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 and its subtypes are rare diseases according to the National Organization for Rare Disorders (NORD). It is currently estimated that 5-10 people per million are diagnosed with a type of Myositis each year. In the U.S., that equates to only 1,600 to 3,200 cases per year. The exact number of Myositis cases is difficult to measure, but according to the latest estimate, it was thought, with all forms combined, that there are 50,000 to 75,000 people living with Myositis in the U.S.
Although Myositis can affect 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 years of age. Like many autoimmune diseases, most types of Myositis affect more women than men with the exception being Inclusion Body Myositis, which affects more men than women, and more so for those over the age of 50.
Self diagnosis – Symptoms of myositis can include muscle weakness, muscle pain and muscle tenderness. Other symptoms vary, depending on the specific cause of myositis: Idiopathic inflammatory myopathies. These conditions typically cause painless muscle weakness that develops slowly over weeks, months or years.
How does Myositis affect your body?
Myositis are a group of muscle diseases that involve inflammation of the muscles or associated tissues, such as the blood vessels that supply the muscles. The inflammatory process leads to destruction of muscle tissue, and is accompanied by weakness and sometimes pain. Over time, there can be loss of muscle bulk (atrophy).
What are the Causes of Myositis?
Common causes include :
- 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), are associated with myositis.
- Certain medications (such as statins) and illegal drugs (like cocaine) can cause myositis.
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What are the Risk Factors of Myositis?
Common risk factors include
- Genetic mutations – Both MHC and non-MHC genes are associated with myositis.
- Exposure to UV light – There is an observed correlation between the occurrence of dermatomyositis and UV-light exposure
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What are the symptoms of Myositis?
Symptoms of myositis may include:
- Trouble rising from a chair
- Difficulty climbing stairs or lifting arms
- Tired feeling after standing or walking
- Trouble swallowing or breathing
- Muscle pain and soreness that does not resolve after a few weeks
- Known elevations in muscle enzymes by blood tests (CPK or aldolase)
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How is Myositis diagnosed?
- Blood test for enzymes – Many patients with Myositis have elevated levels of muscle enzymes which may indicate the presence of muscle damage. These enzymes include :
ALAT/ALT/SGPT (Alanine aminotransferase, serum glutamate pyruvate transaminase)
ASAT/AST/SGOT (Aspartate aminotransferase, serum glutamic-oxaloacetic transaminase)
Creatine Phosphokinase (CPK)
- Blood test for antigen – Factor VIII-related antigen (also called von Willebrand factor VIII-related antigen) shows damage to the lining of blood vessels and can help physicians see the extent of the problem, especially in Juvenile Myositis (JM). This may assist in determining a treatment plan
- Blood test for Antibodies –
ANA (Antinuclear Antibodies panel) The immune system normally makes antibodies that help fight infection. Antinuclear antibodies often attack the body’s own tissues (autoimmune). In this case, these attack a cell’s nucleus. This testing does not confirm a specific disease diagnosis, however specific patterns can assist with a differential diagnosis.
Myositis-Specific Antibodies (MSA) MSA’s are almost never found outside of patients with myositis, meaning the presence of these strongly support evidence for a diagnosis. There is a lot of research being done with myositis antibodies.
Myositis-Associated Antibodies (MAA) Myositis-Associated antibodies can be found in patients outside of a myositis diagnosis, however positive test results can provide supporting evidence of association with other diseases. There is a lot of research being done with myositis antibodies
- EMG (Electromyography) – An EMG is performed to identify the location and type of inflammation due to damaged muscle tissue. A thin needle electrode is inserted through the skin into muscles. Electrical activity is measured and recorded as muscles are tensed and relaxed. The doctor or tech performing the EMG will move the needle electrode various times to measure different areas of the same muscle or various muscle locations. Changes in the pattern of electrical activity can confirm a muscle disease and distribution.
- Nerve Conduction Study (NCS) – A nerve conduction study measures how well and how fast nerves send electrical signals. It evaluates the functional ability of electrical conduction of the body’s motor and sensory nerves. A NCS is used to identify damage in the peripheral nervous system (nerves that lead away from the brain and spinal cord and connect the central nervous system to the limbs and organs). Several electrodes are attached to the patient’s skin, and a shock-emitting electrode is placed over a nerve while a recording electrode is placed over the muscles controlled by that nerve. Electrical pulses are given to the nerve, and the time it takes for the muscle to contract in response to the electrical pulse is recorded. The speed of this response is the conduction velocity. Nerve conduction studies are performed prior to an EMG and may include both sides of the body for comparison. Unless neuropathy exists, someone with Myositis should have a negative NCS.
- Muscle Biopsy – A muscle biopsy is performed to assess the musculoskeletal system for abnormalities. A variety of diseases can cause muscle weakness, pain and inflammation and can be related to problems with the nervous system, connective tissue, vascular system or musculoskeletal system. The muscles often selected for sampling are the bicep (upper arm muscle), deltoid (shoulder muscle), or quadriceps (thigh muscle). The procedure requires only a few small pieces of tissue to be removed from the designated muscle. The tissue and cells removed are viewed microscopically. The laboratory report can often take several weeks for results to be read and released. The muscle biopsy is considered the “gold standard” in diagnosing myositis and can rule out other diseases.
- MRI (Magnetic Resonance Imaging) – An MRI gives a cross-section image of muscles in a specific area to show if inflammation exists. It is sometimes done prior to a muscle biopsy to indicate a specific inflamed location from which to take muscle tissue samples for the muscle biopsy.
- Chest X-ray – An x-ray is a simple way to check for symptoms of lung damage or disease. Lung disease can accompany Myositis, so if Myositis is suspected or confirmed, this test is frequently conducted.
- Pulmonary Function Test – Pulmonary function tests are a group of tests that measure how well the lungs take in and release air and how well they move gases such as oxygen from the atmosphere into the body’s circulation. For those with lung involvement, this test may be performed at various intervals to determine improvement or disease progression.
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How to prevent & control Myositis?
Common preventive measures include :
- Keep the skin clean
- Get flu shot every year
- Cook meat thoroughly
- Never take illegal drugs
Treatment of Myositis Allopathic treatment –
- Steroid medication – Steroids are the main type of medication used to treat polymyositis and dermatomyositis. They include steroid creams which can be used to treat the affected areas of skin in dermatomyositis and higher doses of steroid tablets if there’s severe muscle weakness.
- Disease-modifying anti-rheumatic drugs (DMARDs) – If the inflammation in your muscles flares up, your doctor may prescribe a disease-modifying anti-rheumatic drug (DMARD). DMARDs, such as azathioprine, methotrexate, cyclophosphamide or mycophenolate suppress your immune system and help reduce inflammation.
- Intravenous immunoglobulin therapy – Intravenous immunoglobulin therapy may be needed in very severe cases of myositis where severe muscle weakness is causing life-threatening breathing or swallowing problems. It involves having an injection of normal antibodies from donated blood. This temporarily changes the way your immune system operates.
- Biologic therapies – It’s thought that biologic therapies, which are widely used to treat conditions such as rheumatoid arthritis and psoriatic arthritis, may also play a part in managing myositis in people whose symptoms don’t respond to conventional steroids and immunosuppressive medication. For example, rituximab is a biological medicine which helps reduce inflammation that’s recently been approved for treating myositis. It’s given by intravenous infusion (directly into a vein through an intravenous line, needle or catheter) on two occasions two weeks apart.
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Myositis – Lifestyle Tips
- Exercise – After drug treatment takes effect, a program of regular stretching exercises prescribed by your doctor can help maintain range of motion in weakened arms and legs. Physical therapy may also help prevent permanent muscle shortening. You may also want to add whirlpool baths, heat and gentle massage.
- Rest – Getting enough rest is an important component of managing myositis. Take frequent breaks during the day and limit your activity.
- Nutrition – What you eat can affect your overall health. Consult a trained nutritionist to help design a diet that’s right for you and your lifestyle.
- Reduction of Stress – It is imperative that myositis patients find outlets for the daily stress that most of us have in our lives. To that end, your doctor may suggest exercise as a form of relaxation, like yoga, or biofeedback exercises.
What are Recommended Exercises for Person with Myositis?
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. See lifestyle tips above for further details.
Myositis & Pregnancy – Things to know
Pregnancy in myositis patients is rare and incompletely understood. Systematic review of myositis pregnancy reports suggests that disease activity during pregnancy (even when subclinical) may be associated with adverse pregnancy outcome. Massive deposition of fibrin in the placenta has been described in several myositis patients. Treatment during pregnancy, usually corticosteroid, appears to be associated with greater likelihood of live birth. IVIG has been used successfully and may be an effective alternative to high-dose corticosteroids.
Common Complications Related to Myositis
- Aspiration Pneumonia – Aspiration pneumonia, a complication of pulmonary aspiration, is a lung infection that develops after you aspirate (inhale) food, liquid, saliva, or vomit into your lungs. You can also aspirate food or liquid from your stomach that backs up into your esophagus. If you are not able to cough up the aspirated material, bacteria can grow in your lungs and cause a serious infection.
- Dysphagia – Dysphagia means trouble swallowing. Learn more about Dysphagia, general tips, treatment approaches, and how a Speech Therapist may help. Dysphagia can be a dangerous complication causing choking and aspiration pneumonia (see more about aspiration pneumonia)
- Myositis – Cancer Connection – There are increased risks of cancer with Dermatomyositis and Polymyositis. Learn more about cancer and Myositis, and how cancer screenings may help to catch anything early on to avoid severe complications.
- Interstitial Lung Disease – Interstitial Lung Disease (ILD) is a broad term used to describe a variety of conditions characterized by the scarring of lung tissue.
Other FAQs about Myositis
On this page:
Q. Is myositis a disability?
A. Yes, myositis which is a rare autoimmune muscle disease may cause temporary or even permanent disability.
Q. Is myositis a form of muscular dystrophy?
A. Myopathy is a muscle disease, and inflammation is response to cell damage. Another word for inflammatory myopathy is myositis. Inflammatory cells invading muscle tissues is one characteristic of IBM, but the disease is distinct from other inflammatory myopathies in that muscle degeneration also occurs.
Q. What does myopathy feel like?
A. Initially, individuals may feel fatigued doing very light physical activity. Walking and climbing stairs may be difficult because of weakness in the pelvic and leg muscles that stabilize the trunk. Patients often find it difficult to rise from a chair. As the myopathy progresses, there may be muscle wasting.