Myositis
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What is myositis?
The word myositis refers to inflammation of muscle tissue which can lead to pain, weakness, and fatigue. The weakness is usually in the upper arms and legs. Myositis can also affect other parts of the body such as the lungs, skin, and heart.
How do I get myositis?
Myositis is a rare autoimmune condition, where the body’s immune system which usually fights off infections, instead attack the body’s muscles and other tissues.
How is the diagnosis made?
A specialist familiar with rheumatic autoimmune diseases, such as a neurologist or rheumatologist, can help to make the diagnosis. Laboratory tests (autoantibodies), imaging (magnetic resonance imaging), and other investigations are usually needed. Sometimes a muscle biopsy and electrophysiology are required to help with the diagnosis.
How is myositis treated?
Unlike other muscle diseases such as muscular dystrophy, myositis can be treated. Steroids are often used to treat the inflammation associated with myositis. Steroid sparing drugs are also used to dampen down the body’s overactive immune response. Exercise and supporting a patient’s mental health and well-being are also vital aspects of the treatment pathway.
For Healthcare Professionals
Background
The idiopathic inflammatory myopathies (IIM) are a rare and heterogeneous group of multisystem autoimmune diseases, also referred to as ‘myositis spectrum disorders’ or ‘myositis’, affecting 19 adults per million person-years and 4 children per million person-years.
IIM traditionally encompasses polymyositis, dermatomyositis, juvenile dermatomyositis and inclusion body myositis. More recently, immune-mediated necrotising myopathy, anti-synthetase syndrome and connective tissue disease-overlap disorders have become recognised as distinct clinical entities within the label of IIM-spectrum disease
Patients with IIM can experience significant negative impacts on quality of life. This occurs from skeletal muscle inflammation and consequent weakness, and extra-muscular manifestations including skin disease, gastrointestinal involvement, interstitial lung disease and cardiac involvement.
Symptoms may include muscle weakness, pain, fatigue, rashes and shortness of breath. A specialist referral is needed to confirm the diagnosis and start treatment. The specialist may arrange for bloods, electrical muscle tests, magnetic resonance imaging muscle scans, and muscle biopsy.
Unfortunately, many patients with IIM experience aggressive or treatment-resistant disease, and organ damage can occur, causing disability. Side effects from medications, particularly steroids, are common and can be serious. New treatment options are becoming available, including ‘biologic’ – drugs manufactured from living proteins. Biologics are more effective than steroids and have a better side effect profile. One example is rituximab, however access to this drug is variable, not all patients are eligible and some don’t respond.
We need better tools to help us predict which patients with IIM will best respond to the right treatments.
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