Understanding Myositis

Myositis is an autoimmune disorder that results in painful, weak, and aching muscles. This rare condition causes chronic inflammation and is also known as a type of myopathy, a term for diseases affecting the skeletal muscles connected to bones.

Classification of Myositis

Myositis is generally categorized into three types:

1. Polymyositis: It affects numerous muscles simultaneously, usually those near the body's centre. Polymyositis develops gradually over time and primarily affects adults.
2. Dermatomyositis: This form of myositis affects both muscles and skin. When it affects children, it's known as juvenile dermatomyositis.
3. Inclusion Body Myositis (IBM): This degenerative muscle disease typically affects individuals over 50. It causes muscle weakness in the hands, legs (below knees), and sometimes throat muscles. Approximately 30% of IBM patients develop dysphagia (difficulty swallowing).

Signs and Symptoms of Myositis

Myositis typically presents with muscle pain that intensifies with movement and palpation. Muscle weakness is another common symptom. Some patients also experience skin redness (hyperemia), fever, headaches, and an increased white blood cell count.

Potential Causes of Myositis

While the exact cause of myositis remains unknown, it's believed to be an autoimmune disease where the body attacks its muscles. Some potential triggers include:

1. Autoimmune conditions like lupus and rheumatoid arthritis.
2. Infections, particularly viral ones (common cold, flu, HIV), but occasionally fungal and bacterial infections as well.
3. Physical injury.
4. Certain medications and drugs, including cocaine, colchicine, and statins.

Diagnosing Myositis

Diagnosing myositis can be challenging due to its overlapping symptoms with other conditions. Diagnostic methods include:

• Blood tests.
• Electromyography (EMG) to measure muscle electrical activity.
• Muscle biopsy, which can reveal scattered and regenerating fibres.
• Magnetic Resonance Imaging (MRI).

Myositis Treatment Options

The treatment for myositis typically involves:

• Corticosteroids, a type of anti-inflammatory drug.
• Immunosuppressants to prevent the immune system from damaging healthy cells and tissues.
• Intravenous immunoglobulin.

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