The authors present a 33-year-old woman with a gradual onset of lower limb proximal muscle weakness since she was 3 years old. The diagnostic work up detected elevated creatinine kinase levels and dystrophic changes on muscle biopsy. There was no family history. Now she presents a myopathic walk with reduced lower limb mobility.
We performed a MR scan on the patient. There was a symmetric generalised muscle atrophy with fatty replacement seen in the muscles of the thigh (Fig. 1, 4). The vastus lateralis muscles were particularly affected (Fig. 2).
There was relative sparing of the quadratus femoris, adductors, rectus femoris and gracilis muscles (Fig. 1, 2, 3).
Axial gadolinium enhanced images showed diffuse enhancement of all the thigh muscles relatively spared to the fatty infiltration (Fig. 5, 6).
Hip joints were unremarkable and the underlying femur was normal.
A. Background
Limb-girdle muscular dystrophy (LGMD) is a group of progressive muscle weakness genetically determined diseases [1]. There are autosomal recessive (90%) and autosomal dominant (10%) forms. LGMD2A (autosomal recessive) is the most common variant, accounting for 8-26% of all LGMDs and is caused by a mutation in the gene encoding the proteolytic enzyme calpain-3 [2].
B. Clinical Perspective
LGMD have a variable age of onset with autossomal recessive forms presenting typically childhood onset and autosomal dominant forms with typical adult onset (as late as 40 years of age). The clinical picture consists of mostly symmetrical muscular atrophy with rare muscle hypertrophy or contractures. Slowly progressive muscular weakness with predominantly involvement of shoulder or pelvic-girdle muscles with variable rates of progression is characteristic [3], a common feature with congenital dystrophinopathies such as Duchenne and Becker muscular dystrophies.
C. Imaging Perspective
Ultrasound allows evaluation of muscle echogenicity (fatty infiltration) and thickness. MR imaging is the modality of choice due to its superior soft tissue contrast allowing evaluation of atrophy and pseudohypertrophy [4]. T1W images are useful for evaluation of relative fatty infiltration, T2W for evaluation of oedema-like changes. MR also presents a potential tool for evaluation of therapy response and biopsy planning (by showing the areas of muscular oedema). Some studies demonstrate dystrophic muscles to show increased gadolinium-enhancement and advocate potential clinical use of contrast-enhanced MRI [7].
LGMD2A presents a common pattern of muscle atrophy with early atrophy of the posterior thigh muscles, the adductors and semimembranosus. The muscles relatively spared commonly are vastus lateralis and intermedius, sartorius and gracilis [5]. In this patient the atrophic vastus lateralis is unusual, probably due to the late disease state.
The final diagnosis is obtained by muscle biopsy with immunohistochemical staining.
D. Outcome
There is a variable rate of disease progression with severe disability usually occurring within 20-30 years. Cardiac arrhythmias are a major cause of morbidity and mortality [6].
No specific treatment is available for any of the LGMD syndromes, though aggressive supportive care is essential.
Low-impact aerobic exercise may improve cardiovascular and musculoskeletal function.
E. Take Home Message
Diagnosis and evaluation of muscular dystrophy depend on clinical, pathologic, and biochemical parameters. MR imaging has a role in the work up and management of muscular dystrophies. The variation in pattern of muscle involvement and relative sparing may allow differentiation of subtypes of muscular dystrophies. In LGMD2A patients usually have early atrophy of the adductors and semimembranosus.
Limb-girdle muscular dystrophy, LGMD2A autosomal recessive.
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Based on the bilateral lower limb MRI images provided, different degrees of atrophy and fatty infiltration can be observed in the thigh muscles on both sides, with particularly notable involvement of the posterior thigh muscles (e.g., semitendinosus, semimembranosus, and adductor group) as well as part of the quadriceps (e.g., vastus lateralis).
In T1-weighted sequences, the affected muscle groups show reduced muscle fiber signals with markedly high signals in the fat component. In T2-weighted sequences, fat replacement and possible mild edema signals can be seen in the affected muscles. Comparatively, the sartorius and partial regions of the vastus medialis retain relatively preserved muscle structure.
Overall, these findings are consistent with certain known subtypes of progressive muscular dystrophy, suggesting a chronic, symmetrical process of skeletal muscle atrophy and fatty replacement.
Based on the patient’s childhood (after age 3) slow onset of proximal lower limb weakness, elevated creatine kinase (CK), muscular dystrophic changes on muscle biopsy, and the aforementioned MRI findings, the following potential diagnoses may be considered:
Considering the patient is female, has a slow onset, no clear family history, evidence of muscular dystrophic changes on biopsy, and MRI findings of early involvement of the posterior thigh muscles and parts of the quadriceps, the most likely diagnosis is:
Limb-Girdle Muscular Dystrophy (LGMD), likely LGMD2A (Calpain-3 deficiency).
If precise subtyping is required, further genetic testing and immunohistochemical staining can be pursued. Clinical follow-up and cardiopulmonary function monitoring are also helpful for comprehensive evaluation of disease status and prognosis.
As there is currently no definitive cure for LGMD, the main approach includes comprehensive supportive and symptomatic treatment:
This report provides a reference-based analysis using the available medical images and clinical information. It does not replace face-to-face clinical diagnosis or individualized treatment planning. Patients should seek in-person consultation with professional physicians, integrating genetic testing, pathological findings, and personal health status to finalize the diagnosis and rehabilitation guidance.
Limb-girdle muscular dystrophy, LGMD2A autosomal recessive.
