What is Polymyositis, Know its Causes, Symptoms, Treatment, Prognosis

Amongst the many chronic inflammatory diseases of muscles, Polymyositis is an uncommon one. This condition causes weakness of the muscles.

The term Polymyositis refers to a group of muscle diseases that in general refer to the inflammation of the muscles as well as the blood vessels and tissues that are associated with the muscles.¹ The term myositis comes from “myo” which means muscle and “itis” that means inflammation. When there is a group of inflammation in the muscles, it is referred to as Polymyositis.

The exact causes of Polymyositis are not clearly known. However, research studies have shown that it has an association with the immune system.¹ The immune system disorder mistakenly attacks the tissues of the body and thereby, the muscles are weakened, leading to polymyositis.

Though the disease is not a genetic one, there are still chances that genetic factors make the disease more or less likely to be affecting the next generations of a sufferer.

Polymyositis is a disease that mostly affects the sufferers after the age of 20. It gradually progresses in severity. However, there are effective treatments that can completely or at least partially treat the condition, reducing the difficulties. Polymyositis is not a life-threatening problem.

The common symptom of polymyositis is weakness of the muscle. The weakness is majorly seen in the muscles of –

• Shoulder
• Hip
• Upper arms
• Neck
• Thighs.

The affected muscles also experience pain and tenderness.

The other signs and symptoms of Polymyositis include –

• Weakness of the neck muscle
• Swallowing troubles or dysphagia
• Fatigue while walking
• Lymphocytic inflammation
• Weakness of the muscles of lungs and heart.

In that case, heart failure and conduction abnormalities may also be experienced.

As the muscles are weakened due to Polymyositis, there can be general daily-life problems such as –

• Difficulty in climbing stairs ¹
• Difficulty in rising from a seated position
• Falling and difficulty in getting up
• Difficulty in lifting objects.

What makes Polymyositis a serious problem is the increased risk of malignancy that this disease is associated with. There are certain factors that contribute into this increased risk and these are –

• Age above 45
• Cutaneous necrosis
• Dysphagia
• Rapid onset of myositis
• Cutaneous vasculitis
• Higher ESR
• Elevated CK
• Higher CRP levels.

Those, who comply with these factors and have Polymyositis, have a higher risk of malignancy. Usually the malignancies are mostly associated with lung, bladder, nasopharyngeal and non-hodgkins lymphoma.

For the diagnosis, the doctors check for the –

• Weakness of the muscles of hips and shoulders
• Abnormalities in the electrical activity of the muscles – this can be measured by electromyography test
• Increased levels of certain muscle enzymes in blood – this will indicate weakness or damage in the muscles
• Biopsy test of the muscular tissue.

Polymyositis patients have a good prognosis in case the diagnosis is made faster. About 50% of all patients have had apparent recovery within 5 years of the diagnosis. Children or young patients have an even better prognosis. Children die from polymyositis when the blood vessels that supply bowel suffer from inflammation. Cancer patients, who have Polymyositis, die from cancer rather than of Polymyositis. However, if polymyositis affects or weakens the muscles of lungs and heart, the chances of death are higher.

In many cases, there has been long remission from the condition of polymyositis; but this depends on how fast the treatment has been started. Though there is no complete cure for polymyositis, with early treatment, the problems and complications can be reduced to a great extent.

The medicines that are prescribed to increase the muscle strength include –

• Corticosteroids
• Rituximab
• Corticosteroid-sparing agents.

Along with that, certain other therapies are also recommended for Polymyositis patients and these include –

• Speech therapy that helps in overcoming the swallowing troubles
• Physical therapy to increase muscle flexibility
• Diet assessment that will help in modifying the diet so that swallowing is less difficult.

Sometimes, to control polymyositis from progressing further, the doctors use Intravenous immunoglobulin (IVIg) treatment. It is an infusion of purified blood product that is given through a vein. It contains healthy antibodies that can actually block the action of the unhealthy antibodies that actually affect the muscle tissues. However, this is an expensive treatment and it must be continued for long for effective results.

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