Polymyositis-Weakened Muscles

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Category: Other Autoimmune Diseases Published on Monday, 01 August 2005 Written by Yong Tsai, MD
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The father in the movie, “My Big Fat Greek Wedding” was not always exaggerating about the Greek’s influence on our vocabulary. A case in point is the word polymyositis, meaning poly (many) myos (muscle) itis (inflammation).

Polymyositis is an autoimmune disease, which occurs when our immune system attacks our own muscles, causing generalized muscle weakness, especially in the shoulders, upper arms, thighs, and hips, due to inflammation of muscle tissue.

It is estimated that only five out of every million people each year are diagnosed with polymyositis, so it is considered relatively rare. Although men, women, and children can develop polymyositis, it seems to target women between the ages of 30 to 60.

Nicole, a healthy 27-year-old teacher, suddenly developed muscle weakness and pain in her arms and legs. Because she was finding it difficult to reach with her arms or get out of a chair, she became worried and went to see her doctor.

Blood tests showed an elevated CPK of 5670 and an EMG (electromyogram) and muscle biopsy confirmed a diagnosis of polymyositis. Her doctor started her on high doses of corticosteroids, followed by intravenous immunoglobulin infusion therapy, and her muscle weakness gradually improved.

Because she was improving, her corticosteroids were decreased and then stopped, leaving her with the current treatment regiment of Methotrexate and physical therapy to increase muscle strength and endurance.

Usually, the first symptom experienced with polymyositis is muscle weakness, making it difficult to lift your arms, comb your hair, or get out of a chair. Its onset can be either gradual or quite sudden, and symptoms may vary from person to person.

Frequently, people experience muscle and joint paint, fatigue, and fever. However, occasionally, shortness of breath or an irregular heart beat can occur if the lungs or heart become affected.

CPK, an enzyme found primarily in our muscles, leaks into the blood stream when muscles are damaged or inflamed, thus creating an elevated level of CPK. In general, the greater the muscle damage, the higher the level of CPK, as in Nicole’s case.

Distinguishing whether or not the weakness is due to nerve or muscle damage can be revealed via an EMG (electromyogram), which measures the electrical activity within a muscle by inserting needle-like electrodes into muscles to stimulate and record their activity.

Finally, a muscle biopsy to examine muscle damage under a microscope may be ordered to confirm the diagnosis.

Fortunately, over the past 20 years, the outlook of polymyositis has improved significantly, thanks to corticosteroids, intravenous gamma globulin, and Methotrexate treatment to decrease inflammation and restore muscle strength.

However, along with medical treatment, getting adequate rest remains a vital aspect of managing myositis, particularly when it is active. Polymyositis can be well managed if you know your limits and listen to your body.

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