Nesprin proteins: bridging nuclear envelope dynamics to muscular dysfunction

This review presents a comprehensive exploration of the pivotal role played by the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex, with a particular focus on Nesprin proteins, in cellular mechanics and the pathogenesis of muscular diseases. Distinguishing itself from prior works, the analysis delves deeply into the intricate interplay of the LINC complex, emphasizing its indispensable contribution to maintaining cellular structural integrity, especially in mechanically sensitive tissues such as cardiac and striated muscles. Additionally, the significant association between mutations in Nesprin proteins and the onset of Dilated Cardiomyopathy (DCM) and Emery-Dreifuss Muscular Dystrophy (EDMD) is highlighted, underscoring their pivotal role in disease pathogenesis. Through a comprehensive examination of DCM and EDMD cases, the review elucidates the disruptions in the LINC complex, nuclear morphology alterations, and muscular developmental disorders, thus emphasizing the essential function of an intact LINC complex in preserving muscle physiological functions. Moreover, the review provides novel insights into the implications of Nesprin mutations for cellular dynamics in the pathogenesis of muscular diseases, particularly in maintaining cardiac structural and functional integrity. Furthermore, advanced therapeutic strategies, including rectifying Nesprin gene mutations, controlling Nesprin protein expression, enhancing LINC complex functionality, and augmenting cardiac muscle cell function are proposed. By shedding light on the intricate molecular mechanisms underlying nuclear-cytoskeletal interactions, the review lays the groundwork for future research and therapeutic interventions aimed at addressing genetic muscle disorders.

A retrospective study of accuracy and usefulness of electrophysiological exercise tests

OBJECTIVES

This study aimed to determine the usefulness of electrophysiological exercise tests. The significance of slightly abnormal exercise tests was also examined.

METHODS

We identified all the patients who had undergone exercise testing between February 2007 to June 2022 in Tampere University Hospital, Finland. Their medical records after diagnostic workup and exercise test reports were reviewed. A binary logistic regression was performed to evaluate the association between positive test result in short exercise test, long exercise test, or short exercise test with cooling and genetically confirmed skeletal muscle channelopathy or myotonic disorder.

RESULTS

We identified 256 patients. 27 patients were diagnosed with nondystrophic myotonia, periodic paralysis, myotonic dystrophy type 1, myotonic dystrophy type 2, or other specified myopathy. 14 patients were suspected to have a skeletal muscle channelopathy, but pathogenic variants could not be identified. The remaining 215 patients were diagnosed with other conditions than skeletal muscle channelopathy or myotonic disorder. The combined sensitivity of exercise tests was 59.3% and specificity 99.1%. Abnormal exercise test result was associated with increased risk of skeletal muscle channelopathy or myotonic disorder (OR 164.3, 95% CI 28.3-954.6, p < 0.001).

CONCLUSIONS

Electrophysiological exercise test is not optimal to exclude skeletal muscle channelopathy. It may be useful if a skeletal muscle channelopathy is suspected and genetic testing is negative or indeterminate and further evidence is required. Slightly abnormal exercise test results are possible in various conditions and result from different aetiologies. There is a demand for neurophysiological studies with higher sensitivity to detect skeletal muscle channelopathies.

Magnetic resonance imaging scoring system of the lower limbs in adult patients with suspected idiopathic inflammatory myopathy

PURPOSE

We aim to propose a visual quantitative score for muscle edema in lower limb MRI to contribute to the diagnosis of idiopathic inflammatory myopathy (IIM).

MATERIAL AND METHODS

We retrospectively evaluated 85 consecutive patients (mean age 57.4 ± 13.9 years; 56.5% female) with suspected IIM (muscle weakness and/or persistent hyper-CPK-emia with/without myalgia) who underwent MRI of lower limbs using T2-weighted fast recovery-fast spin echo images and fat-sat T2 echo planar images. Muscle inflammation was evaluated bilaterally in 11 muscles of the thigh and eight muscles of the leg. Edema in each muscle was graded according to a four-point Likert-type scale adding up to 114 points ([11 + 8)] × 3 × 2). Diagnostic accuracy of the total edema score was explored by assessing sensitivity and specificity using the area under the ROC curve. Final diagnoses were made by a multidisciplinary Expert Consensus Panel applying the Bohan and Peter diagnostic criteria whenever possible.

RESULTS

Of the 85 included patients, 34 (40%) received a final diagnosis of IIM (IIM group) while 51 (60%) received an alternative diagnosis (non-IIM group). A cutoff score ≥ 18 was able to correctly classify patients having an IIM with an area under the curve of 0.85, specificity of 96%, and sensitivity of 52.9%.

CONCLUSION

Our study demonstrates that a quantitative MRI score for muscle edema in the lower limbs (thighs and legs) aids in distinguishing IIM from conditions that mimic it.

Monensin poisoning outbreak in free-ranging and captive birds

Monensin poisoning is uncommon and has been rarely reported in birds. This work aimed to described clinical-pathological aspects of an outbreak of monensin poisoning in captive and free-ranging birds. Thirty-seven of 600 captive birds fed a diet containing 893.19 mg/kg of monensin died within 10 days (mortality 6.17%). There was no ionophore antibiotics on the feed label supplied to captive birds, which established an error in feed production. Necropsies were performed on twelve animals: Muscovy duck (Cairina moschata) (2/12), greater rhea (Rhea americana) (2/12), black-necked swan (Cygnus melancoryphus) (2/12), garganey (Anas querquedula) (1/12), ostrich (Struthio camelus) (1/12), and common pigeon (Columbus livia) (4/12). These four common pigeons were free-ranging birds and died after eating the same contaminated feed. Birds were mainly found dead, however in animals which clinical signs were observed (Columba livia, Rhea americana, Cairina moschata, Anas querquedula, and Struthio camelus), they included incoordination, inability to stand, and intense prostration, that ranged from 24 to 72 h until death. Grossly, five birds had focally extensive pale firm areas in the myocardium and two had in the skeletal muscles, one being concomitant lesions. Histologically, muscle necrosis and degeneration were observed in striated musculature (skeletal and/or heart) in all birds analyzed. Monensin poisoning outbreaks can affect free-ranging birds that are fed on external feeders, as well as captive birds, due to an error in the feed formulation.

Intravesical bacillus Calmette-Guérin-induced myopathy presenting as rhabdomyolysis: a case report

Intravesical bacillus Calmette-Guérin (BCG) instillation is an adjuvant treatment for non-muscle-invasive urinary bladder cancer. Although most complications associated with BCG immunotherapy are mild and self-limiting, rare albeit serious complications have been reported. Only a few cases of BCG-related rhabdomyolysis have been reported. In this study, we present the case of a 72-year-old woman who developed severe weakness and hyperCKemia following intravesical BCG instillation. A muscle biopsy was performed, and a diagnosis of drug-induced myopathy was made.

[Statin intolerance-Statin tolerance]

BACKGROUND

Statins are the first-line treatment for reducing low-density lipoprotein (LDL) cholesterol levels, because the evidence regarding safety, tolerability, and reduction of cardiovascular morbidity and mortality is very good. For combination treatment several options are available. Nevertheless, LDL cholesterol values are often not sufficiently lowered. One reason is intolerance of the lipid-lowering medications.

OBJECTIVE

In addition to the study situation regarding statin tolerability, possible approaches to overcome intolerability are also shown.

RESULTS

In randomized trials adverse effects due to statin treatment are as rare as in the placebo groups. In clinical practice patients more frequently report complaints, particularly muscular symptoms. One important reason for intolerability is the nocebo effect. Complaints during treatment can lead to the fact that statins are not taken or are taken in insufficient doses. As a result, the LDL cholesterol level is insufficiently lowered with unfavorable effects on the incidence of cardiovascular events. Therefore, it is important to establish a tolerable treatment together with the patient on an individual basis. Information about the facts is one important aspect. In addition, a positively guided communication with the patient helps to reduce the nocebo effect.

CONCLUSION

Most adverse effects that patients attribute to statins are not caused by statins. This shows that other reasons are frequent and should be the focus of medical care. In this article international recommendations and personal experiences of a specialized lipid outpatient clinic are described.

SELENON-Related Myopathy Across the Life Span, a Cross-Sectional Study for Preparing Trial Readiness

BACKGROUND

SELENON(SEPN1)-related myopathy (SELENON-RM) is a rare congenital neuromuscular disease characterized by proximal and axial muscle weakness, spinal rigidity, scoliosis and respiratory impairment. No curative treatment options exist, but promising preclinical studies are ongoing. Currently, natural history data are lacking, while selection of appropriate clinical and functional outcome measures is needed to reach trial readiness.

OBJECTIVE

We aim to identify all Dutch and Dutch-speaking Belgian SELENON-RM patients, deep clinical phenotyping, trial readiness and optimization of clinical care.

METHODS

This cross-sectional, single-center, observational study comprised neurological examination, functional measurements including Motor Function Measurement 20/32 (MFM-20/32) and accelerometry, questionnaires, muscle ultrasound, respiratory function tests, electro- and echocardiography, and dual-energy X-ray absorptiometry.

RESULTS

Eleven patients with genetically confirmed SELENON-RM were included (20±13 (3-42) years, 73% male). Axial and proximal muscle weakness were most pronounced. The mean MFM-20/32 score was 71.2±15.1%, with domain 1 (standing and transfers) being most severely affected. Accelerometry showed a strong correlation with MFM-20/32. Questionnaires revealed impaired quality of life, pain and problematic fatigue. Muscle ultrasound showed symmetrically increased echogenicity in all muscles. Respiratory function, and particularly diaphragm function, was impaired in all patients, irrespective of the age. Cardiac assessment showed normal left ventricular systolic function in all patients but abnormal left ventricular global longitudinal strain in 43% of patients and QRS fragmentation in 80%. Further, 80% of patients showed decreased bone mineral density on dual-energy X-ray absorptiometry scan and 55% of patients retrospectively experienced fragility long bone fractures.

CONCLUSIONS

We recommend cardiorespiratory follow-up as a part of routine clinical care in all patients. Furthermore, we advise vitamin D supplementation and optimization of calcium intake to improve bone quality. We recommend management interventions to reduce pain and fatigue. For future clinical trials, we propose MFM-20/32, accelerometry and muscle ultrasound to capture disease severity and possibly disease progression.

Proximal myopathy: causes and associated conditions

Proximal myopathy presents as generalized muscle weakness commonly involving the muscles of upper and/or lower limbs. Toxins, long-term use of statins, corticosteroids, alcohol, SGLT2 inhibitors, COVID-19 vaccination, and antimalarials have been attributed to its development. In endocrine and metabolic disorders, adrenal dysfunction including both overproduction and insufficiency of the adrenal gland hormones has been reported to cause myopathy. Moreover, parathyroid and thyroid disorders along with pituitary gland disorders can also directly or indirectly contribute to this condition. In idiopathic inflammatory myopathies including polymyositis, dermatomyositis, inclusion body myositis (IBM), and Systemic Lupus Erythematosus (SLE), Sjögren's Syndrome, and overlap syndromes, moderate to severe muscle weakness has been observed. IBM has been reported to be the most prevalent acquired myopathy above the age of 50. Hereditary or congenital myopathies include limb girdle muscular dystrophies, facioscapulohumeral muscular dystrophy, Duchenne and Becker muscular dystrophy, and proximal myotonic myopathy. In addition to these, glycogen storage diseases such as the McArdle disease can also cause fast exhaustion, myalgia, and cramping in working muscles. It is pertinent to mention here that a class of hereditary metabolic myopathies, referred to as "lipid deposition myopathy" causes lipids to accumulate in skeletal muscle fibers, leading to lesions and degeneration. Among viral causes, HIV, dengue virus, influenza virus, hepatitis B virus, hepatitis C virus, SARS-CoV2 are also associated with muscle weakness. Sarcoidosis, an inflammatory disease, can also manifest as muscle weakness and myalgia. Owing to this complicated pathophysiology of proximal myopathy, this review aims to summarize the existing literature on conditions associated with this phenomenon and other recent developments that have been made regarding events leading to development of generalized muscle weakness. To the authors' knowledge this is the first narrative review that discusses causes and conditions associated with proximal myopathy in thorough detail.

The clinical use of impulse oscillometry in neuromuscular diseases

BACKGROUND

The patients with neuromuscular diseases (NMD) are very fragile and it is hard to evaluate respiratory involvement of the primary disease in this group. Therefore, our study aimed to reveal the relationship between pulmonary function tests (PFT) and impulse oscillometry (IOS) and their correlation with respiratory clinical findings in NMD.

MATERIAL AND METHODS

A total of 86 consecutive patients with NMD were included. The clinical findings of respiratory involvement, PFT, and IOS results of the patients were analyzed.

RESULTS

Forty patients out of 86 were female. There were 29 patients with amyotrophic lateral sclerosis, four patients with myasthenia gravis, and 53 patients with muscular dystrophies/myopathies. According to the PFT results, 47 patients had restrictive PFT. However, there was no difference in IOS parameters when we compared the patients according to restrictions in PFT. A positive correlation was found with FVC %pred and X₅. PEF %pred values were positively correlated with X₁₀, X₁₅, and X₂₀, and negatively correlated with A_X and R_5-20. The patients with worse swallowing capability had increased R_rs levels, and more negative X_rs levels. The shortness of breath led to lower FEV₁ %pred., higher R₅, A_X and R_5-20, and also more negative X₁₀, X₁₅, and X₃₅.

CONCLUSION

Clinically reported dysphagia, a decreased capability of coughing, and shortness of breath in patients with NMD make R_rs increase in general, but X_rs parameters, which mainly express rib cage elasticity, turn more negative. In patients with NMD, IOS monitoring may help in evaluating the regression in respiratory functions, however, future studies are needed to understand more.

A New Perspective on the Quality of Life of Children with Glycogen Storage Diseases

PURPOSE

This study aimed to assess the quality of life (QoL) of children with glycogen storage disease (GSD) and their parents and to determine the impact of myopathies.

METHODS

A prospective case-control study was conducted at the Cairo University Children's Hospital and National Liver Institute, Menoufia University. A promising new style of questionnaire called the Stark Quality of Life Questionnaire was used to assess the quality of life.

RESULTS

Fifty-two children diagnosed with GSD (cases) and 55 age- and sex-matched healthy children (controls) were included. A statistically significant difference was found between cases and controls regarding food intake; mental behavior parameters such as mood, energy, and social contact; and physical behavior parameters such as running and tying shoelaces. Children with myopathies had significantly lower QoL scores in most of the parameters.

CONCLUSION

GSDs alter children and their parents' mental and physical abilities. Lower QoL scores were detected in children with both skeletal myopathy and cardiomyopathy, but the difference was not statistically significant when compared with the children without myopathies.

Role of ultrasound and magnetic resonance imaging in the prognosis and classification of muscle injuries in professional football players: correlation between imaging and return to sport time

Purpose

To study distractive muscle injuries applying US and MRI specific classifications and to find if any correlation exists between the results and the return to sport (RTS) time. The second purpose is to evaluate which classification has the best prognostic value and if the lesions extension correlates with the RTS time.

Methods

A total of 26 male, professional soccer players (age 21.3 ± 5.6), diagnosed with traumatic muscle injury of the lower limbs, received ultrasound and MRI evaluation within 2 days from the trauma. Concordance between US and MRI findings was investigated. The relationships between MRI and US based injury grading scales and RTS time were evaluated. Correlation between injuries’ longitudinal extension and RTS time was also investigated.

Results

The correlation between US and MRI measurements returned a Spearman value of r_s = 0.61 (p = .001). Peetrons and Mueller-Wohlfahrt grading scales correlations with RTS time were r = 0.43 (p = .02) and r = 0.83 (p =  < .001). The lesion’s extension correlation with RTS time was r = 0.63 (p < .001). The correlation between the site of the lesion and its location with the RTS time were r_s = 0.2 and r_s = 0.25.

Conclusions

Both US and MRI can be used as prognostic indicators along with the Peetrons (US) and the Mueller-Wohlfahrt (MRI) classifications. MRI is more precise and generates more reproducible results. The lesion craniocaudal extension must be considered as a prognostic indicator, while the injury location inside the muscle or along its major axis has doubtful significance.

Dact1 is expressed during chicken and mouse skeletal myogenesis and modulated in human muscle diseases

Vertebrate skeletal muscle development and repair relies on the precise control of Wnt signaling. Dact1 (Dapper/Frodo) is an important modulator of Wnt signaling, interacting with key components of the various Wnt transduction pathways. Here, we characterized Dact1 mRNA and protein expression in chicken and mouse fetal muscles in vivo and during the differentiation of chick primary and mouse C2C12 myoblasts in vitro. We also performed in silico analysis to investigate Dact1 gene expression in human myopathies, and evaluated the Dact1 protein structure to seek an explanation for the accumulation of Dact1 protein aggregates in the nuclei of myogenic cells. Our results show for the first time that in both chicken and mouse, Dact1 is expressed during myogenesis, with a strong upregulation as cells engage in terminal differentiation, cell cycle withdrawal and cell fusion. In humans, Dact1 expression was found to be altered in specific muscle pathologies, including muscular dystrophies. Our bioinformatic analyses of Dact1 proteins revealed long intrinsically disordered regions, which may underpin the ability of Dact1 to interact with its many partners in the various Wnt pathways. In addition, we found that Dact1 has strong propensity for liquid-liquid phase separation, a feature that explains its ability to form nuclear aggregates and points to a possible role as a molecular 'on'-'off' switch. Taken together, our data suggest Dact1 as a candidate, multi-faceted regulator of amniote myogenesis with a possible pathophysiological role in human muscular diseases.

MR imaging of inherited myopathies: a review and proposal of imaging algorithms

PURPOSE OF REVIEW

The aims of this review are to discuss the imaging modalities used to assess muscle changes in myopathies, to provide an overview of the inherited myopathies focusing on their patterns of muscle involvement in magnetic resonance imaging (MR), and to propose up-to-date imaging-based diagnostic algorithms that can help in the diagnostic workup.

CONCLUSION

Familiarization with the most common and specific patterns of muscular involvement in inherited myopathies is very important for radiologists and neurologists, as imaging plays a significant role in diagnosis and follow-up of these patients.

KEY POINTS

• Imaging is an increasingly important tool for diagnosis and follow-up in the setting of inherited myopathies. • Knowledge of the most common imaging patterns of muscle involvement in inherited myopathies is valuable for both radiologists and neurologists. • In this review, we present imaging-based algorithms that can help in the diagnostic workup of myopathies.

Texture analysis using T1-weighted images for muscles in Charcot-Marie-Tooth disease patients and volunteers

OBJECTIVES

To explore whether texture features using T1-weighted images correlate with fat fraction, and whether they differ between Charcot-Marie-Tooth (CMT) disease patients and volunteers.

METHODS

The institutional review board approved this retrospective study, and the requirement for informed consent was waived; data of eighteen CMT patients and eighteen healthy volunteers from a previous study was used. Texture features of the muscles including mean, standard deviation (SD), skewness, kurtosis, and entropy of the signal intensity were derived from T1-weighted images. Spearman's correlation analysis was used to assess the relationship between texture features and fat fraction measured by 3D multiple gradient echo Dixon-based sequence. Mann-Whitney U test was used to compare the texture features between CMT patients and volunteers. Intraobserver and interobserver agreements for the texture features were assessed using the intraclass correlation coefficient.

RESULTS

The SD (ρ = 0.256, p < 0.001) and entropy (ρ = 0.263, p < 0.001) were significantly and positively correlated with fat fraction; skewness (ρ = - 0.110, p = 0.027) and kurtosis (ρ = - 0.149, p = 0.003) were significantly and inversely correlated with fat fraction. The CMT patients showed a significantly higher SD (63.45 vs. 49.26; p < 0.001), skewness (1.06 vs. 0.56; p < 0.001), kurtosis (4.00 vs. 1.81; p < 0.001), and entropy (3.20 vs. 3.02; p < 0.001) than did the volunteers. Intraobserver and interobserver agreements were almost perfect for mean, SD, and entropy.

CONCLUSIONS

Texture features using T1-weighted images correlated with fat fraction and differed between CMT patients and volunteers.

KEY POINTS

• Standard deviation and entropy of muscles derived from T1-weighted images were significantly and positively correlated with the muscle fat fraction. • Mean, standard deviation, and entropy were considered highly reliable in muscle analyses. • Texture features may have the potential to diagnose early stage of intramuscular fatty infiltration.

Bilateral swelling of the forearms revealing muscular sarcoidosis: a case-based review

Muscular sarcoidosis is rarely symptomatic and mainly affects proximal muscles of the lower extremities. However, the distal localization in the upper extremities is rare. We used systematic approach to analyze all relevant literature review and we identified only three cases of muscular sarcoidosis of the upper extremities. We report the case of a 56-year-old woman who presented distal and bilateral swelling of the extensor surface of the forearms revealing muscular sarcoidosis. The laboratory exams associated elevated acute phase reactants with elevated serum angiotensin-converting enzyme levels and normal serum muscle enzymes. Ultrasound and MRI showed a bilateral and symmetrical muscle hypertrophy of the extensors of the fingers. Histological examination of muscle specimen and minor salivary gland biopsy revealed noncaseating epithelioid-cell granulomas. Therefore, the diagnosis of muscular sarcoidosis of the finger extensor muscles was made. Swelling of the forearms disappeared gradually under prednisolone 1 mg/kg/day. We used methotrexate as a steroid-sparing agent. Muscular MRI in sarcoidosis is not specific, but is to make a diagnosis of the lesion to optimize the biopsy which the cornerstone of the diagnosis ofsarcoidosis.

Modelling the skeletal muscle injury recovery using in vivo contrast-enhanced micro-CT: a proof-of-concept study in a rat model

Background

Skeletal muscle injury characterisation during healing supports trauma prognosis. Given the potential interest of computed tomography (CT) in muscle diseases and lack of in vivo CT methodology to image skeletal muscle wound healing, we tracked skeletal muscle injury recovery using in vivo micro-CT in a rat model to obtain a predictive model.

Methods

Skeletal muscle injury was performed in 23 rats. Twenty animals were sorted into five groups to image lesion recovery at 2, 4, 7, 10, or 14 days after injury using contrast-enhanced micro-CT. Injury volumes were quantified using a semiautomatic image processing, and these values were used to build a prediction model. The remaining 3 rats were imaged at all monitoring time points as validation. Predictions were compared with Bland-Altman analysis.

Results

Optimal contrast agent dose was found to be 20 mL/kg injected at 400 μL/min. Injury volumes showed a decreasing tendency from day 0 (32.3 ± 12.0mm³, mean ± standard deviation) to day 2, 4, 7, 10, and 14 after injury (19.6 ± 12.6, 11.0 ± 6.7, 8.2 ± 7.7, 5.7 ± 3.9, and 4.5 ± 4.8 mm³, respectively). Groups with single monitoring time point did not yield significant differences with the validation group lesions. Further exponential model training with single follow-up data (R² = 0.968) to predict injury recovery in the validation cohort gave a predictions root mean squared error of 6.8 ± 5.4 mm³. Further prediction analysis yielded a bias of 2.327.

Conclusion

Contrast-enhanced CT allowed in vivo tracking of skeletal muscle injury recovery in rat.

Exercise as a treatment for sarcopenia: an umbrella review of systematic review evidence

BACKGROUND

Sarcopenia is a progressive and generalised skeletal muscle disorder, and a powerful predictor of adverse health outcomes. Exercise is a widely recommended treatment but consensus about the best approach is lacking.

OBJECTIVE

To synthesise current systematic review evidence on the effectiveness of exercise in the treatment of sarcopenia to inform clinical practice.

DATA SOURCES

Five electronic databases were searched (15 November 2018): Cochrane Database of Systematic Reviews; MEDLINE without revisions; EMBASE; Scopus; and Web of Science.

STUDY SELECTION OR ELIGIBILITY CRITERIA

Systematic reviews and meta-analyses of randomised controlled trials evaluating exercise to treat sarcopenia in adults including sarcopenic outcomes.

STUDY APPRAISAL AND SYNTHESIS METHODS

Review data were extracted and quality assessed (using the AMSTAR 2) by two independent assessors. Due to a lack of eligible reviews, a narrative synthesis of the evidence was performed.

RESULTS

Two reviews were identified which included seven studies with 619 participants. Study exercise interventions included: resistance; mixed and whole body vibration training programmes. Review findings demonstrate limited low quality evidence of positive effects of mixed and resistance training in treating sarcopenia.

LIMITATIONS

Limited eligible reviews restricted synthesis and interpretation of findings.

CONCLUSION AND IMPLICATIONS OF KEY FINDINGS

There is a lack of high quality research with which to inform the treatment of sarcopenia with exercise. Further research using more precision when selecting sarcopenic populations and outcomes is required in this field. This will enable the identification of effective ways of treating sarcopenia with exercise before evidence-based clinical guidelines can be established.

A novel missense mutation in CAV3 gene in an Italian family with persistent hyperCKemia, myalgia and hypercholesterolemia: Double-trouble

Caveolins are essential proteins in caveolae architecture, small plasma membrane invaginations that play a key role in a variety of cellular processes, including vesicular trafficking and signal transduction. Mutations in the gene encoding caveolin-3 (CAV3) cause a broad spectrum of clinical phenotypes, ranging from isolated hyperCKemia to most severe limb girdle muscular dystrophy and cardiomyopathy. We report a novel heterozygous p.Val44Met (c.130G > A) CAV3 mutation in two brothers presenting with persistent elevation of serum creatine kinase, myalgia and hypercholesterolemia. Immunofluorescence study with anticaveolin-3 antibodies on muscle biopsy of the proband confirmed a reduced immuno-reactivity of caveolin-3 on the sarcolemma. This findings support the pathogenic effect of this novel mutation and extend the genotypic and clinical spectrum of Caveolinopathies. Finally, we discuss the hypothesis that the association between CAV3 mutations and hypercholesterolemia may not be coincidental.

Distinguishing bone and soft tissue infections mimicking sarcomas requires multimodal multidisciplinary team assessment

INTRODUCTION

The aims of this study were to report the presenting characteristics and identify how best to distinguish bone and soft-tissue infections that mimic sarcomas.

MATERIALS AND METHODS

A total of 238 (211 osteomyelitis and 27 soft-tissue infections) patients referred to a tertiary sarcoma multidisciplinary team with suspected sarcoma who were ultimately diagnosed with a bone or soft tissue infection were included. Data from a prospectively collated database was analysed retrospectively.

RESULTS

Of all possible bone and soft-tissue sarcoma referrals, a diagnosis of infection was made in 2.1% and 0.7%, respectively. Median age was 18 years in the osteomyelitis group and 46 years in the soft-tissue infection group. In the osteomyelitis group, the most common presenting features were pain (85.8%) and swelling (32.7%). In the soft-tissue infection group, the most common clinical features were swelling (96.3%) and pain (70.4%). Those in the soft-tissue group were more likely to have raised inflammatory markers. Radiological investigations were unable to discern between tumour or infection in 59.7% of osteomyelitis and 81.5% of soft-tissue infection cases. No organism was identified in 64.9% of those who had a percutaneous biopsy culture.

CONCLUSIONS

This study has highlighted that infection is frequently clinically indistinguishable from sarcoma and remains a principle non-neoplastic differential diagnosis. When patients are investigated for suspected sarcoma, infections can be missed due to falsely negative radiological investigations and percutaneous biopsy. As no single clinical, biochemical or radiological feature or investigation can be relied upon for diagnosis, clinicians should have a low threshold for tissue biopsy and discussion in a sarcoma multidisciplinary team meeting.

[Neurogenic myopathies and imaging of muscle denervation]

CLINICAL ISSUE

Neurogenic myopathies are primary diseases of the nervous system, which secondarily result in denervation of the target musculature. The spectrum of potential causes is manifold ranging from acute traumatic injuries and chronic compression to neurodegenerative, inflammatory, metabolic and neoplastic processes.

STANDARD DIAGNOSTIC METHODS

The medical history, clinical neurological examination, and electrophysiological tests including electromyography and nerve conduction studies are crucial in diagnosing neuropathic myopathies. Electromyography is the gold standard for diagnosing muscle denervation.

METHODICAL INNOVATIONS

Additional imaging methods and magnetic resonance imaging (MRI) in particular, are capable of contributing valuable information. The MRI examination of denervated musculature shows edema, an increase in the apparent diffusion coefficient (ADC) and hyperperfusion. Chronic denervation results in fatty degeneration and atrophy of affected muscles, which are also detectable by MRI.

PERFORMANCE

Although the MRI findings in muscle denervation are relatively unspecific, they show a high sensitivity, comparable to electromyography. Dedicated MR neurography may often visualize the underlying lesion(s) of the innervating nerve(s).

ACHIEVEMENTS

Besides high sensitivity, comparable to electromyography, MRI is capable of evaluating muscles which are inaccessible for needle electromyography. Due to its non-invasive character, MRI is ideal for follow-up examinations.

PRACTICAL RECOMMENDATIONS

The use of MRI is often a meaningful addition to the diagnostics of neurogenic myopathies. The extent and distribution pattern of muscular alterations often provide information on the localization of the causative nerve damage. A correct diagnosis or at least a narrowing down of possible differential diagnoses can often be achieved using MRI.

[Skeletal muscle MRI of lower limbs in patients with facioscapulohumeral dystrophy]

Objective: To investigate MRI features of lower limbs in patients with facioscapulohumeral dystrophy(FSHD). Methods: The clinical manifestations, myopathological findings and MRI images of 5 FSHD patients were studied retrospectively from June 2016 to December 2017 at Department of Neurology, Henan Provincial People's Hospital, 3 of which had a family history. Analysis of T(1)WI images enabled us to describe muscle fatty infiltration and STIR images to describe muscle edema. Each muscle was scored according to its fatty degeneration (fat replacement score range from 0-4). Results: The 5 patients were all asymmetrically involved. At the thigh level, the hamstrings were more affected than anterior muscles in 4 patients, and anterior muscles were more affected than hamstrings in only 1 patient. The most affected thigh muscles were usually the adductor magnus, semimembranosus, semitendinosus, femoral biceps long head and vastus medialis muscles (average fat replacement score of each muscle was more than 3). The calves were less affected than thighs.The average fat replacement score of the calf muscles was 1.0 for soleus, 0.9 for medial gastrocnemius, 0.8 for tibialis anterior, and 0.4 for lateral gastrocnemius. There was no fatty infiltration in peroneus and tibialis posterior. 4 out of 5 patients had edema in the lower limb muscles. Conclusion: Asymmetric involvement is a definitely helpful clue suggesting FSHD, and edema is a common phenomenon. At the thigh level, no unique imaging pattern can be highlighted in all the FSHD patients, overall, the hamstring, adductor magnus and vastus medialis are usually the most severely affected muscles. The calf muscles are less affected than the thigh muscles or spared. Soleus, medial gastrocnemius, and tibialis anterior are preferentially involved at the calf level.

Musculoskeletal "don't touch" lesions: pictorial essay

Focal bone lesions are not uncommon findings in the daily practice of radiology. Therefore, it is essential to differentiate between lesions with aggressive, malignant potential that require action and those that have no clinical significance, many of which are variants or benign lesions, sometimes self-limited and related to reactive processes. In some cases, a diagnostic error can have catastrophic results. For example, a biopsy performed in a patient with myositis ossificans can lead to an incorrect diagnosis of sarcomatous lesions and consequently to mutilating surgical procedures. The present study reviews the main radiological aspects of the lesions that are most commonly seen in daily practice and have the potential to be confused with aggressive, malignant bone processes. We also illustrate these entities by presenting cases seen at our institution.

What is the diagnostic accuracy of single nerve conduction studies and muscle ultrasound to identify critical illness polyneuromyopathy: a prospective cohort study

Background

Critical illness polyneuromyopathy (CIPNM) is a major cause of weakness in intensive care unit (ICU) patients, but current diagnostic tests are limited. We evaluated the generalizability and validity of single nerve conduction studies (NCS) and muscle ultrasound testing to identify CIPNM, and we also assessed the ability of muscle ultrasound to prognosticate patient outcomes.

Methods

This was a prospective cohort study of mechanically ventilated medical, cardiac, surgical, and neurosurgical ICU patients. We performed weekly strength testing, NCS, electromyography (EMG), and muscle ultrasound. We calculated the sensitivity, specificity, and other test characteristics of single NCS and muscle ultrasound, and we used multivariable regression models to assess the prognostic ability of muscle ultrasound.

Results

Ninety-five patients were enrolled. The incidence of probable CIPNM was 18% and did not differ significantly by type of ICU (p = 0.49). For diagnosing probable CIPNM, the peroneal motor NCS had a sensitivity of 94% (95% confidence interval (CI) 71–100%) and specificity of 91% (95% CI 82–96%), the sural sensory NCS had a sensitivity of 100% (95% CI 80–100%) and specificity of 42% (95% CI 31–54%), and abnormal muscle ultrasound echogenicity had a sensitivity of 82% (95% CI 48–98%) and specificity of 57% (95% CI 43–70%). Abnormal echogenicity was associated with reduced likelihood of discharge to home (9% vs 50%, p = 0.0001), fewer ICU-free days (median 3 (interquartile range 0–15) days vs 16 (9.3–19.3) days, p = 0.0002), and increased ICU mortality (42% vs 12%, p = 0.004).

Conclusions

In a diverse cohort of critically ill patients, single NCS and muscle ultrasound achieved diagnostic accuracy for patients at risk for CIPNM. The routine utilization of these tests could be beneficial for all critically ill patients at risk for CIPNM.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2281-9) contains supplementary material, which is available to authorized users.

Muscular MRI-based algorithm to differentiate inherited myopathies presenting with spinal rigidity

OBJECTIVES

Inherited myopathies are major causes of muscle atrophy and are often characterized by rigid spine syndrome, a clinical feature designating patients with early spinal contractures. We aim to present a decision algorithm based on muscular whole body magnetic resonance imaging (mWB-MRI) as a unique tool to orientate the diagnosis of each inherited myopathy long before the genetically confirmed diagnosis.

METHODS

This multicentre retrospective study enrolled 79 patients from referral centres in France, Brazil and Chile. The patients underwent 1.5-T or 3-T mWB-MRI. The protocol comprised STIR and T1 sequences in axial and coronal planes, from head to toe. All images were analyzed manually by multiple raters. Fatty muscle replacement was evaluated on mWB-MRI using both the Mercuri scale and statistical comparison based on the percentage of affected muscle.

RESULTS

Between February 2005 and December 2015, 76 patients with genetically confirmed inherited myopathy were included. They were affected by Pompe disease or harbored mutations in RYR1, Collagen VI, LMNA, SEPN1, LAMA2 and MYH7 genes. Each myopathy had a specific pattern of affected muscles recognizable on mWB-MRI. This allowed us to create a novel decision algorithm for patients with rigid spine syndrome by segregating these signs. This algorithm was validated by five external evaluators on a cohort of seven patients with a diagnostic accuracy of 94.3% compared with the genetic diagnosis.

CONCLUSION

We provide a novel decision algorithm based on muscle fat replacement graded on mWB-MRI that allows diagnosis and differentiation of inherited myopathies presenting with spinal rigidity.

KEY POINTS

• Inherited myopathies are rare, diagnosis is challenging and genetic tests require specialized centres and often take years. • Inherited myopathies are often characterized by spinal rigidity. • Whole body magnetic resonance imaging is a unique tool to orientate the diagnosis of each inherited myopathy presenting with spinal rigidity. • Each inherited myopathy in this study has a specific pattern of affected muscles that orientate diagnosis. • A novel MRI-based algorithm, usable by every radiologist, can help the early diagnosis of these myopathies.

Calcium dysregulation, functional calpainopathy, and endoplasmic reticulum stress in sporadic inclusion body myositis

Sporadic inclusion body myositis (IBM) is the most common primary myopathy in the elderly, but its pathoetiology is still unclear. Perturbed myocellular calcium (Ca²⁺) homeostasis can exacerbate many of the factors proposed to mediate muscle degeneration in IBM, such as mitochondrial dysfunction, protein aggregation, and endoplasmic reticulum stress. Ca²⁺ dysregulation may plausibly be initiated in IBM by immune-mediated membrane damage and/or abnormally accumulating proteins, but no studies to date have investigated Ca²⁺ regulation in IBM patients. We first investigated protein expression via immunoblot in muscle biopsies from IBM, dermatomyositis, and non-myositis control patients, identifying several differentially expressed Ca²⁺-regulatory proteins in IBM. Next, we investigated the Ca²⁺-signaling transcriptome by RNA-seq, finding 54 of 183 (29.5%) genes from an unbiased list differentially expressed in IBM vs. controls. Using an established statistical approach to relate genes with causal transcription networks, Ca²⁺ abundance was considered a significant upstream regulator of observed whole-transcriptome changes. Post-hoc analyses of Ca²⁺-regulatory mRNA and protein data indicated a lower protein to transcript ratio in IBM vs. controls, which we hypothesized may relate to increased Ca²⁺-dependent proteolysis and decreased protein translation. Supporting this hypothesis, we observed robust (4-fold) elevation in the autolytic activation of a Ca²⁺-activated protease, calpain-1, as well as increased signaling for translational attenuation (eIF2α phosphorylation) downstream of the unfolded protein response. Finally, in IBM samples we observed mRNA and protein under-expression of calpain-3, the skeletal muscle-specific calpain, which broadly supports proper Ca²⁺ homeostasis. Together, these data provide novel insight into mechanisms by which intracellular Ca²⁺ regulation is perturbed in IBM and offer evidence of pathological downstream effects.

Heart Disease in Disorders of Muscle, Neuromuscular Transmission, and the Nerves

Little is known regarding cardiac involvement (CI) by neuromuscular disorders (NMDs). The purpose of this review is to summarise and discuss the major findings concerning the types, frequency, and severity of cardiac disorders in NMDs as well as their diagnosis, treatment, and overall outcome. CI in NMDs is characterized by pathologic involvement of the myocardium or cardiac conduction system. Less commonly, additional critical anatomic structures, such as the valves, coronary arteries, endocardium, pericardium, and even the aortic root may be involved. Involvement of the myocardium manifests most frequently as hypertrophic or dilated cardiomyopathy and less frequently as restrictive cardiomyopathy, non-compaction, arrhythmogenic right-ventricular dysplasia, or Takotsubo-syndrome. Cardiac conduction defects and supraventricular and ventricular arrhythmias are common cardiac manifestations of NMDs. Arrhythmias may evolve into life-threatening ventricular tachycardias, asystole, or even sudden cardiac death. CI is common and carries great prognostic significance on the outcome of dystrophinopathies, laminopathies, desminopathies, nemaline myopathy, myotonias, metabolic myopathies, Danon disease, and Barth-syndrome. The diagnosis and treatment of CI in NMDs follows established guidelines for the management of cardiac disease, but cardiotoxic medications should be avoided. CI in NMDs is relatively common and requires complete work-up following the establishment of a neurological diagnosis. Appropriate cardiac treatment significantly improves the overall long-term outcome of NMDs.

A Rare Manifestation of Hypothyroid Myopathy: Hoffmann's Syndrome

Hypothyroid myopathy is observed frequently and the resolution of the clinical manifestations of myopathy following thyroid hormone replacement is well known. However, a specific subtype of hypothyroid myopathy, Hoffmann's syndrome, characterized by increased muscular mass (pseudohypertrophy), proximal muscle weakness, muscle stiffness and cramps, is rarely reported. Herein, we describe a 34-year-old male who presented with proximal muscle weakness and non-pitting edema of the lower extremities. He initially visited the neurology department where he was suspected of having polymyositis. Additional laboratory evaluation revealed profound autoimmune hypothyroidism and elevated muscle enzymes including creatine kinase. The patient was started on levothyroxine treatment and, subsequently, clinical symptoms and biochemical parameters resolved with the treatment. The present case highlights that hypothyroidism should be considered in the differential diagnosis of musculoskeletal symptoms even in the absence of overt manifestations of hypothyroidism. To our knowledge, this is the first case reported in Korea.

Clinical massively parallel sequencing for the diagnosis of myopathies

Massively parallel sequencing, otherwise known as high-throughput or next-generation sequencing, is rapidly gaining wide use in clinical practice due to possibility of simultaneous exploration of multiple genomic regions. More than 300 genes have been implicated in neuromuscular disorders, meaning that many genes need to be considered in a differential diagnosis for a patient affected with myopathy. By providing sequencing information for numerous genes at the same time, massively parallel sequencing greatly accelerates the diagnostic processes of myopathies compared to the classical "gene-after-gene" approach by Sanger sequencing. In this review, we describe multiple advantages of this powerful sequencing method for applications in myopathy diagnosis. We also outline recent studies that used this approach to discover new myopathy-causing genes and to diagnose cohorts of patients with muscular disorders. Finally, we highlight the key aspects and limitations of massively parallel sequencing that a neurologist considering this test needs to know in order to interpret the results of the test and to deal with other issues concerning the test.

Quantitative analysis of magnetic resonance imaging of the neck and its usefulness in management of congenital muscular torticollis

Objective

To quantify magnetic resonance imaging (MRI) findings of congenital muscular torticollis (CMT) and to demonstrate the usefulness of quantitative MRI findings in the management of CMT.

Methods

This was a retrospective study of 160 subjects with CMT who had undergone neck MRI at the age of 48 months or younger at a tertiary medical center. Among the 160 subjects, 54 had undergone surgical release of CMT and 106 subjects had not undergone surgery. For the quantitative analysis, the ratios of area and intensity of the MRI findings were measured and compared between the two groups (ratio of area = the largest cross-sectional area of the SCM with CMT - the cross-sectional area of the contralateral SCM without CMT / the cross-sectional area of the contralateral SCM without CMT; ratio of intensity = the mean gray color intensity of the contralateral SCM without CMT - the lowest mean gray color intensity of the SCM with CMT / the mean gray color intensity of the contralateral SCM without CMT). Receiver operating characteristic (ROC) curve analysis was conducted for the ratios of area and intensity in order to find the optimal cutoff value for determining the need for surgery in CMT cases.

Results

The ratios of area and intensity were significantly higher in the surgical group than in the non-surgical group (p≤0.001), suggesting that the sternocleidomastoid muscle (SCM) was thicker and darker in the surgical group than in the non-surgical group. The optimal cutoff value for the ratio of area was 0.17 and that for the ratio of intensity was 0.05. All subjects with a ratio of intensity less than 0.03 belonged to the non-surgical group, and all subjects with a ratio of intensity greater than 0.16 were categorized in the surgical group.

Conclusion

The quantitative MRI findings, i.e., ratios of area and intensity, may provide a guideline for deciding the need for surgical intervention in CMT patients. Further prospective studies are required to verify these findings.

Acute Kidney Injury and Quadriparesis Due to Rosuvastatin Induced Rhabdomyolysis- A Case Report

Statins as lipid lowering drugs, are safe and effective in reducing cardiovascular disease risk, but rarely produce myopathy like myalgia, myositis or rhabdomyolysis. We report the case of Rosuvastatin induced rhabdomyolytic acute renal failure and quadriparesis in a 67-year old male, a known case of type-2 diabetes mellitus and with a history of coronary angioplasty four months back. He was on antihypertensive, oral hypoglycemic and antiplatelet medications with Rosuvastatin 40mg/day. He was admitted with altered sensorium, breathlessness, vomiting, muscle weakness and decreased urine output and had raised serum creatinine, creatinine phosphokinase and myoglobin. After ruling out all other causation for rhabdomyolysis, we stopped Rosuvastatin and started supportive management and hemodialysis. Patient showed gradual recovery in renal function and quadriparesis. Patient was discharged with good urine output and on antihypertensive, hypoglycemic drug and diet restrictions for lipid control. He recovered completely and had normal renal function with well controlled lipid level on follow up of 6 months after discharge. Thus, prompt diagnosis of Rhabdomyolysis due to Rosuvastatin in absence of other aetiology and the multidisciplinary management can prevent further complication with favorable outcome.

[Rocuronium and sugammadex use for the management of neuromuscular blockade in urgent abdominal surgery in a patient with Landouzy-Dejerine myopathy]

In patients with neuromuscular diseases, the use of rocuronium in the general anesthesia rapid sequence induction provides safety intubation conditions, but induces a deep and prolonged neuromuscular blockade. We report dose reduction to 0.8mg/kg for a 47-year-old female with Landouzy-Dejerine myopathy. Therefore, less dose of sugammadex was given to reverse the neuromuscular block.

Alterations in central motor representation increase over time in individuals with rotator cuff tendinopathy

OBJECTIVE

To investigate whether rotator cuff tendinopathy leads to changes in central motor representation of a rotator cuff muscle, and to assess whether such changes are related to pain intensity, pain duration, and physical disability.

METHODS

Using transcranial magnetic stimulation, motor representation of infraspinatus muscle was assessed bilaterally in patients with unilateral rotator cuff tendinopathy.

RESULTS

Active motor threshold is significantly larger for the affected shoulder comparatively to the unaffected shoulder (n=39, p=0.01), indicating decreased corticospinal excitability on the affected side compared to unaffected side. Further, results suggest that this asymmetry in corticospinal excitability is associated with duration of pain (n=39; r=0.45; p=0.005), but not with pain intensity (n=39; r<0.03; p>0.43). In contrast with findings in other populations with musculoskeletal pain, no significant inter-hemispheric asymmetry was observed in map location (n=16; p-values ⩾ 0.91), or in the amplitude of motor responses obtained at various stimulation intensities (n=16; p=0.83).

CONCLUSION

Chronicity of pain, but not its intensity, appears to be a factor related to lower excitability of infraspinatus representation.

SIGNIFICANCE

These results support the view that while cortical reorganization correlates with magnitude of pain in neuropathic pain syndromes, it could be more related to chronicity in the case of musculoskeletal disorders.

Role of skeletal muscle proteoglycans during myogenesis

Skeletal muscle formation during development and the adult mammal consists of a highly organised and regulated the sequence of cellular processes intending to form or repair muscle tissue. This sequence includes, cell proliferation, migration, and differentiation. Proteoglycans (PGs), macromolecules formed by a core protein and glycosaminoglycan chains (GAGs) present a great diversity of functions explained by their capacity to interact with different ligands and receptors forming part of their signalling complex and/or protecting them from proteolytic cleavage. Particularly attractive is the function of the different types of PGs present at the neuromuscular junction (NMJ). This review is focussed on the advances reached to understand the role of PGs during myogenesis and skeletal muscular dystrophies.

Long-term treatment efficacy and safety of clevudine therapy in naïve patients with chronic hepatitis B

Background/Aims

Clevudine (CLV) has potent antiviral activity against chronic hepatitis B (CHB) virus infection. The long-term efficacy and safety of CLV therapy in naïve patients with CHB were investigated.

Methods

In this retrospective study, 152 naïve Korean patients with CHB who received 30 mg of CLV once daily for at least 12 months were investigated.

Results

The cumulative rates at months 12, 24, and 36, respectively, were 65.8%, 74.7%, and 74.7% for undetectable serum hepatitis B virus (HBV) DNA (<12 IU/mL); 77.6%, 86.2%, and 86.2% for normalization of serum alanine aminotransferase (<40 IU/L); 17.6%, 23.5%, and 23.5% for hepatitis B e antigen (HBeAg) loss or seroconversion; and 6.6%, 22.5%, and 30.0% for viral breakthrough. HBeAg positivity (p=0.010), baseline serum HBV DNA level ≥6 log₁₀ IU/mL (p=0.032) and detectable serum HBV DNA (≥12 IU/mL) at week 24 (p=0.023) were independently associated with the development of viral breakthrough. During follow-up, CLV-induced myopathy developed in 5.9% of patients.

Conclusions

The results of long-term CLV therapy for the treatment of naïve patients with CHB showed a high frequency of antiviral resistance and substantial associated myopathy. Therefore, we advise that CLV should not be used as a first-line treatment for naïve patients given the availability of other more potent, safer antiviral agents.

Lung carcinoma with metastasis to biceps muscle: report of a case and review of literature

A case of intramuscular metastasis in biceps muscle due to a squamous cell carcinoma of the lung (Pancoast) is presented. One year after treatment of the lung disease, the patient complained of pain and a sensation of swelling in the anterior aspect of her right arm. The excision of the infiltrated muscles showed proliferation of carcinomatous tissue.