Drug-induced and toxic myopathies

Glucocorticoid-Induced Myopathy: Typology, Pathogenesis, Diagnosis, and Treatment

Glucocorticoid-induced myopathy is a non-inflammatory toxic myopathy typified by proximal muscle weakness, muscle atrophy, fatigue, and easy fatigability. These vague symptoms coupled with underlying disorders may mask the signs of glucocorticoid-induced myopathy, leading to an underestimation of the disease's impact. This review briefly summarizes the classification, pathogenesis, and treatment options for glucocorticoid-induced muscle wasting. Additionally, we discuss current diagnostic measures in clinical research and routine care used for diagnosing and monitoring glucocorticoid-induced myopathy, which includes gait speed tests, muscle strength tests, hematologic tests, bioelectrical impedance analysis (BIA), dual-energy X-ray absorptiometry (DXA), computed tomography (CT), magnetic resonance imaging (MRI), electromyography, quantitative muscle ultrasound, histological examination, and genetic analysis. Continuous monitoring of patients receiving glucocorticoid therapy plays an important role in enabling early detection of glucocorticoid-induced myopathy, allowing physicians to modify treatment plans before significant clinical weakness arises.

The impact of glucocorticoids on bone health and growth: endocrine and non-endocrine effects in children and young patients

Glucocorticoids have numerous applications in short and/or long-term therapy both in pediatric and young adults, based on their significant anti-inflammatory and immunosuppressive effects. Different routes of administration can be provided including topical, inhalatory and oral. Topical treatments are the first choice for many dermatologic conditions. The inhalatory form is widely used in asthma management while systemic pathologies often require oral administration. The risks for adverse effects are related to the dose and duration of therapy as well as the specific agent used. Therefore, long-term treatment has a negative impact on different metabolic systems and can lead to hypertension, dyslipidemia and insulin resistance. In particular, many studies emphasize the direct and indirect effects of glucocorticoids on bone health. Glucocorticoids are the most common iatrogenic cause of osteoporosis and can alter bone development in young adults. These side effects are due to an early and transient increase in bone resorption and a decrease in bone formation. Glucocorticoid-induced changes can act on the bone multicellular unit, bone cells and intracellular signaling pathways. Chronic use can also modify bone mass though indirect endocrine and non-endocrine effects by reducing the anabolic function of sex steroids and GH/IGF-1 axis, interfere with calcium metabolism, as well as muscle atrophy and central fat accumulation. The aim of our review was to revise the available evidence on the impact of glucocorticoid treatment on bone health related to endocrine and non-endocrine effects in Young patients.

Muscle involvement in systemic lupus erythematosus: multimodal ultrasound assessment and relationship with physical performance

OBJECTIVES

The objectives of this study were (1) to explore US findings for muscle mass, muscle quality and muscle stiffness in SLE patients and healthy subjects; (2) to investigate the relationship between the US muscle findings and physical performance in SLE patients and healthy subjects.

METHODS

Quadriceps muscle thickness was used for assessment of muscle mass, muscle echogenicity (using a visual semi-quantitative scale and grayscale analysis with histograms) for assessment of muscle quality, and point shear-wave elastography (SWE) for assessment of muscle stiffness in 30 SLE patients (without previous/current myositis or neuromuscular disorders) and 15 age-, sex- and BMI-matched healthy subjects. Hand grip strength tests and short physical performance battery (SPPB) tests were carried out in the same populations.

RESULTS

No difference was observed between SLE patients and healthy subjects for quadriceps muscle thickness (35.2 mm ±s.d. 6.8 vs 34.8 mm ± s.d. 6.0, respectively, P = 0.79). Conversely, muscle echogenicity was significantly increased in SLE patients (visual semi-quantitative scale: 1.7 ± s.d. 1.0 vs 0.3 ± s.d. 0.5, respectively, P < 0.01; grayscale analysis with histograms: 87.4 mean pixels ± s.d. 18.8 vs 70.1 mean pixels ± s.d. 14.0, respectively, P < 0.01). Similarly, SWE was significantly lower in SLE patients compared with healthy subjects {1.5 m/s [interquartile range (IQR) 0.3] vs 1.6 m/s (IQR 0.2), respectively, P = 0.01}. Muscle echogenicity was inversely correlated with grip strength (visual semi-quantitative scale, Rho: -0.47, P = 0.01; grayscale analysis with histograms, Rho: -0.41, p < 0.01) and SPPB (visual semi-quantitative scale, Rho: -0.50, P < 0.01; grayscale analysis with histograms Rho: -0,46, P < 0.01).

CONCLUSIONS

US assessment of muscle echogenicity and stiffness is useful for the early detection of muscle involvement in SLE patients.

Persistence of Chemotherapy-Induced Peripheral Neuropathy Despite Vincristine Reduction in Childhood B-Acute Lymphoblastic Leukemia

BACKGROUND

Children with B-acute lymphoblastic leukemia (B-ALL) are at risk for chemotherapy-induced peripheral neuropathy (CIPN). Children's Oncology Group AALL0932 randomized reduction in vincristine and dexamethasone (every 4 weeks vs 12 weeks during maintenance in the average-risk subset of National Cancer Institute standard-B-ALL (SR AR B-ALL). We longitudinally measured CIPN, overall and by treatment group.

METHODS

AALL0932 standard-B-ALL patients aged 3 years and older were evaluated at T1-T4 (end consolidation, maintenance month 1, maintenance month 18, 12 months posttherapy). Physical and occupational therapists (PT/OT) measured motor CIPN (hand and ankle strength, dorsiflexion and plantarflexion range of motion), sensory CIPN (finger and toe vibration and touch), function (dexterity [Purdue Pegboard], and walking efficiency [Six-Minute Walk]). Proxy-reported function (Pediatric Outcome Data Collection Instrument) and quality of life (Pediatric Quality of Life Inventory) were assessed. Age- and sex-matched z scores and proportion impaired were measured longitudinally and compared between groups.

RESULTS

Consent and data were obtained from 150 participants (mean age = 5.1 years [SD = 1.7], 48.7% female). Among participants with completed evaluations, 81.8% had CIPN at T1 (74.5% motor, 34.1% sensory). When examining severity of PT/OT outcomes, only handgrip strength (P < .001) and walking efficiency (P = .02) improved from T1-T4, and only dorsiflexion range of motion (46.7% vs 14.7%; P = .008) and handgrip strength (22.2% vs 37.1%; P = .03) differed in vincristine and dexamethasone every 4 weeks vs vincristine and dexamethasone 12 weeks at T4. Proxy-reported outcomes improved from T1 to T4 (P < .001), and most did not differ between groups.

CONCLUSIONS

CIPN is prevalent early in B-ALL therapy and persists at least 12 months posttherapy. Most outcomes did not differ between treatment groups despite reduction in vincristine frequency. Children with B-ALL should be monitored for CIPN, even with reduced vincristine frequency.

Impact of Resistance Exercise and Nutritional Endorsement on physical performance in patients with GvHD (IRENE-G study) - design and rational of a randomized controlled trial

BACKGROUND

Graft-versus-host disease (GvHD) remains a major complication and limitation to successful allogeneic hematopoietic stem cell transplantation. Treatment of GvHD is challenging due to its heterogeneous nature of presentation, with steroids remaining the established first-line treatment. Long-term doses of systemic corticosteroids have many well-known side-effects including muscle atrophy. Despite the fact that reports in non-cancer clinical populations treated with glucocorticoids demonstrated that resistance training can reverse atrophy and weakness, no RCT has evaluated the potential of resistance training on preventing the disease- and treatment-induced loss of skeletal muscle mass and function in GvHD patients yet. In this context, ensuring adequate nutrition is important as protein deprivation may accelerate the wasting process. As GvHD patients are commonly found to be malnourished, nutritional medical care should be considered when investigating the effect of exercise in GvHD patients. Therefore, the aim of the present "Impact of Resistance Exercise and Nutritional Endorsement on physical performance in patients with GvHD" - Study (IRENE-G) is to evaluate the effects of resistance exercise in combination with nutritional endorsement on physical, nutritional and patient-reported outcomes in GvHD patients.

METHODS

IRENE-G is a 24-week prospective interventional RCT. One hundred twelve participants will be randomly allocated (1:1) to one of two arms: resistance exercise and nutritional optimization (experimental) vs. nutritional optimization only (control). Participants in the experimental group will engage in a supervised, progressive moderate-to-high intensity resistance training that is consistent with exercise guidelines for cancer patients, while additionally receiving nutritional support/therapy. Subjects of the control group solely receive nutritional support/therapy based on individual needs. Participants will be assessed at baseline, at 8, 16, 24 weeks for physical performance and various physiological, nutritional and patient-reported outcomes. Follow-up will be 6 months after intervention completion.

DISCUSSION

To our knowledge, this will be the first RCT to assess and compare the effects of a resistance intervention supplemented by nutritional support/therapy against nutritional support only on various health-related outcomes in GvHD patients. The study will contribute to our understanding of the value of exercise and nutritional endorsement in counteracting the negative consequences of GvHD and its treatment.

TRIAL REGISTRATION

ClinicalTrials.gov : NCT05111834 . Registered 8 November 2021 - Retrospectively registered.

Imaging of Joint and Soft Tissue Involvement in Systemic Lupus Erythematosus

PURPOSE OF REVIEW

To highlight the potential uses and applications of imaging in the assessment of the most common and relevant musculoskeletal (MSK) manifestations in systemic lupus erythematosus (SLE).

RECENT FINDINGS

Ultrasound (US) and magnetic resonance imaging (MRI) are accurate and sensitive in the assessment of inflammation and structural damage at the joint and soft tissue structures in patients with SLE. The US is particularly helpful for the detection of joint and/or tendon inflammation in patients with arthralgia but without clinical synovitis, and for the early identification of bone erosions. MRI plays a key role in the early diagnosis of osteonecrosis and in the assessment of muscle involvement (i.e., myositis and myopathy). Conventional radiography (CR) remains the traditional gold standard for the evaluation of structural damage in patients with joint involvement, and for the study of bone pathology. The diagnostic value of CR is affected by the poor sensitivity in demonstrating early structural changes at joint and soft tissue level. Computed tomography allows a detailed evaluation of bone damage. However, the inability to distinguish different soft tissues and the need for ionizing radiation limit its use to selected clinical circumstances. Nuclear imaging techniques are valuable resources in patients with suspected bone infection (i.e., osteomyelitis), especially when MRI is contraindicated. Finally, dual energy X-ray absorptiometry represents the imaging mainstay for the assessment and monitoring of bone status in patients with or at-risk of osteoporosis. Imaging provides relevant and valuable information in the assessment of MSK involvement in SLE.

Reduction in stiffness of proximal leg muscles during the first 6 months of glucocorticoid therapy for giant cell arteritis: A pilot study using shear wave elastography

AIM

To investigate muscle stiffness changes in patients treated for giant cell arteritis (GCA) with high-dose oral glucocorticoids.

METHODS

Using ultrasound elastography, shear wave velocity (SWV) was measured in the quadriceps, hamstrings and biceps brachii muscles of 14 patients with GCA (4 male, mean age ± SD, 68.2 ± 4.3 years) within the first 2 weeks of initiating glucocorticoid treatment (baseline) and repeated after 3 and 6 months treatment. Muscle strength and performance tests were performed at each visit. Baseline measures were compared with those from 14 healthy controls. Linear mixed models were used to test for change in patient measures over time.

RESULTS

At baseline, muscle SWV in patients was not significantly different from controls. With glucocorticoid treatment, there was a reduction in SWV in the leg but not the arm muscles. SWV decreased by a mean of 14% (range 8.3%-17.3%; P = .001) after 3 months and 18% (range 10.2%-25.3%; P < .001) after 6-months in the quadriceps and hamstrings during the resting position. The baseline, 3 and 6 months mean SWV (±SD) for the vastus lateralis were 1.62 ± 0.16 m/s, 1.40 ± 0.10 m/s and 1.31 ± 0.06 m/s, respectively (P < .001). In the patient group as a whole, there was no significant change in muscle strength. However, there were moderate correlations (r = .54-.69) between exhibiting weaker muscle strength at follow-up visits and a greater reduction in SWV.

CONCLUSION

Glucocorticoid therapy in patients with GCA was associated with a significant reduction in proximal leg muscle stiffness during the first 6 months. Future research should study a larger sample of patients for a longer duration to investigate if diminished muscle stiffness precedes signs of glucocorticoid-induced myopathy.

A Schiff-base receptor based chromone derivate: Highly selective fluorescent and colorimetric probe for Al(III)

Upon excitation of the visible light, probes show colorimetric and fluorescent responses to the specific metal ion, which can be easily detected by the naked eye. Owing to the excitation of the visible light at 423 nm, a novel and simple Schiff-base receptor based chromone derivative called 7-methoxychromone-3-carbaldehyde-(indole-3-formyl) hydrazone (MCIH2) had been investigated as a selective and sensitive probe for Al³⁺ with colorimetric and fluorescent responses. Upon addition of Al³⁺ to compound MCIH2 solution, compound MCIH2 could respond to Al³⁺ with a good selective colorimetric signal, which was easily observed from colorless to yellow-green by the naked eye. Furthermore, a remarkable fluorescence emission enhancement with an "OFF-ON" signal by over 700-fold was triggered, but other various metal ions had no such significant effects on the fluorescence emission. In addition, the detection limit of compound MCIH2 for recognizing Al³⁺ was evaluated to be as low as 1 × 10^-7 M level, which was sufficiently low for sensing Al³⁺ widely distributed in various environmental and biological systems.

Negative impact of chronic graft-versus-host disease and glucocorticoid on the recovery of physical function after allogeneic hematopoietic stem cell transplantation

Quality of life of patients who undergo allogeneic hematopoietic stem cell transplantation (HSCT) temporally deteriorates and recovers over several years. We retrospectively evaluate the impact of chronic graft-versus-host disease (GVHD) and glucocorticoid on physical recovery. We included 162 patients who underwent their first allogeneic HSCT between October 2010 and December 2015 in a single hospital. All patients are planned to undergo physical function tests before and 1, 3, 12 months after allogeneic HSCT. Scores of knee extension strength and distance covered in the 6-min walk test (6MWT) recovered at the 12-month assessment. Both chronic GVHD and high dose glucocorticoid were associated with delayed recovery of body mass index (BMI), hand grip strength, knee extension strength, and duration of standing on one foot. Lung GVHD and high dose glucocorticoid had negative impact on the distance covered in the 6MWT. A multivariate analysis revealed that chronic GVHD and glucocorticoid was an independent risk factor for decreased BMI and delayed recovery of muscle strength, respectively. Our results suggest that high-risk patients who have chronic GVHD or who receive glucocorticoid therapy may require reduced dose of glucocorticoid and long-term physical support to recover physical function after transplantation.

Succinylcholine-Induced Rhabdomyolysis in Adults: Case Report and Review of the Literature

PURPOSE

A case of succinylcholine (SCh) and sevoflurane as a probable cause of rhabdomyolysis in an adult is presented, along with a review of the relevant literature and strategies for prevention.

SUMMARY

A nondiabetic, morbidly obese 32-year-old female developed rhabdomyolysis after administration of SCh and sevoflurane for diagnostic procedures of 30 minutes' duration. Thirty-three hours following anesthesia, the patient developed diffuse muscle tenderness and progressive weakness with a creatinine kinase (CK) of 4319 U/L. Urinalysis findings indicated contamination, a white blood cells of 12.1 × 10³/μL was stress induced, while all other labs were normal. Following 26 hours of intravenous fluids, the patient's CK decreased to 1243 U/L, with pain responsive to acetaminophen and improved mobility, resulting in discharge. With a lack of reasonable alternative causes and a temporal association of symptoms, procedural medication-induced rhabdomyolysis was suspected. Based on Naranjo scale evaluation, SCh and sevoflurane were probable causes of rhabdomyolysis. We reviewed the literature for SCh-induced rhabdomyolysis among adults and found 10 cases. The majority of patients received halogenated anesthesia (HA) and prophylaxis for SCh myopathy, with no known personal or family history of neuromuscular disorders (NMD) reported.

CONCLUSION

Rhabdomyolysis was observed in a woman following the administration of SCh and sevoflurane for diagnostic procedures lasting 30 minutes. While avoidance is possible in adults with histories of NMDs, a high index of suspicion for occurrence of rhabdomyolysis is needed whenever combining SCh with HA in all adults.

Antipsychotic-induced disorders: Reported cases and prospective study on muscle biomarkers after high exposure to haloperidol

Antipsychotic drugs are known to induce neuromuscular effects. In this study, we review 13 years (2002-2014) of antipsychotic intoxications reported by the anti-poisoning center of Algiers (APCA). The most recorded symptoms were neuromuscular/muscular disorders, of which haloperidol was the most inducer among all antipsychotics. A prospective study was conducted between December 2012 and January 2017 to evaluate muscle effects generated after intentional or accidental ingestion of haloperidol. Fifty-one patients admitted in different emergency departments in Algiers were included in this study. Urine and blood samples were collected from each patient for biological and toxicological monitoring and a group of healthy volunteers was assessed for comparison purpose. There was no significant difference in plasma lactate dehydrogenase (LDH) activity between healthy volunteers and exposed patients even when high levels of haloperidol were recorded. In contrast, selenium concentration and creatine kinase (CK) activity in plasma samples were significantly higher in patients exposed to high levels of haloperidol compared to healthy volunteers. Large percentage of patients exposed to high levels of haloperidol presented a significant elevated CK activity and high selenium concentration regarding the physiological thresholds. Additionally, CK activity and selenium concentration correlated positively with plasma content of haloperidol suggesting a dose-dependent relationship. In conclusion, some biomarkers (CK and selenium) may reflect muscle adverse effects of high haloperidol exposure that result possibly from muscle rigidity.

Hereditary spastic paraplegia protein spartin is an FK506-binding protein identified by mRNA display

Here, we used mRNA display to search for proteins that bind to FK506, a potent immunosuppressant drug, and identified spartin, a hereditary spastic paraplegia protein, from a human brain cDNA library. We demonstrated that FK506 binds to the C-terminal region of spartin and thereby inhibits the interaction of spartin with TIP47, one of the lipid droplet-associated proteins. We further confirmed that FK506 inhibits localization of spartin and its binder, an E3 ubiquitin ligase AIP4, in lipid droplets and increases the protein level of ADRP (adipose differentiation-related protein), which is a regulator of lipid homeostasis. These results strongly suggest that FK506 suppresses the proteasomal degradation of ADRP, a substrate of AIP4, by inhibiting the spartin-TIP47 interaction and thereby blocking the localization of spartin and AIP4 in lipid droplets.

Blood cardiac troponin in toxic myocardial injury: archetype of a translational safety biomarker

A translational safety biomarker for toxic myocardial injury is needed in drug discovery and development. This need reflects the increasing recognition of occurrence of cardiotoxicities, prior lack of preclinical blood biomarkers for toxic cardiac injury, introduction of troponin as a biomarker, and regulatory and industry drivers. Cardiac troponin is considered the gold-standard biomarker in humans for cardiac injury due to ischemic injury and drug toxicity. It has been demonstrated to correlate highly with histopathological extent of injury, degree of impairment of cardiac function, and prognosis. Numerous studies have now clearly demonstrated that both cardiac troponin T and cardiac troponin I are sensitive and specific biomarkers of cardiac injury in laboratory animals. Their use is highly recommended for incorporation into preclinical drug-safety studies, especially whenever there is any history of cardiac effect in prior studies with a compound of the same or similar chemical or pharmacological class. The main caveats with respect to cross-species use of specific cardiac troponin assays are the need for species-specific validation, definition of cut-offs based on relevant assessments of imprecision and reference ranges or concurrent controls, and knowledge of the species-dependent kinetics of release into, and clearance from, the blood. Future development of high-sensitivity assays should determine whether minimal increases below a threshold concentration of troponin might reflect reversible myocardial effects.

Classification, diagnosis, and management of idiopathic inflammatory myopathies

The detection and characterization of a large array of autoantibodies, including at least 8 different antisynthetase, anti-SRP, -200/100 (HMGCR), -Mi-2, -CADM-140 (MDA5), -SAE, -p155, -MJ (NXP-2), and -PMS1, frequently associated with distinct and well-defined clinicopathological features, allowed for significant improvement in the definition and diagnosis of idiopathic inflammatory myopathies (IIM). Classification remains difficult, with lingering divergence between the different specialties involved in IIM care, but several categories clearly stand out, including dermatomyositis (DM), overlap myositis (OM), polymyositis, necrotizing myositis, and sporadic inclusion body myositis (s-IBM). Biopsy and histological analysis remain crucial, particularly in the absence of autoantibodies, to accurately specify the diagnosis and rule out mimics such as muscular dystrophies and metabolic myopathies. Numerous infectious agents (in particular human immunodeficiency virus and human T cell lymphotrophic virus-1) and drugs (statins, tumor necrosis factor inhibitors, and proton pump inhibitors) can cause mimic IIM that must also be excluded. Pharmacological treatment, in addition to glucocorticoids and immunoglobulins, now includes mycophenolate mofetil and rituximab, which proved helpful in resistant cases, particularly rituximab in DM and OM. Exercise, initially seen as potentially deleterious, recently was shown to be efficacious and safe. IIM can thus be reasonably well controlled in most cases, although aggressive disease remains refractory to treatment, including some cases of necrotizing myopathy. Sporadic IBM still seems resistant to all medications tested to date.

Advances in the epidemiology, pathogenesis, and management of Cushing's syndrome complications

Cushing's syndrome (CS) is a clinical condition resulting from chronic exposure to glucocorticoid excess. As a consequence, hypercortisolism contributes significantly to the early development of systemic disorders by direct and/or indirect effects. Complications such as obesity, hypertension, diabetes, dyslipidemia, and hypercoagulability cause premature atherosclerosis and increase cardiovascular mortality. Impairment of the skeletal system is a relevant cause of morbidity and disability in these patients especially due to the high prevalence of vertebral fractures. In addition, muscle weakness, emotional lability, depression, and impairment of quality of life are very common. Clinical management of these patients is complex and should be particularly careful in identifying global cardiovascular risks and aim at controlling all complications. Although the primary goal in the prevention and treatment of complications is the correction of hypercortisolism, treatment does not completely eliminate these comorbidities. Given that cardiovascular risk and fracture risk can persist after cure, early detection of each morbidity could prevent the development of irreversible damage. In this review we present the various complications of CS and their pathogenetic mechanisms. We also suggest the clinical management of these patients based on our extensive clinical experience and on the available literature.

Essential muscle pathology for the rheumatologist

This review introduces/refreshes some basic histopathologic methods and findings of skeletal muscle biopsies with emphasis on those diseases commonly encountered in a rheumatologist's practice. The 3 general areas of myopathology discussed are metabolic myopathies, toxic myopathies, and inflammatory myopathies. The authors, neuropathologists, hope to provide in this article what they think are some commonalities and disease-specific methods in their pathologic workup as well as a practical approach to the collaboration that pathologists undertake with their rheumatology colleagues to come to a working diagnosis.

Statins alter intracellular calcium homeostasis in malignant hyperthermia susceptible individuals

AIMS

Statines, HMG-CoA reductase inhibitors, are widely used to treat hypercholesterinemia. These substances are well tolerated, but myotoxic effects have been reported. The exact mechanisms of the induced myotoxicity are unknown but an involvement of intracellular calcium handling is suspected. Individuals susceptible to malignant hyperthermia (MH) have an impaired calcium homeostasis. An in vitro test measuring contracture responses of isolated muscle bundles is used to investigate cellular processes of MH. Aim of this study was to investigate if statins modify the contracture response of isolated muscle bundles from MH susceptible (MHS) and nonsusceptible (MHN) pigs.

METHODOLOGY

With approval of the local ethics committee muscle biopsies of 18 MH susceptible and 12 nonsusceptible pigs were performed. Muscle bundles were mounted on an isometric force transducer, preloaded, and electrically stimulated. After establishment of a stable baseline, muscle bundles were exposed to simvastatin, atorvastatin, gemfibrocil, and the pure solvent. Baseline tension was measured and analyzed for changes with P < 0.05 considered to be significant.

RESULTS

There were no differences in weight, length, and predrug baseline tension between the groups. Both simvastatin and atorvastatin induced significant contractures in muscle bundles from MHS pigs. Gemfibrocil and the solvent methanol showed no effect. In MHN muscle bundles, none of the tested substances induced a contracture. Statines induce contractures only in MHS muscle bundles.

CONCLUSION

We therefore conclude that the underlying mechanism may be a pathologic influence on intracellular calcium handling that is absent in MHN. A preexisting impairment of the calcium homeostasis seems to be necessary for this behavior because muscle bundles of MHN pigs showed no pathologic reaction. A higher muscle cell vulnerability toward statins is assumed in MHS patients. Statins ought to be used with caution in these individuals. Analogous a diagnostic workup for MH should be considered for patients with statin-induced rhabdomyolyis.

Environmental factors preceding illness onset differ in phenotypes of the juvenile idiopathic inflammatory myopathies

Objective. To assess whether certain environmental factors temporally associated with the onset of juvenile idiopathic inflammatory myopathies (JIIMs) differ between phenotypes.

Methods. Physicians completed questionnaires regarding documented infections, medications, immunizations and an open-ended question about other noted exposures within 6 months before illness onset for 285 patients with probable or definite JIIM. Medical records were reviewed for 81% of the patients. Phenotypes were defined by standard clinical and laboratory measures.

Results. Sixty per cent of JIIM patients had a reported exposure within 6 months before illness onset. Most patients (62%) had one recorded exposure, 26% had two and 12% had three to five exposures. Patients older than the median age at diagnosis, those with a longer delay to diagnosis and those with anti-signal recognition particle autoantibodies had a higher frequency of documented exposures [odds ratios (ORs) 95% CI 3.4, 31]. Infections were the most common exposure and represented 44% of the total number of reported exposures. Non-infectious exposures included medications (18%), immunizations (11%), stressful life events (11%) and unusual sun exposure (7%). Exposures varied by age at diagnosis, race, disease course and the presence of certain myositis autoantibodies.

Conclusion. The JIIMs may be related to multiple exposures and these appear to vary among phenotypes.

Glucocorticoid-induced myopathy

Glucocorticoid-induced myopathy, characterized by muscle weakness without pain, fatigue and atrophy, is an adverse effect of glucocorticoid use and is the most common type of drug-induced myopathy. This muscle disturbance has a frequency of 60%, and it has been most often associated with fluorinated glucocorticoid preparations. Glucocorticoids have a direct catabolic effect on muscle, decreasing protein synthesis and increasing the rate of protein catabolism leading to muscle atrophy. In clinical practice, it is important to differentiate myopathy due to glucocorticoid from muscle inflammatory diseases. The treatment is based on reduction or, if possible, on discontinuation of the steroid. Fluorinated glucocorticoids such as dexamethasone should be replaced with nonfluorinated glucocorticoids such as prednisone. Other experimental treatments may be tried such as IGF-I, branched-chain amino acids, creatine, androgens such as testosterone, nandrolone and dehydroepiandrosterone (DHEA), and glutamine.

Statin use and its association with musculoskeletal symptoms--a cross-sectional study in primary care settings

INTRODUCTION

Musculoskeletal complaints are very common in primary care settings. Lipid-lowering drugs are one of several causes of musculoskeletal symptoms. However, data showing an association of lipid-lowering drug therapy and increased odds of musculoskeletal complaints in primary care patients are lacking.

OBJECTIVE

To investigate the association between statin use and the reporting of muscular complaints by patients and simultaneously control for several known factors of musculoskeletal complaints.

METHODS

In a cross-sectional study with 1031 consecutive patients (>50 years of age) in 26 offices of GPs, two investigators collected the data from the office files and by interviewing the patients. A logistic regression model was used to identify variables affecting the odds of muscular symptoms.

RESULTS

The prevalence of lipid-lowering drug prescription was 23% (n = 239) and that of muscular complaints was 40% (n = 411). In all, 44% (n = 106) of the patients with lipid-lowering drug prescription had muscular complaints compared to 39% (n = 305) of the patients without lipid-lowering drug therapy. Statin prescription and 10 variables remained in the final model. Statin prescription is associated with a 1.5-fold odds of musculoskeletal complaints compared to non-prescription {odds ratio [OR] = 1.5 [95% confidence interval (CI), 1.1-2.0], P = 0.02}.

CONCLUSION

Having a statin prescription appears to be an independent factor associated with musculoskeletal symptoms in primary care settings. Statin use may be more often associated with musculoskeletal complaints than previously assumed.

Cardiac troponin is the most effective translational safety biomarker for myocardial injury in cardiotoxicity

There is an overwhelming weight of evidence that certifies cardiac troponin (cTn) as the preferred, defacto, translational, safety biomarker for myocardial injury in cardiotoxicity. As well as being the gold standard for cardiac injury in man, it has been widely used for clinical assessment and monitoring of cardiac toxicity in humans being treated for cancer. Furthermore, several dozen preclinical published studies have directly confirmed its effectiveness in laboratory animals for assessment of cardiotoxicity. It is gradually being reverse translated from human into animal use as a safety biomarker. Its use is especially merited whenever there is any safety signal indicating potential cardiotoxicity and its required inclusion as a routine biomarker in preclinical safety studies seems on the horizon. There are some considerations that are unique to use of cTn assays in animals. Lack of awareness of these has, historically, significantly inhibited the introduction of cTn as a safety biomarker in preclinical toxicology. Firstly, cross-species reactivity is usually but not always high. Secondly, there is a background of cardiac injury that needs to be controlled for, including spontaneous cardiomyopathy in Sprague Dawley rats, and inappropriate blood collection methods. Also, there are faster kinetics of clearance in rats than for humans. Also, coincident muscle injury is frequent with cardiotoxicity and requires a skeletal muscle biomarker. Because cTn assays were developed for detection of gross cardiac necrosis, such as occurs with myocardial infarct, the more sensitive assays should be used for preclinical studies. However, analytic sensitivity is higher for standard preclinical studies than for clinical diagnostic testing because of use of concurrent controls and use of batch analysis that eliminates interassay variability. No other biomarker of myocardial injury comes close to cTn in effectiveness, including CK-MB, LDH-1 and 2, myoglobin, and FABP3. In addition to the use of cTn for monitoring active myocardial degeneration, there is growing evidence that measurements of brain natriuretic peptide (BNP) may be effective for monitoring drug-induced left ventricular dysfunction.

The syndrome of rhabdomyolysis: Pathophysiology and diagnosis

Rhabdomyolysis is defined as a pathological condition of skeletal muscle cell damage leading to the release of toxic intracellular material into the blood circulation. Its major causes include trauma, ischemia, drugs, toxins, metabolic disorders, and infections. The pathophysiological hallmark of the syndrome is an increase in intracellular free ionized calcium due to either cellular energy depletion, or direct plasma membrane rupture. The increased intracellular calcium activates several proteases, intensifies skeletal muscle cell contractility, induces mitochondrial dysfunction, and increases the production of reactive oxygen species, ultimately resulting in skeletal muscle cell death. Clinically, the syndrome presents with severe muscular pain, weakness and myoglobinuria. Increased myoglobin and creatine phosphokinase as a consequence of muscular cell death are the major laboratory findings, which, in combination with the clinical presentation, lead the clinician to the final diagnosis of the syndrome.

In vivo and in vitro characterization of skeletal muscle metabolism in patients with statin-induced adverse effects

OBJECTIVE

Statins (3-hydroxymethylglutaryl-coenzyme A reductase inhibitor) are widely used to treat hypercholesterolemia. They are generally well tolerated, but myotoxic effects have been reported and the corresponding mechanisms are still a matter of debate. The aim of the present study was to determine whether impairment of calcium homeostasis and/or mitochondrial impairment could account for the adverse effects of statins in skeletal muscle.

METHODS

Eleven patients with increased creatine kinase levels and myalgias after statin treatment were evaluated using in vitro contracture tests (IVCTs), histology, and 31P magnetic resonance spectroscopy (31P-MRS).

RESULTS

IVCT results were abnormal in 7 of the 9 patients, indicating an impaired calcium homeostasis. The 31P-MRS investigation disclosed no anomaly at rest, and the aerobic function assessed during the postexercise recovery period was normal. On the contrary, the pH recovery kinetics was significantly slowed down as indicated by a reduced proton efflux, which could be ultimately linked to a failure of calcium homeostasis. Overall, our observations indicate a normal mitochondrial function and raise the possibility that statins may unmask a latent pathology involving an impairment of calcium homeostasis such as malignant hyperthermia (MH).

CONCLUSION

In case of susceptibility to MH, statins treatment must be administered with caution, and signs of adverse effects should be checked.

Systemic sarcoidosis: the “leopard–man” sign

Systemic sarcoidosis is often diagnosed late. A 37 year-old man from the Antilles was admitted for evaluation of arthralgia, subcutaneous and cutaneous nodules, multiple enlarged lymph nodes, and an epididymal lump. He had been given a diagnosis of epididymal and nodal tuberculosis but had not responded to antitubercular agents. Gallium-67 scintigraphy showed multiple hot spots in the soft tissues, skin, muscles, mediastinum, and lachrymal glands, producing a diffuse dappled pattern. Magnetic resonance imaging of the thighs confirmed the muscular and subcutaneous involvement. Systemic sarcoidosis was diagnosed. Prednisone therapy was promptly effective. We suggest the term "dappled-body sign" or "leopard-man sign" to designate the heretofore undescribed scintigraphic pattern in our patient.

Dermatomyosite induite par la pravastatine

INTRODUCTION

The toxic myopathy caused by statins (HMG-CoA reductase inhibitors) is well established. Recent reports add to these effects systemic immune diseases including systemic lupus erythematosus, vasculitis, polymyositis or dermatomyositis.

EXEGESIS

We report a case of dermatomyositis in a 69-year-old patient treated with pravastatin [Elisor]. She presented with typical features of dermatomyositis 2 years after she started a treatment with pravastatin. The treatment was discontinued and she slowly improved, with a transient dermocorticosteroid treatment. Eight other patients with dermatomyositis and chronic treatment with HMG-CoA reductase inhibitors are reported in the literature. All of them presented with classical features of dermatomyositis. The discontinuation of the treatment was followed by spontaneous clinical and biological improvement in 3/9 patients. The other patients received high doses of corticosteroids and improved, except one patient who died of respiratory failure (pulmonary fibrosis) despite the adjunction of oral cyclophosphamide [Endoxan]. In these patients, dermatomyositis can be considered as a severe adverse reaction to HMG-CoA reductase inhibitors although a distinct casual link cannot be definitely established.

CONCLUSION

The increasing prescription of statins has led to the parallel increment of reported side-effects, where autoimmune diseases are now described. Among them, our case of dermatomyositis in a patient receiving pravastatin adds to the eight reported cases in the literature and highlights the potential role of statins as triggers of immune systemic diseases.

Acute Myopathy in a Patient with Concomitant Use of Pravastatin and Colchicine

OBJECTIVE

To report a case of acute myopathy after concomitant use of colchicine and pravastatin.

CASE SUMMARY

A 65-year-old woman was admitted to the hospital with an acute episode of gout. She had been taking pravastatin 20 mg once daily for 6 years. On admission, blood urea nitrogen and serum creatinine levels were 48 mg/dL and 1.3 mg/dL, respectively. Colchicine 1.5 mg/day was added to the treatment regimen, but 20 days after the initiation of colchicine therapy, symmetrical proximal muscle weakness developed in the woman's legs. Physical examination, laboratory findings, and electromyelogram findings suggested myopathy. The Naranjo probability scale indicated a probable relationship between myopathy and combined therapy. Seven days after discontinuation of colchicine and pravastatin, the patient's weakness improved and enzyme levels returned to normal. Colchicine was restarted at 1.0 mg/day 5 days later; no myopathy occurred.

DISCUSSION

Hydroxymethylglutaryl coenzyme A reductase inhibitors (statins) and colchicine are known to cause myopathy. Most of the statins and colchicine are biotransformed in the liver primarily by the CYP3A4 system, which may increase the risk of myopathy when concurrent therapy is used. However, pravastatin is not primarily metabolized by cytochrome P450 isoenzymes. The cause of myopathy in our patient may be related to the interaction of colchicine and pravastatin via P-glycoprotein. In addition, the presence of mild renal dysfunction could have contributed to the development of myopathy.

CONCLUSIONS

We suggest that clinicians be aware that neuromuscular toxicity can occur in patients with mild renal dysfunction with combined use of colchicine and pravastatin.

[Cyclosporin-induced toxic neuromyopathy]

INTRODUCTION

Cyclosporine is an immunosuppressive treatment whose side effects limit its usefulness. Among neurological side effects, neuropathies or myopathies have been reported, specially inpatients given combinations of cyclosporine with co-enzyme A reductase inhibitors.

CASE REPORT

We report here the case of a 67-year-old woman who developed few months after a kidney graft sensorimotor disorders which progressed rapidly. Since all etiologies of such a disorder were ruled out, the hypothesis of toxicity exclusively induced by cyclosporine was suggested and confirmed by the improvement observed after its withdrawal.

CONCLUSION

This observation highlights the fact that cyclosporine may induce neuromyopathies even when given alone at the therapeutic dosage.

Fluoroquinolones and tendon disorders

Fluoroquinolones are the most potent oral antibiotics in clinical use today. Increasingly, these drugs are being prescribed for relatively benign infections and for new categories of patients, including paediatric patients. As their use becomes more frequent, so will the adverse events. This review focuses on a rare but debilitating adverse reaction, the fluoroquinolone-associated tendinopathy. Despite many published case reports and approximately 3500 cases reported to the World Health Organization Collaborating Centre for Drug Monitoring, little is known about the mechanisms behind this fluoroquinolone-specific toxicity. Data on chemical properties, mode of action, pharmacokinetic features, clinical presentation and risk factors in relation to tendon toxicity are discussed and the literature reviewed. As long as the musculoskeletal toxicity cannot be predicted by in vitro or in vivo models and this class of antibiotics is one of the most commonly linked to selection of resistant bacteria, a more prudent use of fluoroquinolones is warranted.

Complications of anaesthesia in neuromuscular disorders

The purpose of this review is to alert non-anaesthesiologists to the various complications from which patients with neuromuscular disorders and those susceptible to malignant hyperthermia can suffer during anaesthesia. The patient's outcome correlates with the quality of consultation between anaesthesiologists, surgeons, neurologists and cardiologists. Special precautions must be taken, since many anaesthetics and muscle relaxants can aggravate the clinical features or trigger life-threatening reactions. Complications frequently occur in these patients, although anaesthetic procedures have become safer by the reduced administration of suxamethonium and the use of total intravenous anaesthesia, new volatile anaesthetics and non-depolarising relaxants. This review provides a synopsis of pre-operative anaesthetic considerations and adverse drug effects on skeletal, cardiac and smooth muscle tissue. It describes the pathogenetic aspects of typical complications and introduces anaesthetic procedures for the various neuromuscular disorders, including regional anaesthesia for patients in whom a restriction of respiratory and/or cardiac function is predicted.