atrophy. The combination of electromyography and ultrasound can increase the diagnostic certainty of amyotrophic lateral sclerosis, aid in the localization of brachial plexus or peripheral nerve trauma and allow for surveillance of nerve tumor progression in neurofibromatosis. Potential limitations of ultrasound include an inability to image deeper structures, with lower sensitivities in detecting neuromuscular diseases in young children and those with mitochondrial myopathies, due to subtle changes or early phase of the disease. As well, its utility in detecting critical illness neuromyopathy remains unclear. This review will focus on the clinical applications of neuromuscular ultrasound. The diagnostic values of ultrasound for screening of myopathies, neuropathies, and motor neuron diseases will be presented.
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Martucci MG, McIlduff CE, Shin C, Gutierrez HV, Nam JY, Greenstein P, Phillips K, Uhlmann EJ, Wong ET, Rutkove SB. Quantitative ultrasound of muscle can detect corticosteroid effects. Clin Neurophysiol 2019; 130:1460-1464. [PMID: 31122815 DOI: 10.1016/j.clinph.2019.04.709] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 03/20/2019] [Accepted: 04/07/2019] [Indexed: 11/18/2022]
Abstract
OBJECTIVES In this study, we sought to determine whether quantitative ultrasound (QUS) could detect the impact of corticosteroids on muscle in the absence of frank weakness. METHODS QUS was performed on selected limb muscles of 20 brain tumor patients treated with dexamethasone and 30 healthy controls. Echointensity was quantified using gray scale level (GSL) analysis and compared between groups; correlation to corticosteroid exposure was also performed. RESULTS Average 4-muscle GSL (±standard deviation) was greater in patients compared to controls (35.5 ± 5.61 arbitrary units (AU) versus 30.4 ± 4.17 AU, p = 0.001), with the greatest differences in tibialis anterior. Average muscle GSL also correlated to length of corticosteroid therapy (rho = 0.52, p = 0.01). CONCLUSIONS These findings suggest that QUS may be able to quantify skeletal muscle alterations associated with chronic corticosteroid use. Further study of this approach is warranted. SIGNIFICANCE The findings of this study may provide a tool to evaluate corticosteroid myopathy.
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Affiliation(s)
- Maria G Martucci
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Courtney E McIlduff
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Carmen Shin
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Hilda V Gutierrez
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Joo Yeon Nam
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Patricia Greenstein
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Kester Phillips
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Erik J Uhlmann
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Eric T Wong
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA
| | - Seward B Rutkove
- Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA.
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Helmy H, Aboumousa A, Abdelmagied A, Alsayyad A, Nasr SA. The role of muscle ultrasound in helping the clinical diagnosis of muscle diseases. THE EGYPTIAN JOURNAL OF NEUROLOGY, PSYCHIATRY AND NEUROSURGERY 2018; 54:29. [PMID: 30459502 PMCID: PMC6223737 DOI: 10.1186/s41983-018-0039-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/24/2018] [Indexed: 03/06/2023] Open
Abstract
Background Selective involvement of certain muscles is an indicator for muscle diseases and helps to direct the diagnosis, but in some cases, it cannot be detected clinically; hence, the roles of muscle MRI and ultrasound are to detect this selectivity and facilitate the diagnosis. Objectives The possibility of using muscle ultrasound as a screening tool when muscle diseases are suspected and as an alternative to MRI. Subjects and methods This cross-sectional descriptive study included 38 patients presented with clinical manifestations suggestive of muscle diseases. The patients were selected over a period of 1 year. All patients were subjected to thorough clinical assessment and muscle ultrasound of the thigh and leg for all patients, while 15 were subjected to MRI. Clinical and radiological assessments were performed separately, followed by both clinical and radiological findings to assess the power of combining the clinical and radiological assessments for the diagnosis of muscle diseases. Results The clinical assessment reached a main provisional probable diagnosis in 53% cases, and radiological assessment blind to clinical data suggested diagnosis in 18 of the total cases, while the combination of both ultrasound and MRI could suggest diagnosis in 87% of the cases. The concordance ratio of ultrasound to MRI ranged between 78 and 100%. Conclusion The combination of clinical and radiological assessments of muscle diseases can suggest a main provisional probable diagnosis, especially when genetic diagnosis is not accessible, or to direct the genetic testing when it is available. Ultrasound can be used as a routine tool in screening and follow-up of muscle diseases.
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16
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Lori S, Lolli F, Molesti E, Bastianelli M, Gabbanini S, Saia V, Trapani S, Marinoni M. Muscle-ultrasound evaluation in healthy pediatric subjects: Age-related normative data. Muscle Nerve 2018; 58:245-250. [PMID: 29679375 DOI: 10.1002/mus.26151] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 04/12/2018] [Accepted: 04/17/2018] [Indexed: 12/13/2022]
Abstract
INTRODUCTION The muscle ultrasound examination (MUS) is a noninvasive and inexpensive technique for evaluating neuromyopathies. Standardized MUS normative data are incomplete in pediatric subjects. METHODS We performed a MUS study with 120 healthy children (59 males; mean age, 10.44 years; age range, 2-16 years). We measured the width and the echogenicity bilaterally in the following muscles: biceps brachii and brachialis, brachioradialis, forearm-flexors, rectus femoris and vastus intermedius, tibialis anterior, extensor hallucis longus, lateral and medial gastrocnemius. RESULTS The muscle thickness increased with age for all muscles. Confidence limits were set for each age group muscle width. Echogenicity increased with age only in some muscles. DISCUSSIONS Our MUS study provides new data on physiological muscle structural changes in healthy children to address the limited available references in this age group. Muscle Nerve 58: 245-250, 2018.
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Affiliation(s)
- Silvia Lori
- University Hospital Careggi, Dipartimento Neuromuscolo Scheletrico e degli organi di senso, Firenze, Italy
| | - Francesco Lolli
- University Hospital Careggi, Dipartimento Neuromuscolo Scheletrico e degli organi di senso, Firenze, Italy.,University of Florence, Dipartimento di Scienze Biomediche Sperimentali e Cliniche Mario Serio, viale Pieraccini 6 Firenze, 50134, Italy
| | - Elisabetta Molesti
- University Hospital Careggi, Dipartimento Neuromuscolo Scheletrico e degli organi di senso, Firenze, Italy
| | - Maria Bastianelli
- University Hospital Careggi, Dipartimento Neuromuscolo Scheletrico e degli organi di senso, Firenze, Italy
| | - Simonetta Gabbanini
- University Hospital Careggi, Dipartimento Neuromuscolo Scheletrico e degli organi di senso, Firenze, Italy
| | - Valentina Saia
- University Hospital Careggi, Dipartimento Neuromuscolo Scheletrico e degli organi di senso, Firenze, Italy
| | - Sara Trapani
- University Hospital Careggi, Dipartimento Neuromuscolo Scheletrico e degli organi di senso, Firenze, Italy
| | - Marinella Marinoni
- University Hospital Careggi, Dipartimento Neuromuscolo Scheletrico e degli organi di senso, Firenze, Italy.,University of Florence, Dipartimento di Scienze Biomediche Sperimentali e Cliniche Mario Serio, viale Pieraccini 6 Firenze, 50134, Italy
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17
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Santos R, Valamatos MJ, Mil-Homens P, Armada-da-Silva PAS. Muscle thickness and echo-intensity changes of the quadriceps femoris muscle during a strength training program. Radiography (Lond) 2018; 24:e75-e84. [PMID: 30292517 DOI: 10.1016/j.radi.2018.03.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 03/21/2018] [Accepted: 03/29/2018] [Indexed: 10/17/2022]
Abstract
INTRODUCTION Ultrasound (US) has an important role in musculoskeletal (MSK) evaluation, allowing the study of muscle morphology and function. Muscle thickness (MT) and muscle echo-intensity (EI) are two important parameters that may quantify muscle structural adaptations to a variety of stimuli. The aim was to explore the potential of quantitative US imaging for assessing the adaptations and responses of the muscle tissue to increased contractile activity using B-mode US. This study was centred on the quadriceps femoris muscle contractile activity on MT and EI. METHODS AND MATERIALS Twenty-eight young male adults participated in the study, divided in a control group and two training groups performing concentric or eccentric strength training, respectively. The effect of a 15-week strength program was studied on MT and EI in several regions of the heads of the quadriceps femoris using B-mode US. All images acquisitions and measurements were done by the same experience sonographer. RESULTS Strength training resulted in an increase of MT at all muscles and sites (p < 0.05), except the VM. Strength training failed in changing EI in most of the quadriceps femoris, except in the VI and some regions of the VL. No statistically significant differences were observed in our quantitative US parameters between concentric and eccentric training (p > 0.05). CONCLUSION These results emphasise the value of MT as a quantifiable muscle US method for evaluating muscle adaptation to exercise training. However, the inconsistency of the EI values indicates that more studies are needed to develop it as an accurate diagnostic tool.
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Affiliation(s)
- R Santos
- Universidade de Lisboa, Faculdade de Motricidade Humana, Estrada da Costa 1499-002, Portugal; Instituto Politécnico de Coimbra, Escola Superior de Tecnologia de Saúde de Coimbra, Departamento Imagem Médica e Radioterapia, Rua 5 de Outubro, Apartado 7006, 3046-854 Coimbra, Portugal.
| | - M J Valamatos
- Universidade de Lisboa, Faculdade de Motricidade Humana, Estrada da Costa 1499-002, Portugal; Universidade de Lisboa, Faculdade de Motricidade Humana, Centro para o Estudo da Performance Humana, Estrada da Costa 1499-002, Portugal
| | - P Mil-Homens
- Universidade de Lisboa, Faculdade de Motricidade Humana, Estrada da Costa 1499-002, Portugal; Universidade de Lisboa, Faculdade de Motricidade Humana, Centro para o Estudo da Performance Humana, Estrada da Costa 1499-002, Portugal
| | - P A S Armada-da-Silva
- Universidade de Lisboa, Faculdade de Motricidade Humana, Estrada da Costa 1499-002, Portugal; Universidade de Lisboa, Faculdade de Motricidade Humana, Centro para o Estudo da Performance Humana, Estrada da Costa 1499-002, Portugal
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18
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Takamatsu N, Sogawa K, Nodera H, Hashiguchi S, Osaki Y, Saito M, Mori A, Izumi Y, Kaji R. Preferential changes of skeletal muscle echogenicity in myotonic dystrophy type 1. Eur J Neurol 2016; 24:366-373. [PMID: 27933692 DOI: 10.1111/ene.13212] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 10/25/2016] [Indexed: 11/28/2022]
Abstract
BACKGROUND AND PURPOSE In myotonic dystrophy type 1 (DM1), weakness of distal limb muscles affects quality of life. Non-invasive evaluation of muscular involvement by muscle sonography could be useful for characterizing muscle-specific involvement. METHODS Sonography of the lower leg and forearm was performed in 19 patients with DM1 and 10 control subjects. The mean echo intensities (EIs) of seven limb muscles were obtained by computer-assisted histogram analysis and compared within DM1 according to the overall clinical severity. RESULTS The EIs of the muscles were significantly higher in DM1 than in the controls (P < 0.01), except for the soleus (P = 0.4). Comparison of adjacent muscles showed the following: (i) greater EIs in flexor digitorum profundus than flexor carpi ulnaris (P < 0.01) and flexor digitorum superficialis (P = 0.02), and (ii) greater EIs in the medial head of the gastrocnemius than the soleus (P < 0.00001). In a subgroup analysis of DM1 according to the modified Rankin Scale (mRS), the more severe subgroup (mRS = 4-5) had lower mean EIs than the less severe subgroup (mRS from 1-3) (P = 0.01) in the flexor digitorum superficialis but not in other muscles. CONCLUSIONS Preferential high echogenicity in the medial gastrocnemius and deep finger flexors is suggestive of DM1. Muscle echogenicity is not generally related to functional dysfunction in DM1.
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Affiliation(s)
- N Takamatsu
- Department of Neurology, Tokushima University, Tokushima, Japan
| | - K Sogawa
- Faculty of Medicine - Student Laboratory, Tokushima University, Tokushima, Japan
| | - H Nodera
- Department of Neurology, Tokushima University, Tokushima, Japan
| | - S Hashiguchi
- Department of Neurology, Tokushima Hospital, Tokushima, Japan
| | - Y Osaki
- Department of Neurology, Tokushima University, Tokushima, Japan.,Department of Neurology, Tokushima Hospital, Tokushima, Japan
| | - M Saito
- Department of Internal Medicine, Tokushima Hospital, Tokushima, Japan
| | - A Mori
- Department of Neurology, Tokushima University, Tokushima, Japan
| | - Y Izumi
- Department of Neurology, Tokushima University, Tokushima, Japan
| | - R Kaji
- Department of Neurology, Tokushima University, Tokushima, Japan
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19
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Abstract
Muscle ultrasound is an ideal imaging modality that allows for noninvasive, radiation-free point-of-care neuromuscular imaging. There are many potential applications of muscle ultrasound, including identification of abnormal muscle movements such as fasciculations, evaluation of muscle trauma, identification of physiologic parameters such as pennation angle, accurate performance of chemodenervation, and improved accuracy of challenging electrodiagnostic studies such as phrenic nerve conduction studies or needle electromyogram (EMG) of the diaphragm. Tissue Doppler imaging can be used to help identify inflammatory myopathies. With computer-assisted quantification, muscle ultrasound has high sensitivity and specificity in the diagnosis of pediatric neuromuscular disease and amyotrophic lateral sclerosis, and is a valuable addition to other diagnostic techniques for neuromuscular disease. When used as a first-line screening tool it can obviate the need for more invasive procedures such as EMG or muscle biopsy in certain patients. This chapter provides an overview of the fundamentals, clinical applications, and validation of muscle ultrasound for patients with neuromuscular disorders.
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Affiliation(s)
- Sigrid Pillen
- Department of Sleep Medicine, Kempenhaeghe Expertise Center for Epileptology, Sleep Medicine and Neurocognition, Heeze, The Netherlands.
| | - Andrea Boon
- Department of Physical Medicine and Rehabilitation and Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Nens Van Alfen
- Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands
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20
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Stunnenberg BC, Woertman W, Raaphorst J, Statland JM, Griggs RC, Timmermans J, Saris CG, Schouwenberg BJ, Groenewoud HM, Stegeman DF, van Engelen BGM, Drost G, van der Wilt GJ. Combined N-of-1 trials to investigate mexiletine in non-dystrophic myotonia using a Bayesian approach; study rationale and protocol. BMC Neurol 2015; 15:43. [PMID: 25880166 PMCID: PMC4407841 DOI: 10.1186/s12883-015-0294-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 02/27/2015] [Indexed: 01/22/2023] Open
Abstract
Background To obtain evidence for the clinical and cost-effectiveness of treatments for patients with rare diseases is a challenge. Non-dystrophic myotonia (NDM) is a group of inherited, rare muscle diseases characterized by muscle stiffness. The reimbursement of mexiletine, the expert opinion drug for NDM, has been discontinued in some countries due to a lack of independent randomized controlled trials (RCTs). It remains unclear however, which concessions can be accepted towards the level 1 evidence needed for coverage decisions, in rare diseases. Considering the large number of rare diseases with a lack of treatment evidence, more experience with innovative trial designs is needed. Both NDM and mexiletine are well suited for an N-of-1 trial design. A Bayesian approach allows for the combination of N-of-1 trials, which enables the assessment of outcomes on the patient and group level simultaneously. Methods/Design We will combine 30 individual, double-blind, randomized, placebo-controlled N-of-1 trials of mexiletine (600 mg daily) vs. placebo in genetically confirmed NDM patients using hierarchical Bayesian modeling. Our results will be compared and combined with the main results of an international cross-over RCT (mexiletine vs. placebo in NDM) published in 2012 that will be used as an informative prior. Similar criteria of eligibility, treatment regimen, end-points and measurement instruments are employed as used in the international cross-over RCT. Discussion The treatment of patients with NDM with mexiletine offers a unique opportunity to compare outcomes and efficiency of novel N-of-1 trial-based designs and conventional approaches in producing evidence of clinical and cost-effectiveness of treatments for patients with rare diseases. Trial registration ClinicalTrials.gov Identifier: NCT02045667
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Affiliation(s)
- Bas C Stunnenberg
- Department of Neurology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Willem Woertman
- Department of Health Evidence, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Joost Raaphorst
- Department of Neurology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Jeffrey M Statland
- Department of Neurology, University of Kansas Medical Center, PO Box 2012, KS 66160, Kansas City, USA.
| | - Robert C Griggs
- Department of Neurology, University of Rochester Medical Center, PO Box 420669, Rochester, NY, 14642, USA.
| | - Janneke Timmermans
- Department of Cardiology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Christiaan G Saris
- Department of Neurology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Bas J Schouwenberg
- Department of Pharmacology-Toxicology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Hans M Groenewoud
- Department of Health Evidence, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Dick F Stegeman
- Department of Neurology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Baziel G M van Engelen
- Department of Neurology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Gea Drost
- Department of Neurology and Neurosurgery, University Medical Center Groningen, PO Box 30001, 9700 RB, Groningen, The Netherlands.
| | - Gert Jan van der Wilt
- Department of Health Evidence, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
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21
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Muscle Quality in Aging: a Multi-Dimensional Approach to Muscle Functioning with Applications for Treatment. Sports Med 2015; 45:641-58. [DOI: 10.1007/s40279-015-0305-z] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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22
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Bickerstaffe A, Beelen A, Zwarts MJ, Nollet F, van Dijk JP. Quantitative muscle ultrasound and quadriceps strength in patients with post-polio syndrome. Muscle Nerve 2014; 51:24-9. [DOI: 10.1002/mus.24272] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 04/10/2014] [Accepted: 04/26/2014] [Indexed: 12/13/2022]
Affiliation(s)
- Alice Bickerstaffe
- Department of Rehabilitation; Academic Medical Center; Postbus 22660 1100 DD Amsterdam The Netherlands
| | - Anita Beelen
- Department of Rehabilitation; Academic Medical Center; Postbus 22660 1100 DD Amsterdam The Netherlands
| | | | - Frans Nollet
- Department of Rehabilitation; Academic Medical Center; Postbus 22660 1100 DD Amsterdam The Netherlands
| | - Johannes P. van Dijk
- Department of Orthodontics; University of Ulm; Ulm Germany
- Epilepsy Centre Kempenhaeghe; Heeze The Netherlands
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23
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Corrochano S, Männikkö R, Joyce PI, McGoldrick P, Wettstein J, Lassi G, Raja Rayan DL, Blanco G, Quinn C, Liavas A, Lionikas A, Amior N, Dick J, Healy EG, Stewart M, Carter S, Hutchinson M, Bentley L, Fratta P, Cortese A, Cox R, Brown SDM, Tucci V, Wackerhage H, Amato AA, Greensmith L, Koltzenburg M, Hanna MG, Acevedo-Arozena A. Novel mutations in human and mouse SCN4A implicate AMPK in myotonia and periodic paralysis. ACTA ACUST UNITED AC 2014; 137:3171-85. [PMID: 25348630 PMCID: PMC4240299 DOI: 10.1093/brain/awu292] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Mutations in the skeletal muscle channel (SCN4A), encoding the Nav1.4 voltage-gated sodium channel, are causative of a variety of muscle channelopathies, including non-dystrophic myotonias and periodic paralysis. The effects of many of these mutations on channel function have been characterized both in vitro and in vivo. However, little is known about the consequences of SCN4A mutations downstream from their impact on the electrophysiology of the Nav1.4 channel. Here we report the discovery of a novel SCN4A mutation (c.1762A>G; p.I588V) in a patient with myotonia and periodic paralysis, located within the S1 segment of the second domain of the Nav1.4 channel. Using N-ethyl-N-nitrosourea mutagenesis, we generated and characterized a mouse model (named draggen), carrying the equivalent point mutation (c.1744A>G; p.I582V) to that found in the patient with periodic paralysis and myotonia. Draggen mice have myotonia and suffer from intermittent hind-limb immobility attacks. In-depth characterization of draggen mice uncovered novel systemic metabolic abnormalities in Scn4a mouse models and provided novel insights into disease mechanisms. We discovered metabolic alterations leading to lean mice, as well as abnormal AMP-activated protein kinase activation, which were associated with the immobility attacks and may provide a novel potential therapeutic target.
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Affiliation(s)
| | - Roope Männikkö
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - Peter I Joyce
- 1 MRC Mammalian Genetics Unit, Harwell, Oxfordshire, UK
| | - Philip McGoldrick
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - Jessica Wettstein
- 3 University of Aberdeen, Institute of Medical Sciences, Scotland, UK
| | - Glenda Lassi
- 4 Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy
| | - Dipa L Raja Rayan
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | | | - Colin Quinn
- 6 Brigham and Women's Hospital, Harvard Medical School, Boston, US
| | - Andrianos Liavas
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | | | - Neta Amior
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - James Dick
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - Estelle G Healy
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | | | - Sarah Carter
- 1 MRC Mammalian Genetics Unit, Harwell, Oxfordshire, UK
| | | | - Liz Bentley
- 1 MRC Mammalian Genetics Unit, Harwell, Oxfordshire, UK
| | - Pietro Fratta
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - Andrea Cortese
- 7 Mondino National Institute of Neurology Foundation, IRCCS, Pavia, Italy
| | - Roger Cox
- 1 MRC Mammalian Genetics Unit, Harwell, Oxfordshire, UK
| | | | - Valter Tucci
- 4 Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genova, Italy
| | | | - Anthony A Amato
- 6 Brigham and Women's Hospital, Harvard Medical School, Boston, US
| | - Linda Greensmith
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - Martin Koltzenburg
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
| | - Michael G Hanna
- 2 UCL Institute of Neurology, MRC Centre for Neuromuscular Diseases, London, UK
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Abstract
INTRODUCTION Skeletal muscle channelopathies are rare disorders of muscle membrane excitability. Their episodic nature may result in diagnostic difficulty and delays in diagnosis. Advances in diagnostic clinical electrophysiology combined with DNA-based diagnosis have improved diagnostic accuracy and efficiency. Ascribing pathogenic status to identified genetic variants in muscle channel genes may be complex and functional analysis, including molecular expression, may help with this. Accurate clinical and genetic diagnosis enables genetic counselling, advice regarding prognosis and aids treatment selection. AREAS COVERED An approach to accurate and efficient diagnosis is outlined. The importance of detailed clinical evaluation including careful history, examination and family history is emphasised. The role of specialised electrodiagnostics combined with DNA testing and molecular expression is considered. New potential biomarkers including muscle MRI using MRC Centre protocols are discussed. EXPERT OPINION A combined diagnostic approach using careful clinical assessment, specialised neurophysiology and DNA testing will now achieve a clear diagnosis in most patients with muscle channelopathies. An accurate diagnosis enables genetic counselling and provides information regarding prognosis and treatment selection. Genetic analysis often identifies new variants of uncertain significance. In this situation, functional expression studies as part of a diagnostic service will enable determination of pathogenic status of novel genetic variants.
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Affiliation(s)
- Jennifer Spillane
- UCL, Institute of Neurology, MRC Centre for Neuromuscular Diseases , Queen Square, London, WC1N3BG UK ,
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Morrow JM, Matthews E, Raja Rayan DL, Fischmann A, Sinclair CDJ, Reilly MM, Thornton JS, Hanna MG, Yousry TA. Muscle MRI reveals distinct abnormalities in genetically proven non-dystrophic myotonias. Neuromuscul Disord 2013; 23:637-46. [PMID: 23810313 PMCID: PMC3744809 DOI: 10.1016/j.nmd.2013.05.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 04/05/2013] [Accepted: 05/03/2013] [Indexed: 01/07/2023]
Abstract
We assessed the presence, frequency and pattern of MRI abnormalities in non-dystrophic myotonia patients. We reviewed T1-weighted and STIR (short-tau-inversion-recovery) 3T MRI sequences of lower limb muscles at thigh and calf level in 21 patients with genetically confirmed non-dystrophic myotonia: 11 with CLCN1 mutations and 10 with SCN4A mutations, and 19 healthy volunteers. The MRI examinations of all patients showed hyperintensity within muscles on either T1-weighted or STIR images. Mild extensive or marked T1-weighted changes were noted in 10/21 patients and no volunteers. Muscles in the thigh were equally likely to be affected but in the calf there was sparing of tibialis posterior. Oedema was common in calf musculature especially in the medial gastrocnemius with STIR hyperintensity observed in 18/21 patients. In 10/11 CLCN1 patients this included a previously unreported “central stripe”, also present in 3/10 SCN4A patients but no volunteers. Degree of fatty infiltration correlated with age (rho = 0.46, p < 0.05). Muscle MRI is frequently abnormal in non-dystrophic myotonia providing evidence of fatty infiltration and/or oedema. The pattern is distinct from other myotonic disorders; in particular the “central stripe” has not been reported in other conditions. Correlations with clinical parameters suggest a potential role for MRI as a biomarker.
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Affiliation(s)
- Jasper M Morrow
- MRC Centre for Neuromuscular Diseases, Department of Molecular Neurosciences, UCL Institute of Neurology, London, UK.
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Zaidman CM, Holland MR, Noetzel MJ, Park TS, Pestronk A. Newborn brachial plexus palsy: Evaluation of severity using quantitative ultrasound of muscle. Muscle Nerve 2012; 47:246-54. [DOI: 10.1002/mus.23518] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2012] [Indexed: 12/12/2022]
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Zaidman CM, Holland MR, Hughes MS. Quantitative ultrasound of skeletal muscle: reliable measurements of calibrated muscle backscatter from different ultrasound systems. ULTRASOUND IN MEDICINE & BIOLOGY 2012; 38:1618-1625. [PMID: 22763008 PMCID: PMC3632310 DOI: 10.1016/j.ultrasmedbio.2012.04.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 02/27/2012] [Accepted: 04/25/2012] [Indexed: 06/01/2023]
Abstract
Widespread implementation of quantitative muscle ultrasonography in assessing skeletal muscle pathology is limited by an inability to replicate results between different ultrasound systems. We have developed a measurement of skeletal muscle pathology, calibrated muscle backscatter (cMB), which should be reproducible between different ultrasound systems. We compared the reliability of grayscale and cMB measurements between different ultrasound systems, configurations and region-of-interest (ROI) sizes. cMB of skeletal muscle was reliably measured (intraclass correlation coefficient [ICC] ≤0.98) despite very dissimilar grayscale levels (ICC ≤0.54). cMB reliability was highest between systems using similar settings (ICC: 0.82-0.98) and was lowest when transducer type varied (ICC: 0.47-0.71). Reliability was better from ROIs spanning a narrow range of depths compared with larger ranges. cMB measurements are more reliable than grayscale between different ultrasound systems and configurations. Measuring cMB could improve widespread implementation of quantitative ultrasound in assessments of skeletal muscle pathology.
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Affiliation(s)
- Craig M Zaidman
- Department of Neurology, Neuromuscular Division, Washington University School of Medicine, St. Louis, MO, USA.
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Jiménez-Díaz F, Jimena I, Luque E, Mendizábal S, Bouffard A, Jiménez-Reina L, Peña J. Experimental muscle injury: correlation between ultrasound and histological findings. Muscle Nerve 2012; 45:705-12. [PMID: 22499098 DOI: 10.1002/mus.23243] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
INTRODUCTION In this study we correlated ultrasound findings with histological changes taking place during experimentally induced degeneration-regeneration in rat skeletal muscle. METHODS Gastrocnemius muscles were injected with mepivacaine, and the progress of the muscle injury was monitored by ultrasound from day 1 to day 20. Muscles were extracted on the same days for histological examination. RESULTS The degenerative phase was characterized by increased echogenicity in the injured area; thereafter, echogenicity gradually diminished during the regenerative phase, attaining normal levels by 20 days postinjection. By this stage, histological examination revealed that regeneration was complete. The heteroechoic texture observed from day 4 to day 10 appeared to reflect the coexistence of degenerative and regenerative processes. CONCLUSIONS The results suggest that the degenerative and regenerative phases of muscle injury may be distinguished sonographically through differences in echogenicity and echotexture and, using Doppler ultrasound, differences in the degree of vascularization.
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Affiliation(s)
- Fernando Jiménez-Díaz
- Laboratory of Performance and Sports Readaptation, Faculty of Sport Sciences, University of Castilla-La Mancha, Spain
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Skeletal muscle involvement in myotonic dystrophy type 2. A comparative muscle ultrasound study. Neuromuscul Disord 2012; 22:492-9. [DOI: 10.1016/j.nmd.2012.01.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2011] [Revised: 12/22/2011] [Accepted: 01/10/2012] [Indexed: 12/13/2022]
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Kornegay JN, Childers MK, Bogan DJ, Bogan JR, Nghiem P, Wang J, Fan Z, Howard JF, Schatzberg SJ, Dow JL, Grange RW, Styner MA, Hoffman EP, Wagner KR. The paradox of muscle hypertrophy in muscular dystrophy. Phys Med Rehabil Clin N Am 2012; 23:149-72, xii. [PMID: 22239881 DOI: 10.1016/j.pmr.2011.11.014] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Mutations in the dystrophin gene cause Duchenne and Becker muscular dystrophy in humans and syndromes in mice, dogs, and cats. Affected humans and dogs have progressive disease that leads primarily to muscle atrophy. Mdx mice progress through an initial phase of muscle hypertrophy followed by atrophy. Cats have persistent muscle hypertrophy. Hypertrophy in humans has been attributed to deposition of fat and connective tissue (pseudohypertrophy). Increased muscle mass (true hypertrophy) has been documented in animal models. Muscle hypertrophy can exaggerate postural instability and joint contractures. Deleterious consequences of muscle hypertrophy should be considered when developing treatments for muscular dystrophy.
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Affiliation(s)
- Joe N Kornegay
- Department of Pathology and Laboratory Medicine, School of Medicine, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA.
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Pereira AZ, Marchini JS, Carneiro G, Arasaki CH, Zanella MT. Lean and Fat Mass Loss in Obese Patients Before and After Roux-en-Y Gastric Bypass: A New Application for Ultrasound Technique. Obes Surg 2011; 22:597-601. [DOI: 10.1007/s11695-011-0538-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Fukumoto Y, Ikezoe T, Yamada Y, Tsukagoshi R, Nakamura M, Mori N, Kimura M, Ichihashi N. Skeletal muscle quality assessed from echo intensity is associated with muscle strength of middle-aged and elderly persons. Eur J Appl Physiol 2011; 112:1519-25. [DOI: 10.1007/s00421-011-2099-5] [Citation(s) in RCA: 298] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Accepted: 07/25/2011] [Indexed: 12/25/2022]
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Matthews E, Fialho D, Tan SV, Venance SL, Cannon SC, Sternberg D, Fontaine B, Amato AA, Barohn RJ, Griggs RC, Hanna MG. The non-dystrophic myotonias: molecular pathogenesis, diagnosis and treatment. ACTA ACUST UNITED AC 2009; 133:9-22. [PMID: 19917643 DOI: 10.1093/brain/awp294] [Citation(s) in RCA: 142] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The non-dystrophic myotonias are an important group of skeletal muscle channelopathies electrophysiologically characterized by altered membrane excitability. Many distinct clinical phenotypes are now recognized and range in severity from severe neonatal myotonia with respiratory compromise through to milder late-onset myotonic muscle stiffness. Specific genetic mutations in the major skeletal muscle voltage gated chloride channel gene and in the voltage gated sodium channel gene are causative in most patients. Recent work has allowed more precise correlations between the genotype and the electrophysiological and clinical phenotype. The majority of patients with myotonia have either a primary or secondary loss of membrane chloride conductance predicted to result in reduction of the resting membrane potential. Causative mutations in the sodium channel gene result in an abnormal gain of sodium channel function that may show marked temperature dependence. Despite significant advances in the clinical, genetic and molecular pathophysiological understanding of these disorders, which we review here, there are important unresolved issues we address: (i) recent work suggests that specialized clinical neurophysiology can identify channel specific patterns and aid genetic diagnosis in many cases however, it is not yet clear if such techniques can be refined to predict the causative gene in all cases or even predict the precise genotype; (ii) although clinical experience indicates these patients can have significant progressive morbidity, the detailed natural history and determinants of morbidity have not been specifically studied in a prospective fashion; (iii) some patients develop myopathy, but its frequency, severity and possible response to treatment remains undetermined, furthermore, the pathophysiogical link between ion channel dysfunction and muscle degeneration is unknown; (iv) there is currently insufficient clinical trial evidence to recommend a standard treatment. Limited data suggest that sodium channel blocking agents have some efficacy. However, establishing the effectiveness of a therapy requires completion of multi-centre randomized controlled trials employing accurate outcome measures including reliable quantitation of myotonia. More specific pharmacological approaches are required and could include those which might preferentially reduce persistent muscle sodium currents or enhance the conductance of mutant chloride channels. Alternative strategies may be directed at preventing premature mutant channel degradation or correcting the mis-targeting of the mutant channels.
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Affiliation(s)
- E Matthews
- MRC Centre for Neuromuscular Diseases, UCL, Institute of Neurology, Queen Square, London, WC1N 3BG, England
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