Muscle abnormalities in juvenile dermatomyositis patients: P-31 magnetic resonance spectroscopy studies

Metabolomics Analysis Identifies a Lipidomic Profile in Treatment Naïve Juvenile Dermatomyositis Patients versus Healthy Control Subjects

Objectives

To perform an exploratory study to identify a JDM serum metabolic profile that differs from healthy controls (HCs) and responds to immunosuppressive treatment.

Methods

Blood was collected from 9 HCs and 10 patients diagnosed with probable (n = 4) or definite (n = 6) JDM based on the criteria of Bohan and Peter for myositis, with 7 of the 10 providing longitudinal samples following initiation of treatment; these patients comprised the treatment-naïve cohort. Sera underwent mass spectroscopy–based measurements of targeted metabolic intermediates, including 15 amino acids, 45 acylcarnitines (ACs), 15 ceramides and 29 sphingomyelins. Principal components analysis reduced metabolites into smaller sets of factors each comprised of correlated metabolic intermediates. Factor scores and metabolite concentrations were compared with HCs using two-sample t-tests while treatment effects were evaluated using paired t-tests.

Results

Of eight principal components analysis–derived metabolite factors (one AC, two amino acids, three sphingosine and two ceramide), two were significantly associated with JDM: one AC factor containing mostly long-chain ACs (P = 0.049) and one ceramide factor (P < 0.01). For 12 individual ACs, mostly long chain, and three ceramides, concentrations were significantly greater for JDM than HCs. Factors based on these individual metabolites showed decreasing scores with treatment (P = 0.03 and P < 0.01, respectively).

Conclusion

While additional validation is needed, these lipids have potential as JDM serum diagnostic and/or treatment biomarkers. Additionally, the significant association of long-chain ACs and ceramides with JDM offers insights regarding pathogenesis, implicating dysregulation of mitochondrial fatty acid β-oxidation.

Dermatomyositis: Patterns of MRI findings in muscles, fascia and skin of pelvis and thigh

PURPOSE

This review discusses characteristic, subtle, and florid changes in muscle, fascia, skin, and subcutaneous tissue of the lower limbs in MR imaging in patients with dermatomyositis.

MATERIAL AND METHODS

This review is based on the analysis of 43 patients with dermatomyositis who were imaged from January 2014 to March 2021 in our institute as well a critical review of literature of MRI in dermatomyositis.

RESULTS

Muscle involvement is predominantly bilaterally symmetric and involves anterior, posterior as well as medial compartments of the thigh. Diffuse intramuscular hyperintensity on T2-weighted images is a common pattern of involvement. Isolated myofascial involvement or muscular with myofascial involvement can also occur. Nodular areas of hyper intensity and enhancement is another uncommon pattern of muscle involvement. Reticular pattern of subcutaneous tissue involvement and skin thickening is best seen on fat saturated T2 -weighted images. Calcification in the subcutaneous tissues appears hypointense with a surrounding hyperintense rim on all pulse sequences which shows peripheral enhancement. MRI patterns of involvement range from subtle myofascial and skin involvement to florid muscular involvement. Diffusion weighted imaging is useful for myofascial involvement. Whole body MR can detect changes at unusual sites in muscles and extra skeletal involvement. Contrast enhanced imaging has no added benefit. Treatment responders show a return to normal signal intensity on MRI.

CONCLUSION

This review highlights the patterns of muscle, skin, and subcutaneous tissue involvement of thighs in dermatomyositis on conventional MRI and the role of whole-body MR, diffusion weighted imaging and limited role of contrast enhanced imaging.

The Effect of Creatine Supplementation on Muscle Function in Childhood Myositis: A Randomized, Double-blind, Placebo-controlled Feasibility Study

OBJECTIVE

To evaluate the feasibility of studying creatine in juvenile dermatomyositis (JDM). Secondary objectives were to determine the effect of creatine on muscle function and metabolism, aerobic capacity, fatigue, physical activity, and quality of life (QOL), as well as its safety.

METHODS

We conducted a 6-month, double-blind, randomized, multiple-baseline design; patients were assigned to creatine or placebo. Feasibility was assessed using attended study visits, completed study procedures, and adherence. Muscle function, aerobic capacity, and muscle strength were assessed with standardized exercise tests. Muscle metabolism was assessed using a 31-Phosphorus Magnetic Resonance Spectroscopy protocol. Fatigue, physical activity, and QOL were assessed by questionnaires. Statistical significance was estimated using a randomization (permutation) test. Changes in outcome measures taken at baseline and end-of-study were calculated using paired t-tests.

RESULTS

Median (range) adherence to the study drug was 88.5% (20.5-95.5%) and the proportion of subjects with 80% adherence or higher was 76.9%. There were no missed study visits. There were no statistically significant changes in muscle function, strength, aerobic capacity, disease activity, fatigue, physical activity, or QOL while subjects were receiving creatine compared to placebo. There were statistically significant adaptations in muscle metabolism (e.g., decrease in change in muscle pH following exercise, and decrease in phosphate/phosphocreatine ratio) at the end-of-study compared to baseline. There were no significant adverse effects.

CONCLUSION

Creatine supplementation in children with JDM is feasible to study, and is safe and well-tolerated; it may lead to improvements in muscle metabolism.

Functional and Structural Adaptations of Skeletal Muscle in Long-Term Juvenile Dermatomyositis: A Controlled Cross-Sectional Study

OBJECTIVE

To compare muscle strength and endurance of the knee extensors between patients with long-term juvenile dermatomyositis (DM) and controls and between patients with active disease and those with inactive disease, and to explore associations between strength/endurance and 1) clinical parameters, 2) physical activity, and 3) humoral/structural adaptation in the skeletal muscle of patients.

METHODS

In a cross-sectional study (44 patients and 44 age- and sex-matched controls), we tested isometric muscle strength (peak torque, in Nm) and dynamic muscle endurance (total work, in Joules) of the knee extensors, physical activity (measured by accelerometer), and serum myokine levels (by enzyme-linked immunosorbent assay). Patients were examined with validated tools (clinical muscle tests and measures of disease activity/damage and inactive disease) and using magnetic resonance imaging of the thigh muscles, which included evaluation of the quadriceps cross-sectional area (CSA). Needle biopsy samples of the vastus lateralis muscle (obtained from 12 patients ages ≥18 years) were assessed by histochemistry.

RESULTS

After a mean ± SD disease duration of 21.8 ± 11.8 years, peak torque was lower in patients with juvenile DM compared to controls (mean difference 29 Nm, 95% confidence interval 13-46; P = 0.001). Similarly, total work of the knee extensors was lower in patients compared to controls (median 738J [interquartile range 565-1,155] versus 1,249J [interquartile range 815-1,665]; P < 0.001). Both peak torque and total work were lower in patients with active juvenile DM compared to those with inactive disease (both P < 0.019); in analyses controlled for quadriceps CSA, only total work remained lower in patients with active disease. Moreover, peak torque and total work correlated with findings from clinical muscle tests in patients with active disease (r = 0.57-0.84). Muscle biopsy results indicated that the fiber type composition was different, but capillary density was similar, between patients with active disease and those with inactive disease.

CONCLUSION

In patients with long-term juvenile DM, both muscle strength and endurance of the knee extensors were lower when compared to matched controls, and also lower in patients with active disease compared to those with inactive disease. Our results indicate a need for more sensitive muscle tests in this clinical setting. We hypothesize that impaired muscle endurance in patients with active juvenile DM may be influenced by structural/functional adaptations of muscle tissue independent of muscle size.

Value of MRI in diagnostics and evaluation of myositis

PURPOSE OF REVIEW

This review aims at covering the role of muscle MRI in supporting the diagnosis of myositis, in aiding to differentiate it from other muscle disorders, and in monitoring myositis patients over time by assessing response to treatment and by discriminating between muscle inflammation and chronic damage.

RECENT FINDINGS

MRI can assist in 'pattern recognition' of muscle involvement across numerous myopathies, including myositis. Novel applications of magnetic resonance such as cardiac MRI, MR elastography and blood oxigenation level-dependent magnetic resonance can shed light on different aspects of myositis and usefully complement conventional MRI in assessing patients with myositis.

SUMMARY

MRI can guide therapy by determining whether muscle weakness is related to edema (active inflammation) or muscle atrophy/fat replacement (chronic damage). There is a need to better standardize the assessment of MRI findings in myositis to provide defined outcome measures for use in clinical trials. VIDEO ABSTRACT.

Non-invasive assessment of phosphate metabolism and oxidative capacity in working skeletal muscle in healthy young Chinese volunteers using (31)P Magnetic Resonance Spectroscopy

Background. Generally, males display greater strength and muscle capacity than females while performing a task. Muscle biopsy is regarded as the reference method of evaluating muscle functions; however, it is invasive and has sampling errors, and is not practical for longitudinal studies and dynamic measurement during excise. In this study, we built an in-house force control and gauge system for quantitatively applying force to quadriceps while the subjects underwent ³¹P Magnetic Resonance Spectroscopy (³¹P-MRS); our aim was to investigate if there is a sex difference of phosphate metabolite change in working muscles in young heathy Chinese volunteers.

Methods. Volunteers performed knee-extending excises using a force control and gauge system while lying prone in a Philips 3T Magnetic Resonance (MR) scanner. The ³¹P-MRS coil was firmly placed under the middle of the quadriceps . ³¹P-MRS measurements of inorganic phosphate (Pi), phosphocreatine (PCr) and adenosine triphosphate (ATP) were acquired from quadriceps while subjects were in a state of pre-, during- and post-exercise. The PCr, Pi, PCr/Pi, PCr/ATP, pH, work/energy cost ratio (WE), k_PCr and oxidative capacity were compared between males and females.

Results. A total of 17 volunteers underwent the study. Males: N = 10, age = 23.30 ± 1.25years; females: N = 7, age = 23.57 ± 0.79 years. In this study, males had significantly greater WE (16.33 ± 6.46 vs. 7.82 ± 2.16, p = 0.002) than females. Among PCr, Pi, PCr/Pi, PCr/ATP, pH, kPCr and oxidative capacity at different exercise status, only PCr/Pi (during-exercise, males = 5.630 ± 1.647, females = 4.014 ± 1.298, p = 0.047), PCr/ATP (during-exercise, males =1.273 ± 0.219, females = 1.523 ± 0.167, p = 0.025), and ATP (post-exercise, males = 24.469 ± 3.911 mmol/kg, females = 18.353 ± 4.818 mmol/kg, p = 0.035) had significant sex differences. Males had significantly greater PCr/Pi, but less PCr/ATP than females during exercise, suggesting males had higher energy transfer efficiency than females. At the post-exercise status, the recovery of PCr did not show sex difference.

Conclusions. Our in-house force control and gauge system quantitatively applied force during the exercise for ³¹P-MRS experiments, and a sex difference of higher energy transfer efficiency and WE was detected in males with mild loaded exercising quadriceps. This noninvasive technology allows us to further study and understand the sex difference of high energy phosphate metabolism in the future.

Efficacy and safety of creatine supplementation in juvenile dermatomyositis: A randomized, double-blind, placebo-controlled crossover trial

INTRODUCTION

It has been suggested that creatine supplementation is safe and effective for treating idiopathic inflammatory myopathies, but no pediatric study has been conducted to date. The objective of this study was to examine the efficacy and safety of creatine supplementation in juvenile dermatomyositis (JDM) patients.

METHODS

In this study, JDM patients received placebo or creatine supplementation (0.1 g/kg/day) in a randomized, crossover, double-blind design. Subjects were assessed at baseline and after 12 weeks. The primary outcome was muscle function. Secondary outcomes included body composition, aerobic conditioning, health-related quality of life, and muscle phosphocreatine (PCr) content. Safety was assessed by laboratory parameters and kidney function measurements.

RESULTS

Creatine supplementation did not affect muscle function, intramuscular PCr content, or any other secondary outcome. Kidney function was not affected, and no side effects were reported.

CONCLUSIONS

Twelve weeks of creatine supplementation in JDM patients were well-tolerated and free of adverse effects, but treatment did not affect muscle function, intramuscular PCr, or any other parameter.

Muscle Metabolic Responses During Dynamic In-Magnet Exercise Testing: A Pilot Study in Children with an Idiopathic Inflammatory Myopathy

RATIONALE AND OBJECTIVES

The clinical utility of supine in-magnet bicycling in combination with phosphorus magnetic resonance spectroscopy ((31)P MRS) to evaluate quadriceps muscle metabolism was examined in four children with juvenile dermatomyositis (JDM) in remission and healthy age- and gender-matched controls.

MATERIALS AND METHODS

Two identical maximal supine bicycling tests were performed using a magnetic resonance-compatible ergometer. During the first test, cardiopulmonary performance was established in the exercise laboratory. During the second test, quadriceps energy balance and acid/base balance during incremental exercise and phosphocreatine recovery were determined using (31)P MRS.

RESULTS

During the first test, no significant differences were found between patients with JDM and their healthy peers regarding cardiopulmonary performance. The outcomes of the first test indicate that both groups attained maximal performance. During the second test, quadriceps phosphocreatine and pH time courses were similar in all but one patient experiencing idiopathic postexercise pain. This patient demonstrated faster phosphocreatine depletion and acidification during exercise, yet postexercise mitochondrial adenosine triphosphate synthesis rate measured by phosphocreatine recovery kinetics was approximately twofold faster than control (time constant 23 seconds vs 43 ± 7 seconds, respectively).

CONCLUSIONS

These results highlight the utility of in-magnet cycle ergometry in combination with (31)P MRS to assess and monitor muscle energetic patterns in pediatric patients with inflammatory myopathies.

High cytochrome c oxidase expression links to severe skeletal energy failure by (31)P-MRS spectroscopy in mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes

AIMS

The purpose of this study was to evaluate the energy metabolism and mitochondrial function in skeletal muscle from patients with Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) or chronic progressive external ophthalmoplegia (CPEO) using phosphorus magnetic resonance spectroscopy ((31)P-MRS), to determine whether abnormally increasing cytochrome c oxidase (COX), as detected in muscle biopsy, could be a cause for MELAS.

METHODS

(31)P-MRS was performed on the quadriceps femoris muscle of 12 healthy volunteers and 11 patients diagnosed as MELAS or CPEO by muscle biopsy and genetic analysis. All subjects experienced a state of rest, 5-min exercise, and 5-min recovery protocol in a supine position.

RESULTS

Compared to CPEO, MELAS patients typically exhibited COX-positive ragged-red fibers (RRFs) as well as strongly SDH-positive blood vessels (SSVs). However, based on (31)P-MRS results, MELAS showed a higher inorganic phosphate (Pi)/phosphocreatine (PCr) ratio and lower ATP/PCr ratio during exercise and delayed Pi/PCr and ATP/PCr recovery to normal.

CONCLUSIONS

This study suggests that high COX expression contributes to severe skeletal energy failure by (31)P-MRS spectroscopy in MELAS.

Magnetic resonance imaging of pediatric muscular disorders: recent advances and clinical applications

This review describes various quantitative magnetic resonance imaging techniques that can be used to objectively analyze the composition (T2 relaxation time mapping, Dixon imaging, and diffusion-weighted imaging), architecture (diffusion tensor imaging), mechanical properties (magnetic resonance elastography), and function (magnetic resonance spectroscopy) of normal and pathologic skeletal muscle in the pediatric population.

Juvenile dermatomyositis: correlation of MRI at presentation with clinical outcome

OBJECTIVE

The clinical course of juvenile dermatomyositis (JDMS) is unpredictable. MRI is used to determine muscle biopsy site and to monitor disease activity. It is unknown whether soft-tissue features on MRI obtained at diagnosis correlate with clinical outcome. The purpose of our study is to determine whether initial MRI findings in the pelvis and thighs in children with JDMS can predict clinical disease course.

MATERIALS AND METHODS

Forty-five children (31 girls and 14 boys; median age, 6 years; range, 1-18 years) with clinically diagnosed biopsy-proven JDMS and at least 24 months of clinical follow-up were included. Clinical outcome was categorized as limited or chronic disease, according to the established Crowe clinical classification scheme. Pretreatment MRI examinations of the pelvis and thighs were evaluated for signal abnormalities of muscle and fascia and reticulated signal changes in subcutaneous fat; associations with clinical outcome were examined.

RESULTS

Twenty-two patients had limited disease and 23 had chronic disease. Signal intensity ranged from normal (n = 3) to floridly increased in all muscle compartments (n = 17). Muscle and fascial involvement were not associated with clinical outcome. Controlling for duration of symptoms, the adjusted odds of progressing to chronic disease were higher for patients with abnormal subcutaneous fat signal than for those with normal fat signal (odds ratio, 9.0; 95% CI, 1.5-53.5; p < 0.02).

CONCLUSION

MRI findings of muscle or fascia involvement do not predict clinical outcome in children with newly diagnosed JDMS. Abnormal subcutaneous fat signal appears to have a significant association with a more aggressive chronic disease course.

Diversity of human skeletal muscle in health and disease: contribution of proteomics

Muscle represents a large fraction of the human body mass. It is an extremely heterogeneous tissue featuring in its contractile structure various proportions of heavy- and light-chain slow type 1 and fast types 2A and 2X myosins, actins, tropomyosins, and troponin complexes as well as metabolic proteins (enzymes and most of the players of the so-called excitation-transcription coupling). Muscle is characterized by wide plasticity, i.e. capacity to adjust size and functional properties in response to endogenous and exogenous influences. Over the last decade, proteomics has become a crucial technique for the assessment of muscle at the molecular level and the investigation of its functional changes. Advantages and shortcomings of recent techniques for muscle proteome analysis are discussed. Data from differential proteomics applied to healthy individuals in normal and unusual environments (hypoxia and cold), in exercise, immobilization, aging and to patients with neuromuscular hereditary disorders (NMDs), inclusion body myositis and insulin resistance are summarized, critically discussed and, when required, compared with homologous data from pertinent animal models. The advantages as well as the limits of proteomics in view of the identification of new biomarkers are evaluated.

Evidence for prescribing exercise as treatment in pediatric rheumatic diseases

There has been an increasing recognition of adverse short-, mid-, or long-term effects associated with the treatment as well as the disease itself that impair the health-related quality of life and functional capacity of children and adolescents with rheumatic diseases. Interestingly, cumulative evidence has suggested that exercise training may benefit patients with juvenile idiopathic arthritis, juvenile systemic lupus erythematosus, juvenile dermatomyositis and juvenile fibromyalgia, attenuating several clinical symptoms related to physical disability. Remarkably, recent evidence also suggests that exercise may have direct effects on the pathogenesis of autoimmune diseases by attenuating chronic low-grade systemic inflammation. It is also important to emphasize that no exercise-related adverse effects have been reported. This short review provides the evidence for physical training as a treatment of pediatric rheumatic diseases, introducing a novel concept that exercise is a treatment for these populations.

Update on idiopathic inflammatory myopathies

The inflammatory myopathies are a group of acquired diseases, characterized by an inflammatory infiltrate of the skeletal muscle. On the basis of clinical, immuno-pathological and demographic features, three major diseases can be identified: dermatomyositis (DM); polymyositis (PM); and inclusion body myositis (IBM). New diagnostic criteria have recently been introduced, which are crucial for discriminating between the three different subsets of inflammatory myopathies and for excluding other disorders. DM is a complement-mediated microangiopathy affecting skin and muscle. PM and IBM are T cell-mediated disorders, where CD8-positive cytotoxic T cells invade muscle fibres expressing MHC class I antigens, thus leading to fibre necrosis. In IBM, vacuolar formation with amyloid deposits are also present. This article summarizes the main clinical, laboratory, electrophysiological, immunological and histologic features as well as the therapeutic options of the inflammatory myopathies.

MRI in juvenile idiopathic arthritis and juvenile dermatomyositis

The use of MRI in the assessment of the musculoskeletal system in children has important differences from its use in adults. Growth in children has significant impact on the epiphysis and growth plate, which are important structures in the growing child, and there are radiological features that differ from those in adults: disease may alter structures during a period of growth; the pathologies themselves are a distinct group of diseases at variance with adult arthritis and myositis, with a different spectrum of differential diagnoses; and many technical issues are different when imaging a child. These are important considerations in choosing the appropriate imaging. MRI is a powerful and valuable imaging technique in pediatric musculoskeletal pathologies, with considerable potential for future developments to enhance its role in diagnosis, management, and therapeutic intervention for these children.

Clinical use of creatine in neuromuscular and neurometabolic disorders

Many of the neuromuscular (e.g., muscular dystrophy) and neurometabolic (e.g., mitochondrial cytopathies) disorders share similar final common pathways of cellular dysfunction that may be favorably influenced by creatine monohydrate (CrM) supplementation. Studies using the mdx model of Duchenne muscular dystrophy have found evidence of enhanced mitochondrial function, reduced intra-cellular calcium and improved performance with CrM supplementation. Clinical trials in patients with Duchenne and Becker's muscular dystrophy have shown improved function, fat-free mass, and some evidence of improved bone health with CrM supplementation. In contrast, the improvements in function in myotonic dystrophy and inherited neuropathies (e.g., Charcot-Marie-Tooth) have not been significant. Some studies in patients with mitochondrial cytopathies have shown improved muscle endurance and body composition, yet other studies did not find significant improvements in patients with mitochondrial cytopathy. Lower-dose CrM supplementation in patients with McArdle's disease (myophosphorylase deficiency) improved exercise capacity, yet higher doses actually showed some indication of worsened function. Based upon known cellular pathologies, there are potential benefits from CrM supplementation in patients with steroid myopathy, inflammatory myopathy, myoadenylate deaminase deficiency, and fatty acid oxidation defects. Larger randomized control trials (RCT) using homogeneous patient groups and objective and clinically relevant outcome variables are needed to determine whether creatine supplementation will be of therapeutic benefit to patients with neuromuscular or neurometabolic disorders. Given the relatively low prevalence of some of the neuromuscular and neurometabolic disorders, it will be necessary to use surrogate markers of potential clinical efficacy including markers of oxidative stress, cellular energy charge, and gene expression patterns.

A systematic review of juvenile-onset clinically amyopathic dermatomyositis

BACKGROUND

Dermatomyositis (DM) presenting during childhood or adolescence classically encompasses hallmark cutaneous changes, proximal muscle weakness, and laboratory evidence of myositis. When cutaneous manifestations of DM are present without muscle weakness for > 6 months, the term 'clinically amyopathic DM' applies (syn. DM sine myositis).

OBJECTIVES

To review the clinical and epidemiological features of published cases of juvenile-onset clinically amyopathic DM, with comparison with adult-onset clinically amyopathic DM and juvenile-onset classical DM.

METHODS

Systematic review of the published literature.

RESULTS

We identified 68 cases of juvenile-onset clinically amyopathic DM published during 1963-2006. The disease in 18 of 68 (26%) patients subsequently evolved to classical DM. Overall, the mean age at diagnosis was 10.8 years (range 2-17) with nearly equal male/female ratio and mean follow-up of 3.9 years. Among cases with diagnostic testing, 10 of 19 had a positive antinuclear antibody titre, two of nine had elevated erythrocyte sedimentation rate and two of 51 had elevated creatine kinase (CK). Of patients with normal CK, three of 22 had abnormal electromyography, one of 19 had abnormal muscle biopsy, and one of nine had abnormal magnetic resonance imaging. Calcinosis was reported in three of 68. No cases of severe vasculopathy (resulting in ulceration), interstitial lung disease or internal malignancy were reported.

CONCLUSIONS

This review suggests a good prognosis for children with clinically amyopathic DM. A minority of patients with negative muscle enzymes had positive ancillary testing for myositis, and these patients rarely developed muscle weakness. Predictive factors for progression to classical DM were not identified. Symptomatic treatment of cutaneous involvement and close clinical monitoring may be an alternative to aggressive immunosuppression.

Creatine supplements in patients with idiopathic inflammatory myopathies who are clinically weak after conventional pharmacologic treatment: Six-month, double-blind, randomized, placebo-controlled trial

OBJECTIVE

To test the hypothesis that oral creatine supplements with exercise are more effective than exercise alone in improving muscle function in patients with established dermatomyositis or polymyositis receiving chronic medical therapies who are clinically weak yet stable.

METHODS

In a 6-month, 2-center, double-blind, randomized controlled trial, patients were randomized to receive oral creatine supplements (8 days, 20 gm/day then 3 gm/day) or placebo. All patients followed a home exercise program. The primary outcome was aggregate functional performance time (AFPT), reflecting the ability to undertake high-intensity exercise. Secondary outcomes included a functional index measuring endurance and muscle bioenergetics on (31)P magnetic resonance spectroscopy ((31)P MRS). Patients were receiving stable immunosuppressive treatment and/or corticosteroids.

RESULTS

A total of 37 patients with polymyositis or dermatomyositis were randomized (19 to creatine, 18 to placebo); 29 completed 6 months. Intent-to-treat analyses demonstrated that AFPT improved significantly at 6 months with creatine (median decrease 13%, range -32-8%) compared with placebo (median decrease 3%, range -13-16%; P = 0.029 by Mann-Whitney U test). A completer analysis also showed significant benefits from creatine (P = 0.014). The functional index improved significantly with both creatine and placebo (P < 0.05 by paired Wilcoxon's rank sum test), with a significant benefit between groups in the completer analysis only. Phosphocreatine/beta-nucleoside triphosphate ratios using MRS increased significantly in the creatine group (P < 0.05) but not in the control group. No clinically relevant adverse events were associated with creatine.

CONCLUSION

Oral creatine supplements combined with home exercises improve functional performance without significant adverse effects in patients with polymyositis or dermatomyositis. They appear safe, effective, and inexpensive.

Muscle fatigue during high-intensity exercise in children

Children are able to resist fatigue better than adults during one or several repeated high-intensity exercise bouts. This finding has been reported by measuring mechanical force or power output profiles during sustained isometric maximal contractions or repeated bouts of high-intensity dynamic exercises. The ability of children to better maintain performance during repeated high-intensity exercise bouts could be related to their lower level of fatigue during exercise and/or faster recovery following exercise. This may be explained by muscle characteristics of children, which are quantitatively and qualitatively different to those of adults. Children have less muscle mass than adults and hence, generate lower absolute power during high-intensity exercise. Some researchers also showed that children were equipped better for oxidative than glycolytic pathways during exercise, which would lead to a lower accumulation of muscle by-products. Furthermore, some reports indicated that the lower ability of children to activate their type II muscle fibres would also explain their greater resistance to fatigue during sustained maximal contractions. The lower accumulation of muscle by-products observed in children may be suggestive of a reduced metabolic signal, which induces lower ratings of perceived exertion. Factors such as faster phosphocreatine resynthesis, greater oxidative capacity, better acid-base regulation, faster readjustment of initial cardiorespiratory parameters and higher removal of metabolic by-products in children could also explain their faster recovery following high-intensity exercise.From a clinical point of view, muscle fatigue profiles are different between healthy children and children with muscle and metabolic diseases. Studies of dystrophic muscles in children indicated contradictory findings of changes in contractile properties and the muscle fatigability. Some have found that the muscle of boys with Duchenne muscular dystrophy (DMD) fatigued less than that of healthy boys, but others have reported that the fatigue in DMD and in normal muscle was the same. Children with glycogenosis type V and VII and dermatomyositis, and obese children tolerate exercise weakly and show an early fatigue. Studies that have investigated the fatigability in children with cerebral palsy have indicated that the femoris quadriceps was less fatigable than that of a control group but the fatigability of the triceps surae was the same between the two groups. Further studies are required to elucidate the mechanisms explaining the origins of muscle fatigue in healthy and diseased children. The use of non-invasive measurement tools such as magnetic resonance imaging and magnetic resonance spectroscopy in paediatric exercise science will give researchers more insight in the future.

[Non-invasive investigation of muscle function using 31P magnetic resonance spectroscopy and 1H MR imaging]

31P MRS and 1H MRI of skeletal muscle have become major new tools allowing a complete non invasive investigation of muscle function both in the clinical setting and in basic research. The comparative analysis of normal and diseased muscle remains a major requirement to further define metabolic events surrounding muscle contraction and the metabolic anomalies underlying pathologies. Also, standardized rest-exercise-recovery protocols for the exploration of muscle metabolism by P-31 MRS in healthy volunteers as well as in patients with intolerance to exercise have been developed. The CRMBM protocol is based on a short-term intense exercise, which is very informative and well accepted by volunteers and patients. Invariant metabolic parameters have been defined to characterize the normal metabolic response to the protocol. Deviations from normality can be directly interpreted in terms of specific pathologies in some favorable cases. This protocol has been applied to more than 4,000 patients and healthy volunteers over a period of 15 years. On the other hand, MRI investigations provide anatomical and functional information from resting and exercising muscle. From a diagnostic point of view, dedicated pulse sequences can be used in order to detect and quantify muscle inflammation, fatty replacement, muscle hyper and hypotrophy. In most cases, MR techniques provide valuable information which has to be processed in conjunction with traditional invasive biochemical, electrophysiological and histoenzymological tests. P-31 MRS has proved particularly useful in the therapeutic follow-up of palliative therapies (coenzyme Q treatment of mitochondriopathies) and in family investigations. It is now an accepted diagnostic tool in the array of tests which are used to characterize muscle disorders in clinical routine. As a research tool, it will keep bringing new information on the physiopathology of muscle diseases in animal models and in humans and should play a role in the metabolic characterization of gene and cell therapy.

Anaerobic exercise capacity in patients with juvenile-onset idiopathic inflammatory myopathies

OBJECTIVE

To 1) report the feasibility of an "all-out" 30-second cycling exercise test (Wingate Anaerobic Exercise Test [WAnT]) in juvenile-onset idiopathic inflammatory myopathy (JIIM) patients, 2) describe the anaerobic exercise capacity in juvenile dermatomyositis patients, and 3) determine if the anaerobic exercise capacity could be related to disease duration or disease phase.

METHODS

Twenty patients (age 14.13 +/- 5.4 years) with JIIM participated in this study. All patients were able to perform the WAnT without adverse events.

RESULTS

Comparison with healthy controls revealed a -29.3 +/- 26.58% (P = 0.001) and -27.6 +/- 25.7% (P = 0.002) impairment in mean power and peak power on the WAnT, respectively. The WAnT correlated with disease phase and with knee extensor muscle strength.

CONCLUSION

The WAnT might be a valuable adjunct next to other assessment tools in the followup of JIIM patients.

Radiologic investigation of rheumatic diseases

This article reviews the current use of the wide variety of imaging modalities now available, presenting the imaging features of common and important causes of acute and chronic rheumatic disorders including juvenile idiopathic arthritis, spondyloarthropathies/enthesitis-related arthritis, sepsis, autoimmune diseases, vasculitis, and osteoporosis.

Imaging and skeletal muscle disease

Imaging techniques have assumed increasing importance in the diagnostic approach to patients with muscle disease. These techniques include computed tomography, ultrasound, and magnetic resonance imaging (MRI). For most disorders of muscle, ultrasound and MRI are more useful than computed tomography. Advantages of ultrasound include accessibility at the bedside and lower cost. However, MRI remains the gold standard for detecting changes in muscle tissue. In some cases, MRI examinations can take the place of muscle biopsy for diagnosis. New advances in MRI include diffusion-weighted imaging, which permits assessment of fluid motion in muscles, and blood-oxygen-level-dependent imaging to evaluate tissue oxygenation.

MR neurography and muscle MR imaging for image diagnosis of disorders affecting the peripheral nerves and musculature

Recent advances in the technology of MR imaging are beginning to transform the fundamental methodology of diagnostic evaluations in neuromuscular disorders. When properly implemented, MR neurography is capable of providing high-quality information about nerve compression, nerve inflammation, nerve trauma, systemic neuropathies, nerve tumors, and recovery of nerve from pathologic states. Muscle MR imaging can identify denervation on a precise anatomic basis, document the progression of various conditions causing myopathy and myositis; and even provide insight into abnormal patterns of muscle activation. There is an essential role for the neurologist as well as for the specialist radiologist that requires a high level of familiarity of the various new types of image findings in this steadily advancing field.

Fitness as a determinant of the oxygen uptake/work rate slope in healthy children and children with inflammatory myopathy

There is evidence that the slope of the change in oxygen uptake accompanying changes in work rate (delta VO2/delta W). during moderate incremental exercise is influenced by fitness (peak VO2). We set out to determine whether delta VO2/delta W was related to fitness in a group of healthy children and in children with juvenile dermatomyositis (JDM), a condition associated with decreased peak VO2. We also hypothesized that delta VO2/delta would be significantly decreased in children with JDM compared to healthy children.

METHODS

Twelve children (2 boys) with JDM, mean age 11.6 +/- 3.6 yrs, and 20 healthy children (4 boys), mean age 11.3 +/- 2.9 years, performed an incremental exercise test using a cycle ergometer. delta VO2/delta W below the anaerobic threshold was analyzed using linear regression. Correlations between peak VO2 and delta VO2/delta W were calculated, and differences between the JDM and healthy groups were analyzed using independent t-tests.

RESULTS

The delta VO2/delta W was significantly correlated with peak VO2 for children with JDM (r = 0.71, p < 0.01), healthy children (r = 0.53, p < 0.01), and all children combined (r = 0.78, p < 0.001). The delta VO2/delta W (7.4 +/- 1.4 vs. 10.8 +/- 1.2 ml O2.min-1.watt-1) and peak oxygen uptake (VO2peak) (19.2 +/- 5.0 vs. 31.4 +/- 7.2 ml O2.kg-1, min-1) were significantly lower in children with JDM than in healthy children, respectively (all p < or = 0.001).

CONCLUSION

Fitness is significantly related to delta VO2/delta W in healthy children and those with JDM. Children with JDM have a significantly lower delta VO2/delta W than healthy children. Further study is needed to identify specific factors influencing delta VO2/delta W.

Metabolic disturbances during short exercises in dermatomyositis revealed by real-time functional 31P magnetic resonance spectroscopy

OBJECTIVE

(31)P magnetic resonance spectroscopy (MRS) is useful for evaluating metabolic disturbances in dermatomyositis (DM). However, short-term alterations of metabolic parameters such as Pi/PCr (inorganic phosphate/phosphocreatine) have not been assessed in detail, although they may reveal insights into the origin of the known long-term changes. We therefore performed real-time functional (31)P MRS to find out if there are characteristic short-term alterations of metabolic dynamics during muscular exercise and if they are of diagnostic relevance.

METHODS

MRS measurements were performed on lower calf muscles of 10 DM patients and 18 healthy subjects throughout five short (1 min) cycles of submaximal exercise (50% maximum voluntary contraction).

RESULTS

Pi/PCr ratios during exercise increased in patients and controls. They rapidly returned to baseline values in the controls, but both Pi and PCr remained above baseline values in patients and resulted in irregular Pi/PCr ratios. This was true for each individual patient, but resulted in broad variation in individual Pi/PCr values. To compare groups with limited patient numbers, it was therefore more appropriate to use a recovery index, i.e. the quotient of the Pi/PCr ratio during and after exercise, which was independent of individual parameters, such as age and the work/energy cost ratio.

CONCLUSION

Evaluation of short-term changes by real-time functional (31)P MRS provides insight into alterations of Pi/PCr ratios and could improve diagnostic parameters in DM.

Drug treatment for facioscapulohumeral muscular dystrophy

BACKGROUND

Facioscapulohumeral muscular dystrophy is a progressive muscle disease which has no agreed treatment. Early suggestions that corticosteroids might be helpful were not supported by a subsequent open label study. The beta 2 adrenergic agonist albuterol, also known as salbutamol, is known to have anabolic effects which might be beneficial for facioscapulohumeral muscular dystrophy. Creatine has been used as a muscle performance enhancer by athletes and it might be helpful in muscular dystrophies including facioscapulohumeral muscular dystrophy.

OBJECTIVES

The objective of the review was to determine whether there is any drug treatment which alters the progression of facioscapulohumeral muscular dystrophy.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group specialised register (searched August 2003), MEDLINE (January 1966 to August 2003) and EMBASE (January 1980 to August 2003) for any references to facioscapulohumeral muscular dystrophy. Abstracts from the major neurological meetings and trial bibliographies were also searched for further references to trials. Experts were contacted for information regarding unpublished trials or trials in progress.

SELECTION CRITERIA

We included all randomised or quasi-randomised trials of any drug treatment for facioscapulohumeral muscular dystrophy, in adults with a recognised diagnosis of facioscapulohumeral muscular dystrophy. Trials had to include an assessment of muscle strength at one year.

DATA COLLECTION AND ANALYSIS

All identified trials were independently assessed by both reviewers to ensure that they fulfilled the selection criteria and were then rated for their quality. Trial data were extracted and entered by one reviewer and checked by the other. If appropriate data existed a weighted treatment effect was to be calculated across trials using the Cochrane statistical package, Review Manager. The results were to have been expressed as relative risks and 95% confidence intervals and risk differences and 95% confidence intervals for dichotomous outcomes, and weighted mean differences and 95% confidence intervals for continuous outcomes.

MAIN RESULTS

Two published high quality randomised controlled trials fulfilled the selection criteria. One compared creatine supplementation with placebo and the other compared high and low-dose albuterol with placebo. A further unpublished randomised controlled trial of albuterol in facioscapulohumeral muscular dystrophy was identified. The creatine trial showed a non-significant difference in favour of creatine. The albuterol trial showed no significant difference in muscle strength at one year but some secondary measures such as lean body mass and handgrip strength did improve.

REVIEWERS' CONCLUSIONS

There is no evidence from randomised controlled trials to support any drug treatment for facioscapulohumeral muscular dystrophy but only two randomised controlled trials have been published.

Decreased aerobic capacity in children with juvenile dermatomyositis

OBJECTIVE

To determine whether patients with juvenile dermatomyositis (DM) have limited aerobic capacity compared with healthy controls.

METHODS

Fourteen juvenile DM patients with inactive to moderately active, stable disease (age range 7-17 years) and 14 age- and sex-matched controls performed a maximal exercise test using a cycle ergometer. Oxygen uptake and power were measured at peak exercise (VO(2peak) and W(peak), respectively) and at anaerobic threshold (AT and W(AT)). Juvenile DM disease activity and damage were also assessed.

RESULTS

Patients with juvenile DM had significantly reduced VO(2peak) (19.6 ml O(2)/kg/minute in juvenile DM versus 31.1 ml O(2)/kg/minute in controls), peak heart rate (166 versus 184 beats per minute), W(peak) (1.6 versus 2.7 watts/kg), AT (11.1 versus 18.0 ml O(2)/kg/minute) and W(AT) (0.6 versus 1.4 watts/kg), compared to controls (P <or= 0.05 for each). Aerobic exercise parameters correlated with physician global disease activity and damage, T1-weighted magnetic resonance imaging, and Childhood Myositis Assessment Scale scores (r(s) = 0.58 - 0.82, P <or= 0.05).

CONCLUSION

Patients with juvenile DM with a range of disease activity have a decreased aerobic and work capacity compared to healthy children. Aerobic exercise limitation in juvenile DM correlates best with measures of disease damage (global damage assessment, T1-weighted magnetic resonance imaging, and disease duration). Aerobic exercise testing may be valuable in the assessment of physical endurance, and aerobic training may be indicated as part of the therapeutic regimen in myositis patients with inactive to moderately active, stable disease.

Magnesium abnormalities of skeletal muscle in dermatomyositis and juvenile dermatomyositis

OBJECTIVE

To characterize abnormalities in magnesium levels in the muscles of patients with dermatomyositis (DM) and juvenile dermatomyositis (JDM) and to evaluate the beneficial effects of prednisone and immunosuppressive therapy in elevating free magnesium (Mg(2+)) and ATP-bound magnesium (Mg-ATP).

METHODS

The study groups consisted of 12 adult patients with DM and 10 juvenile patients with JDM. The 2 control groups were 11 normal adults and 6 healthy children. Levels of total ATP in the quadriceps muscles of the subjects were determined during rest, exercise, and recovery, using noninvasive P-31 magnetic resonance spectroscopy (MRS). Concentrations of the biologically active free Mg(2+) and the enzymatically active Mg-ATP complex were determined from the spectroscopy data by calculation of the chemical shifts of the beta-phosphate peak of ATP.

RESULTS

Mg-ATP levels in DM and JDM myopathic muscles were at least 37% lower than those in normal muscles during rest, exercise, and recovery from exercise (P < 0.0005). Free Mg(2+) levels were normal in DM and JDM myopathic muscles at rest, but were significantly lower than control values during exercise and recovery (P < 0.029 and P < 0.005 for DM and JDM, respectively). Prednisone and immunosuppressive therapy partially reversed the magnesium abnormalities, as evidenced by elevation of the levels of Mg-ATP and free Mg(2+).

CONCLUSION

Low levels of Mg-ATP and free Mg(2+) are concordant with weakness and fatigue observed in DM and JDM patients. Immunosuppressive therapy alleviates, in part, the magnesium deficits in the diseased muscles. Therefore, Mg-ATP and free Mg(2+) may play a significant role in the pathophysiology of these diseases.

Myositis in children

Idiopathic inflammatory myositis in children includes multiple disease entities, but is primarily made up of juvenile dermatomyositis and, to a lesser degree, juvenile polymyositis. Much new information has been published in the last few years about these diseases, including the epidemiology, pathogenesis, clinical diagnosis, and outcomes and treatment. This includes information on onset of symptoms, potential inciting agents, and regional differences. Exciting data have emerged in our understanding of the immune response gene associations and the description of chimerism in children with these disorders. Finally, new advances in clinical evaluations and outcomes have been described as well as new treatment protocols to provide a more effective therapy with less toxicity. Continued investigation is needed to further understand these diseases, but great strides are being made in our understanding and ability to care for children with idiopathic inflammatory myositis.

Utility of magnetic resonance imaging in the evaluation of patients with inflammatory myopathies

Magnetic resonance imaging (MRI) and P-31 magnetic resonance spectroscopy (P-31 MRS) provide unique, quantitative data that cannot be obtained from routine laboratory tests. MRI is the method of choice for imaging of muscle abnormalities. It is also a very sensitive technique for localizing nonhomogeneous inflammation in inflammatory myopathies such as dermatomyositis, juvenile dermatomyositis, amyopathic dermatomyositis, polymyositis, and inclusion body myositis. During treatment of inflammatory myopathies, the extent and severity of inflammation may decrease at varying rates, but weakness and fatigue remain serious clinical problems. The metabolic abnormalities detected with P-31 MRS are more persistent and can be used for objective patient evaluation after the disappearance of inflammation and normalization of serum levels of muscle enzymes. With P-31 MRS, biochemical defects are quantitated, including low levels of ATP and phosphocreatine (PCr) and elevated concentrations of ADP and inorganic phosphate (Pi), which may all be related to weakness and fatigue. Thus, MRI and P-31 MRS are useful in assessing the status of patients with inflammatory myopathies during treatment with prednisone and immunosuppressive drugs.

Amyopathic dermatomyositis

Amyopathic dermatomyositis is a variant of dermatomyositis that is characterized by the typical skin rash but without the muscle abnormalities. It has been proposed that the amyopathic and myopathic forms of dermatomyositis exist on a continuum, a concept that is supported by family and genetic studies and the observation that a small proportion of amyopathic patients transform to a frankly myopathic state. The amyopathic state is defined by a lack of muscle weakness and through diagnostic tests, including serum muscle enzymes, electromyogram studies, and muscle biopsies, that are usually normal or show only minimal abnormalities. Despite the lack of weakness, many patients complain of debilitating fatigue. More sensitive measures of muscle function, such as P-31 magnetic resonance spectroscopy, suggest that muscle metabolism is abnormal in amyopathic patients. The amyopathic form is more commonly seen in adults than in children, although juvenile cases are reported. Some early series suggested no association with underlying malignancies, but recent reports indicate that malignancies occur. Determining whether a patient has amyopathic rather than myopathic disease may have prognostic implications.

Current awareness in NMR in biomedicine

In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of NMR in biomedicine. Each bibliography is divided into 9 sections: 1 Books, Reviews ' Symposia; 2 General; 3 Technology; 4 Brain and Nerves; 5 Neuropathology; 6 Cancer; 7 Cardiac, Vascular and Respiratory Systems; 8 Liver, Kidney and Other Organs; 9 Muscle and Orthopaedic. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted.