What is Shrinking Lung Syndrome?
Shrinking lung syndrome (SLS) is a uncommon problem that can happen in people suffering from diseases where the body’s immune system attacks its own tissues. These diseases usually include ones like systemic lupus erythematosus (disease in which the body’s immune system mistakenly attacks healthy tissue), and it can also happen, but less commonly, in diseases like systemic sclerosis (skin hardening), Sjogren’s syndrome (immune system disorder causing dry eyes and mouth), and rheumatoid arthritis (a long-term autoimmune disorder that primarily affects joints).
This condition should be considered if a patient with any of the aforementioned autoimmune diseases experiences difficulty in breathing when exercising or has chest pain that worsens when you breathe deeply or cough. This can be identified via medical imaging, which may show one or both sides of the diaphragm (muscle involved in breathing) elevated or risen than normal.
People with SLS usually have decreased lung size and face troubles in lung function. It is important to confirm its diagnosis by ruling out other potential illnesses, so other tests like a chest CT scan, which provides detailed images of structures within the chest, are often performed to rule out other possible causes.
What Causes Shrinking Lung Syndrome?
Shrinking lung syndrome is a condition that often happens in conjunction with certain diseases where the body’s immune system attacks its own tissues, most typically in systemic lupus erythematosus and less frequently in Sjogren’s syndrome, scleroderma, and rheumatoid arthritis.
There are different theories as to why this happens, including inflammation of the membranes of the lungs, dysfunction or damage of the main muscle involved in breathing (diaphragm), damage to the nerves that control the diaphragm, fibrous tissue bands (pleural adhesions) formed inside the chest cavity, or muscle diseases (myopathy). However, the exact way in which shrinking lung syndrome occurs isn’t fully understood yet.
Risk Factors and Frequency for Shrinking Lung Syndrome
Shrinking lung syndrome, or SLS, is most often seen in individuals with lupus, a type of autoimmune disease. The exact amount of people with lupus who also develop SLS is not perfectly clear, but it’s thought to be between 0.5% and 1.53%. It can happen at any time during the course of the disease.
Lupus itself tends to affect women more than men, with about 9 women for every 1 man being diagnosed. SLS follows a similar pattern within the lupus community, but the ratio of affected women to men varies between 6:1 and 17:1. Typically, the diagnosis of SLS is made when a person is around 36 years old.
Signs and Symptoms of Shrinking Lung Syndrome
Shrinking lung syndrome is a condition often suspected in patients who have difficulty breathing, sometimes accompanied by sharp chest pains, and have a history of autoimmune diseases like Systemic Lupus Erythematosus (SLE). Less common symptoms include coughing and difficulty breathing while lying down, thought to be caused by weakness in the diaphragm. Some patients may also have experienced past episodes of inflammation of the lungs’ outer lining. Other symptoms related to lupus, like joint pain, skin rashes, hair loss, and kidney inflammation, can also be present.
Physical examination may reveal decreased chest expansion and, less commonly, small, sharp, bursting sounds during inhalation. Breathing may be fast and shallow. About half of all patients have active disease outside the chest at the time of diagnosis. In some instances, shrinking lung syndrome may be the first sign of Systemic Lupus Erythematosus.
- Difficulty breathing
- Sharp chest pains
- History of autoimmune diseases like SLE
- Coughing (less common)
- Difficulty breathing while lying down (less common)
- Previous episodes of lung inflammation
- Joint pain, skin rashes, hair loss, and kidney inflammation related to lupus
- Decreased chest expansion
- Fast and shallow breathing
Testing for Shrinking Lung Syndrome
Shrinking lung syndrome is a condition that can cause difficulty in breathing and chest pain in patients with the autoimmune disease Systemic Lupus Erythematosus (SLE), or lupus. To diagnose it, doctors must first rule out other potential causes for these symptoms.
Your doctor may perform a variety of tests and studies including laboratory tests, imaging studies and lung function tests, to nail down the cause of your symptoms.
Commonly, blood tests might be the first step. By looking at the white cell count, they can check for infections. High levels of an inflammation marker called C-reactive protein (CRP) or increased Erythrocyte Sedimentation Rate (ESR) hint that your lupus might be currently active. Normal renal (kidney) function and Creatine Kinase levels (a muscle enzyme) are typically expected unless there are more complications with your lupus.
If it’s not already known that you have an autoimmune disease, your doctor may consider a full autoimmune profile that includes checking for antibodies related to rheumatism and scleroderma (another autoimmune disease). Occasionally, your body may have started reacting to itself, but an autoimmune disease has not been fully formed yet.
Testing your arterial blood gases (how well your lungs move oxygen into your blood and remove carbon dioxide) can show a variety of results. In some patients, the result is normal, while others show lower oxygen levels, which worsen during physical activity.
Imaging studies including chest X-rays and CT scans can also be important in the evaluation. In shrinking lung syndrome, X-rays often show an upward shift of the diaphragm, the muscle that aids in breathing. Reduced lung volumes are also common. CT scans help rule out other lung abnormalities and diseases like interstitial lung disease and blood clots (pulmonary emboli) in the lungs.
In some instances, an ultrasound to assess diaphragm movement may be requested. But, it’s not always conclusive. Interestingly, one study noted that many SLE patients with shrinking lung syndrome have approximately normal diaphragm movement, indicating such movement can’t always rule out the disease.
Lastly, lung function tests commonly show a restrictive deficit in shrinking lung syndrome, which means the lungs are unable to fully expand with air. Other findings may include reduced total lung capacity (TLC), lower ability to transfer carbon monoxide (DLCO), and reduced lung volumes. Some patients may also show decreased strength of their respiratory muscles.
Remember, these tests are performed to provide your doctor with a clearer picture of what’s going on in your body, and to ensure you get the correct diagnosis and treatment.
Treatment Options for Shrinking Lung Syndrome
There aren’t any specific guidelines on how to treat a condition known as shrinking lung syndrome. However, doctors typically prescribe medicines known as corticosteroids to treat this condition. These medications can help to reduce inflammation in the body. Depending on how severe the condition is, some patients might initially receive the medication through an intravenous (IV) line.
Other supplemental treatments can include inhaled medications to help open up the airways, medication to control pain, and physical therapy designed to improve breathing. Sometimes the corticosteroids alone can successfully treat the condition, but occasionally other treatments are needed.
In cases where the condition doesn’t improve with the use of corticosteroids, a medication called rituximab has shown promising results. Other types of medications that suppress the immune system, like cyclophosphamide, azathioprine, mycophenolate mofetil, and methotrexate, generally haven’t been successful when corticosteroid treatment has failed. However, one of these, named azathioprine, can sometimes be useful in reducing the amount of corticosteroids needed.
What else can Shrinking Lung Syndrome be?
Shrinking lung syndrome is a condition that’s identified only after ruling out other diseases. It can cause shortness of breath or chest pain. That means before a doctor decides that someone has shrinking lung syndrome, they need to make sure the person doesn’t have other illnesses that cause similar symptoms. These other illnesses can include:
- Pneumonia
- Viral or bacterial pleurisy (inflammation of the tissues that line the lungs and chest cavity)
- Pericarditis (inflammation of the tissue around the heart)
- Pulmonary embolism (a blood clot in the lungs)
- Interstitial lung disease (a group of diseases that cause inflammation and scarring of the lung tissue)
- Chronic obstructive pulmonary disease (a type of obstructive lung disease characterized by long-term breathing problems)
- Heart failure
- Pulmonary hypertension (high blood pressure in the arteries to the lungs)
- Musculoskeletal chest wall disorders
- Anxiety
If the doctor finds that one half of the diaphragm (the muscle that helps us breathe) is raised, which is a common sign in shrinking lung syndrome, they must still rule out other causes. These other causes can include:
- Pulmonary atelectasis (collapsed lung)
- Pulmonary hypoplasia (underdeveloped lungs)
- Prior lobectomy (surgical removal of a lobe of an organ)
- Prior pneumonectomy (surgical removal of a lung)
- Phrenic nerve palsy (paralysis of the diaphragm)
- Contralateral stroke (a stroke that affects the opposite side of the body)
- Subphrenic abscess (a pocket of pus below the diaphragm)
- Distended stomach or colon
- Abdominal tumors
Last of all, the doctor needs to rule out other conditions that cause restrictive lung deficit, which means the lungs can’t fully expand with air. This could include conditions like:
- Pulmonary fibrosis (a lung disease that occurs when lung tissue becomes damaged and scarred)
- Large pleural effusions (buildup of fluid between the tissues that line the lungs and the chest)
- Kyphoscoliosis (a deformity of the spine characterized by abnormal curvature)
- Morbid obesity
- Neuromuscular disorders like motor neuron disease and myasthenia gravis (a weakness and rapid fatigue of muscles under voluntary control)
What to expect with Shrinking Lung Syndrome
Shrinking lung syndrome, for the most part, has a positive outlook. When patients receive suitable treatment geared towards suppressing their immune system, many see improvements. It is common for patients to feel better, suggesting the treatment is working.
Typically, most patients have stable or improved lung function based on medical testing. However, improvements seen via x-rays or other imaging techniques are less common. In one study, 57% of cases showed visible improvements.
It’s important to note that a complete recovery – meaning the patient is symptom-free, lung function is back to normal, and there are no remaining signs of the disease on radiographic images – is rare. Still, many people see at least some degree of improvement.
Possible Complications When Diagnosed with Shrinking Lung Syndrome
If shrinking lung syndrome is not treated, it can lead to severe complications. This includes severe breathlessness and, in some rare cases, it can also lead to respiratory failure, where your body is unable to breathe properly.
- Severe breathlessness
- Respiratory failure (rare)
Preventing Shrinking Lung Syndrome
Shrinking lung syndrome is a rare problem that sometimes happens in people with systemic autoimmune conditions, most commonly one known as SLE. People with this condition may find it harder to breathe when they’re active, and they might also have chest pain that feels similar to a bad stitch. Although it’s quite rare and only affects about 1% of people with SLE, it can happen at any time during the disease.
When a doctor sees a raised hemidiaphragm (the muscle that helps you breathe) in an X-ray and notices that your lungs aren’t working as well as they should be, and there’s no other reason for it, shrinking lung syndrome might be suspected. The usual first step in treatment is a type of medication called corticosteroids. If these don’t work well enough, stronger medications which modify the disease or are biological drugs might be used. The good news is most patients see an improvement with treatment.