Rippling muscle disease (RMD) is caused by dominant mutations of the caveolin-3 gene (CAV3), and presents with overlapping limb-girdle muscle weakness, elevated creatine kinase (hyper- CKemia), RMD, and distal myopathy. We report a patient with a CAV3 mutation who presented with myalgia, exercise-induced muscle stiffness, hyperCKemia, and percussion-induced rapid muscle contraction and muscle mounding. A familial genetic study revealed the same mutation in two family members, with physical examinations showing that both of them had rippling muscles.
AGel amyloidosis is an autosomal dominantly inherited disease caused by a GSN mutation, and affected patients typically present with the clinical triad of corneal lattice dystrophy, progressive cranial neuropathy, and cutis laxa. We report a Korean family with AGel amyloidosis with predominant manifestations of facial and bulbar muscle weakness. Whole-exome sequencing revealed a common missense mutation (p.Asp214Tyr) in GSN. This case strongly suggests that AGel amyloidosis should be considered when a patient presents with progressive facial and bulbar palsies.
Muscle and nerve biopsy may be vital diagnostic tools in various neuromuscular disorders. Since these procedures are invasive, it matters to decide when to perform a biopsy, which muscle or nerve to be selected, and how to interpret the pathologies. This review addresses the indications, methods of biopsies, and also significant pathological findings frequently encountered in muscle and nerve pathology.
X-linked Charcot Marie Tooth disease type 1 (CMTX1) is a clinically heterogenous X-linked hereditary neuropathy caused by mutation of the gene encoding gap junction beta 1 protein (GJB1). Typical clinical manifestations of CMTX1 are progressive weakness or sensory disturbance due to peripheral neuropathy. However, there have been some CMTX1 cases with accompanying central nervous system (CNS) manifestations. We report the case of a genetically confirmed CMTX1 patient who presented recurrent transient CNS symptoms without any symptom or sign of peripheral nervous system involvement.
New therapeutics in neurology are expanding at an unprecedented pace. In addition to the classic enzyme-replacement therapies, monoclonal antibodies are increasingly being used to modulate autoimmunity. RNA therapeutics are an emerging class, together with gene and cell therapies. The nomenclature of international nonproprietary names helps us to recognize these new drugs according to their class and function. Suffixes denote major categories of the drug, while infixes provide additional information such as the source and target.
Muscle pathology findings may guide the diagnosis of neuromuscular disorders since they are helpful for understanding the pathological processes causing muscle weakness and also provide significant clues for the diagnosis of muscle diseases. Recent advances in molecular genetics mean that a muscle biopsy can be omitted when diagnosing inherited muscle diseases. However, the muscle pathology can still play a role in those cases and its findings are also required when diagnosing inflammatory myopathies.
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Sarcolemmal Excitability Properties of the Trapezius Mitchell J. Lycett, James Lee, Robert Boland‐Freitas, Karl Ng Muscle & Nerve.2025; 71(4): 600. CrossRef
Redox-active metals and oxidative stress–mediated myopathies in Callinectes amnicola, blue crab populations from impacted sites of the Lagos Lagoon: inferences for adverse ecological outcomes Azubuike Victor Chukwuka, Fisayo C. Jerome, Adesola Hassan, Benjamin Ebonwu, Aina O. Adeogun Environmental Science and Pollution Research.2023; 30(50): 108565. CrossRef
Focal eosinophilic myositis (FEM) is the most limited form of eosinophilic myositis that commonly affects the muscles of the lower leg without systemic manifestations. We report a patient with FEM who was studied by magnetic resonance imaging and muscle biopsy with a review of the literature.
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Origins and functions of eosinophils in two non-mucosal tissues Katie S. Day, Lucas Rempel, Fabio M. V. Rossi, Marine Theret Frontiers in Immunology.2024;[Epub] CrossRef
Acute sarcoid myositis is rarely complicated by sarcoidosis, and steroid therapy is considered the standard treatment. We experienced a patient with acute sarcoid myositis who did not respond to aggressive high-dose corticosteroid therapy, but showed a dramatic improvement after the addition of weekly low-dose oral methotrexate (MTX). This intervention allowed the resumption of normal daily activities after 6 months. Our case strongly suggests that MTX should be considered in patients with acute sarcoid myositis that is resistant to corticosteroid therapy.
Ullrich congenital muscular dystrophy (UCMD) is caused by mutations in one of three genes encoding collagen VI. Although UCMD usually shows an early onset, progressive weakness, contractures and hyperlaxity of the joints, and respiratory failure, it is well known to exhibit a wide spectrum of clinical severities. The severities of the phenotypic subtypes are mainly divided according to the ambulation status. We report a patient with the early-severe phenotype of UCMD who was diagnosed by the detection of novel recessive mutations in COL6A1.
In facioscapulohumeral muscular dystrophy (FSHD), prominent inflammatory cellular infiltrates mimicking inflammatory myopathies are often observed in muscle biopsies. We report extensive inflammatory changes in a 16-year-old girl who was genetically confirmed as to have FSHD. Immunohistochemical staining revealed that this could be clearly distinguished from inflammatory myopathies, both in terms of cell subsets and the expression of antigenic targets. Our observations strongly suggest that the inflammatory cellular infiltrates in FSHD differ from those observed in inflammatory myopathies.
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The DUX4 protein is a co‐repressor of the progesterone and glucocorticoid nuclear receptors Julieta Quintero, Nizar Y. Saad, Sabrina M. Pagnoni, Daniela K. Jacquelin, Laura V. Gatica, Scott Q. Harper, Alberto L. Rosa FEBS Letters.2022; 596(20): 2644. CrossRef
Interaction between mesenchymal stem cells and myoblasts in the context of facioscapulohumeral muscular dystrophy contributes to the disease phenotype Ekaterina Kiseleva, Olesya Serbina, Anna Karpukhina, Vincent Mouly, Yegor S. Vassetzky Journal of Cellular Physiology.2022; 237(8): 3328. CrossRef
Facioscapulohumeral muscular dystrophy: genetics, gene activation and downstream signalling with regard to recent therapeutic approaches: an update Teresa Schätzl, Lars Kaiser, Hans-Peter Deigner Orphanet Journal of Rare Diseases.2021;[Epub] CrossRef
Background Telbivudine is a nucleoside analogue used for the treatment of chronic hepatitis B, but it often develops mitochondrial toxicity leading to symptomatic myopathy. In this study, three patients with telbivudine induced myopathy were enrolled in order to investigate the nature and pathogenesis of mitochondrial toxicity caused by long-term use of telbivudine.
Methods Clinical features, laboratory findings, muscle pathology, and quantitation of mitochondrial DNA were studied in three patients.
Results Patients presented with progressive muscle weakness with high serum creatine kinase levels. Light microscopic findings of muscle pathology showed ragged red fibers that reacted strongly with succinate dehydrogenase stain, but negative for cytochrome c oxidase activities. Electron microscopy revealed abnormal mitochondrial accumulation with rod shaped inclusions. The quantitative peroxidase chain reaction showed a depletion of mitochondrial DNA in skeletal muscle of the patients.
Conclusions Nucleoside analogues including telbivudine are potent inhibitors of viral DNA polymerases. However, they are not specific for viral DNA and can disturb mitochondrial replication at the same time. All nucleotide analogues should be used with close clinical observation in order to avoid development of mitochondrial myopathy.
Some patients with leprosy may present with atypical features, such as isolated peripheral neuropathy without skin lesions, or marked proprioceptive dysfunction. We report a 56-year-old female who presented with predominant proprioceptive loss without skin lesion, but was finally confirmed as leprous neuropathy by sural nerve biopsy. It is postulated that large myelinated fibers were affected by chronic immunological reactions triggered by inactive bacterial particles, producing a peripheral neuropathy presenting as predominant proprioceptive sensory loss without typical skin lesions.
Statin is commonly used for lowering cholesterols and can be myotoxic to cause drug-induced necrotizing myopathy. Statininducedmyopathy ranges from asymptomatic hyperCKemia to lethal rhabdomyolysis but is usually reversed by withdrawalof causative drugs. The patient in this study presented with statin-induced necrotizing myopathy, which was finally improvedwith immunosuppressive therapy, but not just with drug withdrawal. Since statin can induce myopathy through autoimmuneprocesses, we should consider using immunomodulating agents in cases with statin-induced myopathy, which is refractoryto drug withdrawal.
Background ad Aims : Nerve conduction study is invaluable in clinical neurology, especially for assessing peripheral neuropathies. Abnormal nerve conduction studies may result not only from peripheral nerve dysfunction itself, but also from other various mechanical, technical, and physiological factors such as age, sex, height and temperature. So we conducted this study to establish the our own normal values. Methods : In this study, from March. 1997 to July. 1998, 40 Korean adults among person came to Health Promotion extremity and distal segments. Physiological factors such as age, height and temperature affect the results of nerve conduction studies in multiple regression analysis. The sex difference is recognized over peroneal motor nerve. There are no sex difference in amplitude transformed into normal distribution. The significant physiological factor affecting
The needle EMG study became a routine diagnostic work-up for various neuromuscular disorders including myopathies, neuromuscular junction disease, motor neuron diseases and other lower motor neuron disorders. The development of the computerized modern EMG machines also enabled accurate and detailed analysis of the motor unit physiology available in most of the electrophysiology laboratory. The main purpose of this article is to illustrate the technique and interpretation of the needle EMG finding. In the first part of the article, the basic anatomy and physiology of the motor unit, technique of the needle EMG examination and motor unit potential(MUP) analysis is reviewed. A MUP, which can be identified with conventional needle EMG study, is composed of action potentials of individual muscle fibers belonging to the same motor unit, and thus, its morphological changes reflect physiological and pathological alterations of the motor unit. In the second part of the article, single fiber electromyography (SFEMG) technique is briefly reviewed. As the action potentials of individual muscle fibers cannot be recorded with the conventional needle EMG technique, this technique requires specialized needle electrode and higher filter setting for the selective recording of the single fiber action potential(SFAP), and lower sweep velocity for the better separation of different SFAPs. Although SFEMG technique can be used for the estimation of the motor unit size and territory, it is practically most useful for the study of the neuromuscular transmission. In conclusion, the thorough understanding of the motor unit physiology and MUP electrophysiology is essential for the correct application and interpretation of the needle EMG.
In the normal neuromuscular junction, the nerve action potential(NAP) opens the P-type calcium channels, and resultant influx of calciumions produces the simultaneous exocytosis of
Limb-girdle muscular dystrophy (LGMD) is a heterogeneous group of inherited muscle disorders caused by the mutationsof different genes encoding muscle proteins. In the past, when the molecular diagnostic techniques were not available,the subtypes of muscular dystrophies were classified by the pattern of muscle weakness and the mode of inheritance,and LGMD had been considered as a
Background Acute brachial plexitis is an acute idiopathic inflammatory disease affecting brachial plexus, which is characterized by initial severe pain in shoulder followed by profound weakness of affected arm. This is a retrospective study to evaluate the clinical and electrophysiological profile of acute brachial plexitis. Methods: Sixteen patients with acute brachial plexitis were sampled. The electrodiagnostic studies included motor and sensory nerve conduction studies (NCSs) of the median and ulnar, sensory NCSs of medial and lateral antebrachial cutaneous nerves, and needle electromyography (EMG) of selected muscles of upper extremities and cervical paraspinal muscles. The studies were performed on both sides irrespective of the clinical involvement. Results: In most of our patient, upper trunk was predominantly affected (14 patients, 87.50%). Only two patients showed either predominant lower trunk affection or diffuse affection of brachial plexus. All had an acute pain followed by the development of muscle weakness of shoulder girdle after a variable interval (7
We report a patient with amyotrophic lateral sclerosis (ALS) who developed a pneumothorax after needle electromyography (EMG), probably of the intercostal muscles. Needle EMG on intercostal muscles has a high risk of pneumothorax, not only because electromyographers are unfamiliar to its technique, but also due to its close anatomical location to the pleural cavity. In our patient, advanced intercostal muscle atrophy due to disease process would have increased the risk further.
Miyoshi myopathy (MM) is caused by the mutations of dysferlin gene (DYSF), which impairs the function of dysferlin protein causing muscle membrane dysfunction. We report a patient showing the MM phenotype who has a sister with LGMD 2B phenotype, along with the results of the immunohistochemical and molecular analyses of the DYSF gene. Immunohistochemical analysis noted negative immunoreactivity against dysferlin. Direct DNA sequencing of whole exons of DYSF gene revealed heterozygous nonsense mutations (c.610C>T + c.2494C>T). To our knowledge, this is the first reported MM case with this very combination of heterozygous mutations.
Ullrich disease is a rare congenital muscular dystrophy, which is clinically characterized by generalized muscular weakness,distal joint hyperextensibility, proximal joint contractures, protuberant calcanei and high-arched palate. The disease is causedby collagen VI deficiency in interstitum and/or sarcolemma of skeletal muscles, for which mutations either in COL6A1,COL6A2 or COL6A3 are responsible. We report a girl who presented with symptoms typical of Ullrich disease, in whomthe diagnosis was confirmed by immunohistochemistry and molecular genetic study.
Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired immune-mediated polyneuropathy. Corticosteroids,intravenous immunoglobulin (IVIG) and plasmapheresis have been reported to be effective treatment. Rarely, CIDP can occurin the patients with HIV infection. The clinical features and electrophysiological findings of CIDP are known to be similarin patients with and without HIV infection. We report a 30-year-old male with HIV infection associated CIDP who improvedafter the administration of intravenous immunoglobulin and long term oral prednisone.
Dysferlinopthy refers to a group of autosomal recessive muscular dystrophy caused by mutations of dysferlin gene (DYSF). The DYSF is located on chromosome 2p13, contains 55 coding exons and spans 150 kb of genomic DNA. The transcript is 6.3 kb large and is mainly expressed in skeletal muscle at the sarcolemmal membrane. Dysferlin is a key calcium ion sensor involved in the Ca2+-triggered synaptic vesicle-plasma membrane fusion process, and plays a role in the sarcolemmal membrane repair mechanism of skeletal muscle fibers that permits rapid resealing of membrane disrupted by mechanical stress. Three main clinical subtypes of dysferlinopathy consist of Miyoshi myopathy (MM), limb-girdle muscular dystrophy type 2B (LGMD2B), and distal myopathy with onset in tibialsis anterior (DMAT). Regardless of their clinical phenotype, patients with dysferlinopathy share common features such as onset in late teens to early twenties, slow progression, extremely high serum CK levels, and loss of dysferlin on immunohistochemistry (IHC) and Western blot (WB). Muscle imaging is helpful for the evaluation of the degree of affection in different muscle groups and monitoring the progression of the disease. On muscle biopsy, it is frequently associated with inflammatory cellular infiltrates, and should be differentiated from polymyositis in order to avoid unnecessary treatment. IHC or WB is the golden standard for the diagnosis of dysferlinopathy. Although DNA test for the identification of DYSF mutations can further help to confirm the disease, high risk of diagnostic errors related to the large gene size can limit its usefulness as a reliable diagnostic test.
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