Polymyositis

What is polymyositis?

Polymyositis is a rare inflammatory disease that causes muscle weakness affecting both sides of the body. Polymyositis is one of several idiopathic inflammatory myopathies – a group of muscle diseases that involves inflammation of the muscles or associated tissues, such as the blood vessels. A myopathy is a muscle disease.

What are the symptoms of polymyositis?

The muscle weaknesses associated with polymyositis involve the following muscles/parts of the body:

• Hips
• Thighs
• Shoulders
• Upper arms
• Neck

The weakness affects both the left and right sides of the body and tends to gradually worsen.

What causes polymyositis?

The exact cause of polymyositis is unknown, but it shares many characteristics with autoimmune disorders, in which the immune system mistakenly attacks its own body tissues.

How is polymyositis diagnosed?

Polymyositis is often suspected in people with muscle weakness and other associated signs and symptoms. Additional testing can then be ordered to confirm the diagnosis, including:

• Blood tests
• Electromyography
• Imaging tests such as an MRI
• Muscle biopsy

What are the available treatments for polymyositis?

To date, there is no cure for polymyositis. Treatment options exist to improve muscle strength and function, including:

• Corticosteroids
• Corticosteroid-sparing agents.
• Rituximab (Rituxan)

Other options include physical and speech therapies, dietetic assessment, and intravenous immunoglobulin (IVIg).

Where can I find out more about polymyositis?

• NIH
• Medscape
• Mayo Clinic