Introduction

Myositis is a general term used to describe swelling of the muscles. It may occur as a part of several different illnesses, including polymyositis, dermatomyositis, inclusion body myositis, and juvenile myositis. Myositis can affect many parts of the body, including the joints, heart, lungs, intestines, and skin.

Myositis is a rare disease. An estimated 5 to 10 people out of every million in the United States get some form of Myositis. Although Myositis affects people of any age, most children who get the disease are between 5 and 15 years of age and most adults are between 30 and 60. Most forms of Myositis attack more women than men.

Causes

The cause of myositis is unknown.

Symptoms

The major symptom of myositis is muscle weakness, particularly the muscles of the hip and shoulder. At times, neck and throat muscles are involved making it hard to swallow, lift the head, sing, or even speak clearly. Chest and lung muscles can also be affected, resulting in breathing trouble.

Other possible symptoms include fever, weight loss, pain, muscle tenderness, and arthritis. There have been cases when Raynaud’s phenomenon, an extreme sensitivity to cold most often felt in the fingers, develops. Raynaud’s causes a reduction in blood flow to the fingers causing fingers to turn white then gradually turn blue.

Occasionally, myositis damages the heart resulting in an irregular heartbeat. The heart may also become enlarged leading to lower leg swelling.

Severity of symptoms varies from person to person. Some people initially experience rashes while others may have shortness of breath or arthritis. Children are more likely than adults to develop a condition called calcinosis in which small lumps of calcium are deposited in the skin and muscle fibers.

The different categories of Myositis and their symptoms include:

• Polymyositis inflames and weakens muscles in many parts of the body, especially those closest to the trunk. Difficulty swallowing, fatigue, and joint and muscle pain are common.
• Dermatomyositis damages muscle fibers and skin because of the inflammation it causes. Muscle weakness, pain, and fatigue are common. A patchy, reddish rash also develops on the eyelids, cheeks, bridge of the nose, back or upper chest, elbows, knees and knuckles.
• Inclusion Body Myositis begins very gradually with weakening of muscles throughout the body. Trouble swallowing, weakened wrists or fingers, and wasting away (atrophy) of forearms and/or thigh muscles are common.
• Juvenile Myositis affects children with symptoms of muscle weakness, skin rash and dysphagia.

Diagnosis

A physical examination along with blood tests, a muscle biopsy, and electromyogram often confirms myositis.

Treatment

Although there is no cure for myositis, there are many forms of symptomatic treatment, including medications, exercise, physical therapy, and rest. Treatment varies from person to person and will change over time in a single person. Specific therapy depends on the severity and type of Myositis, the presence of other medical conditions, and adverse reactions to previous therapy.

The most effective drugs in treating myositis are corticosteriods. However, great care must be taken when using corticosteriods as they have many side effects, including weight gain, thinning of the bones, depression, high blood pressure, and increased risk of infection.

If corticosteriods aren’t alleviating all the symptoms, immunosuppressants may be added to the therapy. Immunosuppressants are drugs, which can suppress the body’s immune system. These drugs are used in the treatment of autoimmune diseases such as myositis. As with corticosteriods, immunosuppressants can result in serious side effects. It is recommended that regular doctor visits be scheduled to monitor the effects of these powerful drugs.