A thymectomy is a surgical procedure to remove the thymus gland. It’s a common treatment for myasthenia gravis (MG), particularly when a thymoma, a tumors of the thymus gland, has been identified. Here’s what patients with MG should know about thymus removal.
What is the role of the thymus?
The thymus is a small gland that is part of the lymphatic system (which is itself part of the immune system) and the endocrine system (which makes and releases hormones). It is located at the top of the chest, behind the breastbone and in front of and above the heart.
The thymus is where the body trains a type of white blood cell called T lymphocytes. As they mature in the thymus these cells learn to identify and fight infections — and not to attack the body’s own cells, which can lead to autoimmune disorders like MG.
The thymus is the most active in childhood, and usually shrinks in size after puberty.
Why does the thymus cause problems in MG?
People with MG often have problems with their thymus, but scientists don’t yet know the exact reason why.
Around 65% to 70% of people with AChR antibody-positive MG have inflammation of the thymus gland, and another 15% to 20% have thymomas.
In people with MG, the thymus may contribute to the production of acetylcholine receptor antibodies that target proteins on muscle cells, progressively causing muscle weakness and fatigue.
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When is a thymectomy recommended in MG?
By reducing abnormal immune activity, removing the thymus has been shown to improve muscle strength, reduce disease severity and lower a patient’s need for immunosuppressive medication.
The surgery is usually recommended for patients with a thymoma. It is also often recommended for patients who are positive for acetylcholine receptor (AChR) antibodies, have symptoms that are moderate to severe and are below 50 years old. But a thymectomy isn’t the best treatment for everyone with MG: for example, it’s not usually suggested for patients with antibodies to muscle-specific kinase (MuSK).
The benefits of a thymectomy can take months to become evident. However, within the first year following surgery, 70% of people have a reduction in symptoms and medication, and 30% to 40% of patients report full remission of their symptoms. Early-stage cases of MG tend to to have a better response to thymectomy.
What does a thymectomy involve?
Before the procedure, you will need to have blood and urine tests, as well as imaging, to accurately measure the size and location of the thymoma. Your healthcare team will wait for you to be in good health before you can get surgery.
There are two different surgical methods for removing the thymus:
- Traditional surgery, where an incision is made in the sternum and the breastbone is split open to gain access to the thymus.
- Newer minimally invasive techniques that require only small incisions, such as video-assisted thoracoscopic surgery (VATS) and robotic-assisted thymectomy. Minimally invasive procedures are favored as they reduce blood loss, recovery time, hospital stay and the risk of complications.
In both cases, a thymectomy requires a short stay in hospital. Depending on the procedure and your individual situation, it may be one to three nights, or it could be longer.
Recovery can take one to two weeks or as long as three months, depending on your MG and overall health, and is likely to include chest pain, swelling and localized pain at the incision sites. MG symptoms often temporarily worsen during this time.
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