Myositis: Symptoms, Causes & Treatment

Myositis is inflammation of the muscles that can cause weakness. It may lead to muscle pain, tenderness, and difficulty with everyday activities such as climbing stairs, raising the arms, standing, walking, or getting up from a chair.

Myositis can happen because of genetic changes or as a result of infections. It is important to see a primary care provider or rheumatologist for an evaluation to identify the cause of the muscle inflammation.

Myositis can affect any part of the body, and in some cases it improves with treatment, which usually includes medication and exercises to help maintain muscle strength. In other cases, myositis is a chronic condition that lasts for life, but symptoms can still be managed with treatment.

Myositis can affect any part of the body. In some cases, it improves with treatment, which usually includes medication and exercises to help maintain muscle strength. In other cases, it becomes a chronic condition, but symptoms can still be managed with treatment.

Main symptoms

The main symptoms of myositis are:

• Progressive muscle weakness that gets worse over time

• Muscle pain (myalgia), which may or may not be present

• Weight loss

• Fever

• Irritability

• Voice changes, including hoarseness or a nasal quality

• Difficulty swallowing or breathing

Symptoms can vary depending on the type and cause of myositis, so it is important to see a rheumatologist or primary care provider for an evaluation so the condition can be diagnosed and the most appropriate treatment can be started.

Confirming a diagnosis

According to the National Institute of Neurological Disorders and Stroke (NINDS), diagnosis of inflammatory myopathies is based on medical history, a physical exam with muscle-strength testing, and blood tests that may show elevated muscle enzymes and autoantibodies.

Blood tests such as CK, LDH, AST, and ALT may be ordered to check for inflammation and muscle damage. Other blood tests may also be used to measure specific antibodies associated with myositis.

In some cases, additional tests such as autoimmune studies, bone marrow biopsy, or genetic testing may be requested. Imaging tests such as an MRI or electromyography may also be recommended.

Possible causes

Myositis can develop because of genetic conditions or changes in the immune system, which cause the body to attack its own tissues and lead to muscle inflammation and symptoms.

Myositis can also happen as a result of infection caused by viruses, parasites, or bacteria, or as a side effect of certain medications.

Main types

Myositis can be classified into several main types according to its cause:

1. Ossifying myositis

Progressive ossifying myositis, also called fibrodysplasia ossificans progressiva, is a rare genetic disease in which muscles, ligaments, and tendons gradually turn into bone after trauma such as bone fractures or muscle injury.

Symptoms usually include loss of movement in the joints affected by the disease, which can lead to an inability to open the mouth, pain, hearing loss, or difficulty breathing.

2. Childhood myositis

Childhood myositis affects children between 5 and 15 years of age. Its cause is still unknown, but it is a disease that causes muscle weakness, reddish skin lesions, and widespread pain, leading to difficulty climbing stairs, getting dressed, combing hair, or swallowing.

3. Infectious myositis

According to the CDC, infectious myositis is usually caused by an infection such as the flu or trichinellosis, which can be acquired by eating raw or undercooked pork or wild game.

It can cause symptoms such as muscle pain, muscle weakness, and, in the case of the flu, a runny nose and fever.

4. Acute viral myositis

Acute viral myositis is a rare type of the disease that causes the muscles to become inflamed, weak, and painful. HIV and common flu viruses can cause this muscle infection.

Symptoms develop quickly, and the person may even be unable to get out of bed because of severe pain and weakness during the infection.

Treatment options

Treatment for myositis depends on the cause of the muscle inflammation and the symptoms present, and it should be guided by a rheumatologist or primary care provider.

In general, corticosteroid medications may be recommended to reduce inflammation and relieve symptoms. If myositis is caused by an infection, antiviral or antimicrobial medications may also be needed.

When myositis is associated with an autoimmune disease, a healthcare provider may prescribe immunosuppressive medications. In both autoimmune and genetic cases, regular medical follow-up is important to monitor the condition and help maintain quality of life.

In some cases, physical therapy sessions may also be recommended to relieve pain and muscle discomfort.