Immune-mediated necrotizing myopathy (IMNM)
Overview
Characterized by proximal muscle weakness (muscles closest to the body’s midline), IMNM can exist in different subtypes depending on the presence of different autoantibodies in the blood.
the three subtypes include:
Common Symptoms
Weakness in the proximal muscles, difficulty climbing stairs and standing up from a chair, difficulty lifting arms over the head, falling, and fatigue.
Symptoms differ in severity with each subtype. Anti-SRP myopathy typically has the most severe weakness and most prevalent extra-muscular features along with cardiac involvement.
Coexisting Diseases and Conditions
Malignancies (autoantibody-negative IMNM), myocarditis (anti-SRP myopathy), and interstitial lung disease (anti-SRP myopathy).
Risk Factors and Prevalence
Exposure to statin (a cholesterol-lowering drug) is thought to be a risk for anti-HMGCR myopathy. Tumors have also been identified as a potential trigger for developing autoantibody-negative IMNM.
Recent Research
- Anti-SRP immune-mediated necrotizing myopathy: A critical review of current concepts (2022)
- Immune-mediated necrotizing myopathy: unusual presentations of a treatable disease (2021)
- Immune-mediated necrotizing myopathy (IMNM): a mythological challenge (2021)
- Immune-mediated necrotizing myopathy: clinical features and pathogenesis (2020)
Sources
- Article Sources
Allenbach, Y., Benveniste, O., Stenzel, W., & Boyer, O. (2020). Immune-mediated necrotizing myopathy: Clinical features and pathogenesis. Nature Reviews Rheumatology, 16(12), 689–701. https://doi.org/10.1038/s41584-020-00515-9
The Myositis Association. (2019, May 15). Necrotizing myopathy. The Myositis Association. https://www.myositis.org/about-myositis/types-of-myositis/necrotizing-myopathy/
Pinal-Fernandez, I., Casal-Dominguez, M., & Mammen, A. L. (2018). Immune-Mediated Necrotizing Myopathy. Current rheumatology reports, 20(4), 21. https://doi.org/10.1007/s11926-018-0732-6