Myositis (inc. Polymyositis, Dermatomyositis)

What is Myositis?

Myositis is a term meaning inflammation in the muscles. There are several types of myositis, the most common being polymyositis and dermatomyositis. Polymyositis causes muscle weakness around the middle of the body and affects both sides of the body. Dermatomyositis causes muscle weakness as well as a skin rash.

Juvenile dermatomyositis differs from the adult form because of the coexistence of vasculitis (inflammation of blood vessels).

Inclusion body myositis mainly affects older individuals. As muscle weakness becomes severe, it is accompanied by muscle wasting and diminished deep-tendon reflexes. Unlike polymyositis and dermatomyositis, the muscle weakness is often not symmetric, and may be prominent in the smaller muscles of the forearms and calves.

Myositis Causes

Myositis can be brought about by an injury, infection or an autoimmune diseases, such as rheumatoid arthritis and lupus. Viruses, including the common cold, flu and human immunodeficiency virus (HIV), also are associated with myositis. Certain medications (such as statins) and illegal drugs (like cocaine) can cause myositis, as well.

Myositis Symptoms

In addition to muscle weakness, people with myositis may have muscle pain, fatigue, difficulty moving limbs, risk of falls or difficulty swallowing or breathing.

Polymyositis is characterized by symptom flares, muscle weakness (especially in the thighs, hips and shoulders), lung issues, joint pain, fever, weight loss, Raynaud’s phenomenon and a general ill feeling.

Dermatomyositis is characterized by a skin rash that may precede, accompany or follow muscle weakness. Patchy purple or red rashes may develop on the eyelids or on muscles used for extending joints, like the knuckles, elbows, knees and toes. Rashes can appear on the face, neck, chest and back. People with dermatomyositis may also have weight loss, fever, lung issues and sensitivity to light.

Myositis Diagnosis

There are many reasons for someone to have muscle weakness and fatigue. This can make diagnosing myositis a long and challenging process. Doctors will rely on physical examination, imaging scans, lab tests and finally a muscle biopsy to confirm a diagnose of myositis.

Myositis Treatment

There is no cure for myositis, but symptoms can be managed. Typically, treatment begins with high doses of corticosteroids to quickly reduce inflammation. However, myositis varies from person to person, so it is important to treat the underlying cause of the disease, be it antibiotics for infections or disease-modifying antirheumatic drugs (DMARDs) for autoimmune disease.

Disease-modifying immunosuppressant drugs, such as azathioprine and methotrexate, may be used when corticosteroids fail to work. Intravenous immunoglobulin may also be used.

Myositis Self Care

Self care involves taking a proactive part in treatment. Exercise is a very important part of the treatment plan for myositis. It is important to keep muscles strong and flexible. Physical therapy can help prevent muscle atrophy and regain muscle strength and range of motion. Doctors may also recommend supplements that help support muscle strength.