Endocrine Myopathies Research Articles

Myopathies of endocrine origin: A review for physicians

Myopathies are a common manifestation of endocrine disorders. Endocrine myopathies are often overlooked while considering differential diagnoses in patients with musculoskeletal symptoms. The hindrance to mobility and the musculoskeletal discomfort owing to these myopathies are important causes of disability and depreciated quality of life in these patients. Endocrine myopathies occur due to the effects of endogenous or iatrogenic hormonal imbalance on skeletal muscle protein and glucose metabolism, disrupting the excitation-contraction coupling. Abnormalities of the pituitary, thyroid, parathyroid, adrenal, and gonadal hormones have all been associated with myopathies and musculoskeletal symptoms. Endocrine myopathies can either be the complication of a secondary endocrine disorder or a presenting symptom of a missed underlying disorder. Therefore, an underlying endocrine abnormality must always be excluded in all patients with musculoskeletal symptoms. This review presents a compilation of various endocrine myopathies, their etiopathogenesis, clinical presentation, diagnostic modalities, and treatment protocols.

Vitamin D Deficiency Presenting as Proximal Myopathy: An Overlooked Diagnosis - A Case Series and Review of the Literature

The prevalence of vitamin D deficiency is ubiquitous. Severe disease can present very dramatically and can be misleading to the treating physician, resulting in mismanagement. A high index of suspicion in vulnerable patients should help circumvent this problem, including a thorough history and physical examination to lead the clinician in the right direction. Insidious onset and progressive proximal pelvic girdle myopathy, in the absence of other neurological findings, in the appropriate patient should prompt the physician to test for serum 25 hydroxyvitamin D levels. The literature on endocrine myopathy does not highlight this condition as much as it does the thyroid, parathyroid, and adrenal aetiologies. Testing for vitamin D deficiency is simple, and treatment is available all over the world. The following article presents three patients, in different scenarios, with the condition. In all three patients, incapacitating pelvic girdle weakness resolved and quality of life improved dramatically with timely intervention. Most importantly, the correct approach prevented misdiagnosis and mismanagement.

A Rare Case of COVID-19 Related Necrotizing Myopathy

Research ObjectivesTo report a case of COVID-19 associated necrotizing myopathy.DesignCase report.SettingFollowing the patient through acute hospitalization, acute rehab to outpatient therapy follow up.ParticipantsA 76-year-old man with known hypogammaglobulinemia on monthly IVIG infusions who presented to the hospital with 1 week of dyspnea and myalgias. He was a former athlete who participated in daily cardiovascular workouts before admission. He was found to have COVID-19 pneumonia.InterventionsPatient was treated with remdesivir and oral dexamethasone. He was transferred to the ICU for 9 days where he received convalescent plasma, intravenous methylprednisolone, and high flow oxygen. He did not require intubation nor sedatives.Main Outcome MeasuresFollowing transfer to the floor, he reported new-onset muscle weakness. Physical examination revealed symmetrical proximal upper and lower extremity weakness with elevated CK at 3665 IU/L. His atorvastatin was held, and steroids were tapered. However, his creatinine kinase continued to rise, peaking at 8335 IU/L. High dose methylprednisolone was resumed with improvement in creatinine kinase. Extensive myositis panel and Anti HMGCR antibody were normal. Thyroid studies revealed transient thyroiditis thought to be induced by COVID-19 infection that did not require treatment.ResultsRight thigh MRI revealed edema of the lateral thigh muscles. Biopsy of the quadriceps showed necrotizing myopathy. Electromyography and NCS revealed inflammatory/immune myositis. Findings were not typical for a steroid, endocrine, or disuse myopathy. He was discharged to an IRF at a dependent level with bilateral hip flexor strength 2/5, triceps 3+/5, and the remainder of his extremity muscles 5/5. By day 40, he was independent with a rolling walker with significant gains in strength.ConclusionsTimely recognition of COVID-19 related myopathy may prevent serious necrotizing muscle injury.Author(s) DisclosuresNone.

МикроРНК и эндокринная офтальмопатия, участие в глюкокортикоидном ответе

The accumulated clinical experience proves the existence of glucocorticoid-resistant forms of endocrine ophthalmopathy. It is assumed that epigenetic factors (miRNA) affect the pathogenesis of the disease and are involved in the formation of the glucocorticoid response. Purpose. To study the role of miRNA-146a and miRNA-155 in patients with clinical forms of endocrine ophthalmopathy and to assess their effect on the glucocorticoid response. Material and method: The study included 20 patients (40 orbits) with image intensifier tubes, treated with glucocorticoids (GC) with a negative result, mean age – 52.65 ± 12.6 years. The control group - 28 volunteers without autoimmune and tumor diseases, age 62.9 ± 7.54 years. The expression level of miRNA-155 and miRNA-146a was determined by real-time PCR. Results: The obtained data indicate an increase in the expression level of miRNA-146a and miRNA-155 in patients with clinical forms of endocrine ophthalmopathy at the stage of fibrosis (p <0.01). Conclusion: The obtained results of the functional activity of miRNA-146a and miRNA-155 confirm their participation in the pathogenesis of the development of edematous exophthalmos and endocrine myopathy by activating the fibroplastic process. Key words: endocrine ophthalmopathy, GC therapy, microRNA.

Endocrine myopathies: clinical and histopathological features of the major forms.

Endocrinopathies, such as thyroid and parathyroid diseases, disorders of the adrenal axis, and acromegaly are included among the many causes of myopathy. Muscle disturbances caused by endocrine disorders are mainly due to alterations in the protein and carbohydrate metabolisms. Either a deficiency or excess of hormones produced by the glands can cause muscle dysfunction that can be reversed by starting hormone replacement therapy or acting on hormone dysfunction. The diagnosis is usually easy if a muscle disorder occurs in an overt endocrinopathy; however, in few patients, myopathy could be the first manifestation of the underlying endocrinopathy. In this article we discuss pathophysiology, clinical features and management of muscle involvement related to the major endocrine diseases.

Endocrine ophthalmopathy: pharmacogenetic markers of efficiency of glucocorticoid therapy

The pathological process of endocrine ophthalmopathy is based on damage to the soft tissues of the orbit against the background of impaired thyroid function and even its euthyroid state. The pathogenetic mechanisms of the development of clinical symptoms of endocrine ophthalmopathy (EOP) are based on morphological changes in extraocular muscles (EOM) and orbital tissue: cellular tissue infiltration by representatives of the immune system (T- and B-lymphocytes, macrophages, mast and plasma cells), with the production of pro-inflammatory cytokines, fibroblasts and glycosaminoglycans, contributing to an increase in the contents of the orbit in volume with the development of exophthalmos and tissue fibrosis at the end of the inflammatory process. Glucocorticoids are the gold standard for the pathogenetic treatment of patients with clinical forms of endocrine ophthalmopathy: edematous exophthalmos and endocrine myopathy. The properties of drugs of this group are such that they can be used to suppress all stages of inflammation in the orbital tissues, preventing the progression of the disease. Despite the many years of experience in applying various glucocorticoid therapy techniques, to date there are no uniform criteria for the effectiveness of this treatment in patients with endocrine ophthalmopathy. The article presents the features of glucocorticoid therapy of endocrine ophthalmopathy, as well as literature data, on the basis of which attempts have been made to explain the causes of glucocorticoid resistance taking into account the pharmacogenetic profile.

Comprehensive Analysis of Systemic Immunosuppression (SIS) Duration after Allogeneic Hematopoietic Stem Cell Transplant: Risk Score Model Provides Stratification of Patients According to Probability of SIS Discontinuation

BACKGROUNDSystemic immunosuppression (SIS) is the standard treatment for significant acute and chronic graft versus host disease (GVHD) after allogeneic hematopoietic cell transplantation (HCT). Previous studies have shown that 30-70% of patients require immunosuppressive treatment for GVHD for more than 2 years. Prolonged SIS increases the risk of infections, recurrence of malignancy and multi-organ complications including endocrine dysfunction, hypertension, myopathy and ocular complications. This study aimed to evaluate the predictive factors associated with increased likelihood of SIS discontinuation from 3 different time points: from the day of transplant in all patients, from the day of treatment of acute GVHD (aGVHD) and from the day of treatment of chronic GVHD (cGVHD). METHODSA retrospective review was conducted in 674 consecutive patients who underwent allogeneic HCT at Princess Margaret Cancer Centre from 2004 to 2013. Analyses were done using cumulative incidence method considering competing risks for SIS discontinuation. The incidence of SIS discontinuation was calculated from 3 time points: from the day of transplant in all patients, from the day of treatment of aGVHD and from the day of treatment of cGVHD. Univariate and multivariate analyses were conducted to identify the predictive factors for SIS discontinuation and hazard ratio (HR) with 95% confidence interval (CI) was calculated using Fine-Gray model.Risk score models were generated based on the results from the multivariate analysis with respect to the 3 time points. Each predictive factor was weighted according to the HR. Risk score models are presented in the Table below: for each risk score model, the patients were divided into 3 risk groups based on the scores. The cumulative incidence of SIS discontinuation was compared according to the risk group for each risk score model as shown in the Figure below. RESULTSWith a median follow-up duration of 3.5 years, the probability of SIS cessation at 3 years was 30.7% (27.0-34.5%) in all patients (n=674), 25.4% (21.2-29.8%) in patients treated for aGVHD (n=457) and 34.6% (29.1-40.3%) in patients treated for cGVHD (n=347).Multivariate analysis confirmed the following predictive factors associated with increased likelihood of SIS discontinuation. In all patients (n=654): age >50 years (vs ≤ 50 yrs; p<0.001, HR 1.83), bone marrow (BM) as a source of stem cells (vs peripheral blood [PBSC]; p=0.002, HR 1.78), T-cell depletion (vs no T-cell depletion; p<0.001, HR 1.98), matched related donor (vs others; p<0.001, HR 1.81) and HLA match (vs partially mismatched HLA; p=0.026, HR 2.58). In patients treated for aGVHD (n=457): age>50 (vs ≤ 50 yrs; p<0.001, HR 1.77), BM (vs PBSC; p<0.001, HR 2.38), matched related donor (vs others; p=0.025, HR 1.55) and aGVHD grade 0-2 (vs grade 3/4 aGVHD; p<0.001, HR 1.77). In patients treated for cGVHD (n=347): age >50 (vs ≤ 50 yrs; p=0.002, HR 1.83), BM (vs PBSC; p=0.004, HR 2.13), Grade 0-2 aGVHD (vs grade 3/4 aGVHD; p=0.003, HR 2.32), cGVHD grade (mild vs moderate vs severe; p<0.001, HR 2.02) and classical subtype (vs overlap syndrome; p=0.028, HR 1.52).The risk score model stratified the patients into low, intermediate and high risk groups: for all patients, SIS discontinuation at 3 years was 52.5% (37.9-65.2%), 30.7% (26.5-35.0%) and 17% (8.6-27.7%) respectively (p<0.0001); in patients treated for aGVHD, SIS discontinuation at 3 years was 70.6% (39.0-87.9%), 29.2% (24.0-34.5%) and 2.7% (0.5-8.6%) respectively (p<0.001); in patients treated for cGVHD, SIS discontinuation at 3 years was 62.8% (48.4-74.3%), 36.4% (29.8-43.0%) and 5.7% (1.0-17.1%) respectively (p<0.001). CONCLUSIONSOlder age, bone marrow as a source of stem cells, T-cell depletion, matched related donor and a full matched donor increase the likelihood of discontinuation of SIS after allogeneic HCT. In addition, the severity of aGVHD and cGVHD significantly affects the chance of SIS discontinuation. The proposed risk score stratifies patients into well-defined groups according to the chance of SIS discontinuation. Further studies in a larger number of patients are strongly recommended to validate this finding. Prospective validation is also warranted to confirm the utility of the risk score as a clinical tool for estimation of likelihood of SIS discontinuation in patients after allogeneic HCT. [Display omitted] DisclosuresLipton:Pfizer: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding.

First-line rituximab combined with short-term prednisone versus prednisone alone for the treatment of pemphigus (Ritux 3): a prospective, multicentre, parallel-group, open-label randomised trial

High doses of corticosteroids are considered the standard treatment for pemphigus. Because long-term corticosteroid treatment can cause severe and even life-threatening side-effects in patients with this disease, we assessed whether first-line use of rituximab as adjuvant therapy could improve the proportion of patients achieving complete remission off-therapy, compared with corticosteroid treatment alone, while decreasing treatment side-effects of corticosteroids. We did a prospective, multicentre, parallel-group, open-label, randomised trial in 25 dermatology hospital departments in France (Ritux 3). Eligible participants were patients with newly diagnosed pemphigus aged 18-80 years being treated for the first time (not at the time of a relapse). We randomly assigned participants (1:1) to receive either oral prednisone alone, 1·0 or 1·5 mg/kg per day tapered over 12 or 18 months (prednisone alone group), or 1000 mg of intravenous rituximab on days 0 and 14, and 500 mg at months 12 and 18, combined with a short-term prednisone regimen, 0·5 or 1·0 mg/kg per day tapered over 3 or 6 months (rituximab plus short-term prednisone group). Follow-up was for 3 years (study visits were scheduled weekly during the first month of the study, then monthly until month 24, then an additional visit at month 36). Treatment was assigned through central computer-generated randomisation, with stratification according to disease-severity (severe or moderate, based on Harman's criteria). The primary endpoint was the proportion of patients who achieved complete remission off-therapy at month 24 (intention-to-treat analysis). This study is registered with ClinicalTrials.gov, number NCT00784589. Between May 10, 2010, and Dec 7, 2012, we enrolled 91 patients and randomly assigned 90 to treatment (90 were analysed; 1 patient withdrew consent before the random assignment). At month 24, 41 (89%) of 46 patients assigned to rituximab plus short-term prednisone were in complete remission off-therapy versus 15 (34%) of 44 assigned to prednisone alone (absolute difference 55 percentage points, 95% CI 38·4-71·7; p<0·0001. This difference corresponded to a relative risk of success of 2·61 (95% CI 1·71-3·99, p<0·0001), corresponding to 1·82 patients (95% CI 1·39-2·60) who would need to be treated with rituximab plus prednisone (rather than prednisone alone) for one additional success. No patient died during the study. More severe adverse events of grade 3-4 were reported in the prednisone-alone group (53 events in 29 patients; mean 1·20 [SD 1·25]) than in the rituximab plus prednisone group (27 events in 16 patients; mean 0·59 [1·15]; p=0·0021). The most common of these events in both groups were diabetes and endocrine disorder (11 [21%] with prednisone alone vs six [22%] with rituximab plus prednisone), myopathy (ten [19%] vs three [11%]), and bone disorders (five [9%] vs five [19%]). Data from our trial suggest that first-line use of rituximab plus short-term prednisone for patients with pemphigus is more effective than using prednisone alone, with fewer adverse events. French Ministry of Health, French Society of Dermatology, Roche.

Rheumatic manifestations of hypothyroidism

The rheumatic manifestations of endocrine diseases are well-known. The endocrine system has a complex effect on the structure and function of musculoskeletal tissues. The symptoms of locomotor apparatus injuries often come to the forefront in the clinical picture of an endocrine disease. It is therefore important to put endocrine diseases, including hypothyroidism, arthropathy, myopathy, etc., in a range of differential diagnoses of musculoskeletal system lesions. It should be remembered that changes in the locomotor system are able to partially or completely regress when endocrine disorders are adequately and long compensated for. The paper describes a clinical case in which, despite an obvious diversity of the typical clinical presentations of hypothyroidism, the main complaint was pain in the joints and muscles. In this connection, the female patient was initially misdiagnosed. This could be avoided if there was alertness to endocrine arthropathies and myopathies.

Differential Diagnosis of Thyrotoxic Myopathy

Along with hereditary myopathies, there are many exogenic (the same a not hereditary) muscle affections due to the pathology of endocrine gland’s functioning. These forms of muscle pathology are called endocrine myopathies. In the cases of thyroid gland hyperfunction (the same a thyrotoxicosis), different regions of neuromuscular system may be involved in the pathological process. Thyrotoxic myopathy (TM) which is a subject of this investigation, occupies one of the first places between thyrotoxic (the same a thyrotoxicosis) neuromuscular affections. Meanwhile, for a long time in literature there was no clarity about the degree of muscle weakness and atrophy to diagnose TM in a patient. It’s because of the fact that the majority of patients complain of increased fatigue and general weakness due to thyrotoxicosis. In present time TM diagnostics is very rare. TM is a phenocopy (the clinical similar) of many neuromuscular diseases. However in literature, the data about peculiarities of clinical picture of TM is almost completely absent, it isn’t known about the frequency of affection of the isolated muscles or muscle groups, the topography of muscle weakness and successive involvement of isolated muscles in the pathological process during different stages of thyrotoxicosis and myopathy. The questions of differential diagnosis with similar neuromuscular disorders are described very poorly. In present article, we accent our attention at the clinical differentiation of the TM with other neuromuscular diseases, namely muscular dystrophy, myasthenia gravis, polymyositis, Addison’s disease, proximal spinal muscular atrophy, steroid myopathy and neurosis. In our opinion, the early diagnosis of TM may help the diagnosis of thyrotoxicosis in patients who have no classical clinical signs of this disease, i.e. in patients with latent thyrotoxicosis.

Endocrine myopathy: Case-based review

Endocrine myopathy means muscle weakness in the presence of an abnormal endocrine state. Most of the endocrine disorders are associated with myopathy and it is usually reversible with correction of the underlying disturbance, though, there is an increasing knowledge of the metabolic effects of hormones, endocrine myopathy is a less recognized and often overlooked entity in clinical practice. Here, we describe this association in three of our patients, then, we discuss systematically about endocrine myopathy.

X-ray semiotics of endocrine ophthalmopathy. Part 1. Extraocular muscles and orbital cellular tissue

Objective : to examine the state of the extraocular muscles and orbital cellular tissue of patients with different clinical forms of endocrine ophthalmopathy. Material and methods . The study involved 294 patients (559 orbits) with endocrine ophthalmopathy. In 87 of them (174 orbits), thyrotoxic exophthalmos was diagnosed, in 172 (343 orbits) – edematous exophthalmos (with myogenic type in 30 patients, lipogenic type in 46, mixed type in 96 patients), in 35 patients (42 orbits) – endocrine myopathy. Results. The article presents the volumes of extraocular muscles and orbital cellular tissue in patients with different forms of endocrine ophthalmopathy. The density of the muscles and orbital cellular tissue was studied in details in those groups of patients. The results show that increase of extraocular muscles volume is greater than increase of orbital cellular tissue volume, and have specific features for each form of endocrine ophthalmopathy. Conclusion . We detected significant quantitative differences in orbit soft tissue volume in patients with endocrine ophthalmopathy. That confirms the feasibility of allocating of three forms of endocrine ophthalmopathy and explains its variative clinical presentations.

Extraocular muscles involvement in patients with thyroid-associated ophthalmopathy

To study morphological features of extraocular muscles in patients with endocrine myopathy taking into account the duration of the disease. A total of 16 patients with thyroid eye disease were included in the study. After a routine ophthalmic examination, they all underwent extraocular muscle surgery and orbital decompression. The biopsy material obtained at surgery was studied histopathologically. Particular morphological changes have been found in muscles of endocrine myopathy patients. Their relationship to disease duration has been also established. Considering endocrine-related morphological changes in extraocular muscles, the favorable period for surgical correction has been defined.

Myositis Mimics.

Patients with autoimmune myositis typically present with muscle weakness, elevated serum levels of muscle enzymes, and abnormal muscle biopsies. However, patients with other acquired myopathies or genetic muscle diseases may have remarkably similar presentations. Making the correct diagnosis of another muscle disease can prevent these patients from being exposed to the risks of immunosuppressive medications, which benefit those with myositis, but not those with other types of muscle disease. Here, we review some of the most common acquired and inherited muscle diseases that can mimic autoimmune myositis, including inclusion body myositis, limb girdle muscular dystrophies, metabolic myopathies, mitochondrial myopathies, and endocrine myopathies. We emphasize aspects of the medical history, physical exam, laboratory evaluation, and muscle biopsy analysis that can help clinicians distinguish myositis mimics from true autoimmune myositis.

Endocrine Myopathies: Clinical Review

Endocrinopathy is generally associated with hormonally-mediated systemic disorders. Myopathy is a result of this association and sometimes can be the first manifestation of endocrine diseases. This condition generally misdiagnosed as weakness and diagnosis and treatment of endocrine diseases are delayed. Especially cushing’s disease, exogen glucocorticoid use, hypothyroidism, hyperaldesteronism and osteomalacia can mimic inflammatory myopathies clinically. Endocrine myopathies are group of disease which must be part of differential diagnosis who has proximal muscle weakness. Statin and glucocorticoid use come to the knowledge of physician because these are the most common cause of drug related proximal myopathy. While evaluating patient with proximal myopathy, thyroid function tests, vitamin D levels, parathyroid hormone must be measured and primary hyperaldesteronism work up when clinically suspicion occurs. Treatment of endocrine myopathies are based on correction of endocrine disorder

Sarcopenia in Endocrine Disorders – The Iceberg or Its Tip?

SummaryEndocrine myopathies represent disorders of the musculoskeletal system that significantly impair the state of health. Sarcopenia is their pathophysiological common denominator. Recent reports have shown that endocrine disorders, even when subclinical, may also be associated with tendinopathies. It may thus be suggested that both hormones and hormonal disorders have complex actions on the musculoskeletal system and that musculoskeletal endocrinology represents a fascinating research area still awaiting exploration.

The impact of romance novels on women's sexual and reproductive health

Myoedema is an under-recognised neurological sign that can help the bedside diagnosis of metabolic or endocrine myopathies. Myoedema together with pseudo-hypertrophy make a likely diagnosis of hypothyroid myopathy, and its...

Evidence-based treatment of metabolic myopathy

Objective To evaluate the current treatments and possible adverse reactions of metabolic myopathy, and to develop the best solution for evidence-based treatment. Methods Taking metabolic myopathy, mitochondrial myopathy, lipid storage myopathy, glycogen storage diseases, endocrine myopathy, drug toxicity myopathy and treatment as search terms, retrieve in databases such as PubMed, Cochrane Library, ClinicalKey database, National Science and Technology Library (NSTL), in order to collect the relevant literature database including clinical guidelines, systematic reviews (SR), randomized controlled trials (RCT), controlled clinical trials, retrospective case analysis and case study. Jadad Scale was used to evaluate the quality of literature. Results Twenty-eight related articles were selected, including 6 clinical guidelines, 5 systematic reviews, 10 randomized controlled trials and 7 clinical controlled trials. According to Jadad Scale, 23 articles were evaluated as high-quality literature (≥ 4), and the remaining 5 were evaluated as low-quality literature (< 4). Treatment principles of these clinical trials, efficacy of different therapies and drug safety evaluation suggest that: 1) Acid α-glycosidase (GAA) enzyme replacement therapy (ERT) is the main treatment for glycogen storage diseases, with taking a high-protein diet, exercising before taking a small amount of fructose orally and reducing the patient's physical activity gradually. 2) Carnitine supplementation is used in the treatment of lipid storage myopathy, with carbohydrate and low fat diet provided before exercise or sports. 3) Patients with mitochondrial myopathy can take coenzyme Q10, vitamin B, vitamin K, vitamin C, etc. Proper aerobic exercise combined with strength training is safe, and it can also enhance the exercise tolerance of patients effectively. 4) The first choice to treat the endocrine myopathy is treating primary affection. 5) Myopathies due to drugs and toxins should remove pathogenic drugs and toxins. Conclusions Most of metabolic myopathies are genetic diseases, and they cannot achieve a radical cure at present. Gene therapy is the fundamental way. Endocrine myopathy and drug toxicity myopathy need to remove the primary affection or pathogenic drugs. Evidence-based medicine can provide the best clinical evidence assessment method for metabolic myopathy. doi: 10.3969/j.issn.1672-6731.2014.05.006

Muscle Disease

On the basis of strong research evidence, Duchenne muscular dystrophy (DMD), the most common severe childhood form of muscular dystrophy, is an X-linked recessive disorder caused by out-of-frame mutations of the dystrophin gene. Thus, it is classified asa dystrophinopathy. The disease onset is before age 5 years. Patients with DMD present with progressive symmetrical limb-girdle muscle weakness and become wheelchair dependent after age 12 years. (2)(3). On the basis of some research evidence,cardiomyopathy and congestive heart failure are usually seen in the late teens in patients with DMD. Progressive scoliosis and respiratory in sufficiency often develop once wheelchair dependency occurs. Respiratory failure and cardiomyopathy are common causes of death, and few survive beyond the third decade of life. (2)(3)(4)(5)(6)(7). On the basis of some research evidence, prednisone at 0.75 mg/kg daily (maximum dose, 40 mg/d) or deflazacort at 0.9 mg/kg daily (maximum dose, 39 mg/d), a derivative of prednisolone (not available in the United States), as a single morning dose is recommended for DMD patients older than 5 years, which may prolong independent walking from a few months to 2 years. (2)(3)(16)(17). Based on some research evidence, treatment with angiotensin-converting enzyme inhibitors, b-blockers, and diuretics has been reported to be beneficial in DMD patients with cardiac abnormalities. (2)(3)(5)(18). Based on expert opinion, children with muscle weakness and increased serum creatine kinase levels may be associated with either genetic or acquired muscle disorders (Tables 1 and 3). (14)(15)

The diagnosis and classification of polymyositis

Polymyositis is classified as a separate entity among idiopathic inflammatory myopathies but it is considered as the least common since it is an exclusion diagnosis. This myopathy usually presents with subacute-chronic symmetric proximal limb weakness, although some extramuscular manifestations are common. Creatine kinase values may be increased up to 50-fold in active disease. Muscle biopsy is characterized by endomysial inflammatory infiltrate consisting predominantly of CD8+ T cells that invade healthy muscle fibres expressing the MHC-I antigen. Although serum autoantibodies, EMG and imaging techniques can help in diagnosis, muscle histopathology is a pivotal value. The clinical picture together with the pathological findings confers the also called PM pattern. A broad differential diagnosis is needed before concluding a diagnosis of pure PM. Sporadic inclusion-body myositis, toxic, endocrine and metabolic myopathies as well as muscular dystrophies are the major categories to be ruled out. Finally, a diagnostic algorithm for suspected cases of PM is also proposed.