Thymectomy

The thymus is a soft gland in the upper front part of the chest, in the space between the lungs called the anterior mediastinum. It is important for training the immune system in childhood and gradually shrinks and turns largely to fat in adults, so removing it in adulthood does not cause a noticeable loss of immune function. In many people with myasthenia gravis the thymus is abnormal and is thought to help drive the immune reaction that blocks signals between nerves and muscles. Tumours can also arise from the thymus: thymomas are usually slow-growing, while thymic carcinomas are rarer and more aggressive. Thymectomy removes the whole gland together with the fatty tissue around it, where small islands of thymic tissue can hide, an approach often called extended thymectomy. For a tumour, the aim is complete removal with a margin of healthy tissue, sometimes including part of a nearby structure if the tumour is attached to it.

For myasthenia gravis, thymectomy is mainly recommended for adults with generalised disease, meaning weakness beyond the eye muscles, who have antibodies against the acetylcholine receptor. Clinical trials have shown that in this group, adding thymectomy to medical treatment improves muscle strength and reduces the need for steroids and other immune-suppressing medicines over the following years. It is usually done when the condition is stable, often within the first years after diagnosis, and its role in people without these antibodies, in children and in older adults is decided case by case by a neurologist and a surgeon together. For a thymoma or other mass in the front of the chest, surgery is the main treatment when the tumour can be removed completely, and every thymoma is an indication for removal whether or not myasthenia is present. Some large tumours are first shrunk with chemotherapy or radiotherapy.

Thymectomy is done under general anaesthesia. In the keyhole approach, VATS or robotic, the surgeon makes three or four small cuts in the side of the chest, or sometimes below the breastbone, and uses a camera and fine instruments to free the thymus and the surrounding fat from the heart covering, the large veins and the lung, taking care to protect the phrenic nerves that control the diaphragm. In sternotomy, the breastbone is divided down the middle, which gives wide access for large or invasive tumours, and it is wired together again at the end. The gland is removed in a bag, and a small drain is usually left in the chest for a day or two. The operation commonly takes about 2 to 3 hours. For myasthenia gravis, the anaesthetic team plans carefully for muscle weakness, using medicines that do not interfere with nerve and muscle signals.

Preparation depends on the reason for surgery. For myasthenia gravis, the most important step is to have the condition well controlled before the operation, because surgery and anaesthesia can trigger a worsening of weakness. Your neurologist may adjust your medicines, and some people receive a course of intravenous immunoglobulin or plasma exchange beforehand to strengthen the muscles of breathing and swallowing. Breathing tests check the strength of the breathing muscles. For a mass, a CT or MRI scan of the chest shows its size and relation to nearby structures, and blood tests for myasthenia antibodies are usually done even without symptoms. Fasting, blood tests, a heart check and adjustment of other medicines follow the usual surgical routine. International patients should share their neurologist's notes, medicine list and scans in advance, so the neurology and surgical teams can plan the timing together.

After keyhole thymectomy you are encouraged to walk on the first day, the drain is usually removed after a day or two and most people go home after one to three nights; after sternotomy the stay is longer, usually about four to seven nights. People with myasthenia are watched closely for any increase in weakness, especially of breathing and swallowing, and continue their usual medicines. Pain is generally moderate after keyhole surgery and more marked after sternotomy, which needs about six to eight weeks for the breastbone to heal before heavy lifting or driving. Flying is usually possible about one to two weeks after keyhole surgery and after a longer interval following sternotomy, once your surgeon agrees. Long-term care of myasthenia continues with your own neurologist, who will usually reduce medicines gradually as the benefit of surgery appears over the following months and years.

Thymectomy is a well-established operation, and keyhole approaches generally mean less pain and a faster recovery than sternotomy. Possible complications include bleeding, infection, a collapsed lung or fluid around the lung, and injury to a phrenic nerve, which can weaken half of the diaphragm and cause breathlessness. In myasthenia gravis there is a risk of a myasthenic crisis around the time of surgery, a severe worsening of weakness that may need breathing support; careful preparation makes this uncommon. After sternotomy, wound or breastbone healing problems can occur. Results need honest expectations: in myasthenia, improvement is gradual, often becoming clear only after one to several years, and many people still need some medicine, although usually less. For a thymoma, complete removal is the key to good long-term results, and the tissue report decides whether radiotherapy and long-term scan follow-up are needed.