Myositis: Rare Conditions Affecting Muscles
Introduction
Myositis refers to a group of rare conditions characterized by weak, painful, or aching muscles that progressively worsen over time. This article provides an overview of myositis, including its types, symptoms, diagnosis, and treatment options.
Types of Myositis
Myositis encompasses various types, including:
- Polymyositis: Affects multiple muscles, particularly the shoulders, hips, and thigh muscles. It is more common in women and typically affects individuals aged 30 to 60.
- Dermatomyositis: Affects multiple muscles and presents with a distinct rash. It is more common in women and can also occur in children (known as juvenile dermatomyositis).
- Inclusion Body Myositis (IBM): Results in weakness in the thigh muscles, forearm muscles, and muscles below the knee. It may also cause swallowing difficulties (dysphagia). IBM is more prevalent in men and commonly affects individuals over 50.
For more detailed information on the different types of myositis, refer to Myositis UK, a UK charity dedicated to myositis awareness.
Polymyositis Symptoms
Polymyositis affects various muscles, particularly those surrounding the neck, shoulders, back, hips, and thighs. Symptoms of polymyositis include:
- Muscle weakness
- Aching or painful muscles and extreme fatigue
- Difficulty sitting up or standing after a fall
- Swallowing problems or difficulty holding the head up
- Feeling unhappy or depressed
Individuals with polymyositis may experience difficulty performing tasks like getting up from a chair, climbing stairs, lifting objects, or combing their hair. Muscle weakness can become severe, making even simple activities like picking up a cup of tea challenging. Without treatment, the weakness typically worsens over time, although the rate of progression may vary.
Dermatomyositis Symptoms
In addition to the symptoms seen in polymyositis, dermatomyositis presents with a distinct rash. Prior to the onset of muscle symptoms, individuals with dermatomyositis often develop a red, purple, or dark rash. The rash typically appears on the face (eyelids, nose, and cheeks) and hands (knuckles). It may also manifest on the back, upper chest, elbows, and knees. The rash can be itchy or painful, and hard lumps of tissue may form under the skin.
Diagnosing Myositis
To diagnose myositis, a general practitioner (GP) will inquire about symptoms and conduct a physical examination. Additional tests may be necessary to rule out other conditions with similar symptoms. These tests may include:
- Blood tests to measure enzyme and antibody levels in the blood
- Muscle or skin biopsy to assess inflammation, damage, and other changes
- MRI scans
- Electromyography (EMG) involving the insertion of a small needle-shaped electrode through the skin to record electrical signals from the muscle’s nerve endings after local anesthesia
Treating Myositis
Treatment for myositis involves a combination of approaches, including exercise, medication, and other therapies. The specific treatment plan depends on the type and severity of myositis.
Exercise and Physiotherapy
Exercise is crucial for managing all types of myositis. It can help reduce swelling, increase energy levels, and restore or improve muscle strength. Exercise and physiotherapy are particularly important for individuals with inclusion body myositis (IBM), as no medications are available for this type. Before starting an exercise program, it is essential to consult with a GP and physiotherapist to develop a suitable plan.
During severe myositis flare-ups characterized by significant muscle pain and weakness, exercising is generally not recommended. However, maintaining gentle movement is important, especially if myositis developed during childhood, to prevent joint stiffness.
Steroids
Steroids are the primary medications used to treat polymyositis and dermatomyositis. They effectively reduce swelling and alleviate muscle pain. Steroids can be administered orally, through injections, or intravenously. Typically, a high initial dose is given, which is gradually reduced over time.
Prolonged use of high-dose steroids may lead to side effects, including weight gain, high blood pressure, diabetes, cataracts, and osteoporosis. It is essential to be aware of these potential risks.
Disease-Modifying Anti-Rheumatic Drugs (DMARDs)
During myositis flare-ups, doctors may prescribe disease-modifying anti-rheumatic drugs (DMARDs) to suppress the immune system and reduce inflammation. Examples of DMARDs include azathioprine, methotrexate, cyclophosphamide, and mycophenolate. These medications take time to show effects but can help lower steroid doses in the long term, reducing their side effects.
Immunoglobulin Therapy
Immunoglobulin therapy is a rarely used treatment for myositis that involves injecting healthy antibodies derived from donated blood. This therapy aims to stop the immune system from attacking the muscles. Immunoglobulin therapy is administered in a hospital setting, usually through intravenous infusion, and multiple treatments may be required.
Biologic Therapies
Biologic therapies like rituximab can be employed to manage myositis symptoms. These therapies, widely used for conditions such as rheumatoid arthritis and psoriatic arthritis, help reduce inflammation. They are typically reserved for severe cases of myositis.
Outlook
Most individuals with myositis respond well to a combination of steroid and immunosuppressive therapies, along with controlled exercise. Steroids are often required in low doses for an extended period, which may increase the risk of infections. However, this risk can be managed with antibiotics if necessary.
Complications of Myositis
Some individuals may not respond adequately to treatment, leading to significant impairment of daily activities and diminished quality of life. However, continued exercise is generally beneficial for improving muscle strength. Severe myositis can result in breathing and swallowing difficulties, requiring speech and language therapy. In rare cases, myositis may be associated with cancer, warranting further tests.
Help and Support
Myositis UK and The Myositis Association (of America) provide valuable information and support to individuals diagnosed with myositis and their families.