Assessment Of Myopathies Research Articles

Techniques for in vivo assessment of myopathies in broiler chicken breasts using a biopsy as a support tool

ABSTRACT An experiment was conducted to validate non-invasive evaluation techniques as in vivo evaluation tools for the myopathies wooden breast and white striping that affect broilers, using biopsy as a support tool. It evaluated 30 Cobb 500® broiler chickens in a completely randomized design consisting of two sexes (males and females) and 15 replications per treatment. At 14, 21, 35, 42 and 49 days, the surface temperature of the birds’ breasts was recorded using infrared thermography, analysis of fillet depth, and echogenicity by ultrasound imaging. All broiler chickens were sent for biopsy at 21, 35 and 42 days to collect a fragment of the pectoral muscle for descriptive morphological analyses of histological lesions and muscle fibre morphometry. Males had higher echogenicity values at 14, 21 and 42 days. There was no influence of bird sex on the occurrence of the wooden breast and white striping myopathies at 49 days of age in broilers selected and submitted to the biopsy protocol. There was a general trend of decreasing surface temperature for both sexes according to their age. Muscles with less area occupied with fibres had a lower surface temperature. It was concluded that ultrasonography with a 3.5 MHz transducer detects muscle changes after 28 days of age, which is consistent with the myopathic lesions studied. Infrared thermography is a potential method for detecting changes in breast temperature indicating myopathic lesions. A biopsy can be used as an auxiliary tool in the study of myopathies in broiler chicken breasts. RESEARCH HIGHLIGHTS Detection of changes in the breast muscle after 28 days of age with ultrasonography. Changes in the surface temperature range of pectoral muscle with infrared thermography. Use of biopsy as a tool for early diagnostic evaluation in broiler myopathies.

Safety and efficacy of N-acetylmannosamine (ManNAc) in patients with GNE myopathy: an open-label phase 2 study

PurposeTo evaluate the safety and efficacy of N-acetylmannosamine (ManNAc) in GNE myopathy, a genetic muscle disease caused by deficiency of the rate-limiting enzyme in N-acetylneuraminic acid (Neu5Ac) biosynthesis. MethodsWe conducted an open-label, phase 2, single-center (NIH, USA) study to evaluate oral ManNAc in 12 patients with GNE myopathy (ClinicalTrials.gov NCT02346461). Primary endpoints were safety and biochemical efficacy as determined by change in plasma Neu5Ac and sarcolemmal sialylation. Clinical efficacy was evaluated using secondary outcome measures as part of study extensions, and a disease progression model (GNE-DPM) was tested as an efficacy analysis method. ResultsMost drug-related adverse events were gastrointestinal, and there were no serious adverse events. Increased plasma Neu5Ac (+2,159 nmol/L, p < 0.0001) and sarcolemmal sialylation (p = 0.0090) were observed at day 90 compared to baseline. A slower rate of decline was observed for upper extremity strength (p = 0.0139), lower extremity strength (p = 0.0006), and the Adult Myopathy Assessment Tool (p = 0.0453), compared to natural history. Decreased disease progression was estimated at 12 (γ = 0.61 [95% CI: 0.09, 1.27]) and 18 months (γ = 0.55 [95% CI: 0.12, 1.02]) using the GNE-DPM. ConclusionManNAc showed long-term safety, biochemical efficacy consistent with the intended mechanism of action, and preliminary evidence clinical efficacy in patients with GNE myopathy.

An Exploratory Study on Physical Function in Stem Cell Transplant Patients Undergoing Corticosteroid Treatment for Acute Graft-Versus-Host-Disease.

Acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation is treated with corticosteroids, placing patients at risk for steroid myopathy. In this single-arm cohort study, 23 patients who were started on high-dose corticosteroids for acute graft-versus-host disease underwent a series of functional tests (baseline and days 14, 28, and 56): 6-min walk test, hip flexor and knee extensor strength via dynamometry, five times sit-to-stand, Brooke scale for myopathy, modified Adult Myopathy Assessment Tool, and manual muscle testing. Participants were prescribed home exercises including walking and resistance exercises, with low adherence. Fifteen (63%) participants were male and median (range) age was 60 (36-70) yrs. Median (range) corticosteroid duration and cumulative equivalent methylprednisolone dose were 66 (22-165) days and 3625 (1020-11720) mg, respectively. At day 14, there was a significant decline in five times sit-to-stand (P = 0.0132), knee extensor (P = 0.0182), and manual muscle testing (P = 0.0466). Functional tests negatively associated with cumulative corticosteroid dose included 6-min walk test distance (P = 0.0103), hip flexor strength (P = 0.0262), knee extensor strength (P = 0.0369), and manual muscle testing strength (P = 0.0319). Five times sit-to-stand was positively associated with corticosteroid dose (P = 0.0003). In conclusion, stem cell transplant patients receiving high-dose corticosteroids for acute graft-versus-host disease are at risk for weakness detected as early as day 14. Increasing adherence to exercise may mitigate these changes.

Skeletal Muscle Magnetic Resonance Biomarkers in GNE Myopathy.

To characterize muscle involvement and evaluate disease severity in patients with GNE myopathy using skeletal muscle MRI and proton magnetic resonance spectroscopy (1H-MRS). Skeletal muscle imaging of the lower extremities was performed in 31 patients with genetically confirmed GNE myopathy, including T1-weighted and short tau inversion recovery (STIR) images, T1 and T2 mapping, and 1H-MRS. Measures evaluated included longitudinal relaxation time (T1), transverse relaxation time (T2), and 1H-MRS fat fraction (FF). Thigh muscle volume was correlated with relevant measures of strength, function, and patient-reported outcomes. The cohort was representative of a wide range of disease progression. Contractile thigh muscle volume ranged from 5.51% to 62.95% and correlated with thigh strength (r = 0.91), the 6-minute walk test (r = 0.82), the adult myopathy assessment tool (r = 0.83), the activities-specific balance confidence scale (r = 0.65), and the inclusion body myositis functional rating scale (r = 0.62). Four stages of muscle involvement were distinguished by qualitative (T1W and STIR images) and quantitative methods: stage I: unaffected muscle (T1 = 1,033 ± 74.2 ms, T2 = 40.0 ± 1.9 ms, FF = 7.4 ± 3.5%); stage II: STIR hyperintense muscle with minimal or no fat infiltration (T1 = 1,305 ± 147 ms, T2 = 50.2 ± 3.5 ms, FF = 27.6 ± 12.7%); stage III: fat infiltration and STIR hyperintensity (T1 = 1,209 ± 348 ms, T2 = 73.3 ± 12.6 ms, FF = 57.5 ± 10.6%); and stage IV: complete fat replacement (T1 = 318 ± 39.9 ms, T2 = 114 ± 21.2 ms, FF = 85.6 ± 4.2%). 1H-MRS showed a significant decrease in intramyocellular lipid and trimethylamines between stage I and II, suggesting altered muscle metabolism at early stages. MRI biomarkers can monitor muscle involvement and determine disease severity noninvasively in patients with GNE myopathy. NCT01417533.

Sarcocystis rileyi in UK free-living wildfowl (Anatidae): surveillance, histopathology and first molecular characterisation

BackgroundReports from UK hunters of ‘rice grains’ in muscles of shot wildfowl (Anatidae) coincided temporally with the finding of sarcocystosis in a number of ducks found as part of the...

Preliminary design and validation of the "6-K-scale" for bulbar symptoms evaluation in SBMA.

Spinal and bulbar muscular atrophy (SBMA) is a late onset, X-linked neuromuscular disease. Bulbar symptoms are a main characteristic of the disease but a tool for their clinical evaluation still does not exist. The aim of this study was to design and test a new scale (6-K-scale) for evaluation of bulbar function in SBMA. We considered 60 genetically confirmed SBMA patients and built a scale to evaluate the V, VII, IX, X, and XII cranial nerves (CN) and the ansa cervicalis. Functional status was evaluated through the Spinal and Bulbar Muscular Atrophy Functional Rating Scale (SBMAFRS), 6-min-walk-test (6MWT), Adult Myopathy Assessment Tool (AMAT) scale, and FVC%. Twenty patients underwent a re-test after 3weeks, while 31 were tested longitudinally after 6months. Validation of the scale included reliability assessment and factorial analysis. To evaluate convergent validity, correlations between the 6-K-scale and functional parameters were performed. Internal consistency as measured by Cronbach's alpha was high (0.85) as was test-retest reliability. Principal component analysis yielded a six-factor solution accounting for 71.7% of the variance. The scale score was strongly correlated with the functional parameters. In conclusion, we designed and validated a new scale for bulbar evaluation in SBMA patients. This scale will be a useful tool in the clinical practice as well as a possible outcome measure in clinical trials.

Muscle and not neuronal biomarkers correlate with severity in spinal and bulbar muscular atrophy.

ObjectiveTo determine whether blood biomarkers of neuronal damage (neurofilament light chain [NfL]), muscle damage (creatine kinase [CK]), and muscle mass (creatinine) are altered in spinal and bulbar muscular atrophy (SBMA) and can be used as biomarkers for disease severity.MethodsIn this multicenter longitudinal prospective study, plasma and serum were collected from 2 cohorts of patients with SBMA in London, United Kingdom (n = 50), and Padova, Italy (n = 43), along with disease (amyotrophic lateral sclerosis [ALS]) and healthy controls, and levels of plasma and serum NfL, CK, and creatinine were measured. Disease severity was assessed by the SBMA Functional Rating Scale and the Adult Myopathy Assessment Tool at baseline and 12 and 24 months.ResultsBlood NfL concentrations were increased in ALS samples, but were unchanged in both SBMA cohorts, were stable after 12 and 24 months, and were not correlated with clinical severity. Normal NfL levels were also found in a well-established mouse model of SBMA. Conversely, CK concentrations were significantly raised in SBMA compared with ALS samples, and were not correlated to the clinical measures. Creatinine concentrations were significantly reduced in SBMA, and strongly and significantly correlated with disease severity.ConclusionsWhile muscle damage and muscle mass biomarkers are abnormal in SBMA, axonal damage markers are unchanged, highlighting the relevant primary role of skeletal muscle in disease pathogenesis. Creatinine, but not CK, correlated with disease severity, confirming its role as a valuable biomarker in SBMA.

Safety, tolerability, and preliminary efficacy of an IGF-1 mimetic in patients with spinal and bulbar muscular atrophy: a randomised, placebo-controlled trial

Spinal and bulbar muscular atrophy is an X-linked neuromuscular disease caused by CAG repeat expansion in the androgen receptor gene. Patients with this disease have low concentrations of insulin-like growth factor-1 (IGF-1), and studies of overexpression and administration of IGF-1 showed benefit in a transgenic model; thus the IGF-1 pathway presents as a potential treatment target. We assessed safety, tolerability, and preliminary efficacy of BVS857, an IGF-1 mimetic, in patients with spinal and bulbar muscular atrophy. In this randomised, double-blind, placebo-controlled trial, we recruited patients from neuromuscular centres in Denmark (Copenhagen), Germany (Ulm), Italy (Padova), and three sites within the USA (Bethesda, MD; Irvine, CA; and Columbus, OH). Eligible patients were 18 years or older with a confirmed genetic diagnosis of spinal and bulbar muscular atrophy, were ambulatory, had symptomatic weakness, and had serum IGF-1 concentrations of 170 ng/mL or lower. Patients were randomly assigned (2:1) to study drug or placebo by a number scheme. Patients, investigators, and study personnel were masked to treatment assignment. After a safety and tolerability assessment with eight patients, BVS857 was administered once a week (0·06 mg/kg intravenously) for 12 weeks. Primary outcome measures were safety, tolerability, and the effects of BVS857 on thigh muscle volume (TMV) measured by MRI. The ratio of TMV at day 85 to baseline was analysed with ANCOVA per protocol. Secondary outcomes of muscle strength and function were measured with the Adult Myopathy Assessment Tool, lean body mass through dual energy x-ray absorptiometry, and BVS857 pharmacokinetics. This trial was registered with ClinicalTrials.gov, NCT02024932. 31 patients were assessed for eligibility, 27 of whom were randomly assigned to either BVS857 treatment (n=18) or placebo (n=9), and 24 were included in the preliminary efficacy analysis (BVS857 group, n=15; placebo group, n=9). BVS857 was generally safe with no serious adverse events. No significant differences were found in adverse events between the BVS857 and placebo groups. Immunogenicity was detected in 13 (72%) of 18 patients in the BVS857 group, including crossreacting antibodies with neutralising capacity to endogenous IGF-1 in five patients. TMV decreased from baseline to day 85 in the placebo group (-3·4% [-110 cm3]) but not in the BVS857 group (0% [2 cm3]). A significant difference in change in TMV was observed in the BVS857 group versus the placebo group (geometric-mean ratio 1·04 [90% CI 1·01-1·07]; p=0·02). There were no differences between groups in measures of muscle strength and function. TMV remained stable in patients with spinal and bulbar muscular atrophy after being given BVS857 for 12 weeks. The intervention was associated with high incidence of immunogenicity and did not improve muscle strength or function. Additional studies might be needed to assess the efficacy of activating the IGF-1 pathway in this disease. Novartis Pharmaceuticals and the US National Institutes of Health.

Association of Preoperative Diagnosis with Clinical Yield of Muscle Biopsy.

Background: Muscle biopsy is a common diagnostic marker for myopathy assessment; however, it has a relatively low pathologic yield of less than 60%. Additionally, both diagnostic and non-diagnostic muscle biopsies can provide guidance for treatment, i.e, provide therapeutic usefulness.Purpose: We designed a study to determine if having a documented definitive preoperative differential diagnosis would affect the pathologic yield and therapeutic usefulness of muscle biopsies for myopathy. Methods: This was a retrospective, single institution chart review of 106 consecutive muscle biopsies in adult patients, which looked at the presence or absence of a definitive preoperative differential diagnosis and relation to diagnostic yield and therapeutic usefulness of muscle biopsies. Results: Of 106 muscle biopsies, 50 biopsies (47%) had a definitive preoperative differential diagnosis, 52 biopsies (49%) returned definitive pathology, and 93 biopsies (88%) provided therapeutic information. The presence of a documented differential diagnosis increased the odds of pathologic yield by 3.73 (p-value < 0.01) and therapeutic usefulness by 3.40 (p-value 0.08). If pathology was diagnostic then the therapeutic usefulness of the biopsy was 4.54 times more likely (p-value < 0.01). Conclusion: Documentation of a definitive preoperative differential diagnosis, when pursuing muscle biopsy for myopathy, is associated with an increased pathologic diagnostic yield. Definitive pathology was associated with an increase in the therapeutic usefulness of the muscle biopsy.

Patient reported outcomes in GNE myopathy: incorporating a valid assessment of physical function in a rare disease

Background: The aim of this analysis was to evaluate the psychometric properties of three patient reported outcome (PRO) measures characterizing physical function in GNE myopathy: the Human Activity Profile, the Inclusion Body Myositis Functional Rating Scale, and the Activities-specific Balance Confidence scale.Methods: This analysis used data from 35 GNE myopathy subjects participating in a natural history study. For construct validity, correlational and known-group analyses were between the PROs and physical assessments. Reliability of the PROs between baseline and 6 months was evaluated using the intra-class correlation coefficient model; internal consistency was tested with Cronbach’s alpha.Results: The hypothesized moderate positive correlations for construct validity were supported; the strongest correlation was between the human activity profile adjusted activity score and the adult myopathy assessment endurance subscale score (r = 0.81; p < 0.0001). The PROs were able to discriminate between known high and low functioning groups for the adult myopathy assessment tool. Internal consistency of the PROs was high (α > 0.8) and there was strong reliability (ICC >0.62).Conclusion: The PROs are valid and reliable measures of physical function in GNE myopathy and should be incorporated in investigations to better understand the impact of progressive muscle weakness on physical function in this rare disease population.Implications for RehabilitationGNE myopathy is a rare muscle disease that results in slow progressive muscle atrophy and weakness, ultimately leading to wheelchair use and dependence on a caregiver.There is limited knowledge on the impact of this disease on the health-related quality of life, specifically physical function, of this rare disease population.Three patient reported outcomes have been shown to be valid and reliable in GNE myopathy subjects and should be incorporated in future investigations to better understand how progressive muscle weakness impacts physical functions in this rare disease population.The patient reported outcome scores of GNE myopathy patients indicate a high risk for falls and impaired physical functioning, so it is important clinicians assess and provide interventions for these subjects to maintain their functional capacity.

P.360 - The utility of immunohistochemistry in the assessment of myopathies with tubular aggregates and cylindrical spirals

P.360 - The utility of immunohistochemistry in the assessment of myopathies with tubular aggregates and cylindrical spirals

Arm Swelling - Weight Lifting

HISTORY: A 26-year old female presented to clinic with bilateral arm swelling after exercise. Symptoms started 1 year prior after a crossfit workout that involved upper arm weight training exercises. She developed significant swelling of the upper arms 2 days later with difficulty extending her arms and an associated feeling of tightness in the upper arms. The swelling improved after 1 week with residual pain in the upper arms for about 2 weeks. She saw a physician and was noted to have an elevated C-reactive protein that resolved after several days. She resumed upper body workouts 2 months prior to her clinic visit and again developed swelling in bilateral arms 2 days later. She reported having a total of 4 episodes of swelling and pain in the arms, each occurring after upper extremity exercises and resolving with rest and NSAIDs after 1-2 weeks. She denied any swelling or pain in the lower extremities at rest or after exercise, and she ran regularly. No family history of myopathy or neuromuscular disorders. PHYSICAL EXAMINATION: Examination of the upper extremities revealed no visible ecchymosis, erythema or swelling over the bilateral upper extremities. There was normal muscle bulk of the arms. There was tenderness to palpation of the distal biceps muscle. There was full active and passive range of motion of the elbow and shoulder bilaterally. Strength was 4+/5 with elbow extension bilaterally, otherwise full strength in the upper extremities. Sensation was intact to light touch and reflexes were equal and symmetric in bilateral upper extremities. DIFFERENTIAL DIAGNOSIS: 1. Recurrent exertional rhabdomyolysis 2. Inflammatory Myopathy 3. Mitchondrial disorder 4. Lipid or carbohydrate storage disorder TEST AND RESULTS: EMG/Nerve Conduction Study: abnormalities in upper limbs consistent with myopathic process, with short duration, polyphasic motor units, early recruitment. CRP: 4.2 CPK: 5117 (day after upper arm resistance exercise routine) FINAL WORKING DIAGNOSIS: Recurrent exertional rhabdomyloysis affecting the upper extremities TREATMENT AND OUTCOMES: 1. Activity as tolerated 2. Avoid exercises that causes arms to swell or be painful afterwards 3. Referral to Neurology for assessment of myopathy or related disorder 4. Subsequent muscle biopsy, myoglobinuria panel normal. Negative CPT2 genetic testing.

Ultrasound in Neuromuscular Disorders.

Electrodiagnosis with nerve conduction studies and needle electromyography has been the standard method of diagnosis of neuromuscular conditions for over 80 years. Although ultrasound technology has been in existence for approximately the same time, application of this technology to assessment of the neuromuscular system only began in the 1980s. In the past 2 decades-mainly because of advances in resolution enabled by high frequency transducers and improved image processing-ultrasound has enabled the real-time, morphologic evaluation of focal and diffuse neuropathies, motor neuron diseases, and myopathies. Although methods of nerve and muscle assessment continue to evolve (i.e., Doppler imaging to evaluate intraneural and intramuscular blood flow), nerves have most commonly been evaluated based on their cross-sectional area, which seems to correlate with nerve swelling and pathology, particularly in focal and also in some diffuse neuropathies. Qualitative and more recently quantitative measures of muscle echogenicity have been used in the assessment of myopathies and motor neuron diseases. Collection of normal values in heterogeneous populations, extremes of age and patients with differing anthropometric profiles, has helped develop tables of normal values, thereby allowed ultrasound measurements to be judged against a reference standard, as has previously been established for nerve conduction studies.

A randomized controlled trial of exercise in spinal and bulbar muscular atrophy.

ObjectiveTo determine the safety and efficacy of a home-based functional exercise program in spinal and bulbar muscular atrophy (SBMA).MethodsSubjects were randomly assigned to participate in 12 weeks of either functional exercises (intervention) or a stretching program (control) at the National Institutes of Health in Bethesda, MD. A total of 54 subjects enrolled, and 50 completed the study with 24 in the functional exercise group and 26 in the stretching control group. The primary outcome measure was the Adult Myopathy Assessment Tool (AMAT) total score, and secondary measures included total activity by accelerometry, muscle strength, balance, timed up and go, sit-to-stand test, health-related quality of life, creatine kinase, and insulin-like growth factor-1.ResultsFunctional exercise was well tolerated but did not lead to significant group differences in the primary outcome measure or any of the secondary measures. The functional exercise did not produce significantly more adverse events than stretching, and was not perceived to be difficult. To determine whether a subset of the subjects may have benefited, we divided them into high and low functioning based on baseline AMAT scores and performed a post hoc subgroup analysis. Low-functioning individuals receiving the intervention increased AMAT functional subscale scores compared to the control group.InterpretationAlthough these trial results indicate that functional exercise had no significant effect on total AMAT scores or on mobility, strength, balance, and quality of life, post hoc findings indicate that low-functioning men with SBMA may respond better to functional exercises, and this warrants further investigation with appropriate exercise intensity.

99mTc-Sestamibi Thigh SPECT/CT Imaging for Assessment of Myopathy in Cerebrotendinous Xanthomatosis With Histopathological and Immunohistochemical Correlation

The aim of this study was to determine the effectiveness of using Tc-sestamibi thigh SPECT/CT imaging for evaluating myopathy in cerebrotendinous xanthomatosis (CTX). Four genetically proven CTX patients (Family I, Cases I-1 and I-2; Family II, Cases II-1 and II-2) were included. They all underwent muscle biopsies for histopathologic and ultrastructural studies. Immunohistochemical staining for vinculin expression was also performed. Tc-sestamibi thigh SPECT/CT imaging was conducted on all 4 CTX patients, and both visual interpretation and muscle-to-background (M/B) ratio count were applied for assessment. Correlation analysis of the imaging findings and results of the ultrastructural and immunohistochemical studies was done. In the Tc-sestamibi thigh SPECT/CT imaging study, all 4 CTX cases had abnormal scores of visual interpretation and M/B ratios. The ultrastructural features of the skeletal muscle of the 4 CTX cases showed mitochondrial and membrane system abnormalities, with increased depositions of metabolites. They also had abnormal increases in vinculin expression after immunohistochemical staining of the skeletal muscle. This is the first report on the use of Tc-sestamibi thigh SPECT/CT imaging to assess the mitochondrial status of CTX. The imaging findings may have a correlation with the ultrastructural and immunohistochemical findings on skeletal muscle. Although the Tc-sestamibi thigh SPECT/CT imaging is not specific for CTX, this noninvasive in vivo assessment can be an important tool for the detection and follow-up study of skeletal muscle involvement in CTX.

Assessing Function and Endurance in Adults with Spinal and Bulbar Muscular Atrophy: Validity of the Adult Myopathy Assessment Tool

Purpose. The adult myopathy assessment tool (AMAT) is a performance-based battery comprised of functional and endurance subscales that can be completed in approximately 30 minutes without the use of specialized equipment. The purpose of this study was to determine the construct validity and internal consistency of the AMAT with a sample of adults with spinal and bulbar muscular atrophy (SBMA). Methods. AMAT validity was assessed in 56-male participants with genetically confirmed SBMA (mean age, 53 ± 10 years). The participants completed the AMAT and assessments for disease status, strength, and functional status. Results. Lower AMAT scores were associated with longer disease duration (r = −0.29; P < 0.03) and lower serum androgen levels (r = 0.49–0.59; P < 0.001). The AMAT was significantly correlated with strength and functional status (r = 0.82–0.88; P < 0.001). The domains of the AMAT exhibited good internal consistency (Cronbach's α = 0.77–0.89; P < 0.001). Conclusions. The AMAT is a standardized, performance-based tool that may be used to assess functional limitations and muscle endurance. The AMAT has good internal consistency, and the construct validity of the AMAT is supported by its significant associations with hormonal, strength, and functional characteristics of adults with SBMA. This trial is registered with Clinicaltrials.gov identifier NCT00303446.

Bildgebung bei Myopathien

Until recently, the diagnosis of myopathies was mainly based on clinical examination, laboratory investigations, neurophysiology, muscle biopsy, and genetic analysis. Imaging techniques now play a central role in the evaluation of disorders of the central nervous system and the vessels. Muscle imaging by sonography, CT and MRI can be particularly useful in the assessment of myopathies as well. Sonography shows an increased echogenicity of muscles in many myopathies. On CT, differences in the X-ray absorption of muscles can be detected. Because CT uses ionising radiation, its use will be restricted to special cases. MRI is able to demonstrate subtle changes in muscle by detecting and differentiating fat deposition and oedema. MRI can therefore significantly improve the differential diagnosis of several forms of myositis and muscular dystrophies. In difficult cases it can aid in the selection of the best site for a muscle biopsy. The development of new contrast agents or techniques like magnetic resonance spectroscopy opens up new perspectives for the diagnosis of myositis or metabolic myopathies.

TUO29 Neurophysiological and pathological assessment of myopathy in 33 patients with acquired critical illness weaknes

TUO29 Neurophysiological and pathological assessment of myopathy in 33 patients with acquired critical illness weaknes

Electrical impedance myography in the bedside assessment of inflammatory myopathy

Electrical impedance myography (EIM) is a new technique with potential for the noninvasive bedside assessment of myopathy. EIM was performed on the quadriceps of 10 patients with inflammatory myopathy and 10 normal subjects. The major EIM parameter, the spatially averaged phase, was 35% lower in the myositis patients and correlated with whole-body (r = 0.765, p = 0.01) and quadriceps (r = 0.673, p = 0.03) strength.

Diagnostic principles in myopathies

Myopathies include a broad range of disorders. Diagnostic steps in muscle disorders should therefore be followed sequentially, in order not to miss important information and to avoid unnecessary and cost intensive diagnostic procedures. Specific care should be applied in taking patient's history to ascertain myopathy related complaints, triggers and concomitant diseases possibly being accompanied by a myopathy. Clinical examination may reveal a distribution pattern already suggestive for a specific disorder. An elevated creatine kinase, often leading to neurological evaluation, should at least be repeated once after resting. Metabolic myopathies might be detected by exercise testing. Electromyography, muscle imaging and, usually as the last diagnostic step, muscle biopsy represent further diagnostic tools in the assessment of myopathies. In some disorders molecular genetic techniques can be applied.