Myasthenia gravis is an autoimmune disorder in which muscle fatigue results from impaired transmission. Multiple clinical symptoms are associated with this disorder, affecting any muscle that is under voluntary control. Muscles that are more frequently involved include those that control eye movements, eyelids, chewing, swallowing, coughing and facial expression. Muscles that control breathing and movements of the arms and legs may also be affected. Weakness of the muscles needed for breathing may cause shortness of breath and difficulty taking a deep breath or coughing. This disorder is characterized by periods of worsening and periods of improvement.
Myasthenia gravis may be associated with various abnormalities of the thymus gland. The thymus gland lies behind the breastbone and is an important part of the immune system in infancy and early childhood. The relationship between the thymus gland and myasthenia gravis has led to the medical recommendation that the gland be removed (thymectomy). About 10 percent of myasthenia gravis patients have a tumor of the gland (thymoma) and are treated with surgical removal, or thymectomy, as well. Since the 1940's, myasthenia gravis has been treated by thymectomy with most patients showing some improvement after 6 months to 1 year following surgery.
The degree of improvement after surgery is not predictable, but can be significant. Myasthenia gravis patients who experience more than minimal symptoms should consider thymectomy for treatment. Those patients who experience only minimal symptoms probably do not need thymectomy.
The history of thymectomy dates back to 1901 when a thymoma in a patient with myasthenia gravis was described and the association between the thymus gland and myasthenia gravis was first suggested. In 1913, Schumaker and Roth described the fist thymectomy performed 2 years earlier, in 1911, by Sauerbruch.
The exact mechanism by which thymectomy improves the symptoms of myasthenia gravis is not completely understood. Nevertheless, myasthenia gravis patients who undergo thymectomy do experience fewer exacerbations ("flare-ups"), have milder symptoms, require lower medication doses and have a higher chance of complete remission.
Various types of thymectomy procedures are performed at the University of Maryland Medical Center, a world-renowned teaching institution at the forefront of medical education and research.
Thymectomy can be performed using several surgical approaches. Your surgeon will determine the optimal surgical procedure for you, based upon your general health status, physical build and the absence of or presence of a thymoma.
An incision is made down the middle of the chest through the sternum in order to expose the thymus gland. Once the entire thymus gland is removed, the sternum is repaired with sternal wire and the incision is closed with dissolving sutures. This most invasive technique allows for maximum visualization in situations of suspected thymoma. For this surgery, a chest tube is required for a few days and will be removed before you go home.
A smaller incision is made down the middle of the chest through only half of the sternum is separated in order to expose the thymus gland. Once the thymus is removed, the sternum is repaired and the skin is closed with dissolving sutures. This more limited incision is more cosmetic and may be associated with shorter recuperation time than full sternotomy. For this surgery, a chest tube may be required for a few days and will be removed before you go home.
This approach is less invasive than the sternotomy. With the thoracoscopic technique, the surgeon makes 2 to 3 small incisions (3/4 inch in length) on the side of the chest. A small telescope and dissecting instruments are inserted through the holes. The thymus gland is visualized and removed. For this surgery a chest tube is required for a couple of days and will be removed before you go home. Due to the location and the small size of the incisions, this is the most cosmetic approach for thymectomy.
The transcervical approach to thymectomy is the least invasive method. A small horizontal incision is made across the lower part of the neck. The thymus gland is visualized with a scope, which is placed under the sternum. The surgeon works with the scope and small instruments to carefully remove the entire thymus gland. A very small drain is left in the incision for up to 24-36 hours. This technique is associated with the least postoperative pain and has the shortest recovery period; however, it may not be ideal for every patient. Your surgeon will discuss with you whether or not you are a candidate for a transcervical thymectomy.
The timing of when to have a thymectomy depends upon the patient's symptoms and the recommendation of their neurologist. This timing should be coordinated between the patient and all of the physicians involved in their care. The patient should be in the best possible condition for surgery. The patient's myasthenia gravis symptoms should be well controlled with the lowest dose of medication necessary to decrease the chance of a "flare-up" around the time of surgery. The patient should be as physically active as possible and should stop smoking. The myasthenia gravis patient should be as close to his/her ideal weight as possible. Here, obesity can increase surgical risk and may limit the ability to perform a less invasive surgical approach.
While our thoracic surgeons are very familiar with the management of myasthenia gravis, the myasthenia gravis patient will benefit from expert management by neurologists who have special expertise in caring for patients with myasthenia gravis.
If necessary, available treatments include intravenous immune globulin (IVIG) and plasmapheresis, which can be utilized both before and after the surgery as determined by the neurologist. The neurologist who will be caring for the patient during the hospital stay will communicate with the patient's community neurologist and will keep them informed of their progress during the hospital stay so that they will be prepared to take care of the patient again once they have recovered from thymectomy.
The number of days in the hospital will vary with each patient, surgeon and surgical approach. In most cases, the patient is ready for discharge from the hospital in 1-3 days. Discharge from the hospital may be delayed in the event of a "flare-up" of myasthenia symptoms.
Regardless of the approach used, the surgeon will remove the entire thymus gland and send it for analysis. The pathologist will inspect the tissue for thymoma and other abnormal cells. The final pathology report is usually ready in 10-14 days. The surgeon will notify the patient of the results at the surgical follow-up appointment, usually 2-4 weeks after discharge.
The recovery period or time away from work or school varies with the specific surgical approach used and the type of work or activity the patient does regularly. Recuperation from a full sternotomy approach may require up to 3 months off from work. This time period is significantly shorter with less invasive surgical approaches and may be as little as 1-2 weeks with the transcervical thymectomy approach.
It is especially important that patients ensure that their myasthenia gravis symptoms are well controlled in the postoperative period while they are recovering from surgery. The neurologist will be very involved in adjusting the medication dosages for optimum control of symptoms.
Most patients will notice improvement in their myasthenia gravis symptoms after surgery but may still have flare-ups occasionally, although these flare-ups are likely to be milder than they would be without thymectomy. It may take up to 6 to 12 months for patients to notice significant improvement in their symptoms.
The timing of returning to work or school and resuming driving privileges will be decided by both the neurologist and the surgeon. This usually occurs once the patient is well healed from the surgery and their myasthenia gravis is under control.
If you need additional information or would like to schedule a consultation in our clinic, please contact us at 410-328-6366.