What Causes Myositis?

Rheumatoid Arthritis

There's strong evidence indicating rheumatoid arthritis can cause myositis. It's also likely that other autoimmune diseases could cause myositis. As the immune system floods the body with inflammation, both the joints and muscles are affected. The phenomenon has been dubbed 'rheumatoid myositis,' and though there isn't a lot of published research, the link between autoimmune inflammatory responses and myositis is too compelling to ignore.

Researchers have tried to ascertain the unique presentation and progression of rheumatoid myositis, as opposed to other forms of myositis. They've gathered information from rheumatoid arthritis patients who also have rheumatoid myositis. In one study, every patient with these conditions also had inflammatory deposits present. This implies the same autoimmune cause of rheumatoid arthritis is also behind rheumatoid myositis. It's not yet clear whether every rheumatoid arthritis patient with inflammatory deposits will develop rheumatoid myositis, but the connection makes a lot of sense. Rheumatoid arthritis is caused by an autoimmune inflammation of the joints and other tissues, while rheumatoid myositis is caused by an autoimmune inflammation of the muscles. The only difference is the type of tissue targeted.

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Rhabdomyolysis

Rhabdomyolysis is a serious condition that stems from an indirect or direct muscle injury. When the muscle is injured, the muscle fibers die. Instead of healing like an injury is meant to, the dead fibers release their contents into a patient's bloodstream. In serious cases, the sudden flood of toxicity can lead to kidney failure. From there, if a patient doesn't receive emergency medical treatment, they could die. With that said, the outcome tends to be positive for patients who receive timely medical care. The syndrome is difficult to categorize in terms of symptoms, because there's no telling what parts of the body will be affected. It's most common for patients to experience muscle pain in their lower back, thighs, or shoulders, since the dead muscle fibers are causing inflammation. They may also experience impaired mobility and muscle weakness, along with brown or dark red urine.

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