Myositis [UPSC Notes]

Myositis is an auto-immune condition which leads to painful, weak or aching muscles. Since Myositis is recently shown in news,  it is important for aspirants preparing for the IAS Exam and other Government exams to have knowledge about the topic. Myositis is a part of the Health section of General Studies paper 2 of the UPSC Syllabus.

Myositis 

It is an autoimmune condition which leads to painful, weak or aching muscles. According to the National Health Service (NHS) U.K, myositis is the name given for a group of rare conditions which leads to weak, painful and aching muscles. It can cause chronic inflammation.

• Myositis is a type of myopathy. Myopathy is a general term that refers to diseases that affect the muscles that are connected to bones (skeletal muscles).

Types of Myositis

There are generally three types of myositis –

1. Polymyositis – It affects multiple muscles at the same time. It usually causes symptoms in muscles or near the centre of the body. Polymyositis develops gradually over time. It mostly affects adults.
2. Dermatomyositis – It is a form of myositis that affects skin in addition to muscles. If it affects children, it is known as juvenile dermatomyositis.
3. Inclusion Body Myositis (IBM) – It is a degenerative muscle disease. It usually affects persons older than 50. It causes muscle weakness in hands and legs (below knees). It can also affect throat muscles. Around 30% of people with IBM develop dysphagia (difficulty swallowing). 

Myositis Symptoms 

A characteristic symptom of myositis is aching pain, which increases with movement and palpation of muscles and is accompanied by muscle weakness. In some cases, with myositis, there is a slight redness (hyperemia) of the skin. Sometimes the disease is accompanied by common manifestations: subfebrile fever or fever, headache and an increase in the number of leukocytes in the blood.

Causes of Myositis

Myositis is an autoimmune disease that causes the body to attack its muscles. Most cases do not have a known cause. However some researches are of the opinion that myositis may be caused by –

1. Autoimmune conditions such as lupus & rheumatoid arthritis.
2. Infection – commonly due to viral infections (common cold, flu, HIV) and rarely from fungal and bacterial infection.
3. Injury.
4. Certain medications and drugs including cocaine, colchicine, statins. 

Diagnosis of Myositis

Myositis has overlapping symptoms with other diseases. Diagnosis includes –

• Blood tests.
• Electromyography (EMG) – To test electrical activity of muscles.
• Muscle biopsy – shows scattered and regeneration of fibres.
• Magnetic Resonance Imaging (MRI). 

Treatment of Myositis

Typical treatment of myositis involve –

• Corticosteroids (a type of anti-inflammatory drug).
• Immunosuppressants (stops the immune system from damaging healthy cells and tissues).
• Intravenous immunoglobulin.

Myositis:- Download PDF Here