What are the Types of Inflammatory Myopathy?

Types of Inflammatory Myopathy – Diagnosis & Treatment

Idiopathic inflammatory myopathies are a group of rare diseases that cause muscle inflammation and weakness. The main types are as follows:

1. Dermatomyositis : Dermatomyositis is characterised by skin changes that are not seen in other types of inflammatory myopathies, which makes it easier for doctors to identify. In children and sometimes in adults, it can cause calcium deposits to form in or under the skin.
2. Antisynthetase Syndrome : This form includes a variety of symptoms such as inflammatory arthritis, fever, interstitial lung disease, and rough and thickened skin on the fingers, which affects blood flow to the fingers and toes.
3. Immune-Mediated Necrotising Myopathies : These myopathies tend to cause more severe and rapidly progressing muscle weakness compared to other types.
4. Inclusion Body Myositis : Inclusion body myositis primarily affects older adults and leads to progressive muscle weakness, especially in the legs, hands, and feet. Unlike other forms, it does not respond well to immunosuppressive treatments.
5. Polymyositis : There are no skin changes related to polymyositis; however, it does cause muscle weakness. The shoulders and hips, which are the muscles closest to the body, are usually affected.

What are inflammatory myopathy symptoms?

Many myopathies display similar symptoms. These symptoms include:

• Muscle weakness, primarily affecting the upper arms, shoulders, and thighs
• Muscle cramps, stiffness, and spasms.
• Fatigue during exertion
• Low energy level

How is Inflammatory Myopathy Diagnosed?

To diagnose myopathy, the healthcare provider will begin by reviewing the medical history, including any family history of muscle disorders and a person's use of prescription medications, and current symptoms which are there at present.

Diagnostic tests for inflammatory myopathy symptoms include:

1.  Blood Tests

• Muscle Enzymes Test:In this test elevated levels of enzymes such as creatine kinase (CK) or aldolase may indicate muscle fibre damage.
• Electrolyte Levels Test:In this test, levels of sodium, potassium, magnesium, calcium, and phosphorus are checked to rule out imbalances that can affect muscle function.
• Autoimmune Markers Test:Tests such as antinuclear antibodies (ANA), rheumatoid factor, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) can detect autoimmune activity.
• Endocrine Test:In this, thyroid hormone levels are measured to rule out thyroid-related muscle issues.

2.  Electromyography (EMG) and Nerve Conduction Studies

These tests evaluate the electrical activity of your nerves and muscles. EMG involves inserting a small needle into muscles to detect abnormalities, which helps the doctor to determine the type and extent of muscle damage.

3.  Magnetic Resonance Imaging (MRI)

MRI scans of the muscles provide detailed images that help the doctors to identify inflammation, damage, or fatty replacement in the muscle tissues.

4.  Genetic Testing

Genetic tests may be performed to identify inherited muscle disorders.

5.  Muscle Biopsy

In this a small sample of muscle tissue is surgically removed and examined under a microscope to look for signs of inflammation, damage, or abnormal proteins.

How is Inflammatory Myopathy Treated?

Once the healthcare provider identifies the specific type of myopathy, they will create a personalised treatment plan to address the symptoms and overall condition.

Most treatment strategies involve physical therapy, occupational therapy, and regular exercise to help maintain muscle strength and function.

For inflammatory and autoimmune forms of myopathy, the primary treatment goal is to suppress the immune response and reduce inflammation. Treatment options include:

1.  Immunosuppressive or Immunomodulatory Medications:

These help control the immune system, which are

• Methotrexate
• Cyclosporine
• Tacrolimus
• Azathioprine
• Mycophenolate mofetil
• Rituximab
• Intravenous Immunoglobulin (IVIg) or Subcutaneous Immunoglobulin (SubQIg)

2.  Corticosteroids: 

Medications such as prednisone or methylprednisolone are often prescribed to quickly reduce inflammation and muscle weakness.

3. Other Myopathies:

Acquired myopathies are caused by external factors such as endocrine disorders, toxins, or infections, which are treated by addressing the underlying cause:

In toxin-related myopathies, treatment usually involves removing or discontinuing the harmful substance, such as alcohol or certain medications.

For infectious myopathies, where bacteria or other pathogens affect the muscles, an antibiotic or antiviral therapy is used to treat the infection.

Inflammatory myopathies are rare muscle diseases that mainly cause muscle weakness and inflammation. To make an accurate diagnosis, doctors use a combination of strategies, including medical history, physical exams, blood tests, imaging scans, and sometimes a muscle biopsy. Therefore, early diagnosis and a personalised treatment plan are important for managing myopathy symptoms and helping individuals to stay active.

Also Read:

→ What is Congenital Myopathy

→ What is the Best Treatment for Necrotizing Myopathy

→ Best Treatment for Myopathy

→ How Do You Treat Nemaline Myopathy

→ What are the Five Causes of Myopathy