Toxic myopathies

Exacerbation of Myopathy in Glycogen Debrancher Deficiency After Liver Transplantation: Case Report and Review of the Literature

BACKGROUND

Glycogen storage disorder (GSD) type IIIa is a rare inherited genetic disorder affecting liver and muscle tissue. Liver transplantation (LT) improves metabolic control, but muscle involvement persists.

CASE

We report the case of a 31-year-old man who underwent orthotopic LT for end-stage liver disease caused by GSD type IIIa. After LT, he developed worsening clinical signs of myopathy, along with exponentially increasing levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and creatine kinase. Liver-related elevations of AST and ALT were excluded through liver biopsy and endoscopic cholangiography; consequently, AST and ALT elevations were attributed to the underlying muscle involvement. Exacerbation of muscle disease after LT could be attributed to restoration of liver glycogen metabolism after LT, leading to increased glucose accumulation in muscle cells, where the gene defect persists. A dietary intervention with a high-protein, ketogenic diet was initiated but did not lead to significant improvement of myalgia.

CONCLUSION

LT exacerbated muscle disease in a patient with GSD type IIIa. Patients should be counseled about this possible side effect of LT in GSD type IIIa.

Neurosurgical Intervention for Nerve and Muscle Biopsies

(1) Background: Neurologic and musculoskeletal diseases represent a considerable portion of the underlying etiologies responsible for the widely prevalent symptoms of pain, weakness, numbness, and paresthesia. Because of the subjective and often nonspecific nature of these symptoms, different diagnostic modalities have been explored and utilized. (2) Methods: Literature review. (3) Results: Nerve and muscle biopsy remains the gold standard for diagnosing many of the responsible neurological and musculoskeletal conditions. However, the need for invasive tissue sampling is diminishing as more investigations explore alternative diagnostic modalities. Because of this, it is important to explore the current role of neurosurgical intervention for nerve and muscle biopsies and its current relevance in the diagnostic landscape of neurological and musculoskeletal disorders. With consideration of the role of nerve and muscle biopsy, it is also important to explore innovations and emerging techniques for conducting these procedures. This review explores the indications and emerging techniques for neurological intervention for nerve and muscle biopsies. (4) Conclusions: The role of neurosurgical intervention for nerve and muscle biopsy remains relevant in diagnosing many neurological and musculoskeletal disorders. Biopsy is especially relevant as a supportive point of evidence for diagnosis in atypical cases. Additionally, emerging techniques have been explored to guide diagnostics and biopsy, conduct less invasive biopsies, and reduce risks of worsening neurologic function and other symptoms secondary to biopsy.

Taurine activates the AKT-mTOR axis to restore muscle mass and contractile strength in human 3D in vitro models of steroid myopathy

Steroid myopathy is a clinically challenging condition exacerbated by prolonged corticosteroid use or adrenal tumors. In this study, we engineered a functional three-dimensional (3D) in vitro skeletal muscle model to investigate steroid myopathy. By subjecting our bioengineered muscle tissues to dexamethasone treatment, we reproduced the molecular and functional aspects of this disease. Dexamethasone caused a substantial reduction in muscle force, myotube diameter and induced fatigue. We observed nuclear translocation of the glucocorticoid receptor (GCR) and activation of the ubiquitin-proteasome system within our model, suggesting their coordinated role in muscle atrophy. We then examined the therapeutic potential of taurine in our 3D model for steroid myopathy. Our findings revealed an upregulation of phosphorylated AKT by taurine, effectively countering the hyperactivation of the ubiquitin-proteasomal pathway. Importantly, we demonstrate that discontinuing corticosteroid treatment was insufficient to restore muscle mass and function. Taurine treatment, when administered concurrently with corticosteroids, notably enhanced contractile strength and protein turnover by upregulating the AKT-mTOR axis. Our model not only identifies a promising therapeutic target, but also suggests combinatorial treatment that may benefit individuals undergoing corticosteroid treatment or those diagnosed with adrenal tumors.

Evaluation of Neuromuscular Diseases and Complaints by Quantitative Muscle MRI

Background: Quantitative muscle MRI (qMRI) is a promising tool for evaluating and monitoring neuromuscular disorders (NMD). However, the application of different imaging protocols and processing pipelines restricts comparison between patient cohorts and disorders. In this qMRI study, we aim to compare dystrophic (limb-girdle muscular dystrophy), inflammatory (inclusion body myositis), and metabolic myopathy (Pompe disease) as well as patients with post-COVID-19 conditions suffering from myalgia to healthy controls. Methods: Ten subjects of each group underwent a 3T lower extremity muscle MRI, including a multi-echo, gradient-echo, Dixon-based sequence, a multi-echo, spin-echo (MESE) T2 mapping sequence, and a spin-echo EPI diffusion-weighted sequence. Furthermore, the following clinical assessments were performed: Quick Motor Function Measure, patient questionnaires for daily life activities, and 6-min walking distance. Results: Different involvement patterns of conspicuous qMRI parameters for different NMDs were observed. qMRI metrics correlated significantly with clinical assessments. Conclusions: qMRI metrics are suitable for evaluating patients with NMD since they show differences in muscular involvement in different NMDs and correlate with clinical assessments. Still, standardisation of acquisition and processing is needed for broad clinical use.

PCSK9 inhibitor, ezetimibe, and bempedoic acid: Evidence-based therapies for statin-intolerant patients

Statins are first-line therapy for treating dyslipidemia because of their low-density lipoprotein cholesterol (LDL-C) lowering efficacy, superior event-reduction data and unrivaled cost-effectiveness. Yet, many people are intolerant of statins, whether due to true adverse events or the nocebo effect, so within one year about two-thirds of primary prevention patients and one-third of secondary prevention patients are no longer taking their prescription. Statins still dominate this landscape, but other agents, often used in combination, potently reduce LDL-C levels, regress atherosclerosis and lower risk of major adverse cardiovascular events (MACE). Ezetimibe lowers LDL-C by reducing intestinal absorption of cholesterol. Proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) lower LDL-C by increasing the number and durability of hepatic LDL receptors. Bempedoic acid reduces hepatic cholesterol synthesis. Ezetimibe, PCSK9i and bempedoic are evidence-based, non-statin therapies that synergistically lower LDL-C and reduce risk of MACE; they also have benign side-effect profiles and are generally well tolerated.

Molecular mechanisms in chloroquine-exposed muscle cells elucidated by combined proteomic and microscopic studies

OBJECTIVES

Chloroquine (CQ) is an antimalarial drug with a growing number of applications as recently demonstrated in attempts to treat Covid-19. For decades, it has been well known that skeletal and cardiac muscle cells might display vulnerability against CQ exposure resulting in the clinical manifestation of a CQ-induced myopathy. In line with the known effect of CQ on inhibition of the lysosomal function and thus cellular protein clearance, the build-up of autophagic vacuoles along with protein aggregates is a histological hallmark of the disease. Given that protein targets of the perturbed proteostasis are still not fully discovered, we applied different proteomic and immunological-based studies to improve the current understanding of the biochemical nature of CQ-myopathy.

METHODS

To gain a comprehensive understanding of the molecular pathogenesis of this acquired myopathy and to define proteins targets as well as pathophysiological processes beyond impaired proteolysis, utilising CQ-treated C2C12 cells and muscle biopsies derived from CQ-myopathy patients, we performed different proteomic approaches and Coherent Anti-Stokes Raman Scattering (CARS) microscopy, in addition to immunohistochemical studies.

RESULTS

Our combined studies confirmed an impact of CQ-exposure on proper protein processing/folding and clearance, highlighted changes in the interactome of p62, a known aggregation marker and hereby identified the Rett syndrome protein MeCP2 as being affected. Moreover, our approach revealed-among others-a vulnerability of the extracellular matrix, cytoskeleton and lipid homeostasis.

CONCLUSION

We demonstrated that CQ exposure (secondarily) impacts biological processes beyond lysosomal function and linked a variety of proteins with known roles in the manifestation of other neuromuscular diseases.

Amiodarone-induced muscle tremor in an elderly patient: A case report

BACKGROUND

Amiodarone is a Class III antiarrhythmic drug, which has been adopted for the treatment of atrial fibrillation and ventricular arrhythmia. However, the use of amiodarone can cause lower limb muscle tremors, which is recognized as a rare side effect of this medication.

CASE SUMMARY

An 84-year-old female was administrated with amiodarone for paroxysmal supraventricular tachycardia and frequent ventricular tachycardia. The patient developed a bilateral gastrocnemius tremor in the course of medication, and the strength of the patient’s bilateral knee flexor and extensor reached 4/5 and 3/5, respectively. After the use of amiodarone was stopped, and the patient was given a small dose of levetiracetam, the lower limb tremor symptoms were significantly mitigated, along with activity and function.

CONCLUSION

Attention should be paid to the significance of the side effects of drugs in the elderly, which may be atypical in the elderly. The relevant side effects of drugs may not be as rare as reported due to individual differences and different pharmacokinetics. If the side effects are generated, the medication should be adjusted in time, and the progress of the side effects should be intervened.

3D in vitro Models of Pathological Skeletal Muscle: Which Cells and Scaffolds to Elect?

Skeletal muscle is a fundamental tissue of the human body with great plasticity and adaptation to diseases and injuries. Recreating this tissue in vitro helps not only to deepen its functionality, but also to simulate pathophysiological processes. In this review we discuss the generation of human skeletal muscle three-dimensional (3D) models obtained through tissue engineering approaches. First, we present an overview of the most severe myopathies and the two key players involved: the variety of cells composing skeletal muscle tissue and the different components of its extracellular matrix. Then, we discuss the peculiar characteristics among diverse in vitro models with a specific focus on cell sources, scaffold composition and formulations, and fabrication techniques. To conclude, we highlight the efficacy of 3D models in mimicking patient-specific myopathies, deepening muscle disease mechanisms or investigating possible therapeutic effects.

Drug-induced Myopathies

Differential diagnosis of muscle pain and weakness is extensive, including neurological, vertebral, arthrogenic, vascular, traumatic, immunological, endocrine, genetic and infectious aetiologies, as well as medication or toxin-related causes. Muscles are highly sensitive to a large number of drugs, especially with high doses. Although many drug classes can cause toxic myopathy, a significant number of cases are caused by lipid-lowering drugs, long-term use of corticosteroids, and, most often, alcohol misuse. Some drug interactions, e.g. those that are metabolised via the enzyme CYP3A4, can increase the serum levels of the drugs and drug-induced toxicity. A careful history of patient's drug and alcohol consumption is therefore vital. Clinical symptoms depend on the drug, dosage and patient's sensitivity. They can vary from asymptomatic increase in serum levels of creatine kinase, mild myalgia and cramps to muscle weakness, rhabdomyolysis, kidney failure and even death. The pathogenesis is often only partially known and multifactorial. Toxic myopathy is often reversible once the drug is discontinued, alternative drug therapy is started or a different dosage regimen is chosen. Complications such as acute kidney failure must be avoided, and analgesic therapy may be indicated.

Zebrafish as a Model for the Study of Lipid-Lowering Drug-Induced Myopathies

Drug-induced myopathies are classified as acquired myopathies caused by exogenous factors. These pathological conditions develop in patients without muscle disease and are triggered by a variety of medicaments, including lipid-lowering drugs (LLDs) such as statins, fibrates, and ezetimibe. Here we summarise the current knowledge gained via studies conducted using various models, such as cell lines and mammalian models, and compare them with the results obtained in zebrafish (Danio rerio) studies. Zebrafish have proven to be an excellent research tool for studying dyslipidaemias as a model of these pathological conditions. This system enables in-vivo characterization of drug and gene candidates to further the understanding of disease aetiology and develop new therapeutic strategies. Our review also considers important environmental issues arising from the indiscriminate use of LLDs worldwide. The widespread use and importance of drugs such as statins and fibrates justify the need for the meticulous study of their mechanism of action and the side effects they cause.

Pembrolizumab related Guillain barre syndrome, a rare presentation in a patient with a history of lupus and bladder cancer

Immune checkpoint inhibitor-related neurotoxicity causing Guillain Barre Syndrome is relatively uncommon. We discussed an 80-year-old patient with known systemic lupus erythematosus who presented with lower extremity weakness, areflexia and then progressed to respiratory muscle and upper extremity weakness after receiving immunotherapy with checkpoint inhibitors for metastatic bladder cancer. With the increasing use of immunotherapy for the management of cancer, awareness of neurological autoimmune side effects is essential. Immune checkpoint inhibitor-mediated GBS can be severe and fatal if not diagnosed promptly. The hospitalists, neurologists, and oncologists should be aware of neurotoxicity related to immune checkpoint inhibitor therapy requiring a multidisciplinary approach to patient care. Prompt initiation of immunosuppressive therapy is required for the management of immune checkpoint inhibitor-related neurotoxicity.

Challenges in diagnosing hydroxychloroquine myopathy during the COVID-19 pandemic

Hydroxychloroquine is being used for COVID-19 symptoms and in clinical trials, but can cause a toxic myopathy that leads to muscle weakness. A review of skeletal muscle biopsies from patients with hydroxychloroquine myopathy gives pointers of steps that can be taken to diagnose this toxic myopathy early and help differentiate it from COVID-19-related muscle weakness.

Pregabalin-Induced Myopathy in a Double Lung Transplant Recipient

Pregabalin is a gamma-aminobutyric acid (GABA) derivative that was commercially approved by the Food and Drug Administration (FDA) in 2004. It is commonly used in the treatment of diabetic neuropathy, peripheral neuropathy, and spinal cord injury. We present the case of a 36-year-old Caucasian male double lung transplant recipient who presented with an 18-month history of fatigue and muscle weakness. He had elevated creatinine kinase level and his muscle biopsy showed evidence of drug-induced myopathy that improved after the cessation of pregabalin. We present a case of drug-induced myopathy as a rare complication of pregabalin therapy in a double lung transplant recipient.

Rhabdomyolysis in drug-related deaths

Background

This study aims to detect myoglobin staining in the cases in which were suspected that intoxication was the cause of death.

Materials and method

This study selected the drug-related death cases including those with toxic blood levels of substances. These drug-related death cases were classified into two groups: (1) suggestive of intoxication death group and (2) other causes of death group which was control group. The kidneys of all these cases were immunohistochemically stained with the myoglobin antibody for rhabdomyolysis diagnosis.

Results

There were 50 drug-related deaths separated into 28 study cases and 22 control cases. The positive myoglobin stain was found in 17 cases (60.7%) in the study group and 5 cases (22.7%) in the control group. The difference between two groups was statistically significant (p = 0.007).

Conclusions

Myoglobin detection in kidney by immunohistochemistry should be done to help for confirming the cause of deaths in these drug-related death cases.

Delayed rhabdomyolysis secondary to anabolic-androgenic steroid use

There are literature reports of anabolic-androgenic steroid-induced rhabdomyolysis. Here we describe a case of a patient presenting with acute confusion and rhabdomyolysis, following an unwitnessed seizure. He had a background of alcohol excess. Three days into his admission he developed dysphagia. At first, the patient denied the use of any medication or drugs. However, he later revealed he had used the anabolic steroid 'Anavar' (oxandrolone) for 60 consecutive days ending a month prior to his admission. The brief seizure was itself unlikely to have resulted in the severity of his rhabdomyolysis. Thus, we report a likely case of delayed rhabdomyolysis secondary to anabolic steroid use. The oropharyngeal dysphagia may be secondary to the rhabdomyolysis; there have been cases of this described in literature.

Amiodarone-induced neuromyopathy in a geriatric patient

Amiodarone is an antiarrhythmic medication with many side effects. Neuromyopathy is a rare adverse effect. We present an 87-year-old woman with bilateral leg pain and weakness in the context of amiodarone. She was admitted to the Acute Geriatric Unit in Calgary, Alberta, Canada. On examination, hip flexor and extensor strength were 2/5 bilaterally while knee flexor and extensor strength were 4/5 and 3/5, respectively. Creatine kinase and C-reactive protein levels were normal. MRI of the lumbar spine showed mild central canal stenosis. Electromyography and nerve conduction testing showed a severe axonal length-dependent polyneuropathy of the left lower extremity. There was evidence of myopathic changes to the left iliopsoas muscle. Overall, a neuromyopathic process affecting the lower extremities was supported. After discontinuation of amiodarone, mobility and function significantly improved. Although a rare complication of amiodarone, neuromyopathy should be considered in patients with compatible symptomatology.

How to investigate: Suspected systemic rheumatic diseases in patients presenting with muscle complaints

Muscular symptoms, which may be due to multiple causes, are one of the most common early complaints in a rheumatology practice. Musculoskeletal symptoms in rheumatic conditions are very varied, ranging from mechanical problems to muscular symptoms derived from inflammatory and systemic autoimmune diseases. Several drugs commonly used by different specialists and certain drugs used in rheumatology can also cause a wide variety of muscle symptoms. A description of different systemic autoimmune diseases follows to describe the different forms of involvement of the musculoskeletal system that they cause, as well as the main causes with which a differential diagnosis should be made. In this chapter, we will try to give some clues to reach an early diagnosis using clinical criteria, particularly based on a directed anamnesis and physical examination, discussing possible guidelines for the complimentary tests that may be required in patients with muscle complaints.

Older age at initiation of antiretroviral therapy predicts low bone mineral density in children with perinatally-infected HIV in Zimbabwe

BACKGROUND

Perinatally-acquired HIV infection commonly causes stunting in children; how this affects bone and muscle development is unclear. We investigated differences in bone and muscle mass and muscle function between children with HIV (CWH) and uninfected children.

SETTING

Cross-sectional study of CWH (6-16 years) receiving antiretroviral therapy (ART) for >6 months and similar aged children testing HIV-negative at primary health clinics in Zimbabwe.

METHODS

From Dual-energy X-ray Absorptiometry (DXA) we calculated total-body less-head (TBLH) Bone Mineral Content (BMC) for lean mass adjusted-for-height (TBLH-BMCLBM) Z-scores, and lumbar spine (LS) Bone Mineral Apparent Density (BMAD) Z-scores.

RESULTS

The 97 CWH were older (mean age 12.7 vs. 10.0 years) and taller (mean height 142 cm vs. 134 cm) than 77 uninfected. However, stunting (height-for-age Z-score ≤ -2) was more prevalent in CWH (35% vs. 5%, p < 0.001). Among CWH, 15% had low LS-BMAD (Z-score ≤ -2) and 13% low TBLH-BMCLBM, vs. 1% and 3% respectively in those uninfected (both p ≤ 0.02). After age, sex, height and puberty adjustment, LS-BMAD was 0.33 SDs (95%CI -0.01, 0.67; p = 0.06) lower in CWH, with no differences by HIV status in TBLH-BMCLBM, lean mass (0.11 [-0.03, 0.24], p = 0.11) or grip strength (0.05 [-0.16, 0.27], p = 0.62). However, age at ART initiation was correlated with both LS-BMAD Z-score (r = -0.33, p = 0.001) and TBLH-BMCLBM Z-score (r = -0.23, p = 0.027); for each year ART initiation was delayed a 0.13 SD reduction in LS-BMAD was seen.

CONCLUSION

Size-adjusted low bone density is common in CWH. Delay in initiating ART adversely affects bone density. Findings support immediate ART initiation at HIV diagnosis.

Colchicine Myopathy: A Case Series Including Muscle MRI and ABCB1 Polymorphism Data

Colchicine is a medication most commonly used in the treatment of gout and familial mediterannean fever. A rare complication of therapy is toxicity causing proximal myopathy and polyneuropathy. Colchicine myopathy has been associated with the coadministration of other medications with colchicine, such as statins or tacrolimus, and is more common in patients with renal impairment. Otherwise, it is unclear which patients are at greatest risk of developing this adverse drug reaction. ABCB1 is important to the metabolism of colchicine, so we speculated that it was possible that colchicine myopathy patients may have a particular genotype that is associated with this side effect. We describe two cases of colchicine myopathy which occurred with co-administration of rosuvastatin. From one case, we present the first published data on muscle MRI in this condition. We additionally present an analysis of four genetic polymorphisms in ABCB1 and transcript levels in muscle tissue, and demonstrate the descriptive finding of reduced ABCB1 transcript levels in the colchicine myopathy patients.

Toxic myopathies

PURPOSE OF REVIEW

Our aim is to highlight major advances reported in the last few years in drug-induced muscle toxicity.

RECENT FINDINGS

Our focus is on myopathies induced by statins and immune checkpoint inhibitors with a brief overview of rare steroid myopathies. Statin muscle injury is frequently because of direct toxicity rather than an autoimmune mechanism. Laboratory testing and muscle pathologic features distinguish these two conditions. Statin-associated necrotizing autoimmune myopathy (SANAM) is associated with an autoantibody in 66% of cases targeting the HMGCR enzyme. The later autoantibody is a marker for necrotizing autoimmune myopathy, regardless of statin exposure. In SANAM, MHC-I antigens are expressed on the surface of intact muscle fibers. Genetic HLA loci predispose patients exposed to statins to immunologic toxicity. SANAM requires long-term therapy with multiple immunosuppressive therapies. Immune checkpoint inhibitors are powerful emerging therapies for advanced cancer that pause a novel therapeutic challenge.

SUMMARY

This review is focused on statins, the most prevalent myotoxic drug class. In addition, we examine the accumulating body of evidence of muscle injury and its management with immune checkpoint inhibitors. We anticipate the reader to become more knowledgeable in recent discoveries related to these myotoxic drugs, and their mechanisms of action and management.

Monitoring Kidney Dysfunction in Kugelberg-Welander Syndrome

BACKGROUND Kugelberg-Welander (K-W) syndrome is a type of spinal muscular atrophy that causes weakness of the hip-girdle muscles. If severe enough, this weakness can confine patients to a wheelchair in adult life. Proteinuria, a manifestation of kidney dysfunction, is associated with disorders of many organ systems. The evaluation of kidney function in the context of K-W syndrome is challenging. CASE REPORT A 45-year-old man with K-W syndrome first diagnosed at 5 years of age developed peripheral edema and was found to have proteinuria under 1 g/24 h. His past history was significant for hypertension for 7 years. He was managed conservatively initially, but over the next year the serum creatinine concentration increased from 18 to 32 µmol/L (0.2 to 0.36 mg/dL). A percutaneous kidney biopsy was performed in the fetal position due to an inability of the patient to lay prone or supine. Minimal change disease (MCD) was diagnosed. Treatment consisted of dietary salt restriction, ramipril, amiloride, and hydrochlorothiazide, while avoiding corticosteroids. The serum creatinine concentration initially returned to the 18-20 µmol/L (0.2-0.22 mg/dL) range with increased fluid intake, but then slowly declined to 6 µmol/L (0.07 mg/dL) over the next 14 years. Muscle strength remained poor. CONCLUSIONS K-W syndrome, when associated with proteinuria, presents novel diagnostic and therapeutic challenges to the latter. The serum creatinine concentration may be unhelpful in assessing kidney function in K-W syndrome. A conservative management approach to MCD is reasonable to minimize comorbidity.

A pattern-based approach to the interpretation of skeletal muscle biopsies

The interpretation of muscle biopsies is complex and provides the most useful information when integrated with the clinical presentation of the patient. These biopsies are performed for workup of a wide range of diseases including dystrophies, metabolic diseases, and inflammatory processes. Recent insights have led to changes in the classification of inflammatory myopathies and have changed the role that muscle biopsies have in the workup of inherited diseases. These changes will be reviewed. This review follows a morphology-driven approach by discussing diseases of skeletal muscle based on a few basic patterns that include cases with (1) active myopathic damage and inflammation, (2) active myopathic damage without associated inflammation, (3) chronic myopathic changes, (4) myopathies with distinctive inclusions or vacuoles, (5) biopsies mainly showing atrophic changes, and (6) biopsies that appear normal on routine preparations. Each of these categories goes along with certain diagnostic considerations and pitfalls. Individual biopsy features are only rarely pathognomonic. Establishing a firm diagnosis therefore typically requires integration of all of the biopsy findings and relevant clinical information. With this approach, a muscle biopsy can often provide helpful information in the diagnostic workup of patients presenting with neuromuscular problems.

Diagnostic Imaging of Inflammatory Myopathies: New Concepts and a Radiological Approach

PURPOSE OF REVIEW

The purpose of this review article is to highlight the current role of diagnostic imaging in the assessment of inflammatory myopathies.

RECENT FINDINGS

Recent research demonstrates that imaging plays an important role in evaluating patients with symptoms of an inflammatory myopathy. In general, MRI is the pivotal imaging modality for assessing inflammatory myopathies, revealing precise anatomic details because of changes in the signal intensity of the muscles. Whole-body MR imaging has become increasingly important over the last several years. US is also a valuable imaging modality for scanning muscles. Together with the clinical history, familiarity with the imaging features of inflammatory myopathies is essential for formulating an accurate diagnosis.

Late and Severe Myopathy in a Patient With Glycogenosis VII Worsened by Cyclosporine and Amiodarone

Glycogenosis VII (GSD VII) is a rare autosomal recessive glycogen storage disorder caused by mutations in the PFKM gene encoding the phosphofructokinase (PFK) enzyme. A classical form with exercise intolerance, contractures, and myoglobinuria, a severe multisystem infantile form, an hemolytic variant and a late-onset form usually presenting with muscle pain and mild fixed proximal weakness have been reported. We describe a 65-year-old man affected by muscle PFK deficiency who, since the age of 33, presented with exercise intolerance and myoglobinuria. Muscle biopsy showed a vacuolar myopathy with glycogen storage. The biochemical assay of PFK-M showed very low residual activity (6%). Genetic analysis of PFKM gene evidenced the presence of the heterozygote c.1817A>C (p.Asp543Ala) and c.488 G>A (p.Arg100Gln) pathogenic mutations. In his fifth decade, he started cyclosporine after liver transplantation for hepatocellular carcinoma and, then, amiodarone because of atrial fibrillation. In the following years, he developed a progressive and severe muscle weakness, mainly involving lower limbs, up to a loss of independent walking. Muscle MRI showed adipose substitution of both anterior and posterior thigh muscles with selective sparing of the medial compartment. Marked signs of adipose substitution were also documented in the legs with a selective replacement of gemelli and peroneus muscles. The temporal relationship between the patient's clinical worsening and chronic treatment with cyclosporine and amiodarone suggests an additive toxic damage by these two potentially myotoxic drugs determining such an unusually severe phenotype, also confirmed by muscle MRI findings.

Myogenic fibrosis of the flexor tendons after amphetamine drug abuse

Myogenic fibrosis of the flexor tendons in a 23-year-old patient was caused by intense drug abuse. He was presented in the clinic with spastic flexor tendon contracture of his right hand. The patient was treated by tendon elongation with a satisfactory result. The treatment of flexor tendon contracture in those cases is very difficult and needs to be done in a complex way.

Differential diagnosis of idiopathic inflammatory myopathies in adults - the first step when approaching a patient with muscle weakness

Despite its misleading adjective, the most commonly used diagnostic criteria of idiopathic inflammatory myopathies (IIM) are applicable only after all other non-autoimmune muscle diseases have been excluded. It makes differential diagnosis the first step when approaching a patient with muscle weakness. This article is designed to list the most common conditions from which to differentiate in rheumatological care. In fact, many patients with the diseases described here have been initially misdiagnosed with IIM. For the purpose of this article, only the most commonly found and important conditions according to the authors are listed with the essence of information; other autoimmune muscle diseases, such as sarcoidosis and eosinophilic myositis, are not portrayed. The attached bibliography may serve as a source, when further exploration of a specific subject is needed.

Development and application of human skeletal muscle microphysiological systems

A number of major disease states involve skeletal muscle, including type 2 diabetes, muscular dystrophy, sarcopenia and cachexia arising from cancer or heart disease. Animals do not accurately represent many of these disease states. Human skeletal muscle microphysiological systems derived from primary or induced pluripotent stem cells (hPSCs) can provide an in vitro model of genetic and chronic diseases and assess individual variations. Three-dimensional culture systems more accurately represent skeletal muscle function than do two-dimensional cultures. While muscle biopsies enable culture of primary muscle cells, hPSCs provide the opportunity to sample a wider population of donors. Recent advances to promote maturation of PSC-derived skeletal muscle provide an alternative to primary cells. While contractile function is often measured in three-dimensional cultures and several systems exist to characterize contraction of small numbers of muscle fibers, there is a need for functional measures of metabolism suited for microphysiological systems. Future research should address generation of well-differentiated hPSC-derived muscle cells, enabling muscle repair in vitro, and improved disease models.

Disability, social functioning and school inclusion among older children and adolescents living with HIV in Zimbabwe

OBJECTIVE

Increasing numbers of children with HIV are surviving to adolescence and encountering multiple clinical and social consequences of long-standing HIV infection. We aimed to investigate the association between HIV and disability, social functioning and school inclusion among 6- to 16-year-olds in Zimbabwe.

METHODS

HIV-infected children receiving antiretroviral therapy from a public-sector HIV clinic and HIV-uninfected children attending primary care clinics in the same catchment area were recruited. Standardised questionnaires were used to collect socio-demographic, social functioning and disability data. Multivariable logistic regression was used to assess the relationship between HIV status and disability and functioning.

RESULTS

We recruited 202 HIV-infected and 285 HIV-uninfected children. There was no difference in age and gender between the two groups, but a higher proportion of HIV-infected children were orphaned. The prevalence of any disability was higher in HIV-infected than uninfected children (37.6% vs. 18.5%, P < 0.001). HIV-infected children were more likely to report anxiety (adjusted odds ratio (aOR) 4.4; 95% CI 2.4, 8.1), low mood (aOR 4.2; 2.1, 8.4) and difficulty forming friendships (aOR 14.8; 1.9, 116.6) than uninfected children. Children with HIV also reported more missed school days, repeating a school year and social exclusion in class. These associations remained apparent when comparing children with HIV and disability to those with HIV but no disabilities.

CONCLUSIONS

Children with HIV commonly experience disabilities, and this is associated with social and educational exclusion. Rehabilitation and support services are needed to facilitate educational attainment and social participation in this group.

Necrotizing Autoimmune Myopathy: Clinicopathologic Study from a Single Tertiary Care Centre

BACKGROUND

Idiopathic inflammatory myopathies (IIMs) are a group of chronic, autoimmune disorders which include a new entity, necrotizing autoimmune myopathy (NAM). NAM lacks inflammation and presents with markedly elevated creatinine phosphokinase (CPK) levels. It is associated with connective tissue diseases (CTDs), statin use, malignancies, and most cases are idiopathic.

OBJECTIVES

The objectives of this study are to describe the clinicopathologic features in muscle biopsy-proven cases of NAM. To emphasize the role of laboratory parameters such as CPK levels and myositis profile in the diagnosis of NAM.

MATERIALS AND METHODS

This is a retrospective study including 15 patients of NAM diagnosed on muscle biopsy over a period of 2 years. The slides of the biopsies were reviewed, and clinical data, electromyography findings, and CPK levels were obtained. Myositis profile was done.

RESULTS

Necrotizing myopathy accounted for 13.63% (15 cases) of total inflammatory myopathies (110 cases) in the study. These were grouped into CTD-associated NAM, statin-associated NAM, paraneoplastic NAM and idiopathic NAM which was the common type. All cases presented with progressive proximal muscle weakness and had markedly elevated CPK levels. Anti-3-hydroxy-3-methyl-glutaryl-coenzyme A reductase and antisignal recognition particle antibodies were seen to be positive in six patients. Muscle biopsies showed predominant fiber necrosis with significant fiber degeneration and regeneration in the absence of inflammation. All patients received immunotherapy with significant improvement was seen in six patients with two mortalities.

CONCLUSION

Necrotizing myopathy is a new addition to the spectrum of IIM. Clinicopathologic correlation is important for appropriate diagnosis. It is found to be refractory to corticosteroids monotherapy. The course of illness is not uniform, and in some patients, there can be rapid worsening with mortality.

Statin-Associated Muscle Adverse Events: Update for clinicians

Statins are potent medications which reduce low-density lipoprotein cholesterol (LDL-C) levels. Their efficacy in cardiovascular risk reduction is well established and indications for their use are expanding. While statins are generally well tolerated and safe, adverse events are relatively common, particularly statin-associated muscle adverse events (SaMAEs), which are the most frequently encountered type of adverse event. Recent guidelines and guideline updates on SaMAEs and statin intolerance have included revised definitions of SaMAEs, incorporating new evidence on their pathogenesis and management. As SaMAEs emerge as a therapeutic challenge, it is important for physicians to be aware of updates on management strategies to ensure better patient outcomes. The majority of patients who are considered statin-intolerant can nevertheless tolerate some forms of statin therapy and successfully achieve optimal LDL-C levels. This review article discusses the recent classification of SaMAEs with emphasis on pathogenesis and management strategies.