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Common Muscular System Diseases: Diagnosis and Treatment Overview

Muscular system disorders range from genetic to autoimmune to inflammatory. Early diagnosis improves outcomes.

Major Disorders

  • Muscular dystrophies: Genetic (dystrophin, sarcoglycans, etc.); progressive weakness. Duchenne (childhood), Becker, myotonic, facioscapulohumeral, limb-girdle.
  • Myasthenia gravis: Autoimmune anti-AChR/MuSK antibodies; fatigable weakness (ocular, bulbar, limb).
  • Inflammatory myopathies: Polymyositis, dermatomyositis (skin + muscle), inclusion body myositis (IBM, >50y, asymmetric), necrotizing autoimmune myopathy.
  • Metabolic myopathies: Glycogen storage (McArdle, Pompe), mitochondrial disorders, fatty acid oxidation defects.
  • Channelopathies: Periodic paralyses, myotonia congenita.

Diagnostic Tools

  • EMG/NCS: Myopathic vs. neurogenic; irritability (fibrillations).
  • MRI (STIR/T2): Edema, fatty replacement, pattern recognition.
  • CK (creatine kinase): Elevated in myopathic processes (100s–100,000s).
  • Muscle biopsy: Histology, immunohistochemistry, electron microscopy (gold standard for many).
  • Genetic testing: Panel, exome, genome; confirms dystrophies, channelopathies, metabolic.
  • Autoantibody panels: AChR, MuSK, LRP4, HMGCR, SRP, cN1A, etc.

Treatment Principles

  • No cure for most genetic/primary disorders—but disease-modifying therapies emerging (exon skipping, gene therapy for DMD; enzyme replacement for Pompe).
  • Immunosuppression for autoimmune/inflammatory: steroids, IVIG, rituximab, mycophenolate, methotrexate.
  • Symptomatic: Pyridostigmine (MG), mexiletine (myotonia), physical/occupational therapy, orthotics, respiratory support, cardiac surveillance.
  • Multidisciplinary care: Neurology, PM&R, pulmonology, cardiology, genetics, nutrition, psychosocial.

New therapies (antisense oligonucleotides, CRISPR, molecular chaperones) are in trials. Refer to neuromuscular centers.

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