Search

Purpose of Review: In the last 30 years, there have many publications describing the pattern of muscle involvement of different neuromuscular diseases leading to an increase in the information available for diagnosis. A high degree of expertise is needed to remember all the patterns described. Some attempts to use artificial intelligence or analysing muscle MRIs have been developed. We review the main patterns of involvement in limb girdle muscular dystrophies (LGMDs) and summarize the strategies for using artificial intelligence tools in this field., Recent Findings: The most frequent LGMDs have a widely described pattern of muscle involvement; however, for those rarer diseases, there is still not too much information available. patients. Most of the articles still include only pelvic and lower limbs muscles, which provide an incomplete picture of the diseases. AI tools have efficiently demonstrated to predict diagnosis of a limited number of disease with high accuracy., Summary: Muscle MRI continues being a useful tool supporting the diagnosis of patients with LGMD and other neuromuscular diseases. However, the huge variety of patterns described makes their use in clinics a complicated task. Artificial intelligence tools are helping in that regard and there are already some accessible machine learning algorithms that can be used by the global medical community., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Dystrophin-glycoprotein complex (DGC)-related muscular dystrophies may present similar clinical and pathological features as well as undetectable mutations thus being sometimes difficult to distinguish. We investigated the value of muscle magnetic resonance imaging (MRI) in the differential diagnosis of DGC-related muscular dystrophies and reported the largest series of Chinese patients with sarcoglycanopathies studied by muscle MRI., Results: Fifty-five patients with DGC-related muscular dystrophies, including 22 with confirmed sarcoglycanopathies, 11 with limb-girdle muscular dystrophy 2I (LGMD2I, FKRP-associated dystroglycanopathy), and 22 with dystrophinopathies underwent extensive clinical evaluation, muscle biopsies, genetic analysis, and muscle MRI examinations. Hierarchical clustering of patients according to the clinical characteristics showed that patients did not cluster according to the genotypes. No statistically significant differences were observed between sarcoglycanopathies and LGMD2I in terms of thigh muscle involvement. The concentric fatty infiltration pattern was observed not only in different sarcoglycanopathies (14/22) but also in LGMD2I (9/11). The trefoil with single fruit sign was observed in most patients with dystrophinopathies (21/22), and a few patients with sarcoglycanopathies (4/22) or LGMD2I (2/11). Hierarchical clustering showed that most patients with sarcoglycanopathies or LGMD2I can be distinguished from dystrophinopathies based on the concentric fatty infiltration pattern and trefoil with single fruit sign at the thigh level on muscle MRI., Conclusions: Muscle MRI at the thigh level potentially allows distinction of sarcoglycanopathies or FKRP-associated dystroglycanopathy from dystrophinopathies.

Background: The purpose of this study was to evaluate the diagnostic value of the trefoil (three leaflets formed by relative sparing of the sartorius, gracilis, and adductor longus) with single fruit sign (relative sparing of the semitendinosus) in the evaluation of thigh muscle magnetic resonance imaging (MRI) for dystrophinopathies., Methods: Five examiners blinded to any clinical data analyzed muscle MRI scans from 166 patients with dystrophinopathies (124 cases confirmed genetically and 42 cases confirmed by immunohistochemistry) and from 244 control patients, all treated in our hospital from 2011 to 2014. The controls were patients with other neuromuscular disorders and with dystrophinopathies excluded by genetic testing and/or muscle biopsy. Examiners assessed the presence or absence of the trefoil with single fruit sign approximately at the middle thigh cross-section. Results were analyzed for diagnostic accuracy and inter-examiner agreement., Results: Sensitivity of the trefoil with single fruit sign for all patients with dystrophinopathies was 41.6% (95% confidence interval (CI) of 34.0-49.5). However, specificity was 99.2% (95% CI 97.1-99.9). The positive predictive value (PPV) was 97.2% and negative predictive value (NPV) was 71.4%. Inter-examiner agreement was substantial (Kappa=0.66). The 69 dystrophinopathy patients whose MRIs exhibited the sign were significantly older than the 97 dystrophinopathy patients whose MRIs did not (Z=-3.970, P<0.001)., Conclusions: The trefoil with single fruit sign is a potential imaging marker for diagnosis of dystrophinopathies., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Background: Outcome measures for clinical trials in neuromuscular diseases are typically based on physical assessments which are dependent on patient effort, combine the effort of different muscle groups, and may not be sensitive to progression over short trial periods in slow-progressing diseases. We hypothesised that quantitative fat imaging by MRI (Dixon technique) could provide more discriminating quantitative, patient-independent measurements of the progress of muscle fat replacement within individual muscle groups., Objective: To determine whether quantitative fat imaging could measure disease progression in a cohort of limb-girdle muscular dystrophy 2I (LGMD2I) patients over a 12 month period., Methods: 32 adult patients (17 male;15 female) from 4 European tertiary referral centres with the homozygous c.826C>A mutation in the fukutin-related protein gene (FKRP) completed baseline and follow up measurements 12 months later. Quantitative fat imaging was performed and muscle fat fraction change was compared with (i) muscle strength and function assessed using standardized physical tests and (ii) standard T1-weighted MRI graded on a 6 point scale., Results: There was a significant increase in muscle fat fraction in 9 of the 14 muscles analyzed using the quantitative MRI technique from baseline to 12 months follow up. Changes were not seen in the conventional longitudinal physical assessments or in qualitative scoring of the T₁w images., Conclusions: Quantitative muscle MRI, using the Dixon technique, could be used as an important longitudinal outcome measure to assess muscle pathology and monitor therapeutic efficacy in patients with LGMD2I.

Objective: To evaluate the reliability and accuracy of skeletal muscle CT to correctly identify different muscular dystrophies manifesting with limb-girdle weakness., Methods: Four evaluators assessed scans from 118 patients with limb-girdle muscular dystrophy (LGMD) caused by mutations in 7 different genes and from 32 controls. The conditions studied were scans of genetically confirmed cases of Becker muscular dystrophy (BMD) (n = 28), LGMD2C-F (sarcoglycanopathies) (n = 11), LGMD2I (n = 4), LGMD1B (n = 26), LGMD2A (n = 24), Bethlem myopathy (n = 14), and LGMD2L (n = 11). The control group (n = 32) consisted of patients with neuromuscular disorders manifesting with limb-girdle weakness in which the aforementioned muscular dystrophies were excluded. The scans were compared with the characteristic patterns described in literature., Results: The overall interobserver agreement was poor (κ = 0.27), with markedly higher scores for BMD (κ = 0.51) and Bethlem myopathy (κ = 0.59). The sensitivity to detect selective patterns in relation to the genetic diagnosis was 40% if all LGMDs were taken together. The specificity was 58%, positive predictive value (PPV) 77%, and 1 - negative predictive value (NPV) 79%. Markedly better scores were observed for BMD (sensitivity 91%, PPV 66%, 1 - NPV 3%) and Bethlem myopathy (sensitivity 90%, PPV 69%, 1 - NPV 1%)., Conclusions: Our findings suggest that muscle CT might be an adjunct to the clinical diagnosis of BMD and Bethlem myopathy. However, pattern recognition was cumbersome in the other LGMDs.

Limb girdle muscular dystrophy type 2L (LGMD2L) is an adult-onset slowly progressive muscular dystrophy associated with recessive mutations in the ANO5 gene. We analysed the muscle MRI pattern in a cohort of 25 LGMD2L patients in order to understand the extent and progression of muscle pathology in LGM2L and assess if muscle MRI might help in the diagnostic work-up of these patients. Our results showed a homogeneous pattern of muscle pathology on muscle MRI, with a predominant involvement of the posterior compartment muscles in both the thighs and calves. The muscles of the anterior compartments in the leg together with the sartorius and gracilis muscles were best preserved, which partially overlaps with patterns observed for other recessive LGMDs. Muscle MRI therefore does not appear to be as useful in the diagnostic work up of LGMD2L as for other neuromuscular diseases, such as Bethlem myopathy or myofibrillar myopathy., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Laminopathies are a heterogeneous group of LMNA-gene-mutation-related clinical disorders associated with alterations of cardiac and skeletal muscle and peripheral nerves, metabolic defects, and premature aging. Leg muscle imaging investigations were performed in a cohort of patients with LMNA gene alterations who were suffering from Emery-Dreifuss muscular dystrophy, limb-girdle muscular dystrophy type 1B, isolated cardiac disorders or a phenotype of cardiac disorders, and lipodystrophy, including one individual with peripheral neuropathy. Leg muscle imaging revealed varying degrees of alteration in the soleus and medial head of gastrocnemius in each subject. This study demonstrates that LMNA-gene-mutated patients devoid of any clinically detectable skeletal muscle involvement have the same pattern of leg muscle involvement as patients with overt skeletal muscle compromise. This finding suggests the presence of a continuum of skeletal muscle involvement among phenotypes of LMNA-gene-mutation-related skeletalmyopathy and cardiomyopathy.

Background: Myopathies present with a broad diagnostic spectrum which may ultimately require muscle biopsy. MRI has been established as a non-invasive method in diagnosing adult myopathies; not only does MRI reveal characteristic findings which point in a diagnostic direction, but also aids in determining optimal biopsy sites and controlling therapeutic interventions. Muscle MRI is increasingly finding application to pediatric myopathies, especially dystrophies and myositides. The following paper serves to illustrate the use of MRI using exemplary clinical vignettes., Patients/methods: From 1999 until 2006, 180 children with myopathies of unknown aetiology, ages 10 months to 18 years, were examined with a standardised MRI protocol (axial T1-SE and T2-weighted TIRM sequences). The protocol included imaging of the lower extremities whereas sequences displaying the upper extremities were only acquired in selected patients. Furthermore, intravenous contrast agent was only administered in selected children., Results: All investigations could be performed without sedation due to an examination time of 12 to 15 minutes. The illustrated cases of limb-girdle muscular dystrophy, Duchenne's muscular dystrophy, dermatomyositis, pyomyositis, and chronic neurogenic disease with secondary myopathy all showed disease-characteristic MRI patterns which substantially helped to reach the ultimate diagnosis., Conclusions: Muscle MRI is a non-invasive and effective instrument in helping to diagnose pediatric myopathies of unknown aetiology. It may facilitate muscle biopsy and serves to control therapeutical effects and disease course. Furthermore, muscle MRI may be applicated even to children of less than 4 years of age without sedation.

We report an 18-year-old man with elevation of the creatine kinase (CK) level to 11,068 IU/L. There was no muscle atrophy or fat replacement on CT while muscles in the posterior compartment of lower legs showed high T2 signal intensity on MRI. We performed muscle biopsy from the gastrocnemius muscle. Immunohistochemical analysis demonstrated an absence of dysferlin leading to a diagnosis of preclinical dysferlinopathy. Typical distribution of muscle involvement was demonstrated not by CT but by MRI which may have contributed to facilitating diagnosing the earliest stage of preclinical dysferlinopathy, presenting with asymptomatic elevation of serum creatine kinase.

Interest in muscle MRI has been largely stimulated in the last few years by the recognition of an increasing number of genetic defects in the field of inherited neuromuscular disorders. Muscle ultrasound (US) and computed tomography (CT) have been used to detect the presence of muscle involvement in patients affected by these disorders, but until recently the use of muscle MRI has been, with a few exceptions, limited to detecting inflammatory forms. The aim of this review is to illustrate how muscle MRI, in combination with clinical evaluation, can contribute to the selection of appropriate genetic tests and more generally in the differential diagnosis of genetically distinct forms of neuromuscular disorders. Possible future applications of muscle MRI are also discussed., ((c) 2007 Wiley-Liss, Inc.)

Mutations in the fukutin-related protein (FKRP) have recently been demonstrated to cause limb girdle muscular dystrophy type 2I (LGMD2I), one of the most common forms of the autosomal recessive LGMDs in Europe. We performed a systematic clinical and muscle MRI assessment in 6 LGMD2I patients and compared these findings with those of 14 patients with genetically confirmed diagnosis of other forms of autosomal recessive LGMDs or dystrophinopathies. All LGMD2I patients had a characteristic clinical phenotype with predominant weakness of hip flexion and adduction, knee flexion and ankle dorsiflexion. These findings were also mirrored on MRI of the lower extremities which demonstrated marked signal changes in the adductor muscles, the posterior thigh and posterior calf muscles. This characteristic clinical and MRI phenotype was also seen in LGMD2A. However, in LGMD2A there was a selective involvement of the medial gastrocnemius and soleus muscle in the lower legs which was not seen in LGMD2I. The pattern in LGMD2A and LGMD2I were clearly different from the one seen in alpha-sarcoglycanopathy and dystrophinopathy type Becker which showed marked signal abnormalities in the anterior thigh muscles. Our results indicate that muscular MRI is a powerful tool for differentiating LGMD2I from other forms of autosomal recessive LGMDs and dystrophinopathies.