Heterogeneous characteristics of MRI changes of thigh muscles in patients with dysferlinopathy

Introduction: The aim of this study was to evaluate the pattern of thigh muscle MRI changes in a large cohort of patients with dysferlinopathy. Methods: MRI of the thigh was performed in 60 patients. We correlated the scale of muscle involvement on MRI with the modified Gardner‐Medwin and Walton (GM‐W) scale and disease duration. We also analyzed the relationship between muscle changes and genetic mutations. Results: Fatty infiltration and edema were observed in 95.50% and 86.67% of patients, respectively. The hamstring muscles had the highest frequency and mean score of fatty infiltration, although a posterior‐dominant pattern was found in only 56%. Edema most commonly and severely affected the quadriceps and adductor magnus muscles. Fatty infiltration score correlated positively with disease duration and GM‐W scale. Conclusions: The pattern of fatty infiltration was heterogeneous in dysferlinopathy patients. Muscle edema was common. Fatty infiltration can be used to assess disease progression. Muscle Nerve 54 : 1072–1079, 2016     

Muscle magnetic resonance imaging and histopathology in ACTA1‐related congenital nemaline myopathy

Introduction: Muscle biopsy is usually diagnostic in nemaline myopathy (NM), but some patients may show nonspecific findings, leading to pitfalls in diagnosis. Muscle MRI is a helpful complementary tool. Methods: We assessed the clinical, histopathological, MRI, and molecular findings in a 19‐year‐old patient with NM in whom 2 muscle biopsies with ultrastructural examination showed no nemaline bodies. We analyzed the degree and pattern of muscle MRI involvement of the entire body, including the tongue and pectoral muscles. Results: Muscle MRI abnormalities in sartorius, adductor magnus, and anterior compartment muscles of the leg suggested NM. A previously unreported fatty infiltration of the tongue was found. A third biopsy after the muscle MRI showed scant nemaline bodies. A novel heterozygous de novo ACTA1 c.611C>T/p.Thr204Ile mutation was detected. Conclusions: We highlight the contribution of muscle imaging in addressing the genetic diagnosis of ACTA1‐related NM. Muscle Nerve 50: 1011–1016, 2014     

Whole-Body Muscle Magnetic Resonance Imaging in Glycogen-Storage Disease Type III

Introduction: The main objective of this study was to describe muscle involvement on whole-body magnetic resonance imaging scans in adults at different stages of glycogen-storage disease type III (GSDIII). Methods: Fifteen patients, 16–59 years of age, were examined on a 3-T system. The examinations consisted of coronal and axial T1-weighted images or fat images with a Dixon technique, and were scored for 47 muscles using Mercuri's classification. Muscle changes consisted of internal bright signals of fatty replacement. Results: Distribution across muscles showed predominant signal alteration in the lower limbs and postural muscles. This finding is consistent with the overall clinical presentation of GSDIII and the results of heatmap scores. Review of the MRI scans provided new information regarding recurrent muscle changes, particularly in the soleus, gastrocnemius medial head, and thoracic extensor muscles. Discussion: Whole-body muscle imaging provides clinically relevant information regarding muscle involvement in GSDIII. A severity score may contribute to improved patient management. Muscle Nerve, 2019     

Clinical and imaging hallmarks of the MYH7‐related myopathy with severe axial involvement

Introduction: MYH7 gene mutations are related to a heterogeneous group of skeletal and cardiac myopathies. Methods: We evaluated clinical and muscle MRI changes in patients with mutations in the rod domain of MYH7, including 1 with mosaicism and 3 with novel missense mutations. Results: Patients presented in childhood with a distal and axial phenotype. Biopsy findings were variable. Half of the cases displaying some type of core pathology, including minicores and eccentric cores. Most patients demonstrated internal bands of infiltration (“inverted‐collagen‐VI sign”) in multiple muscles, particularly the soleus, and prominent atrophy and fatty infiltration of the tongue and the paraspinal, gluteus minimus, sartorius, gracilis, tibialis anterior, and extensor digitorum longus muscles. Discussion: Muscle imaging findings in patients with axial involvement provide significant clues permitting the distinction between MYH7‐related myopathies and other axial myopathies such as those related to SEPN1 and LMNA genes. Muscle Nerve 58 : 224–234, 2018     

High‐pass filtering surface EMG in an attempt to better represent the signals detected at the intramuscular level

Surface electromyography (EMG) is often used to represent activation profiles of the underlying musculature. The purpose of this study was to assess the potential of high‐pass (HP) filtering to improve the matching of surface EMG signals to those signals recorded intramuscularly. EMG was recorded at the skin surface over the infraspinatus and supraspinatus muscles as well as from fine‐wire electrodes placed in the infraspinatus, supraspinatus, and teres minor muscles. The surface EMG signals were HP‐filtered at 18 cutoff frequencies (0–510 HZ in 30 HZ increments), and the time‐histories were correlated with the signals from the wire electrodes. HP filtering did not significantly alter the correlated muscle activation waveform relationship between the surface and wire signals until cutoffs reached 240 HZ . HP filtering of the surface signals did not improve the representation of the muscle fiber‐level activation profile, but the results suggest that enough information resides in the high‐frequency components of the signal to reproduce the activation time–history profile of the muscle. Muscle Nerve, 2010     

Thigh magnetic resonance imaging for the evaluation of disease activity in patients with idiopathic inflammatory myopathies followed in a single center

Introduction: In patients with idiopathic inflammatory myopathies (IIM), magnetic resonance imaging (MRI) has been proposed as a useful tool for diagnosis and follow‐up. It may identify muscle inflammation (edema) and fatty infiltration for evaluation of disease activity and damage. Little information is available on the role of MRI in assessment of large cohorts of adult patients with IIM. Methods: Fifty‐one patients underwent MRI of the thigh muscles, laboratory tests, and clinical evaluation, including Physician Global Assessment (PGA) of myositis activity and the Manual Muscle Test 8 (MMT8). Results: Muscle edema correlated significantly with creatine kinase values (P = 0.017) and PGA (P < 0.001). A significant correlation between edema and MMT8 values (P = 0.025) was observed when patients with muscle fatty infiltration were excluded. With respect to clinical diagnosis, the sensitivity of MRI was 92.3%, and specificity was 83.3%. Conclusions: MRI appears to provide additional information that complements clinical and biochemical examinations. Muscle Nerve 54 : 666–672, 2016     

Generating color‐coded anatomic muscle maps for correlation of quantitative magnetic resonance imaging analysis with clinical examination in neuromuscular disorders

Introduction: Fatty infiltration of muscles may be seen in many neuromuscular disorders, including glycogen storage disease (GSD), muscular dystrophy, and amyotrophic lateral sclerosis. Recording pathologic involvement of musculature in these patients is cumbersome, given marked disease heterogeneity within each individual. We describe a novel method for simplifying this process and present its application in a patient with GSD type IIIa. Methods: A color‐coded visual mapping tool was developed based on a commonly used spreadsheet platform. Results: This tool depicts individual muscle groups as shapes linked to data cells corresponding to quantitative MRI‐based measures of fatty infiltration and weakness assessed by physical examination. It allows for rapid evaluation and chronological comparison of all mapped muscle groups on a single graphical sheet, as well as assessment of response to therapy. Conclusion:This approach can be applied in any neuromuscular disorder where muscle function is assessed by clinical or imaging scores. Muscle Nerve, 48: 293–295, 2013     

Bioenergetics and intermuscular fat in chronic obstructive pulmonary disease‐associated quadriceps weakness

Introduction: Chronic obstructive pulmonary disease (COPD) is associated with metabolic abnormalities in muscles of the lower limbs, but it is not known whether these abnormalities are generalized or limited to specific muscle groups, nor is there an easy way of predicting their presence. Methods: Metabolism in the quadriceps and biceps of 14 COPD patients and controls was assessed during sustained contraction using 31‐phosphorus magnetic resonance spectroscopy (³¹P MRS). T1 MRI was used to measure quadriceps intermuscular adipose tissue (IMAT). Results: COPD patients had prolonged quadriceps phosphocreatine time (patients: 38.8 ± 12.7 s; controls: 25.2 ± 10.6 s; P = 0.006) and a lower pH (patents: 6.88 ± 0.1; controls: 6.99 ± 0.06; P = 0.002). Biceps measures were not significantly different. IMAT was associated with a nadir pH <7.0 (area under the curve = 0.84). Conclusions: Anaerobic metabolism during contraction was characteristic of quadriceps, but not biceps, muscles of patients with COPD and was associated with increased IMAT. Because IMAT can be assessed quickly by conventional MRI, it may be a useful approach for identifying patients with abnormal muscle bioenergetics. Muscle Nerve 51 : 214–221, 2015     

Whole‐body magnetic resonance imaging evaluation of facioscapulohumeral muscular dystrophy

Introduction: Facioscapulohumeral muscular dystrophy (FSHD) is a hereditary disorder that causes progressive muscle wasting. Increasing knowledge of the pathophysiology of FSHD has stimulated interest in developing biomarkers of disease severity. Methods: Two groups of MRI scans were analyzed: whole‐body scans from 13 subjects with FSHD; and upper and lower extremity scans from 34 subjects with FSHD who participated in the MYO‐029 clinical trial. Muscles were scored for fat infiltration and edema‐like changes. Fat infiltration scores were compared with muscle strength and function. Results: The analysis revealed a distinctive pattern of both frequent muscle involvement and frequent sparing in FSHD. Averaged fat infiltration scores for muscle groups in the legs correlated with quantitative muscle strength and 10‐meter walk times. Conclusions: Advances in MRI technology allow for acquisition of rapid, high‐quality, whole‐body imaging in diffuse muscle disease. This technique offers a promising disease biomarker in FSHD and other muscle diseases. Muscle Nerve 52: 512–520, 2015     

Longitudinal 2‐point dixon muscle magnetic resonance imaging in becker muscular dystrophy

Introduction: Quantitative MRI techniques detect disease progression in myopathies more sensitively than muscle function measures or conventional MRI. To date, only conventional MRI data using visual rating scales are available for measurement of disease progression in Becker muscular dystrophy (BMD). Methods: In 3 patients with BMD (mean age 36.8 years), the mean fat fraction (MFF) of the thigh muscles was assessed by MRI at baseline and at 1‐year follow‐up using a 2‐point Dixon approach (2PD). The motor function measurement scale (MFM) was used for clinical assessment. Results: The mean MFF of all muscles at baseline was 61.6% (SD 7.6). It increased by 3.7% to 65.3% (SD 4.7) at follow‐up. The severity of muscle involvement varied between various muscle groups. Conclusions: As in other myopathies, 2PD can quantify fatty muscle degeneration in BMD and can detect disease progression in a small sample size and at relatively short imaging intervals. Muscle Nerve 51 : 918–921, 2015     

MRI change metrics of facioscapulohumeral muscular dystrophy: Stir and T1

Introduction: MRI evaluation in facioscapulohumeral muscular dystrophy (FSHD) demonstrates fatty replacement and inflammation/edema in muscle. Our previous work demonstrated short T1 inversion recovery (STIR)‐hyperintense (STIR+) signal in muscle 2 years before fatty replacement. We evaluated leg muscle STIR changes and fatty replacement within 14 months. Methods: FSHD subjects received 2 MRI scans of thigh and calf over a 6.9‐ to 13.8‐month interval. Quality of life measures were collected. One Radiologist rated muscle changes on a semi‐quantitative scale. Results: Fifteen subjects completed longitudinal imaging. Four STIR + muscles and 3 STIR‐normal (STIR?) muscles were rated as progressing to fatty tissue over the study period. Discussion: STIR + muscles with confluent regions of fat at baseline increased more in fat, while STIR? muscles had increases in septal‐fat over the study period. These changes may reflect two phases of FSHD, demonstrating MRI sensitivity is weighted toward gross pathological phases of the disease. Muscle Nerve 57 : 905–912, 2018     

Intramuscular fat infiltration evaluated by magnetic resonance imaging predicts the extensibility of the supraspinatus muscle

Introduction: Rotator cuff (RC) tears result in muscle atrophy and fat infiltration within the RC muscles. An estimation of muscle quality and deformation, or extensibility, is useful in selecting the most appropriate surgical procedure. We determined if noninvasive quantitative assessment of intramuscular fat using MRI could be used to predict extensibility of the supraspinatus muscle. Methods: Seventeen cadaveric shoulders were imaged to assess intramuscular fat infiltration. Extensibility and histological evaluations were then performed. Results: Quantitative fat infiltration positively correlated with histological findings and presented a positive correlation with muscle extensibility (r = 0.69; P = 0.002). Extensibility was not significantly different between shoulders graded with a higher fat content versus those with low fat when implementing qualitative methods. Discussion: A noninvasive prediction of whole‐muscle extensibility may directly guide pre‐operative planning to determine if the torn edge could efficiently cover the original footprint while aiding in postoperative evaluation of RC repair. Muscle Nerve 57 : 129–135, 2018     

Dysferlinopathy: mitochondrial abnormalities in human skeletal muscle

Purpose: Mitochondrial defects have been associated with a series of muscular diseases. Dysferlinopathy, however, has been rarely reported with mitochondrial dysfunction. Here we report a cohort of dysferlinopathy patients with mitochondrial abnormalities found in muscle. Methods: Clinical data and muscle pathologies of nine cases with dysferlinopathy were retrospectively studied. mtDNA copy number, protein levels and activities of mitochondrial enzyme complexes were assayed. Results: Nine patients were diagnosed as having dysferlinopathy by DYSF sequencing and quantification of dysferlin levels in muscle homogenates. Muscle biopsies exhibited dystrophic changes (n = 9), ragged-red fibers (n = 9) and cytochrome c oxidase-deficient fibers (n = 9). mtDNA copy number increased significantly in 56% (15/27) of fibers with mitochondrial histology. Protein levels of complex IV subunits II (n = 5), complex III subunit core 2 (n = 2) and complex I NDUFB1 (n = 1) decreased. Impaired activities of complexes I, III and IV were observed in 56%, 33% and 78% of subjects and the activities were reduced by 21%, 18% and 40%, respectively. Besides, loss activities of complexes I/IV and decreased ATP level were also found in fibroblasts from dysferlinopathy. Conclusion: Prominent mitochondrial abnormalities are common pathological findings in muscle from dysferlinopathy. Our data indicated that mitochondria may play a significant role in the progression of dysferlinopathy and also highlighted the potential of mitochondrial protective drugs in rescuing the symptoms of dysferlinopathy.     

Proteomic analysis of the skeletal muscles from dysferlinopathy patients

Dysferlinopathy is an autosomal recessive disease caused by pathogenic variants in DYSF gene. We compared muscle protein extracts from dysferlinopathy patients and control subjects to identify new biomarkers of this myopathy. We reviewed the medical records from January 2002 to October 2016. Eight vastus lateralis muscle samples from five dysferlinopathy patients and three control subjects were selected. We separated proteins/peptides from all eight muscle protein extracts using two-dimensional electrophoresis (2DE). Data were acquired from liquid chromatography-mass spectrometry protein fragmentation patterns after comparing the spot volumes. Western blotting revealed total dysferlin loss in the dysferlinopathy patients but normal expression in the control subjects. 2DE indicated somewhat diverse protein constellations between the dysferlinopathy and control groups. Image analysis showed that 80 spots were differently expressed between two dysferlinopathy and one control samples. We selected 44 spots with consistently different volume between dysferlinopathy and control groups. Liquid chromatography-mass spectrometry indicated 26 differently expressed proteins. Western blotting revealed that creatine kinase M-type, carbonic anhydrase III (muscle specific) and desmin were significantly elevated in dysferlinopathy muscle. Additionally, four proteins (myosin light chain 1/3, skeletal muscle isoform; lamin A/C; ankyrin repeat domain 2; and eukaryotic translation initiation factor 5A-1) were inconsistently elevated in the dysferlinopathy samples. We confirmed the usefulness of the classic biomarker and have newly identified the altered expression of proteins in the skeletal muscles of dysferlinopathy patients.     

Characteristics of magnetic resonance imaging biomarkers in a natural history study of golden retriever muscular dystrophy

The goal of this study was to assess whether magnetic resonance imaging (MRI) biomarkers can quantify disease progression in golden retriever muscular dystrophy (GRMD) via a natural history study. The proximal pelvic limbs of ten GRMD and eight normal dogs were scanned at 3, 6, and 9–12 months of age. Several MRI imaging and texture analysis biomarkers were quantified in seven muscles. Almost all MRI biomarkers readily distinguished GRMD from control dogs; however, only selected biomarkers tracked with longitudinal disease progression. The biomarkers that performed best were full-length muscle volume and a texture analysis biomarker, termed heterogeneity index. The biceps femoris, semitendinosus and cranial sartorius muscles showed differential progression in GRMD versus control dogs. MRI features in GRMD dogs showed dynamic progression that was most pronounced over the 3- to 6-month period. Volumetric biomarkers and water map values correlated with histopathological features of necrosis/regeneration at 6-months. In conclusion, selected MRI biomarkers (volume and heterogeneity index) in particular muscles (biceps femoris, semitendinosus, and cranial sartorius) adjusted for age effect allow distinction of differential longitudinal progression in GRMD dogs. These biomarkers may be used as surrogate outcome measures in preclinical GRMD trials.     

Multivoxel proton magnetic resonance spectroscopy in facioscapulohumeral muscular dystrophy

Introduction: Facioscapulohumeral muscular dystrophy (FSHD) is a hereditary disorder that causes progressive muscle wasting. This study evaluates the use of proton magnetic resonance spectroscopy (¹H MRS) as a biomarker of muscle strength and function in FSHD. Methods: Thirty‐six individuals with FSHD and 15 healthy controls underwent multivoxel ¹H MRS of a cross‐section of the mid‐thigh. Concentrations of creatine, intramyocellular and extramyocellular lipids, and trimethylamine (TMA)‐containing compounds in skeletal muscle were calculated. Metabolite concentrations for individuals with FSHD were compared with those of controls. The relationship between metabolite concentrations and muscle strength was also examined. Results: The TMA/creatine (Cr) ratio in individuals with FSHD was reduced compared with controls. The TMA/Cr ratio in the hamstrings also showed a moderate linear correlation with muscle strength. Discussion: ¹H MRS offers a potential method of detecting early muscle pathology in FSHD prior to the development of fat infiltration. Muscle Nerve 57 : 958–963, 2018     

Combining MRI and muscle biopsy improves diagnostic accuracy in subacute‐onset idiopathic inflammatory myopathy

Introduction: In 10–20% of patients with subacute‐onset idiopathic inflammatory myopathy (IIM), muscle biopsy is normal or shows nonspecific findings. MRI can be used as a triage test before muscle biopsy and as an add‐on test if the biopsy is nondiagnostic. Methods: MRI scans of skeletal muscles and muscle biopsies were evaluated prospectively in 48 patients suspected to have IIM. The interpretations of MRI and muscle biopsy were compared with the definite diagnosis (based on European Neuromuscular Centre criteria and response to corticosteroids). Results: The false negative rate (FNR) of all muscle biopsies was 0.23. Biopsies of a muscle showing hyperintensity on MRI (as triage test) had an FNR of 0.19. The result of MRI as an add‐on test in patients with a nondiagnostic muscle biopsy decreased the FNR from 0.23 to 0.06. Conclusions: We recommend both MRI and muscle biopsy in patients suspected of having IIM. Muscle Nerve 51 : 253–258, 2015     

Whole-body muscle MRI characteristics of LAMA2-related congenital muscular dystrophy children: An emerging pattern

Merosin-deficient or LAMA2-related congenital muscular dystrophy (CMD) belongs to a group of muscle diseases with an overlapping diagnostic spectrum. MRI plays an important role in the diagnosis and disease-tracking of muscle diseases. Whole-body MRI is ideal for describing patterns of muscle involvement. We intended to analyze the pattern of muscle involvement in merosin-deficient CMD children employing whole-body muscle MRI. Ten children with merosin-deficient CMD underwent whole-body muscle MRI. Eight of which were genetically-confirmed. We used a control group of other hereditary muscle diseases, which included 13 children (mean age was 13 SD +/- 5.5 years), (8 boys and 5 girls) for comparative analysis. Overall, 37 muscles were graded for fatty infiltration using Mercuri scale modified by Fischer et al. The results showed a fairly consistent pattern of muscle fatty infiltration in index group, which differs from that in control group. There was a statistically significant difference between the two groups in regard to the fatty infiltration of the neck, serratus anterior, intercostal, rotator cuff, deltoid, triceps, forearm, gluteus maximus, gluteus medius, gastrocnemius and soleus muscles. Additionally, the results showed relative sparing of the brachialis, biceps brachii, gracilis, sartorius, semitendinosus and extensor muscles of the ankle in index group, and specific texture abnormalities in other muscles. There is evidence to suggest that whole-body muscle MRI can become a useful contributor to the differential diagnosis of children with merosin deficient CMD. The presence of a fairly characteristic pattern of involvement was demonstrated. MRI findings should be interpreted in view of the clinical and molecular context to improve diagnostic accuracy.     

Early effects of muscle atrophy on shoulder joint development in infants with unilateral birth brachial plexus injury

Aim Shoulder deformities in children with a birth brachial plexus injury (BBPI) are caused by muscle imbalances; however, the underlying mechanisms are unclear. The aim of this study was to assess the early interactions between shoulder muscles and shoulder joint development. Method In a retrospective magnetic resonance imaging (MRI) study of 36 infants (21 males, 15 females) younger than 12 months (mean 4.8mo) with unilateral BBPI, volumes and thicknesses of standardized segments of the infraspinatus, subscapularis, and deltoid muscles were measured in both shoulders and expressed as ratios of pathological/unaffected side. The relation between muscle ratios and humeral head subluxation, passive external rotation, glenoid version, and deformity was analysed. Results Compared with the unaffected side, the muscles of the affected side were of significantly smaller volume and thickness. The subscapularis was the most severely affected muscle, its volume being only 64% (SD 21%) and its thickness only 79% (SD 23%) of the corresponding values on the unaffected side (p<0.001). Severe subluxation was predicted by the combination of low infraspinatus and subscapularis volume ratios (r²=0.223; p=0.014), but not by muscle thickness ratios. Subluxation was related to passive external rotation (p<0.05), glenoid version (p<0.01), and deformity (p<0.01). Interpretation In infants with BBPI, muscle size is decreased during in the first months of life by both atrophy and, possibly, by a reduction in the number of sarcomeres in series. These effects are strongly related to shoulder joint subluxation.