The thymus gland plays a major role in the development of the body’s immune system. Its job is to train immature T-cells to develop into mature T-cells which are then are circulated in the body to help activate the immune system’s B-cells to fight infections. The thymus gland enlarges throughout childhood and starts shrinking during puberty. By the time adulthood is reached, the thymus gland’s function is no longer needed. Removal of the thymus in adulthood does not affect the immune system thereafter.

A thymectomy is recommended for patients under the age of 60 with moderate to severe MYASTHENIA GRAVIS weakness. It is sometimes recommended for patients with relatively mild weakness, especially if there is weakness of the respiratory (breathing) or oropharyngeal (swallowing) muscles. A thymectomy is usually not recommended for patients with weakness limited to the eye muscles (ocular myasthenia gravis).

About 10% of MG patients have a tumor of the thymus called a thymoma. Most of these tumors are benign and tend to grow very slowly, however occasionally, a tumor is malignant (cancerous).

Thymectomy improves the patient’s weakness, reduction in the medications being employed, and ideally a permanent remission (complete elimination of all weakness and off all medications). A thymectomy is usually not used to treat active disease but rather it is believed to improve long-term outcome. Results may not be seen for one to two years or more after the thymectomy.