Dr. Kaner began his presentation by stating that more than 40% of patients with dermatomyositis and polymyositis will have symptoms related to the respiratory system at some point in their lives, making this the most common extramuscular organ involvement. These can range from mild to more involved symptoms. One of the ways to handle symptoms more effectively is to seek treatment and testing early. He emphasized the importance of collaboration between the rheumatologist and the pulmonologist.
Symptoms of lung problems in people with myositis include: chest pain, cough, and shortness of breath with exertion.
Types of Lung Issues for People with Myositis
- Upper respiratory tract infections (viruses, bacteria, and fungi). People with myositis may be more susceptible than the general population due to the use of immunosuppressives, such as methotrexate.
- Acute pneumonitis (inflammation and/or infection in the lung tissue)
- Interstitial lung disease (inflammation and scarring of the lung tissue, which is associated with myositis). In order to determine if this is caused by infection or myositis, sometimes further testing must be done.
- Respiratory muscle weakness
- Fibrosis, or scarring, as a result of inflammation
- Pulmonary drug toxicity
Common Diagnostic Tests:
The following are common diagnostic lung tests performed for people with myositis. These tests are important in determining if the cause(s) of symptoms are related to myositis or another process, such as infection. These tests also offer a baseline for comparison to future tests:
- Chest X- ray: is non-invasive and is usually the first step in the evaluation process.
- Chest CT scan: is usually performed without the use of intravenous contrast. It gives more information than x-ray images do, as it provides greater ability to view the structure of the lung. It is an important tool in diagnosing interstitial lung disease.
- Pulmonary function test: is non-invasive and uses spirometry to measure how much air you breathe in and how much you blow out. It helps to assess for conditions such as asthma, chronic obstructive lung disease (COPD), and interstitial lung disease, where results will be abnormal. It is a good idea to have this test even in the absence of any symptoms.
- Lung diffusion capacity test: part of a complete pulmonary function test, it measures certain gases to determine how much the surface area of the lung is damaged, such as in emphysema and pulmonary fibrosis.
- Six minute walk test: people with myositis may develop respiratory muscle weakness, which may lead to shortness of breath. By having the patient walk up and down a hallway for six minutes with an oximeter (measures oxygen level) attached, the doctor is able to evaluate a patient's response to exercise.
- Bronchoscopy: is a way to view the airway and to be able to extract samples for testing of infections that may be present. It is invasive and is performed under local anesthesia with light sedation.
- Blood tests: are important to test white cell counts (for people on medication that suppresses the immune system, such as prednisone). Certain results of these blood tests are more closely associated with interstitial lung disease.
- Surgical lung biopsy: this is a much less common test. This is an invasive test that is done under general anesthesia. It helps the doctor reach an accurate diagnosis when other tests are inadequate to do so.
Treatment
Treatments used for lung involvement are similar to those used to treat myositis: steroids, Rituxan (rituximab), and certain immunosuppressive medications. .
Dr. Kaner noted that how the patient is feeling is the best measure for determining whether treatment is working.
Other ways the doctor can assess response to treatment include:
- Listening to the chest with a stethoscope
- Measuring the distance of the 6-minute walk and oxygen levels - if oxygen level increases, then the patient is getting better
- Improvement in pulmonary function tests (using spirometry, how much air the individual can blow out is a good marker, as is the diffusion test)
- Repeat CT scan.
Treatment Risks and Follow-up Testing
In addressing risks involved in treatment and follow-up testing, Dr. Kaner explained that there are minimal risks in receiving X-Rays and CT scans because of exposure to radiation (more so with CT scans). Medications, such as steroids and immunosuppressives, can have their own side effects. In making these choices and decisions, it is important to weigh the possible risks of treatment against the possible benefits of treatment. These decisions are best made in collaboration with your doctor and healthcare team.
Visit us online for more information about the Myositis Support Group.
Posted: 10/19/2013
Authors
Robert J. Kaner, MD
Associate Attending Physician, NY Presbyterian Hospital
Associate Professor of Clinical Medicine, Weill Cornell Medical College
Associate Professor of Genetic Medicine, Weill Cornell Medical College
Medical Director, Ventilator Management Team, NY Presbyterian Hospital
James P. Smith, M.D. Clinical Scholar, Weill Cornell Medical College
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Summary completed by Suzan Fischbein, LCSW
Coordinator, Myositis Support Group at HSS