What Is Myositis and How Can It Be Treated?

Medically reviewed by Brenda B. Spriggs, MD, MPH, FACP on June 2, 2017Written by Holly J. Bertone, CNHP

What is myositis?

Myositis is a general description for chronic, progressive inflammation of the muscles. Some types of myositis are associated with skin rashes.

This rare disease can be difficult to diagnose, and the cause is sometimes unknown. Symptoms can appear rapidly or gradually over time. Primary symptoms may include muscle pain and soreness, fatigue, trouble swallowing, and difficulty breathing.

In the United States, there are an estimated 1,600 to 3,200 new cases per year and 50,000 to 75,000 people living with myositis.

Myositis can affect both children and adults. With the exception of one type of myositis, women are more likely to be affected by this disease than men.

Types of myositis

The five types of myositis are:

  1. dermatomyositis
  2. inclusion-body myositis
  3. juvenile myositis
  4. polymyositis
  5. toxic myositis

Dermatomyositis

Dermatomyositis (DM) is the easiest form of myositis to diagnose due to the purple-red rashes in the shape of the heliotrope flower. The rash develops on the eyelids, face, chest, neck, and back. It also develops over joints such as knuckles, elbows, knees and toes. Muscle weakness normally follows.

Other symptoms of DM include:

  • scaly, dry, or rough skin
  • Gottron’s papules or Gottron’s sign (bumps found over the knuckles, elbows, and knees, often with a raised, scaly breakout)
  • trouble rising from a seated position
  • fatigue
  • weakness in the neck, hip, back, and shoulder muscles
  • difficulty swallowing
  • hoarseness in the voice
  • hardened lumps of calcium under the skin
  • muscle pain
  • joint inflammation
  • nail-bed abnormalities
  • weight loss
  • irregular heartbeat
  • gastrointestinal ulcers

Learn more about dermatomyositis »

Inclusion-body myositis

Inclusion-body myositis (IBM) is the only myositis which occurs more commonly in men than in women. Most people who develop this condition are over the age of 50. IBM begins with muscle weakness in the wrists and fingers and also in the thigh muscles. The muscle weakness is more prominent in smaller muscles and is asymmetrical, with one side of the body affected more than the other. IBM is believed to be genetic.

Symptoms of IBM include:

  • difficulty walking
  • tripping and loss of balance
  • frequent falls
  • trouble rising from a seated position
  • weakened hand grip and diminished hand and finger dexterity
  • difficulty swallowing
  • muscle weakness
  • muscle pain
  • diminished deep tendon reflexes

Juvenile myositis

Juvenile myositis (JM) occurs in children under 18. It affects 3,000 to 5,000 American children. Girls are twice as likely to develop JM than boys. Similar to the other forms of myositis, JM is characterized by muscle weakness and skin rashes.

Symptoms of JM include:

  • visible, reddish-purple rash over the eyelids or joints, sometimes in the shape of the heliotrope flower
  • fatigue
  • moodiness or irritability
  • stomachaches
  • motor function difficulties, such as trouble climbing stairs, standing from a seated position, and getting dressed
  • difficulty reaching overhead, as when shampooing or combing hair
  • trouble lifting the head
  • swelling or redness of the skin around the fingernails
  • trouble swallowing
  • hardened lumps of calcium under the skin
  • muscle weakness
  • muscle and joint pain
  • hoarse-sounding voice
  • Gottron's papules (bumps found over the knuckles, elbows, and knees)
  • fever

Polymyositis

Polymyositis (PM) begins with muscle weakness in the muscles closest to the trunk of the body and then expands from there. Each case of PM is unique, and people with PM are often found to have additional autoimmune diseases.

Symptoms of PM include:

  • muscle weakness
  • muscle pain
  • difficulty swallowing
  • falling
  • trouble rising from a seated position
  • fatigue
  • chronic dry cough
  • thickening of the skin on the hands
  • difficulty breathing
  • fever
  • weight loss
  • hoarse voice

Toxic myositis

Toxic myositis is thought to be caused by some prescribed medications and illicit drugs. Cholesterol-lowering medications such as statins may be among the most common drugs to cause this condition. Although this is extremely rare, other medications and substances that may cause myositis include:

  • certain immunosuppressants
  • omeprazole (Prilosec)
  • adalimumab (Humira)
  • cocaine
  • toluene (a solvent used in paint thinners that is sometimes used illicitly)

Symptoms of toxic myositis are similar to those of other types of myositis. People who experience this condition typically see improvement once they stop the medication that caused the toxicity.

What causes myositis?

Experts differ in their opinions as to the exact cause of myositis. Myositis is thought to be an autoimmune condition that causes the body to attack the muscles. Most cases don’t have a known cause. However, it’s thought that injury and infection may play a role.

Some researchers believe that myositis may also be caused by:

How is myositis diagnosed?

People with myositis are often given a misdiagnosis. It can be difficult to diagnose myositis since it’s rare, and also because the primary symptoms are muscle weakness and fatigue. These symptoms are found in many other common diseases.

Physicians may use any of the following to aid in the diagnosis:

What is the treatment for myositis?

There are no specific medications that treat myositis. However, corticosteroids such as prednisone (Rayos) are often prescribed. Doctors often prescribe this drug with immunosuppressant drugs such as azathioprine (Azasan) and methotrexate (Trexall).

Due to the nature of this disease, it may take several changes in your therapy for a doctor to find the right treatment plan for you. Work with your doctor until the best course of action is achieved.

Physical therapy, exercise, stretching, and yoga can help keep muscles strong and flexible and prevent muscle atrophy.

What is the outlook for myositis?

There is no cure for myositis. Some people with myositis may require the use of a cane, walker, or wheelchair. If left untreated, myositis may cause morbidity and even death.

However, some people are able to manage their symptoms well. Some may even experience partial or complete remission.

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