[Immune-Mediated Necrotizing Myopathy]

Area of Science:

• Neurology
• Immunology
• Rheumatology

Background:

• Immune-mediated necrotizing myopathy (IMNM) is an autoimmune myositis characterized by muscle necrosis and regeneration.
• Specific autoantibodies, anti-SRP and anti-HMGCR, are key biomarkers for IMNM diagnosis.
• Patients often exhibit severe muscle weakness and significantly elevated serum creatine kinase (CK) levels.

Purpose of the Study:

• To highlight the diagnostic challenges in differentiating IMNM from muscular dystrophy.
• To emphasize the importance of considering IMNM in specific clinical scenarios.
• To recommend diagnostic and therapeutic strategies for IMNM.

Main Methods:

• Clinical assessment focusing on subacute onset and hyperCKemia (>1000 IU/L).
• Consideration of IMNM when muscular dystrophy lacks molecular diagnosis.
• Recommendation for autoantibody measurement (anti-SRP, anti-HMGCR).

Main Results:

• IMNM presents with severe muscle weakness and elevated CK levels.
• Diagnostic confusion with muscular dystrophy can occur.
• Autoantibody testing aids in distinguishing IMNM.

Conclusions:

• IMNM diagnosis should be considered in patients with subacute onset, severe hyperCKemia, and undiagnosed muscular dystrophy.
• Autoantibody testing is essential for accurate diagnosis.
• Treatment involves corticosteroids, immunosuppressants, IVIg, and rituximab.