Definition
Muscle inflammation, also called “myositis“, is an inflammatory process that takes place in the muscle. Such a myositis can have a whole range of causes. It is not always bacterial or viral pathogens that trigger the inflammation, but degenerative diseases or autoimmune reactions can also be behind it.
A distinction is made between three forms of muscle inflammation: so-called “polymyositis“, “dermatomyositis” and “inclusion body myositis“, whereby polymyositis and dermatomyositis are very similar. The most frequently affected group are adults over 50, but children are also sometimes affected. Depending on the cause, the muscle inflammation must be treated differently.
Inflammation caused by pathogens can often be easily treated, systemic or degenerative causes often require lengthy treatment. Accordingly, the prognosis also varies greatly. The clinical picture of affected patients can vary from a symptom-free course to muscle paralysis.
Causes
The causes for muscle inflammation are numerous. Inflammation of muscles is a rather rare disease and when it occurs, it mainly affects children or the elderly. Identifying the type of myositis present often helps to find the cause.
Only very rarely is muscle inflammation caused by pathogens. These include above all bacteria, viruses or parasites. In our regions, they do not represent a clinical relevance.
Myositis is often a concomitant of systemic inflammatory reactions in the body. These include above all rheumatic inflammations. Autoimmune reactions are often the cause of muscle inflammation.
In autoimmune reactions, the immune system mistakenly recognizes the body’s own structures as foreign and tries to eliminate them. In myositis, the reaction is directed against small blood vessels in the muscle. As a result, the blood circulation deteriorates and the muscle may atrophy under certain circumstances.
In most cases, polymyositis has no clear cause. This is called “idiopathic”. Especially in dermatomyositis there is a risk that a tumor is the cause. If a dermatomyositis is newly diagnosed, a tumor must therefore always be considered, especially ovarian carcinomas are often in this context.
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