What is Inflammatory Myositis?
Inflammatory myositis, sometimes referred to as inflammatory myopathies, is a group of rare diseases defined by muscle inflammation, which can cause prolonged muscle weakness, fatigue, and pain. The four main types of long-term or chronic inflammatory myositis are polymyositis, dermatomyositis, inclusion body myositis, and necrotizing autoimmune myositis. These conditions can affect the skin, internal organs, and multiple muscle groups of patients. Inflammatory myositis can affect people of all ages, including children.
Causes of Inflammatory Myositis
The exact cause of inflammatory myositis is not known. The condition is believed to be an autoimmune disease in which the body’s immune system attacks its own skeletal muscles causing inflammation and progressive weakening of these muscles. Most cases do not have a known cause. However, it is believed that infection and injury may play a role.
Some experts believe that inflammatory myositis may also be caused by:
- Drug toxicity
- Viruses such as the flu, common cold, and HIV
- Autoimmune conditions such as lupus and rheumatoid arthritis
- In combination with other autoimmune diseases, such as scleroderma and mixed connective tissue disease
Signs and Symptoms of Inflammatory Myositis
While each inflammatory myositis condition has its own distinctive characteristics and treatments, all of them involve chronic muscle inflammation. This inflammation typically results in muscle fatigue and weakness, swelling of the feet and legs, frequent falling, and joint and muscular pain.
Early symptoms in people with inflammatory myositis include:
- Trouble standing up from a seated position
- Difficulty climbing stairs
- Difficulty lifting the arms
- Fatigue after walking or standing for a long time
- Difficulty swallowing or breathing
- Hoarseness in the voice
- Pain in the muscles that do not abate after a few weeks
- A purple or red-colored rash on body parts such as the elbows, knuckles, knees, and eyelids
Diagnosis of Inflammatory Myositis
Individuals with inflammatory myositis are often given a misdiagnosis. It can be difficult to diagnose myositis since it is a rare condition, and also because the chief symptoms are muscle weakness and fatigue, which can be found in several other common conditions.
Doctors may use any of the following tests to assist in the diagnosis:
- Physical examination
- Biopsy of the muscle
- Blood tests to ascertain creatine phosphokinase (CPK) levels
- Magnetic resonance imaging (MRI)
- Genetic testing
- Nerve conduction study
- Antinuclear antibody (ANA) blood test
- Myositis-specific antibody panel blood test
Treatment for Inflammatory Myositis
There is no cure for inflammatory myositis. Treatment only slows the progression of the disease and is aimed at reducing pain and inflammation, reducing morbidity, restoring muscle performance, and improving quality of life. Treatment recommendations may include rest, exercise, non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, and immune-suppressants.
In general, the treatment for inflammatory myositis varies according to the cause. Inflammatory conditions causing myositis may necessitate treatment with drugs that suppress the immune system and help reduce swelling. These drugs are known as disease-modifying anti-rheumatic drugs (DMARDs) and include:
- Azathioprine (Imuran)
Myositis caused by infection is normally due to a virus, and no specific treatment is required. Myositis caused by bacteria is rare and typically necessitates antibiotics to avert the life-threatening spread of the infection.
Corticosteroids are the main type of medication employed to treat dermatomyositis and polymyositis. They aid in the quick reduction of swelling and ease muscle pain.
Myositis connected to a specific drug is treated by discontinuing the medication. In cases of myositis caused by statin drugs, muscle inflammation normally subsides within a couple of weeks after discontinuing the medication.
Biologic therapies, such as rituximab, can also assist in managing the symptoms of inflammatory myositis. They are extensively utilized to treat diseases such as psoriatic arthritis and rheumatoid arthritis. They help to decrease swelling and tend to be only utilized for severe inflammatory myositis.
Immunoglobulin therapy: This treatment uses blood products obtained from large pools of donated human plasma that consists of a portion of the blood that comprises antibodies.
Physical therapy, exercise, yoga, and stretching may also be involved as a treatment to help keep muscles flexible and strong and prevent muscle atrophy.