A pattern recognition approach to patients with a suspected myopathy

Neuromuscular Emergencies

OBJECTIVE

This article aims to familiarize the reader with the clinical approach, diagnostic considerations, and treatment strategies for patients presenting with abrupt-onset or acutely worsening weakness due to neuromuscular disorders.

LATEST DEVELOPMENTS

Neuromuscular weakness is often the result of an inflammatory process. In recent years, there has been growing recognition of pathologic antibodies that cause neuromuscular injury. This has allowed clinicians to make a more accurate diagnosis. Additionally, neuromuscular junction disorders and myopathies are increasingly identified as the adverse effects of novel anticancer therapies, namely immune checkpoint inhibitors. More data are being incorporated into frameworks for neuroprognostication after neuromuscular emergencies, especially for commonly encountered disorders such as Guillain-Barré syndrome.

ESSENTIAL POINTS

Care of patients with neuromuscular emergencies requires prompt attention to respiratory status. Once supportive measures are in place to protect the airway and facilitate effective ventilation, diagnostic considerations should hinge on appropriate neurologic localization. Aggressive immunosuppression is often required for immune-mediated neuromuscular disorders, and clinicians must be thoughtful in selecting a strategy that best aligns with each patient's risk factors and comorbidities.

Clinicopathological Profile of Muscle Diseases Presenting the Adult Population in Northern India: Preliminary Analysis in a Limited Resource Setting

BACKGROUND

Muscle diseases are of various types, viz., muscular dystrophies, inflammatory myopathies, myotonic disorders, congenital myopathies, and metabolic myopathies. They all present with muscle weakness, be it proximal or distal. The assessment of muscle biopsy with the help of enzyme histochemistry, histopathological, and immunohistochemical methods is an essential component in the diagnosis of neuromuscular disorders. The authors outline brief data on muscle diseases prevalent in the North Indian region.

METHODS

Muscle biopsy was done, and the biopsy was freshly frozen in liquid nitrogen and sections were taken on a cryostat. Slides were then stained with hematoxylin and eosin (H&E), modified Gomori trichome (MGT), nicotinamide adenine dinucleotide hydrogenase (NADH), and succinic dehydrogenase (SDH) stains. Further specific immunohistochemistry tests were also done.

RESULT

Out of n=16 cases, three cases were diagnosed as Becker's muscular dystrophy, two cases were diagnosed as inflammatory myopathy, four cases were diagnosed as Facioscapulohumeral muscular dystrophy, and one each case of dysferlinopathy and alpha sarcoglycanopathy.

CONCLUSION

Muscle diseases can cause different levels of physical disability and thus it is important to diagnose at the appropriate time to ensure proper treatment.

Burkholderia-associated polymyositis

A diagnosis of polymyositis can readily be made when there is a typical history of proximal muscle weakness together with clinical findings, and there is corroboratory evidence in the form of elevated creatine kinase lactate dehydrogenase, aldolase, and serum glutamic-oxaloacetic transaminase (aspartate aminotransferase). A muscle biopsy usually helps in making the confirmatory diagnosis. A female in her 50s presented with non-healing multiple deep necrotic ulcers with muscle weakness. The initial possibility of vasculitis ulcers remained. Later, this proved to be a case of polymyositis with mildly elevated creatine kinase (which is usually not the case), atypical skin manifestations (usually there is no skin involvement), and negative extended myositis specific antibody panel with the growth of Burkholderia cepacia (perhaps the triggering factor). Hence, polymyositis can present with a myriad of atypical findings. Thus, thorough clinical examination and an integrated approach are necessary for early identification and treatment of the disease.

Drosophila Tropomodulin is required for multiple actin-dependent processes within developing myofibers

Proper muscle contraction requires the assembly and maintenance of sarcomeres and myofibrils. Although the protein components of myofibrils are generally known, less is known about the mechanisms by which they individually function and together synergize for myofibril assembly and maintenance. For example, it is unclear how the disruption of actin filament (F-actin) regulatory proteins leads to the muscle weakness observed in myopathies. Here, we show that knockdown of Drosophila Tropomodulin (Tmod), results in several myopathy-related phenotypes, including reduction of muscle cell (myofiber) size, increased sarcomere length, disorganization and misorientation of myofibrils, ectopic F-actin accumulation, loss of tension-mediating proteins at the myotendinous junction, and misshaped and internalized nuclei. Our findings support and extend the tension-driven self-organizing myofibrillogenesis model. We show that, like its mammalian counterpart, Drosophila Tmod caps F-actin pointed-ends, and we propose that this activity is crucial for cellular processes in different locations within the myofiber that directly and indirectly contribute to the maintenance of muscle function. Our findings provide significant insights to the role of Tmod in muscle development, maintenance and disease.

Biomarkers: Role and Scope in Neurological Disorders

Neurological disorders pose a great threat to social health and are a major cause for mortality and morbidity. Effective drug development complemented with the improved drug therapy has made considerable progress towards easing symptoms associated with neurological illnesses, yet poor diagnosis and imprecise understanding of these disorders has led to imperfect treatment options. The scenario is complicated by the inability to extrapolate results of cell culture studies and transgenic models to clinical applications which has stagnated the process of improving drug therapy. In this context, the development of biomarkers has been viewed as beneficial to easing various pathological complications. A biomarker is measured and evaluated in order to gauge the physiological process or a pathological progression of a disease and such a marker can also indicate the clinical or pharmacological response to a therapeutic intervention. The development and identification of biomarkers for neurological disorders involves several issues including the complexity of the brain, unresolved discrepant data from experimental and clinical studies, poor clinical diagnostics, lack of functional endpoints, and high cost and complexity of techniques yet research in the area of biomarkers is highly desired. The present work describes existing biomarkers for various neurological disorders, provides support for the idea that biomarker development may ease our understanding underlying pathophysiology of these disorders and help to design and explore therapeutic targets for effective intervention.

A Symptoms and Signs Approach to the Patient With Neuromuscular Weakness

PURPOSE OF REVIEW

Muscle weakness is a common feature of many neuromuscular disorders. This article outlines a symptoms and signs approach to the patient presenting with neuromuscular weakness, highlighting key aspects of the clinical history and examination.

RECENT FINDINGS

The past several years have seen a dramatic increase in the ability to test for many inherited and autoimmune neuromuscular disorders more reliably and accurately. Similarly, numerous targeted therapies have been recently approved to treat previously untreatable disorders. Therefore, timely and accurate diagnosis is essential so that patients can receive appropriate therapy, ultimately leading to better clinical outcomes.

SUMMARY

Muscle weakness is a common symptom resulting from dysfunction that can occur at any level of the neuraxis and is a cardinal feature of many neuromuscular disorders. An accurate and meticulous history and a thorough neurologic examination are paramount in localizing the lesion in order to generate a differential diagnosis and guide appropriate ancillary testing. The patient's age at symptom onset, any identified inciting factors, tempo of symptom progression, pattern of weakness, and associated symptoms and signs are all important diagnostic clues in the evaluation of a patient presenting with muscle weakness.

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.

Ocular Features and Clinical Approach to Cataract and Corneal Refractive Surgery in Patients with Myotonic Dystrophy

Myotonic dystrophy is the most common inherited muscular dystrophy in adults and presents as two forms, type 1, and type 2. Ocular manifestations such as premature cataract formation, may be the first diagnostic sign or symptom of the disease, offering ophthalmologists a unique diagnostic role. Fuchs' endothelial corneal dystrophy, ptosis and ocular melanoma are other possible findings. Systemic features can help providers better understand the disease and any accommodations to be made in clinical or surgical settings. Some patients with this disease may request evaluation of certain cataract or corneal refractive procedures. This article focuses on pertinent information for clinicians to utilize when evaluating and treating patients with myotonic dystrophy and specific surgical perspectives to consider prior to any ocular interventions. Hydrophobic intraocular lenses are still recommended in these patients with careful observation of capsular phimosis and posterior capsular opacities.

Rapid identification of human muscle disease with fibre optic Raman spectroscopy

The diagnosis of muscle disorders ("myopathies") can be challenging and new biomarkers of disease are required to enhance clinical practice and research. Despite advances in areas such as imaging and genomic medicine, muscle biopsy remains an important but time-consuming investigation. Raman spectroscopy is a vibrational spectroscopy application that could provide a rapid analysis of muscle tissue, as it requires no sample preparation and is simple to perform. Here, we investigated the feasibility of using a miniaturised, portable fibre optic Raman system for the rapid identification of muscle disease. Samples were assessed from 27 patients with a final clinico-pathological diagnosis of a myopathy and 17 patients in whom investigations and clinical follow-up excluded myopathy. Multivariate classification techniques achieved accuracies ranging between 71-77%. To explore the potential of Raman spectroscopy to identify different myopathies, patients were subdivided into mitochondrial and non-mitochondrial myopathy groups. Classification accuracies were between 74-89%. Observed spectral changes were related to changes in protein structure. These data indicate fibre optic Raman spectroscopy is a promising technique for the rapid identification of muscle disease that could provide real time diagnostic information. The application of fibre optic Raman technology raises the prospect of in vivo bedside testing for muscle diseases which would significantly streamline the diagnostic pathway of these disorders.

Inflammatory myopathies: an update for neurologists

Idiopathic inflammatory myopathies (IIM) are a heterogenous group of treatable myopathies. Patients present mainly to the rheumatologist and neurologists, complaining of acute or subacute onset of proximal weakness. Extramuscular manifestations may occur, including involvement of the lungs, skin, and joints. Classically, the diagnosis used to be made based on the creatine kinase level increase, abnormalities in electroneuromyography and presence of inflammatory infiltrates in the muscle biopsy. Recently, the importance of autoantibodies has increased, and now they may be identified in more than half of IIM patients. The continuous clinicoseropathological improvement in IIM knowledge has changed the way we see these patients and how we classify them. In the past, only polymyositis, dermatomyositis and inclusion body myopathy were described. Currently, immune-mediated necrotizing myopathy, overlap myositis and antisynthetase syndrome have been considered the most common forms of IIM in clinical practice, increasing the spectrum of classification. Patients previously considered to have polymyositis, in fact have these other forms of seropositive IIM. In this article, we reviewed the new concepts of classification, a practical way to make the diagnosis and how to plan the treatment of patients suffering from IIM.

Approach to the child with fatigue: A focus for the general pediatrician

BACKGROUND

Fatigue is a common, nonspecific complaint commonly used to describe various conditions, ranging from a vague, subjective sense of weariness to muscular weakness, fatigability, exercise intolerance or excessive daytime somnolence. Despite its high frequency in the general population, literature addressing the approach to the child with fatigue from a general pediatrician perspective is poor. We herein propose a review of the available evidence on the topic, providing a practical framework to assist physicians in dealing with the issue.

METHODS

Data were identified by searches of MEDLINE, UpToDate, Google Scholar and references from relevant articles. Articles published between 1990 and 2021 were considered, prioritizing systematic reviews and meta-analyses. Then, an empirically-based model of approaching the tired child was proposed according to our center experience.

RESULTS

To correctly characterize the meaning of fatigue reporting, specific clues from history and physical examination should be emphasized. Duration, severity, and the age at onset are to be considered. Then, specific queries about everyday activities, sleep hygiene and social domain could be useful in reaching a specific diagnosis and offering an appropriate treatment.

CONCLUSIONS

We suggest a pragmatic approach to fatigue in children based on age assessment, targeted questions, physical examination clues, and some laboratory first-level tests. This could provide pediatricians with a useful tool to discriminate the broad etiology of such a complaint, disentangling between psychological and organic causes. Further studies are needed to investigate the predictive value, specificity and sensitivity of this diagnostic workflow in managing the child with fatigue.

Electrodiagnostic Assessment of Myopathy

Electrodiagnostic testing is a useful tool in the evaluation of suspected myopathy and helps to confirm the presence of a myopathy and exclude disease mimickers. The electrodiagnostic pattern of findings during testing guides subsequent laboratory evaluation, genetic testing, and in identifying potential muscle biopsy targets. It also provides a baseline for subsequent assessment of disease progression or response to therapy. This article summarizes the approach to electrodiagnostic assessment in various myopathic disorders.

Acute lower extremity arterial thrombosis after intraocular foreign body removal under general anesthesia: A case report and review of literature

BACKGROUND

Surgery, which is a major risk factor for venous thrombosis, has rarely been considered a risk factor for arterial thrombosis. Recent studies have suggested that venous and arterial thromboses share common risk factors and have a bidirectional relationship. Accordingly, there is a growing interest in the risk of arterial thrombosis after surgery. We report a case of acute bilateral lower extremity arterial thromboses that developed after a prolonged surgery.

CASE SUMMARY

A 59-year-old man was hospitalized for intraocular foreign body removal surgery. He was a heavy-drinking smoker and had untreated hypertension and varicose veins in both legs. The operation was unexpectedly prolonged, lasting 4 h and 45 min. Immediately after emergence from general anesthesia, the patient complained of extreme pain in both legs. After the surgical drape was removed, cyanosis was evident in both feet of the patient. The pulse was not palpable, and continuous-wave Doppler signals were inaudible in the bilateral dorsalis pedis and posterior tibial arteries. Computed tomography angiography confirmed acute bilateral thrombotic occlusion of the popliteal arteries, proximal anterior tibial arteries, and tibioperoneal trunks. Arterial pulse returned in both lower limbs after 6 h of heparin initiation. The patient was discharged on postoperative day 26 without any sequelae.

CONCLUSION

Acute lower extremity arterial thrombosis can occur after surgery. Anesthesiologists should pay particular attention to patients with risk factors for thrombosis.

Acute non-traumatic tetraparesis - Differential diagnosis

INTRODUCTION

Potentially life-threatening disorders may present in the emergency department with acute tetraparesis, and their recognition is crucial for an appropriate management and timely treatment. Our review aims to systematize the differential diagnosis of acute non-traumatic tetraparesis.

RESULTS

Causes of tetraparesis can be classified based on the site of defect: upper motor neuron (UMN), peripheral nerve, neuromuscular junction or muscle. History of present illness should include the distribution of weakness (symmetric/asymmetric or distal/proximal/diffuse) and associated clinical features (pain, sensory findings, dysautonomia, and cranial nerve abnormalities such as diplopia and dysphagia). Neurological examination, particularly tendon reflexes, helps further in the localization of nerve lesions and distinction between UMN and lower motor neuron. Ancillary studies include blood and cerebral spinal fluid analysis, neuroaxis imaging, electromyography, muscle magnetic resonance and muscle biopsy.

CONCLUSIONS

Acute tetraparesis is still a debilitating and potentially serious neurological condition. Despite all the supplementary ancillary tests, the neurological examination is the key to achieve a correct diagnosis. The identification of life-threatening neurologic disorders is pivotal, since failing to identify patients at risk of complications, such as acute respiratory failure, may have catastrophic results.

Augmenting Neuromuscular Disease Detection Using Optimally Parameterized Weighted Visibility Graph

In this contribution, we propose a novel neuromuscular disease detection framework employing weighted visibility graph (WVG) aided analysis of electromyography signals. WVG converts a time series into an undirected graph, while preserving the signal properties. However, conventional WVG is sensitive to noise and has high computational complexity which is problematic for lengthy and noisy time series analysis. To address this issue in this article, we investigate the performance of WVG by varying two important parameters, namely penetrable distance and scale factor, both of which have shown promising results by eliminating the problem of signal adulteration and decreasing the computational complexity, respectively. We also aim to unfold the combined effect of these two aforesaid parameters on the WVG performance to discriminate between myopathy, amyotrophic lateral sclerosis (ALS) and healthy EMG signals. Using graph theory based features we demonstrated that the discriminating capability between the three classes increased significantly with the increase in both penetrable distance and scale factor values. Three binary (healthy vs. myopathy, myopathy vs. ALS and healthy vs. ALS) and one multiclass problems (healthy vs. myopathy vs. ALS) have been addressed in this study and for each problem, we obtained optimum parameter values determined on the basis of F-value computed using one way analysis of variance (ANOVA) test. Using optimal parameter values, we obtained mean accuracy of 98.57%, 98.09% and 99.45%, respectively for three binary and 99.05% for the multi-class classification problem. Additionally, the computational time was reduced by 96% with optimally selected WVG parameters compared to traditional WVG.

Ethnicity-related DMD Genotype Landscapes in European and Non-European Countries

Objective

Genetic diagnosis and mutation identification are now compulsory for Duchenne (DMD) and Becker muscular dystrophies (BMD), which are due to dystrophin (DMD) gene mutations, either for disease prevention or personalized therapies. To evaluate the ethnic-related genetic assortments of DMD mutations, which may impact on DMD genetic diagnosis pipelines, we studied 328 patients with DMD and BMD from non-European countries.

Methods

We performed a full DMD mutation detection in 328 patients from 10 Eastern European countries (Poland, Hungary, Lithuania, Romania, Serbia, Croatia, Bosnia, Bulgaria, Ukraine, and Russia) and 2 non-European countries (Cyprus and Algeria). We used both conventional methods (multiplex ligation-dependent probe amplification [MLPA] followed by gene-specific sequencing) and whole-exome sequencing (WES) as a pivotal study ran in 28 patients where DMD mutations were already identified by standard techniques. WES output was also interrogated for DMD gene modifiers.

Results

We identified DMD gene mutations in 222 male patients. We identified a remarkable allele heterogeneity among different populations with a mutation landscape often country specific. We also showed that WES is effective for picking up all DMD deletions and small mutations and its adoption could allow a detection rate close to 90% of all occurring mutations. Gene modifiers haplotypes were identified with some ethnic-specific configurations.

Conclusions

Our data provide unreported mutation landscapes in different countries, suggesting that ethnicity may orient genetic diagnosis flowchart, which can be adjusted depending on the mutation type frequency, with impact in drug eligibility.

Diagnostic modelling and therapeutic monitoring of immune-mediated necrotizing myopathy: role of electrical myotonia

Delayed diagnosis of immune-mediated necrotizing myopathy leads to increased morbidity. Patients with the chronic course without 3-hydroxy-3-methylglutaryl-coenzyme-A reductase-IgG or signal recognition particle-IgG are often challenging to diagnose. Immunotherapy response can also be difficult to assess. We created a statistical model to assist immune-mediated necrotizing myopathy diagnosis. Electrical myotonia versus fibrillations were reviewed as biomarkers for immunotherapy treatment response. Identified were 119 immune-mediated necrotizing myopathy cases and 938 other myopathy patients. Inclusion criteria included all having electrophysiological evaluations, muscle biopsies showing inflammatory/necrotizing myopathies, comprehensively recorded neurological examinations, and creatine kinase values. Electrical myotonia was recorded in 56% (67/119) of retrospective and 67% (20/30) of our validation immune-mediated necrotizing myopathy cohorts, and significantly (P < 0.001) favoured immune-mediated necrotizing myopathy over other myopathies: sporadic inclusion body myositis (odds ratio = 4.78); dermatomyositis (odds ratio = 10.61); non-specific inflammatory myopathies (odds ratio = 8.46); limb-girdle muscular dystrophies (odds ratio = 5.34) or mitochondrial myopathies (odds ratio = 14.17). Electrical myotonia occurred in immune-mediated necrotizing myopathy seropositive (3-hydroxy-3-methylglutaryl-coenzyme-A reductase-IgG 70%, 37/53; signal recognition particle-IgG 29%, 5/17) and seronegative (51%, 25/49). Multivariate regression analysis of 20 variables identified 8 (including electrical myotonia) in combination accurately predicted immune-mediated necrotizing myopathy (97.1% area-under-curve). The model was validated in a separate cohort of 30 immune-mediated necrotizing myopathy cases. Delayed diagnosis of cases with electrical myotonia occurred in 24% (16/67, mean 8 months; range 0–194). Half (8/19) had a chronic course and were seronegative, with high model prediction (>86%) at the first visit. Inherited myopathies were commonly first suspected in them. Follow-up evaluation in patients with electrical myotonia on immunotherapy was available in 19 (median 21 months, range 2–124) which reduced from 36% (58/162) of muscles to 7% (8/121; P < 0.001). Reduced myotonia correlated with immunotherapy response in 64% (9/14) as well as with median creatine kinase reduction of 1779 U/l (range 401–9238, P < 0.001). Modelling clinical features with electrical myotonia is especially helpful in immune-mediated necrotizing myopathy diagnostic suspicion among chronic indolent and seronegative cases. Electrical myotonia favours immune-mediated necrotizing myopathy diagnosis and can serve as an adjuvant immunotherapy biomarker.

Andrographolide promotes skeletal muscle regeneration after acute injury through epigenetic modulation

Myopathy is a muscle disease in which muscle fibers do not function properly, and eventually cause severe diseases, such as muscular dystrophy. The properly regeneration of skeletal muscle plays a pivotal role to maintain the muscle function after muscle injury. The aim of this study is to determine whether andrographolide plays an effect role on regulating skeletal muscle regeneration. Mouse satellite cells, C2C12 cells and Cardiotoxin (CTX) intramuscular injection induced acute skeletal muscle injury model were used to evaluate whether andrographolide is essential for skeletal muscle regeneration. The underling mechanism detected using immunohistochemistry stain, western blot, real time PCR. Andrographolide promotes mouse skeletal muscle regeneration. In cardiotoxin induced skeletal muscle injury model, andrographolide treatment enhanced myotube generation and promoted myotube fusion. Andrographolide treatment dramatically increased expression of myotube differentiation related genes, including Desmin, MyoD, MyoG, Myomaker, Tnni2, Dmd, Myoz1 and Myoz3. For the mechanism studies, we observed that andrographolide treatment significantly promoted histone modification, such as H3K4Me2, H3K4Me3 and H3K36Me2, both in vivo and in vitro. Treatment with DZNep, a Lysine methyltransferase EZH2 inhibitor, significantly attenuated andrographolide-induced expression of Myf5, Myomaker, Skeletal muscle α-actin, MyoD and MyoG. Taken together, our data in this study demonstrate andrographolide epigenetically drives differentiation and fusion of myotube, eventually promotes skeletal muscle regeneration. This should be a therapeutic treatment for skeletal muscle regeneration after muscle damage.

The Italian consensus conference on the role of rehabilitation for children and adolescents with leukemia, central nervous system, and bone tumors, part 1: Review of the conference and presentation of consensus statements on rehabilitative evaluation of motor aspects

Because of increasing survival rates in pediatric oncology, attention is focusing on cancer and its treatment-related side effects. Rehabilitation may reduce their impact. However, the literature does not provide strong evidence regarding rehabilitation pathways. Therefore, the Italian Association of Pediatric Hematology and Oncology organized a consensus conference on the role of rehabilitation of motor impairments in children/adolescents affected by leukemia, central nervous system, and bone tumors to define recommendations for daily practice. The grading of recommendation assessment, developing and evaluation (GRADE) method was used in order to formulate questions, select outcomes, evaluate evidence, and create recommendations. This paper includes the results on the rehabilitation assessment.

Early and consistent pattern of proximal weakness in GNE myopathy

BACKGROUND

GNE myopathy is widely regarded as a distal myopathy. Involvement of proximal musculature in this condition has not been systematically studied.

METHODS

The phenotype of genetically confirmed patients with GNE myopathy was analyzed. Fourteen groups of muscles were evaluated with Medical Research Council (MRC) grading and the average muscle scores (AMS:1-10) were calculated.

RESULTS

Fully documented AMS data was available in 31 of 65 patients. It showed a consistent pattern of severe weakness of hip adductors, hip flexors, knee flexors, and foot dorsiflexors, with milder weakness of the hip extensors and abductors. The knee extensors were largely unaffected. The proximal weakness appeared early in the course of the disease. Proximal muscle weakness was also present in the remaining 34 patients in whom the data were limited. A variant in exon 13 (c.2179G > A) was very common (81.5%).

CONCLUSIONS

The GNE phenotype in this Indian cohort exhibited mixed proximal and distal involvement. Weakness of adductors and flexors of the hip formed an integral part of the phenotype.

Approach to Muscle and Neuromuscular Junction Disorders

PURPOSE OF REVIEW

Muscle and neuromuscular junction disorders are a diverse group of disorders that can be difficult to diagnose. This article provides a diagnostic approach based on clinical history and neurologic examination leading to a narrow set of diagnostic tests.

RECENT FINDINGS

Numerous discoveries in recent years have facilitated clinician access to more advanced laboratory and genetic testing to pinpoint the exact diagnosis in patients with muscle or neuromuscular junction disorders. Large-scale genetic testing has become much less expensive, and free testing has become available for many of the rare conditions because of increased research and the availability of effective therapies for these rare disorders.

SUMMARY

The approach to muscle and neuromuscular junction disorders depends on the clinical pattern of muscle weakness. By classifying patients into one of 10 muscle patterns, diagnostic testing can be targeted and gene testing yield will be optimized. With the increased accessibility and reduced cost of genetic testing (eg, gene panels, whole-exome sequencing, whole-genome sequencing, and chromosomal microarray), this clinical approach to muscle weakness and targeted gene testing will ensure a cost-effective investigational plan. This clinical approach should also assist clinicians in making a timely and accurate diagnosis.

Patients with Interstitial Lung Disease Secondary to Autoimmune Diseases: How to Recognize Them?

The diagnostic assessment of patients with Interstitial Lung Disease (ILD) can be challenging due to the large number of possible causes. Moreover, the diagnostic approach can be limited by the severity of the disease, which may not allow invasive exams. To overcome this issue, the referral centers for ILD organized Multidisciplinary Teams (MDTs), including physicians and experts in complementary discipline, to discuss the management of doubtful cases of ILD. MDT is currently considered the gold standard for ILD diagnosis, but it is not often simple to organize and, furthermore, rheumatologists are still not always included. In fact, even if rheumatologic conditions represent a common cause of ILD, they are sometimes difficult to recognize, considering the variegated clinical features and their association with all possible radiographic patterns of ILD. The first objective of this review is to describe the clinical, laboratory, and instrumental tests that can drive a diagnosis toward a possible rheumatic disease. The secondary objective is to propose a set of first-line tests to perform in all patients in order to recognize any possible rheumatic conditions underlying ILD.

Brody disease: when myotonia is not myotonia

A 56-year-old man presented with painless impairment of muscle relaxation on vigorous contraction (eg, eyelid closure, hand grip, running). There were no episodes of paralysis, symptom progression, weakness or extramuscular symptoms. Five of his fifteen siblings had similar complaints. His serum creatine kinase was normal. Electromyography showed electrical silence on muscle relaxation, without myotonic discharges. DMPK, ClCN1 and SCN4A genetic testing was normal, but he had a homozygous pathogenic variant of ATP2A1 (c.1315G>A; pGlu439Lys). Brody disease is a rare autosomal recessive myopathy due to ATP2A1 mutations that reduce sarcoplasmic reticulum calcium-ATPase1 activity, hence delaying muscle relaxation.

Metabolic Myopathies and the Respiratory System

Metabolic myopathies are a heterogeneous group of disorders characterized by inherited defects of enzymatic pathways involved in muscle cellular energetics and adenosine triphosphate synthesis. Skeletal and respiratory muscles are most affected. There are multiple mechanisms of disease. The age of onset and prognosis vary. Metabolic myopathies cause exercise intolerance, myalgia, and increase in muscle breakdown products during exercise. Some affect smooth muscle like the diaphragm and cause respiratory failure. The pathophysiology is complex and the evidence in literature to guide diagnosis and management is sparse. Treatment is limited. This review discusses the pathophysiology and diagnostic evaluation of these disorders.

Acute Proximal Myopathy in a Young Male—A Case of Infectious Myositis

Background and objectives: Acute proximal muscle weakness has a broad differential. Infectious myositis is difficult to differentiate clinically from inflammatory myopathy, often causing a delayed diagnosis. Infectious myositis should be thought of as a differential for proximal muscle pain and weakness in the right context. Case Presentation: A 40-year-old male with diabetes presented with exquisite pain and weakness of proximal extremities. He denied trauma, recent travel, new medications, or substance use. He denied prior rheumatologic, thyroid, or musculoskeletal disorders. The urine culture revealed staphylococcal infection with negative blood cultures. Rheumatologic and endocrine workups were negative. Random muscle biopsy was negative for inflammatory infiltrate. MRI of thighs and arms showed innumerable foci of nodular and ring enhancement in the proximal muscle groups. The patient noted improvement after about 10 days of antibiotics with complete resolution at 2 months. Discussion and Conclusion: Bacterial myositis is most often due to Staphylococcus aureus (70%) and affects a single muscle. Multifocal abscesses are rare and strongly suggest transient bacteremia. Our patient most likely had transient initiating staphylococcal bacteremia leading to diffuse myositis and hematogenous urinary tract infection (UTI). A delay in treatment can be life-threatening.

Spectrum of Neuromuscular Disorders With HyperCKemia From a Tertiary Care Pediatric Neuromuscular Center

Elevated creatine kinase is a useful screening test in the diagnostic workup of patients with neuromuscular disorders. We did a retrospective study of children with hyperCKemia (>175 IU/L) who were followed in the neuromuscular program of a tertiary care pediatric center from 2005 to 2016. Patients with hyperCKemia were divided into 2 groups: myopathic and nonmyopathic. Within the myopathic group, there were 3 arbitrary subgroups based on creatine kinase values: A (creatine kinase >10 times normal), B (creatine kinase 5-10 times normal), and C (creatine kinase 1-5 times normal). The 3 major categories of myopathies across all the subgroups were muscular dystrophies (commonest) followed by metabolic myopathies and inflammatory myopathies. Among the nonmyopathic causes of hyperCKemia, spinal muscular atrophy was the commonest. Muscular dystrophies should be considered in children with hyperCKemia, muscle weakness, or calf hypertrophy, and metabolic myopathies to be considered in children with recurrent rhabdomyolysis.

Williams Syndrome and Right Ventricular Noncompaction: A Rare Association

Ventricular noncompaction and Williams syndrome are genetic disorders with typical clinical and echocardiographic cardiovascular manifestations. Here, we describe a young patient with rare association of clinical phenotype suggestive of Williams syndrome and right ventricular noncompaction.

An Approach to Myopathy for the Primary Care Clinician

Patients with muscle weakness are frequently encountered in the primary care clinic; however, the identification of an underlying disorder of muscle can pose a significant challenge. The aim of this review article is to provide a clinical and diagnostic framework to aid the primary care clinician in the detection and evaluation of suspected myopathies.

Models of clinical reasoning with a focus on general practice: A critical review

INTRODUCTION

Diagnosis lies at the heart of general practice. Every day general practitioners (GPs) visit patients with a wide variety of complaints and concerns, with often minor but sometimes serious symptoms. General practice has many features which differentiate it from specialty care setting, but during the last four decades little attention was paid to clinical reasoning in general practice. Therefore, we aimed to critically review the clinical reasoning models with a focus on the clinical reasoning in general practice or clinical reasoning of general practitioners to find out to what extent the existing models explain the clinical reasoning specially in primary care and also identity the gaps of the model for use in primary care settings.

METHODS

A systematic search to find models of clinical reasoning were performed. To have more precision, we excluded the studies that focused on neurobiological aspects of reasoning, reasoning in disciplines other than medicine decision making or decision analysis on treatment or management plan. All the articles and documents were first scanned to see whether they include important relevant contents or any models. The selected studies which described a model of clinical reasoning in general practitioners or with a focus on general practice were then reviewed and appraisal or critics of other authors on these models were included. The reviewed documents on the model were synthesized.

RESULTS

Six models of clinical reasoning were identified including hypothetic-deductive model, pattern recognition, a dual process diagnostic reasoning model, pathway for clinical reasoning, an integrative model of clinical reasoning, and model of diagnostic reasoning strategies in primary care. Only one model had specifically focused on general practitioners reasoning.

CONCLUSION

A Model of clinical reasoning that included specific features of general practice to better help the general practitioners with the difficulties of clinical reasoning in this setting is needed.

Proximal Limb Weakness in a Patient with Celiac Disease: Copper Deficiency, Gluten Sensitivity, or Both as the Underlying Cause?

Celiac disease has been associated with several neurologic disorders which may result from micronutrient deficiencies, coexisting autoimmune conditions, or gluten sensitivity. Copper deficiency can produce multiple neurologic manifestations. Myeloneuropathy is the most common neurologic syndrome and it is often irreversible, despite copper replacement. We report the case of a 55-year-old man who presented with progressive proximal limb weakness and weight loss in the setting of untreated celiac disease without gastrointestinal symptoms. He had anemia, neutropenia, and severe hypocupremia. The pattern of weakness raised the suspicion that there was an underlying myopathy, although this was not confirmed by electrodiagnostic studies. Weakness and hematologic abnormalities resolved completely within 1 month of total parenteral nutrition with copper supplementation and a gluten-free diet. Myopathy can rarely occur in patients with celiac disease, but the mechanism is unclear. Pure proximal limb weakness has not been previously reported in copper deficiency. We propose that this may represent a novel manifestation of hypocupremia and recommend considering copper deficiency and gluten sensitivity in patients presenting with proximal limb weakness.

Patterns of Weakness, Classification of Motor Neuron Disease, and Clinical Diagnosis of Sporadic Amyotrophic Lateral Sclerosis

When approaching a patient with suspected motor neuron disease (MND), the pattern of weakness on examination helps distinguish MND from other diseases of peripheral nerves, the neuromuscular junction, or muscle. MND is a clinical diagnosis supported by findings on electrodiagnostic testing. MNDs exist on a spectrum, from a pure lower motor neuron to mixed upper and lower motor neuron to a pure upper motor neuron variant. Amyotrophic lateral sclerosis (ALS) is a progressive mixed upper and lower motor neuron disorder, most commonly sporadic, which is invariably fatal. This article describes a pattern approach to identifying MND and clinical features of sporadic ALS.