Polymyositis: An Overview
Guest: Dr. Gary Gilkeson – Rheumatology & Immunology
Host: Dr. Linda Austin – Psychiatry
Dr. Linda Austin: I’m Dr. Linda Austin. I’m interviewing Dr. Gary Gilkeson, who is Professor of Medicine in Rheumatology here at the Medical University of South Carolina. Dr. Gilkeson, let’s talk, today, about an illness that a lot of people don’t know too much about, polymyositis. What are the symptoms of that illness?
Dr. Gary Gilkeson: Polymyositis is an inflammatory disease of the muscle. So, the patients present with muscle pain and muscle weakness.
Dr. Linda Austin: Are there specific muscles of the arms and legs that are more commonly affected?
Dr. Gary Gilkeson: It’d be mainly the biceps and the muscles of the upper arm, the thigh muscles and quadricep muscles of the legs, so, the big muscles close to the hip and the big muscles around the shoulder.
Dr. Linda Austin: Now, everybody, surely, has had pain and stiffness in those muscles from time to time, but what’s characteristic of the polymyositis pain?
Dr. Gary Gilkeson: The pain probably isn’t as characteristic as the fact that you have weakness associated with it and, also, that is lasts for, if we overexert ourselves, a day or two, for this, it lasts weeks and weeks. But the major thing is the weakness associated with it.
Dr. Linda Austin: How severe can that weakness become?
Dr. Gary Gilkeson: The weakness can become very severe. Patients can get to the point that they can’t get up out of a chair. They can’t get out of bed. It can even be so severe that they can’t even breathe. So, it can be a life-threatening illness.
Dr. Linda Austin: If untreated, I would assume?
Dr. Gary Gilkeson: If untreated.
Dr. Linda Austin: What age group is most vulnerable to this?
Dr. Gary Gilkeson: Well, there are two types. There’s a dermatomyositis, where you also have skin rash associated with it, and that can be in children as well as in adults. Polymyositis is exclusively in adults, and it’s typically in your 40 to 60-year-old individual.
Dr. Linda Austin: More common in men or women?
Dr. Gary Gilkeson: With most autoimmune diseases, there’s a tendency for it to be more common in women, although it’s not a marked difference, not like lupus, where it’s ten to one women to men, or RA, where it’s three to four women. It may be a one and a half to two prevalence [men to women].
Dr. Linda Austin: RA, being rheumatoid arthritis?
Dr. Gary Gilkeson: RA being rheumatoid arthritis.
Dr. Linda Austin: Now, what’s seems to trigger polymyositis?
Dr. Gary Gilkeson: For the most part, we don’t know what the trigger is. It is associated with an increased risk of malignancy. So, whenever anyone presents with polymyositis, we do look for potential underlying malignancies, like breast cancer in women or prostate cancer in men, or lung cancer in smokers. So, malignancy is one trigger for it. We don’t know why that is. For the majority of the cases, we don’t know what the trigger is. It is an autoimmune disease, meaning, the body’s immune system has turned against itself and, in this instance, and it has turned against the muscles.
Dr. Linda Austin: So, now, is the body making antibodies against the muscles or immune cells? What is going on there?
Dr. Gary Gilkeson: Well, it’s both. You do get some antibodies against muscle tissues in the disease. But, more of it is an immune cell infiltration, what we call a cellular response.
Dr. Linda Austin: Dr. Gilkeson, how do you diagnose this? How do you become certain that that’s what you’re treating?
Dr. Gary Gilkeson: It’s primarily a clinical diagnosis, based on the symptoms of the muscle weakness and the muscle pain. Diagnostically, there are blood tests that pick up that there is muscle injury occurring, a blood test called a CK, but that is not specific for polymyositis. There are no other real specific blood tests that we can use. The main diagnosis is made clinically, and then we can do a muscle biopsy, taking muscle tissue and looking at it under the microscope, and that’s the diagnostic that’s normally done.
Dr. Linda Austin: How do you treat it?
Dr. Gary Gilkeson: It’s treated with immuno-suppressing drugs primarily, starting with prednisone. Then that’s followed up with other drugs, such as Methotrexate or Imuran, to try to decrease the amount of prednisone that’s being given.
Dr. Linda Austin: How long does that treatment usually last?
Dr. Gary Gilkeson: The treatment normally lasts for a number of years. The disease will have a tendency to go away on its own, but it will normally take two to five years for that to happen. So, you’re looking at a long-term treatment with these drugs.
Dr. Linda Austin: And then, potentially, some of the side effects of the chronic use of those drugs. They’re not light-weight drugs. Those are not necessarily easily tolerated drugs.
Dr. Gary Gilkeson: No.
Dr. Linda Austin: So, this is a pretty serious illness?
Dr. Gary Gilkeson: It is a very serious illness. It can be controlled in the vast majority of the cases. But it does require significant medical treatment in order to control it, in most cases.
Dr. Linda Austin: Does it ever come back, once you’ve successfully treated it?
Dr. Gary Gilkeson: It can come back, when we monitor for that, especially if you only treat for a short period. If you do treat for the two to five years, and the disease is gone, and then you stop therapy, it would be unusual for it to come back, but it can happen.
Dr. Linda Austin: Dr. Gilkeson, thank you so much for talking with us today.
Dr. Gary Gilkeson: Yes. Thank you.
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