Frequently Asked Questions about Idiopathic Inflammatory Myopathies

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Does everyone who has muscle weakness have myositis?

Not at all. There are many muscle and non-muscle diseases that involve muscle weakness, starting with ageing. There is no doubt that as we age, we lose our motor skills. This is known as sarcopaenia (lack of reserves or functional motor capacity). Not only that, but there are many other muscle diseases (myopathies) that are not myositis. For this reason, it is always necessary for a specialist in these diseases to be responsible for establishing the correct diagnosis.

Which tests are most important for diagnosing IIM?

The diagnosis depends on a group of tests, but the most important are the medical history and physical exam, the so-called autoantibodies, imaging tests such as MRI, and, above all, a muscle biopsy. This should, generally, allow an accurate diagnosis to be made.

How do I know if the myositis I have is associated with cancer or not?

20-25% of adult patients with dermatomyositis (DM) or immune-mediated necrotising myopathy (IMNM) suffer associated cancer. This occurs either simultaneously, or within 3-5 years after the diagnosis. The first two years are considered to be the most critical. Close clinical monitoring and appropriate complementary tests, such as CT-PET scans, are recommended.

If my myositis is associated with cancer, will treatment make them both better?

That is very likely, although it does not always happen. It should not be forgotten that drugs, like cortisone, are used in some types of cancer treatment and can therefore help to improve myositis.

Do the skin and muscle issues always appear together, and are they resolved at the same time?

Skin and muscle symptoms progress in parallel in 70-80% of cases, but in other cases the muscle problem is resolved, while the skin lesions persist and require specialised treatment from a dermatologist. On the other hand, there are cases in which the skin is the only thing that is really affected, and there is hardly any impact on the muscles.

If my disease is polymyositis, will I have another associated disease?

This is very likely because pure forms of polymyositis are virtually non-existent. Once again, these patients must be treated by medical experts, as it is likely that there is another autoimmune disease present, such as lupus, scleroderma, or Sjögren syndrome, or with time it may even be shown to be inclusion body myositis.

What happens if I can't have an MRI because I’m claustrophobic?

If your doctor feels it is essential, you can be sedated for an MRI.

Are any new treatments being tested for inclusion body myositis in its sporadic form?

Yes. Although there are few beneficial results. Increasingly, the degenerative nature of the disease is being taken into account, and it is considered to be the Alzheimer's of the muscles.

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Substantiated information by:

Josep M. Grau Junyent
Sergio Prieto González

Published: 25 November 2020
Updated: 25 November 2020

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