ATLANTA—Rheumatologists and health professionals reviewed the latest information on diagnosing and treating inflammatory myopathies during the ACR Clinical Symposium, “Inflammatory Myopathy Update,” here at the 2010 ACR/ARHP Annual Scientific Meeting. [Editor’s Note: This session was recorded and is available via ACR SessionSelect at www.rheumatology.org.] The session’s three presentations focused on modalities to diagnose inflammatory myopathy, the role of autoantibodies in myositis, and exercise intervention.
Diagnosing Inflammatory Myopathy
John A. Carrino, MD, MPH, associate professor of radiology and orthopaedic surgery and section chief of musculoskeletal radiology at Johns Hopkins University in Baltimore, started the session by reviewing some of the clinical features that usually point to myositis, including Gottron’s papules, the body symmetry of the disorder, proximal limb and truncal weakness, Raynaud’s disease, arthritis, and lung disease. He also pointed out clinical features that typically lead away from a myositis diagnosis, such as family history, weakness related to exercise and eating, cranial nerve involvement, muscle cramping, and early atrophy or hypertrophy.
While polymyositis, dermatomyositis, and inclusion body myositis are most commonly considered with inflammatory myopathy, he noted that there are a host of other emerging myopathies, such as necrotizing myopathy, giant cell myositis, eosinophilic myositis, granulomatous myositis, and others.
In the mid-1970s, Bohan and Peter developed criteria for polymoyositis and dermatomyositis before the use of magnetic resonance imaging (MRI).1,2 However, these criteria had some limitations, such as poor specificity in distinguishing polymyositis from late-onset muscular dystrophies, omission of the possible diagnosis of inclusion body myositis, and the fact that inflammation seen on muscle biopsy is not necessarily specific for inflammatory myositis. “There may be other disorders that cause muscle inflammation,” Dr. Carrino said. Other diagnostic criteria subsequently emerged.
MRI is typically used in myosititis to confirm diagnosis and help with the phenotype, to rule out myositis mimics, and to select the site of the muscle biopsy so as to make an accurate histologic diagnosis, Dr. Carrino said. During treatment, MRI can help follow disease progression and therapeutic response.
Sometimes, cases referred to the Johns Hopkins myositis center are not actually myositis but instead are muscular dystrophy, fasciitis, metabolic bone disease, or muscle strains.
—John A. Carrino, MD, MPH
Sometimes, cases referred to the Johns Hopkins myositis center are not actually myositis but instead are muscular dystrophy, fasciitis, metabolic bone disease, or muscle strains, he noted.
Advanced techniques for muscle MRI are not always used but include open-bore 3T MRI and MR spectroscopy, which may be helpful in the future for myositis diagnosis.
Autoantibodies
In his presentation, Harsha Gunawardena, MD, senior research fellow at the University of Bath in Bath, U.K., focused on the role of autoantibodies in myositis. Autoantibodies are now detected in about 70% of adult and 60% of juvenile inflammatory myopathy patients, he said. These autoantibodies include anti-p200/100, anti–Mi-2 dermatomyositis subtype, anti-p155, anti-SAE, and the anti-MDA5 dermatomyositis subtype. Although the signs and symptoms associated with each autoantibody may vary, they can include skin changes, the risk for interstitial pneumonia, and cancer. For example, more than 50% of patients who are anti-p155/140 positive have cancer, Dr. Gunawardena said.
Juvenile dermatomyositis also has a few novel specificities, particularly anti-p140, which is found in 25% of these patients, Dr. Gunawardena said. “Unlike adults, autoantibodies against Jo-1 are rarely seen in juvenile dermatomyositis.”
Dr. Gunawardena concluded that adapting a serological approach to dermatomyositis would be helpful.
Promoting Physical Activity
In the final presentation of the symposium, Ingrid E. Lundberg, MD, PhD, professor in the rheumatology unit at the Karolinska Institutet of the Karolinska University Hopsital in Stockholm, Sweden, focused on the value of physical activity for patients with inflammatory myopathy.
Lack of physical activity is major health problem recognized by the World Health Organization and is a risk factor for cardiovascular disease and death, she said. This is important for patients with an inflammatory myopathy because they are already at a greater risk for cardiovascular problems. Dr. Lundberg shared data from a 2008 study of physical activity in rheumatoid arthritis patients that found that the majority of patients were physically inactive. However, there was a wide variation among patients from the different countries included in the study, with patients from some countries more active than others.3 Dr. Lundberg is not aware of a similar study done with myositis patients. However, she did say that myositis patients have reduced aerobic fitness and that previous work has shown that myositis patients have significantly lower maximum oxygen uptake than controls.4 Maximum oxygen uptake is associated with aerobic endurance. “One question is whether by improved fitness we can change the rate of cardiovascular death in myositis,” she said.
Although it is common to think that exercise may worsen muscle inflammation in myositis patients, Dr. Lundberg was inspired to test the role of exercise by a few patients who were eager to show their physical strength.
Although it is common to think that exercise may worsen muscle inflammation in myositis patients, Dr. Lundberg said she was “inspired to test the role of exercise” by a few patients who were eager to show their physical strength. In a 1999 study, she and fellow researchers performed a pilot study with 10 patients who were treated with low doses of immunosuppressives and were still relatively weak. The program included 15 minutes of muscle work followed by 15 minutes of walking or cycling for five days a week over a 12-week period.5 Researchers did not see any signs of increased inflammation in these patients and found improvement in muscle function in all patients.
Dr. Lundberg also reported on the results of several other studies that tracked the results of exercise in patients with myositis. The studies that she presented found, among other factors, a significant improvement in strength, maximum oxygen uptake, and activities of daily living. Another conclusion from these studies is that the use of creatine helped improve muscle performance.6,7
More studies are needed to track the benefits of exercise in patients with sporadic inclusion body myositis and juvenile dermatomyositis, she noted.
Dr. Lundberg said that as soon as patients on immunosuppressive therapy at her clinic feel they can do exercise, physicians will instruct them to follow a regimen with a physical therapist’s supervision.
“We can say that exercise is safe, at least in polymyositis and dermatomyositis, and that it seems to be effective to improve strength and fitness. I would suggest it as a complement to physical therapy. It may even be that exercise is beneficial to inflammation,” she said. “It may be provocative, but I’d like to suggest that exercise is medicine.”
Vanessa Caceres is a freelance medical writer in Bradenton, Florida.
References
- Bohan A, Peter JB. Polymyositis and dermatomyositis (first of two parts). N Engl J Med. 1975;292:344-347.
- Bohan A, Peter JB. Polymyositis and dermatomyositis (second of two parts). N Engl J Med. 1975;292:403-407.
- Sokka T, Hetland ML, Mäkinen H, et al. Remission and rheumatoid arthritis: Data on patients receiving usual care in twenty-four countries. Arthritis Rheum. 2008; 58:2642-2651.
- Wiesinger GF, Quittan M, Nuhr M, et al. Aerobic capacity in adult dermatomyositis/polymyositis patients and healthy controls. Arch Phys Med Rehabil. 2000;81:1-5.
- Alexanderson H, Stenström CH, Lundberg I. Safety of a home exercise programme in patients with polymyositis and dermatomyositis: A pilot study. Rheumatology (Oxford). 1999;38:608-611.
- Wiesinger GF, Quittan M, Graninger M,et al. Benefit of 6 months long-term physical training in polymyositis/dermatomyositis patients. Br J Rheumatol. 1998;37:1338-1342.
- Chung YL, Alexanderson H, Pipitone N, et al. Creatine supplements in patients with idiopathic inflammatory myopathies who are clinically weak after conventional pharmacologic treatment: Six-month, double-blind, randomized, placebo-controlled trial. Arthritis Rheum. 2007;57:694-702.
