Polymyositis
Polymyositisis an uncommon disease that causes inflammation
in your muscles. It s a type of connective tissue disease. The most noticeable
characteristic of polymyositis is muscle weakness, especially in the muscles
closest to your trunk, such as your shoulder and hip muscles. As a result, you
may find it difficult to get out of chairs, climb stairs, brush your hair or
work with your arms over your head.
Polymyositis can occur at any age, but it mostly affects
adults in their 40s and 50s. It s more common in blacks than in whites, and
women have it more often than men do. Polymyositis usually develops gradually
over weeks or months.
Periods of remission, during which symptoms improve
spontaneously, rarely occur in polymyositis. However, treatment can improve
your muscle strength and function.
Symptoms
Signs and symptoms of polymyositis usually appear gradually,
so it may be difficult to pinpoint when they first started. They may also
fluctuate from week to week or month to month. The most common polymyositis
symptoms include:
Progressive muscle weakness, particularly in the muscles
closest to the trunk, such as those in your hips, thighs, shoulders, upper arms
and neck. This weakness is symmetrical, affecting both the left and right sides
of your body.
Difficulty swallowing (dysphagia).
Mild joint or muscle tenderness.
Fatigue.
Causes
Polymyositis belongs to a group of conditions called
inflammatory myopathies. Myopathies are diseases or abnormal conditions of the
muscles. The cause of most inflammatory myopathies is unknown. Infections
caused by bacteria, parasites or viruses can cause inflammatory myopathies, but
in most cases, doctors aren t able to identify a preceding infection in
polymyositis.
A disease similar to polymyositis is dermatomyositis.
Dermatomyositis leads to many of the same symptoms as polymyositis, but it
causes skin inflammation or a rash as well. Some other inflammatory muscle
diseases are: inclusion body myositis, which progresses more slowly than other
forms; myositis associated with other connective tissue diseases, such as lupus
or scleroderma; and myositis associated with cancer.
Immune system plays role
Doctors suspect that myopathies are autoimmune disorders, in which body s
immune system mistakes normal components of body for foreign substances and
attacks them. If you have polymyositis, an unknown cause seems to trigger
immune system to begin producing autoimmune antibodies (also called
autoantibodies) that may damage healthy body tissues. Many people with
polymyositis show a detectable level of autoantibodies in their blood. It s
still unclear, however, whether these autoantibodies are indeed involved in
causing polymyositis.
Polymyositis has also been associated with several viral
diseases, including HIV. Some researchers speculate that, in some form,
polymyositis may be caused by a viral infection of the muscle. This theory
isn t well supported,.
Tests and diagnosis
Diagnosis of polymyositis isn t always easy and can be a
lengthy process. Even though the attempt to diagnose your condition may be
frustrating, remember that an accurate diagnosis is necessary to receive
appropriate treatment.
In addition to a thorough physical exam, including
assessment of muscle strength, doctor will likely use some or all of the
following information and tests to assist in the diagnosis:
Family medical history. A careful history of muscle disease
in family and age at onset of the disease will help doctor distinguish between
polymyositis and muscular dystrophy. Muscular dystrophy is an inherited
condition; its signs and symptoms usually begin in early childhood.
Electromyography. A thin needle electrode is inserted
through skin into the muscle to be tested. Electrical activity is measured as
you relax or tighten the muscle. Changes in the pattern of electrical activity
can confirm a muscle disease. The distribution of the disease can be determined
by testing different muscles.
Blood analysis. A blood test can let your doctor know if you
have elevated levels of muscle enzymes, such as creatine kinase (CK) and
aldolase. Increased CK and aldolase levels can indicate muscle damage.
A blood test can also determine whether autoantibodies are
present in your blood. In some cases, specific types of autoantibodies have
been associated with certain signs or symptoms of the disease, such as skin or
lung involvement, and with how the disease responds to treatment. Knowing
whether you have these autoantibodies may help doctor determine the best
treatment plan.
Muscle biopsy. A small piece of muscle tissue is removed
surgically for laboratory analysis. A muscle biopsy may reveal abnormalities in
muscles, such as inflammation, damage or infection. The sample also can be
examined for the presence of abnormal proteins and checked for enzyme
deficiencies.
Magnetic resonance imaging (MRI). A scanner creates
cross-sectional images of muscles from data generated by a powerful magnetic
field and radio waves. These images can be viewed from any direction or plane.
MRI scans may help detect inflammation in your muscles.
Monitoring risk of infections
People with polymyositis may also be at an increased risk of infections,
particularly respiratory and digestive infections
Complications
these complications of polymyositis:
Difficulty swallowing. If the muscles in esophagus are
affected, may have problems swallowing (dysphagia), which in turn may cause
weight loss and malnutrition.
Aspiration and pneumonia. Difficulty swallowing may also
lead to entrance of food or liquids, including saliva, into lungs (aspiration),
which can lead to pneumonia.
Breathing problems. If your chest muscles are involved, may
experience breathing problems, such as shortness of breath.
Calcium deposits. Late in the disease, particularly if the
disease for a long time, deposits of calcium can occur in muscles, skin and
connective tissues (calcinosis).
Polymyositis is often associated with other conditions,
including:
Other connective tissue diseases. Diseases such as lupus,
rheumatoid arthritis, scleroderma and Sjogren s syndrome can occur in
combination with polymyositis.
Cardiovascular disease. The muscle of heart may become
inflamed (myocarditis). In a small number of people who have polymyositis, congestive
heart failure and heart arrhythmias may develop.
Lung disease. A condition called interstitial lung disease
may occur with polymyositis. Interstitial lung disease refers to a group of
disorders that cause inflammation and scarring (fibrosis) of lung tissue,
making lungs stiff and inelastic. Signs and symptoms include a dry cough and
shortness of breath. In the late stage of lung disease, high blood pressure in
the pulmonary arteries (pulmonary hypertension) can occur and can lead to
right-sided heart failure.
Cancer. Cancer may be more common in people with
polymyositis, but the evidence for this association is more pronounced in
dermatomyositis.
Concerns during pregnancy
Pregnancy may worsen signs and symptoms in women whose disease is active. Active
polymyositis can also increase the risk of premature birth or stillbirth. If
the disease is in remission, the risk isn t as great
Treatments and drugs
Although there s no cure for polymyositis, treatment can
improve your muscle strength and function. Treatment begun early in the disease
process tends to be more effective, often because there are fewer
complications. Therapies include the following:
Corticosteroids. These medications suppress immune system,
limiting the production of antibodies and reducing muscle inflammation.
Corticosteroids, especially prednisone, are usually the first choice in
treating inflammatory myopathies, such as polymyositis.
doctor may begin with a very high dose then decrease it as
your symptoms improve. Improvement generally takes about two to four weeks.
Significant results are usually evident within three to six months, but therapy
is often needed for years.
Prolonged use of corticosteroids can have serious side
effects including osteoporosis, weight gain, diabetes, increased risk of some
infections, mood swings, cataracts, high blood pressure, a redistribution of
body fat and muscle weakness. As a result, your doctor may also recommend
supplements, such as calcium and vitamin D, and may prescribe bisphosphonates,
such as alendronate (Fosamax) or risedronate (Actonel), to counteract loss of
bone density.
Other immunosuppressants. If your body doesn t respond
adequately to corticosteroids, your doctor may recommend other
immunosuppressive drugs, such as azathioprine (Imuran) or methotrexate
(Rheumatrex). Your doctor may prescribe these alone or in combination with
corticosteroids.
When in combination, these additional immunosuppressants can
be used to lessen the dose and potential side effects of the corticosteroid.
Immunosuppressants, such as cyclophosphamide (Cytoxan) and cyclosporine
(Neoral, Sandimmune), may improve symptoms of polymyositis and interstitial
lung disease.
Physical therapy. A physical therapist can show various
exercises to maintain and improve your strength and flexibility and advise an
appropriate level of activity. Your exercise program is likely to change during
the course of the disease and treatment period. Staying active will help
maintain muscle strength.
Polymyositis treatments that are still under investigation
include:
Plasmapheresis. This treatment, also called plasma exchange,
is a type of blood cleansing in which damaging antibodies are removed from your
blood.
Radiation therapy. This involves irradiation of the lymph
nodes to suppress your immune system.
Intravenous immunoglobulin (IVIg). This involves receiving
intravenous infusions of antibodies from a group of donors over two to five
days. This treatment is usually expensive. It may be an option for you if your
dermatomyositis is severe or resistant to other forms of therapy.
Fludarabine (Fludara). This agent prevents the development
and growth of malignant cells.
Tacrolimus (Prograf). This transplant-rejection drug may
work to inhibit the immune system. Tacrolimus is often used topically to treat
dermatomyositis and other skin problems.
Monoclonal antibodies. These man-made antibodies are
designed to target and destroy specific types of cells. infliximab (Remicade)
and rituximab (Rituxan) on both polymyositis and dermatomyositis
Dermatomyositis
Dermatomyositisis an uncommon disease marked by muscle
weakness and a distinctive skin rash. It s a type of inflammatory muscle
disease — "myo" means "muscles" in Greek; "itis"
means "inflamed." "Derma," which means "skin,"
refers to the skin-related symptoms that accompany the muscle inflammation of
dermatomyositis.
Dermatomyositis may occur at any age, but it mostly affects
adults in their late 40s to early 60s or children between 5 and 15 years of
age. Women have dermatomyositis more often than men do. Dermatomyositis usually
develops over weeks or months.
Periods of remission, when symptoms of dermatomyositis
improve spontaneously, may occur. Treatments can improve your skin and your
muscle strength and function.
Symptoms
The most common signs and symptoms of dermatomyositis
include:
A violet-colored or dusky red rash, most commonly on your
face, eyelids, and areas around your nails, knuckles, elbows, knees, chest and
back. Affected areas are typically more sensitive to sun exposure.
Progressive muscle weakness, particularly in the muscles
closest to the trunk, such as those in your hips, thighs, shoulders, upper arms
and neck. This weakness is symmetrical, affecting both the left and right sides
of your body.
Other dermatomyositis symptoms that may occur include:
Difficulty swallowing (dysphagia)
Muscle pain or tenderness
Fatigue, fever and weight loss
Hardened deposits of calcium under the skin (calcinosis),
especially in children
Gastrointestinal ulcers and infections, also more common in
children
Lung problems
The skin rash usually occurs at the same time as muscle
weakness, but may precede muscle weakness by a few weeks. Sometimes, the skin
rash alone determines the diagnosis. In some children with dermatomyositis, the
skin may become thick and hard in a way similar to scleroderma. When this
happens, the condition is called sclerodermatomyositis.
Weakness in muscles, such as your hips and shoulders, can
lead to difficulty in getting out of chairs, climbing stairs, brushing your
hair or working with your arms over your head. Weakness in your neck muscles
can make it hard to hold your head up.
Causes
Dermatomyositis belongs to a group of conditions called
inflammatory myopathies. Myopathies are diseases or abnormal conditions of the
muscles. The cause of most inflammatory myopathies is unknown.
One of these diseases that s similar to dermatomyositis is
polymyositis. Polymyositis leads to many of the same symptoms as
dermatomyositis, but does not cause skin inflammation or a rash.
Some other inflammatory muscle diseases are: inclusion body
myositis, which progresses more slowly than other forms; myositis associated
with other connective tissue diseases, such as lupus or scleroderma; and
myositis associated with cancer (malignancy).
Immune system plays role
Doctors suspect that inflammatory myopathies are autoimmune disorders, in which
immune system attacks normal body components. Infections caused by bacteria,
parasites or viruses can cause inflammatory myopathies, but in most cases,
doctors aren t able to identify a preceding infection in dermatomyositis. Some
doctors think certain people may have a genetic susceptibility to the disease.
Typically, immune system works to protect your healthy cells
from attacks by foreign substances, such as bacteria and viruses. If you have
dermatomyositis, an unknown cause seems to trigger immune system to begin
producing autoimmune antibodies (also called autoantibodies) that attack your
body s own tissues.
Small blood vessels in muscular tissue appear to be
particularly affected. Inflammatory cells surround the blood vessels and
eventually lead to degeneration of muscle fibers. Many people with
dermatomyositis show a detectable level of autoantibodies in their blood
Tests and diagnosis
Dermatomyositis is the most easily recognized of the
inflammatory muscle diseases because of its characteristic rash. Occasionally,
a rash alone may prompt a diagnosis of dermatomyositis without muscle
involvement (amyopathic dermatomyositis).
In addition to a thorough evaluation, including examination
of muscle strength and a detailed family medical history, doctor may use some
or all of the following tests to assist in the diagnosis:
Electromyography. A doctor with specialized training inserts
a thin needle electrode through the skin into the muscle to be tested.
Electrical activity is measured as you relax or tighten the muscle. Changes in
the pattern of electrical activity can confirm a muscle disease. The doctor can
determine the distribution of the disease by testing different muscles.
Blood analysis. A blood test will let your doctor know if
you have elevated levels of muscle enzymes, such as creatine kinase (CK) and
aldolase. Increased CK and aldolase levels can indicate muscle damage.
A blood test can also determine whether autoantibodies are
present in your blood. In some cases, specific types of autoantibodies have
been associated with certain signs or symptoms of the disease, such as skin or
lung involvement, and with how the disease responds to treatment. Knowing
whether you have these autoantibodies may help your doctor determine the best
treatment plan for you.
Muscle biopsy. A small piece of muscle tissue is removed
surgically for laboratory analysis. A muscle biopsy may reveal abnormalities in
your muscles, such as inflammation, damage or infection. The tissue sample can
also be examined for the presence of abnormal proteins and checked for enzyme
deficiencies.
Skin biopsy. A small piece of skin is removed for laboratory
analysis. The skin sample can confirm the diagnosis of dermatomyositis and rule
out other disorders, such as lupus. If the skin biopsy confirms the diagnosis,
a muscle biopsy may not be necessary.
Magnetic resonance imaging (MRI). A scanner creates
cross-sectional images of your muscles from data generated by a powerful
magnetic field and radio waves. These images can be viewed from any direction
or plane. MRI scans may help detect inflammation in your muscles.
Complications
You may experience these complications of dermatomyositis:
Difficulty swallowing. If the muscles in esophagus are
affected, you may have problems swallowing (dysphagia), which in turn may cause
weight loss and malnutrition.
Aspiration and pneumonia. Difficulty swallowing may also
lead to entrance of food or liquids, including saliva, into your lungs
(aspiration), which can lead to pneumonia.
Breathing problems. If your chest muscles are involved, you
may experience breathing problems, such as shortness of breath.
Gastrointestinal problems. Gastrointestinal ulceration and
bleeding can occur.
Calcium deposits. Late in the disease, particularly if
you ve had the disease for a long time, deposits of calcium can occur in your
muscles, skin and connective tissues (calcinosis).
Dermatomyositis may be associated with other conditions,
including:
Raynaud s phenomenon. This is a condition in which your
fingers, toes, cheeks, nose and ears turn pale when exposed to cold
temperatures.
Other connective tissue diseases. Diseases affecting tissues
that hold your body together, such as your muscles and joints, sometimes occur
in conjunction with each other. Conditions such as lupus, rheumatoid arthritis,
scleroderma and Sjogren s syndrome can occur in combination with
dermatomyositis.
Cardiovascular disease. The muscle of your heart may become
inflamed (myocarditis). In a small number of people who have dermatomyositis,
congestive heart failure and heart arrhythmias may develop.
Lung disease. A condition called interstitial lung disease
may occur with dermatomyositis. Interstitial lung disease refers to a group of
disorders that cause scarring (fibrosis) of lung tissue, making lungs stiff and
inelastic. Signs and symptoms include a dry cough and shortness of breath.
Cancer. Dermatomyositis in adults has been linked to an
increased likelihood of cancer, particularly of the lungs, breasts, ovaries and
gastrointestinal tract. Risk of cancer increases with age, although it appears
to level off three years after a diagnosis of dermatomyositis.
Treatments and drugs
There s no cure for dermatomyositis, but treatment can
improve your skin, muscle strength and function. Treatment begun early in the
disease process tends to be more effective, often because there are fewer
complications. Therapies include the following:
Corticosteroids. These medications suppress your immune
system, limiting the production of antibodies and reducing skin and muscle
inflammation. Corticosteroids, especially prednisone, are usually the first
choice in treating inflammatory myopathies, such as dermatomyositis.
Your doctor may start with a very high dose, and then
decrease it as your signs and symptoms improve. Improvement generally takes
about two to four weeks. Your doctor may also prescribe topical corticosteroids
for your skin. Visible results are usually evident within three to six months,
but therapy is often needed for years.
Prolonged use of corticosteroids can have serious side
effects including osteoporosis, weight gain, diabetes, increased risk of some
infections, mood swings, cataracts, high blood pressure, a redistribution of
body fat and muscle weakness. As a result, your doctor may recommend
supplements, such as calcium and vitamin D, and may prescribe bisphosphonates,
such as alendronate (Fosamax) or risedronate (Actonel).
Immunosuppressants. If your body doesn t respond adequately
to corticosteroids, your doctor may recommend other immunosuppressive drugs,
such as azathioprine (Imuran) or methotrexate (Rheumatrex). Your doctor may
prescribe these alone or in combination with corticosteroids.
When in combination, these additional immunosuppressants can
be used to lessen the dose and potential side effects of the corticosteroid.
Immunosuppressants such as cyclophosphamide (Cytoxan) and cyclosporine (Neoral,
Sandimmune) may improve signs and symptoms of dermatomyositis and interstitial
lung disease.
Antimalarial medications. For a persistent rash, your doctor
may prescribe an antimalarial medication, such as hydroxychloroquine
(Plaquenil) or chloroquine phosphate (Aralen).
Physical therapy. A physical therapist can show you
exercises to maintain and improve your strength and flexibility and advise an
appropriate level of activity. Your exercise program is likely to change during
the course of the disease and treatment period. Keeping active in general and
pacing yourself will help maintain muscle strength.
Surgery. Surgery may be an option to remove painful calcium
deposits.
Pain relievers. Over-the-counter drugs such as aspirin,
ibuprofen (Advil, Motrin, others) and acetaminophen (Tylenol, others), can be
used to treat any accompanying pain. If these aren t sufficient, your doctor
may prescribe a stronger pain reliever, such as codeine.
Dermatomyositis treatments that are still under
investigation include:
Plasmapheresis. This treatment, also called plasma exchange,
is a type of blood cleansing in which damaging antibodies are removed from your
blood.
Radiation therapy. This involves irradiation of the lymph
nodes to suppress your immune system.
Intravenous immunoglobulin (IVIg
Fludarabine (Fludara). This agent prevents the development
and growth of malignant cells.
Tacrolimus (Prograf). This transplant-rejection drug may
work to inhibit the immune system.
Monoclonal antibodies. These man-made antibodies are
designed to target and destroy specific types of cells