What is Thymectomy?
What is Myasthenia Gravis?
Myasthenia gravis is an autoimmune disorder in which the body’s own immune system attacks and weakens the muscles. The common symptoms of MG are:
- Weakness of the eye muscles (ocular myasthenia)
- Drooping of one or both eyelids (ptosis)
- Blurred or double vision (diplopia)
- Changes in facial expressions
- Difficulty swallowing
- Shortness of breath
- Impaired speech (dysarthria)
- Weakness in the arms, hands, fingers, legs, and neck
There are two different forms of MG:
- Occular MG: In Occular MG as the name suggests the weakness is limited to only the eyelids and muscles of the eyes (extra-occular muscles)
- Generalised MG: In Generalised MG, the weakness involves many muscle groups other than the eyes. There can be involvement of the bulbar system, extremities and breathing or respiratory muscles.
The weakness in MG usually fluctuates throughout the day. The weakness tends to be the least in the morning after waking up and is more severe by the end of the day after prolonged usage of the involved muscle groups.
It is a progressive disease in most cases marked by some time periods of remission and relapse. Less than 1/4th of MG patients will also experience a Myasthenic crisis along with severe respiratory failure.
Benefits of Thymectomy in Treating Myasthenia Gravis
The goals of thymectomy treatment can be different for different patients. These may include:
- Reduce symptoms including weakness
- Reduce the use of medicines (dose &/or number)
- Permanent remission of the disease
One of the biggest benefits of thymectomy in treating myasthenia gravis is the potential to reduce symptoms and improve quality of life. Studies have shown that thymectomy can improve muscle strength, reduce fatigue, and improve breathing in MG patients. Thymectomy has also been shown to reduce the number of relapses and the need for medication. In some cases, thymectomy can even lead to a complete remission of MG symptoms.
Types of Thymectomy Surgery
The goal of thymectomy is to remove as much as thymic tissue possible from the standard as well as ectopic sites of thymus. This can be achieved by many different approaches. The different types of thymectomy surgery that can be used to treat MG are as follows:
- Open thymectomy: is the way thymectomy used to be done conventionally. It is also known as the “trans-sternal” approach. This involves making an incision in the front of the chest via the breast bone to access the thymus
- Video-assisted thoracoscopic surgery (VATS) thymectomy: uses tiny cameras and surgical instruments to access the thymus through small incisions in the chest. These days it is the most common approach used for removing the thymus
- Robot-assisted thoracoscopic surgery (RATS) thymectomy: is a newer technique that uses a robotic system to access the thymus. This is also a minimally invasive means of performing a thymectomy
Who is a Good Candidate for Thymectomy in Myasthenia Gravis ?
The best candidates for thymectomy are:
- Patients less than 60 years of age
- Patients with mild form of Generalised MG with AChR antibodies-positive, who have not responded to other treatments
- Patients with mild weakness with involvement of breathing and swallowing muscles
- Any patient with a Thymoma along with MG
Plasmapheresis or intravenous immunoglobulin is recommended before thymectomy in patients with preoperative respiratory or bulbar symptoms
Timing of Thymectomy in Myasthenia Gravis
Although each case should be assessed individually to find the best timing for surgery for that particular patient, there are certain rules which help in having a better outcome:
- MG patients with Thymoma should be immediately evaluated for Thymectomy
- It is best to operate when the symptoms are well controlled with medicines, and there is minimal respiratory compromise
- The best outcomes have been seen in early phase of the disease usually with in the first 3 years of onset of the disease
- The dose of Steroids (Glucocorticoids) should be ideally brought to lowest possible levels before surgery so as to have minimal post surgery infections and less wound complications
Risks of Thymectomy
Thymectomy carries some risks. These patients are not great candidates for general anaesthesia because of respiratory function impairment.
The other risks are:
- Injury to phrenic nerve or recurrent laryngeal nerve
Alternatives to Thymectomy in Myasthenia Gravis
Apart from thymectomy there are three more options for treatment of Myasthenia Gravis.
- AntiCholinesterase Agents: Pyridostigmine (Mestinon) is one the most commonly used drug for treating MG
- Immunosuppressive Agents: Like Azathioprine (Imuran), Corticosteroids and Cyclosporine
- Plasma exchange and rapid immunomodulating treatments with intravenous immunoglobulins: They are used in situations where quick recovery is needed like for preparation for surgery and during a myasthenic crisis
Thymectomy is a surgical procedure that involves the removal of the thymus gland and can be an effective treatment for Myasthenia Gravis. It can reduce symptoms, improve quality of life, and reduce the need for medication. Thymectomy carries some risks, and it is not the right treatment for everyone. It is important to discuss all of your treatment options with your doctor before deciding if thymectomy is right for you.