MYOSITIS

WHAT IS MYOSITIS?

Myositis refers to inflammation of the muscles (myo means muscle and 
itis means inflammation). Myositis is a term that describes several 
different illnesses, including polymyositis, dermatomyositis, and 
inclusion body myositis.

All forms of myositis involve chronic, or persistent, muscle 
inflammation. This muscle inflammation almost always results in 
weakness, and less often in heat, swelling, and pain of the muscles. 
Myositis can affect many parts of the body. Sometimes the joints, heart, 
lungs, intestines, and skin can become inflamed

Some forms of myositis, like dermatomyositis (dermato refers to the 
skin), result in particular rashes over the knuckles, around the eyes, 
or sometimes in other parts of the body. Other forms of myositis occur 
in children. Some forms are seen with other connective tissues diseases, 
like lupus or rheumatoid arthritis. Still other forms may occur in 
people with tumors. Rarely, myositis can occur in a single part of the 
body, such as one arm, one leg, or just the muscles that move the eye.

Like other rheumatic diseases, myositis is unlikely to go away on its 
own. But with proper treatment and management, these chronic diseases 
can be brought under control.

Myositis is a term describing several different illnesses that involve 
chronic muscle inflammation.

WHO GETS MYOSITIS?

Myositis is a rare disease. In the United States, it is estimated that 
each year five to 10 out of every one million people get one of the 
forms of myositis.

Although myositis can affect people of any age, most children who get 
the disease are between five and 15 years of age and most adults are 
between 30 and 60. Like many other inflammatory diseases, most forms of 
myositis attack more women than men. The exception is inclusion body 
myositis, a form of myositis in which holes, called inclusion bodies, 
develop in the muscle fibers. This form affects more men than women.

Myositis is a rare disease that primarily affects children between the 
ages of five and 15 as well as adults between the ages of 3O and 6O.

We do not know what causes myositis. But because myositis has many 
forms, it probably has many causes. Some scientists think that myositis 
results when a person with a certain genetic background is exposed to 
particular chemicals, viruses, or other infectious agents.

Whatever triggers these diseases also results in abnormalities in the 
immune system. The immune system consists of groups of cells called 
lymphocytes that circulate throughout the body. In healthy people, these 
lymphocytes act as a defense force that produces substances that attack 
viruses, bacteria, and other agents of disease. But in many people with 
myositis, there is an abnormality in the immune system that results in 
the production of proteins called autoantibodies. Autoantibodies and 
some of the lymphocytes turn against the body's own tissues and may 
cause damage.

Because illnesses associated with autoantibodies are called autoimmune 
diseases, many doctors consider myositis to be an autoimmune disease. 
Some autoantibodies found in people with myositis are found in other 
autoimmune diseases, but a few special ones are only found in people 
with myositis. These are called myositis-specific autoantibodies. They 
seem to be useful in helping doctors predict the problems that some 
people might develop and how they might respond to treatment.

Although the cause of myositis is unknown, scientists think it may occur 
when a person with a certain genetic background is exposed to particular 
chemicals, viruses, or other infectious agents.

WHAT HAPPENS IN MYOSITIS?

The many forms of myositis begin and progress in different ways. In most 
people the illness develops slowly over a period of months or even 
years, but in some people problems can occur suddenly. The disease often 
appears to come and go for no apparent reason, and sometimes its form 
changes over time.

MUSCLE WEAKNESS

The major symptom of myositis is muscle weakness. Hip and shoulder 
muscles are most likely to be involved. This often results in difficulty 
combing hair; putting on heavy clothes; getting out of a bathtub, bed, 
chair, or car; and climbing stairs. Other muscles sometimes affected are 
those in the front of the neck, making it difficult to raise your head 
when lying down. Occasionally, other neck and throat muscles are 
affected, making it hard for some people to swallow, sing, or even speak 
clearly. If your chest muscles or lungs are affected, you may have 
trouble breathing. Many people with myositis learn ways of compensating, 
however, and adjust so well that even they are not aware of the slow, 
gradual, progression of their disease.

SKIN CHANGES

People with dermatomyositis may develop a bumpy, patchy, reddish or 
purplish skin rash on the face, around the eyes (called heliotrope 
rash), on the knuckles, elbows, or knees (called Gottron's papules), or 
over the chest or back. Some people have puffy eyelids, wrists, or hands 
as a result of myositis. A person with myositis also may develop a rash 
around the base of the fingernails, overgrowth of the cuticle, or 
cracking and bleeding of the skin on the sides and tips of the fingers.

OTHER SYMPTOMS

Other possible symptoms of myositis include fever, weight loss, pain, 
tenderness in the muscles, and arthritis. It sometimes is very difficult 
to tell whether the joints or the muscles between the joints are causing 
pain and problems for people with myositis.

Sometimes Raynaud's phenomenon develops. This is an extreme sensitivity 
and reaction to cold that is most often felt in the fingers. Raynaud's 
phenomenon is caused by a narrowing of the blood vessels in the fingers, 
which reduces blood flow and turns the fingers white and then gradually 
blue.

Occasionally the heart can become damaged by myositis. This damage can 
result in an irregular heartbeat. Occasionally, myositis can cause the 
heart to become enlarged and result in swelling of the lower legs.

COURSE OF THE DISEASE

How myositis begins and progresses is quite variable and differs from 
person to person. Some people first experience rashes, some shortness of 
breath, and some arthritis. Some people may later develop new symptoms, 
and in other people symptoms may go away. Children with myositis 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.

A small minority of people with myositis have tumors that seem to be 
related to their myositis. Scientists have found that tumors occur more 
often in people past the age of 50 and in persons with dermatomyositis. 
Sometimes the removal of the tumor results in the disappearance of the 
myositis.

Myositis can result in muscle weakness and tenderness, rashes and other 
skin changes, fever, weight loss, pain, arthritis, Raynaud's phenomenon, 
and/or heart damage.

DIAGNOSING MYOSITIS

Because myositis closely resembles many other diseases and differs so 
much from person to person, it can be difficult to diagnose. Your doctor 
may have to perform many tests and see you many times before deciding on 
a diagnosis of myositis. It often is necessary for your primary care 
doctor to send you to a rheumatologist, a doctor who is specifically 
trained to diagnose and treat myositis and other similar inflammatory 
conditions. Consultation with a neurologist, who specializes in 
disorders of the nervous system, may also be indicated.

During the process of reaching a diagnosis, your doctor will ask a 
series of questions about the problems you are experiencing and will 
perform a physical examination. There are blood tests that may be done, 
including some for autoantibodies and muscle enzymes. One of the most 
useful is a blood test for a muscle enzyme called creatine kinase, or 
CK. In most people with active myositis, the CK level in the blood is 
abnormally high. The CK level tends to go up with increasing myositis 
disease activity and tends to go down as the myositis improves.

Another procedure very useful in diagnosing myositis is an 
electromyogram (EMG). An EMG measures the electrical pattern of the 
muscles, just as an electrocardiogram (EKG) measures the electrical 
pattern of the heart.

Your doctor will probably also request that a muscle biopsy be done. 
This is the removal of a small piece of muscle for staining and 
examination with a microscope. The muscle biopsy shows your doctor 
whether and how the muscle fibers are damaged.

Diagnosing myositis may be a lengthy process, involving a physical 
examination, blood tests, an electromyogram, and/or a muscle biopsy.

TREATING MYOSITIS

There are many forms of treatment for myositis, but most include 
medications, exercise, physical therapy, and rest. The treatment will 
vary from person to person and will change over time in a single person. 
The specific therapy recommended by your doctor will depend upon the 
severity and type of problems, the presence of other medical conditions, 
and adverse reactions to previous therapy.

MEDICATIONS

Corticosteroids

The most effective drugs in treating myositis are corticosteroids. These 
drugs are related to hormones produced naturally in the body. 
Corticosteroids are powerful and can have serious side effects. Some of 
these side effects include:

weight gain rounding of the face easy bruising thinning of the bones 
depression high blood pressure cataracts diabetes increased risk of 
infection rarely, bleeding from the stomach 

If you take corticosteroids, you should be monitored carefully by your 
doctor and should report any new medical problems to the doctor.

Caution! Anyone taking corticosteroids should be aware of several 
precautions. During such therapy, the body slows or stops its own 
natural production of steroids. For this reason, any time the dose is to 
be lowered, your doctor will gradually reduce the level of steroids you 
are taking over a period of weeks or months. During this time, your body 
will gradually increase its own corticosteroid production. Do not ever 
decide on your own to stop or drastically reduce the amount of 
prednisone or other corticosteroid you are taking, even if you feel 
well. Serious health problems could result if you do! You may want to 
wear a medic alert bracelet that says you are taking corticosteroids.

If you have taken corticosteroids for a long time, be sure to discuss 
your medications with all doctors and dentists treating you. Any 
situation that places extra stress on your body, such as surgery or 
major dental work, may require higher levels of corticosteroids than you 
will be able to produce. This may require that the corticosteroid dosage 
be increased temporarily during such stressful periods.

The corticosteroid most commonly used for myositis is prednisone. If 
your myositis is severe, your doctor may prescribe fairly high doses of 
corticosteroids. This may be done by giving prednisone as pills to be 
taken by mouth or in liquid form given through a plastic tube that 
enters a vein (intravenously). It may take several weeks or months for 
you to notice improvement, even though you may be getting better without 
realizing it. Throughout the treatment of myositis your doctor will 
repeat blood tests for muscle enzymes to watch for signs of progress. 
Often the CK muscle enzyme will begin returning to normal before you 
notice any improvement.

After your strength improves, your doctor probably will begin slowly 
reducing the dose of prednisone to a lower level that may remain the 
same for a long period of time. If your myositis is under good control, 
your doctor may eventually be able to take you off prednisone 
completely, at least for a time.

Immunosuppressants

You may not respond to prednisone therapy alone. Your doctor may then 
prescribe both prednisone and a drug that suppresses the immune system. 
Such drugs are called immunosuppressants, and the most common ones used 
in myositis are methotrexate and azathioprine. Immunosuppressants slow 
down the immune system, reducing its ability to attack infections and 
attack healthy tissue in persons with autoimmune disease.

Immunosuppressant drugs are powerful agents and can result in side 
effects. If you are taking these medications, see your doctor regularly 
so that he or she can check for any side effects and decrease the dosage 
of medicine if necessary. Your doctor may request ongoing consultation 
with a rheumatologist when your treatment includes the use of 
immunosuppressant drugs.

if any of these side effects occur, contact your doctor:

upset stomach loss of appetite mouth sores hair loss skin rash fever 
chills blood in urine diarrhea missed menstrual periods 

Caution: Methotrexate may cause birth defects. Women on methotrexate 
must go off their medication during pregnancy and for several months 
prior to a planned pregnancy'. Methotrexate should not be taken by 
people who have serious kidney or liver disease or who drink alcohol.

EXERCISE AND PHYSICAL THERAPY

A physical therapy or exercise program is an important part of treating 
myositis and can help improve muscle strength. However, you should not 
begin vigorous exercise until the drug treatment takes effect. In the 
early stages of treating myositis, your muscle fibers are fragile and 
could be damaged further by such exercises. Physical examination and 
laboratory tests will help your doctor determine the appropriate time to 
start an exercise program.

But even when strenuous exercise is not recommended, it is important to 
prevent loss of flexibility of your arms, legs, and other parts of your 
body by doing range of motion stretching of the joints and muscles. 
Other physical therapy activities may range from simple exercises at 
home to formal sessions with a specially trained health professional. 
They can also include whirlpool baths, heat and gentle massage, or 
similar therapies. As you get better, your physical therapy program will 
be adjusted accordingly with more vigorous exercises. Pool exercise, 
such as the Arthritis Foundation Aquatics Programs, can be very helpful 
in re- storing your muscle function to normal.

REST

Getting adequate rest is another important aspect of managing myositis. 
During times of increased muscle weakness, you need to take frequent 
rests during the day and to limit your activity to a tolerable level. If 
you are employed, you need to discuss your situation with coworkers, 
supervisors, and your doctors to develop a work plan to accommodate your 
disease. when your myositis is active, you should minimize strong 
physical activity, and your workday should include rest breaks. More 
activity can be undertaken and fewer rest breaks will be needed as your 
condition improves, but you need to avoid overdoing activity at the 
first sign of improvement. Your doctor and physical therapist can help 
decide the proper balance of rest and activity at each stage of 
myositis.

Treatment includes a combination of medication, exercise, physical 
therapy, rest, and regular visits to the doctor to monitor for 
medication side effects.

THE FUTURE

Myositis, like most other forms of rheumatic disorders, is a chronic 
disease. There is no cure at present. The person with myositis will need 
to manage the condition and to adjust to the changes it brings. This may 
involve continuing to take medicine and seeing a doctor regularly. It 
may also require changing some activities, especially during periods of 
increased pain and weakness. For most people with myositis, however, 
treatment of myositis is satisfactory, and they can lead productive 
lives.

Myositis is more serious if it affects the breathing muscles, the heart, 
is combined with a tumor, or if certain autoantibodies are present. 
People with these complications will need to be monitored even more 
closely by their doctors.

Researchers are making some progress in understanding what happens in 
myositis and what goes wrong with the immune system. Currently they 
believe that the muscle fibers in some people with myositis are damaged 
by a group of cells called lymphocytes, which make up part of the immune 
system. Researchers also are studying the possibility that certain 
autoantibodies may travel through the blood and cause damage to the 
muscle. Other researchers are studying how many different forms of 
myositis exist and how they are different from one another in their 
cause and treatment.

As scientists get closer to understanding the process leading to muscle 
damage in the different forms of myositis, they can hope to find new 
ways of stopping the harmful actions. With the scientific progress that 
has been made in recent years, people with myositis have reason to share 
that hope.

Research holds the key to better ways to prevent, diagnose, and control 
myositis.