Myasthenia Gravis is a disease which affects neuromuscular transmission resulting in debilitating weakness of the voluntary muscle structure. At this time researchers believe that the thymus gland plays a key role in this disease. The thymus gland is known to play a role in the development of the immune system as an individual ages and because the vast majority of patients with myasthenia gravis suffer from the type which is immune mediated researchers theorize and believe that the thymus gland plays an integral role.
The basic biochemical problem in patients with myasthenia gravis involves the block of muscle receptors by antibodies formed by her own immune system. The damage to the receptors in the muscles and the impaired neuromuscular transmission is what leads to the symptoms of weakness and fatigue. The muscle receptors are acetylcholine which has led to the popularity of using anti-cholinesterase medications to decrease the symptoms.
Currently physicians are also recommending a thymectomy, or removal of the thymus gland, for patients who have generalized symptoms. At this time the rate of success reported for patients who have received a thymectomy varies from study to study. In some reports approximately 80 percent of patients have verbalized a benefit and potentially remission from their myasthenia gravis symptoms following a thymectomy. Some patients also report that the benefits they do receive are not noticeable for months following the resection.
In another study reported in the Annals of Surgery in 1987 researchers found that a thymectomy in patients who had milder disease and no concurrent growth on the thymus gland reached remission more frequently even when compared with those patients who had ocular myasthenia treated without surgery. Another factor associated with early remission was a shorter duration of the disease prior to the surgery. This study demonstrated that morbidity and mortality for patients with significantly independent of the surgical removal of the thymus and more dependent upon the severity of the symptoms, age, associated growth on the thymus and failure to remove the thymus. (1)
There are two surgical options for removal of the thymus gland. The first is an open sternotomy and the second is a laparoscopy. Research done at Mayo Clinic between 1982 and 1985 indicated that operative mortality for an open sternotomy was 3.1 percent and complications were approximately 39 percent but more frequent in patients who also had cardiovascular disease. The mean length of stay at the hospital was 7.4 days. When available, the laparoscopic surgical removal results in lower hospitalization days and a lower rate of complications. Mortality rates appear to be approximately the same as they were related more to the anesthesia and to the surgical procedure itself.
In a report from the Department of Cardio Thoracic Surgery at the University of California, Los Angeles, researchers looked at 249 patients who had a thymectomy for myasthenia gravis between 1954 and 1981 as well as another 84 patients treated between 1982 and 1987. Follow-up was done on these patients approximately 3 1/2 years following surgery and found that approximately 80 percent benefited from the surgery with remission in approximately 36 percent. The surgeons noted hyperplasia in 38 of the patients but was associated with a higher rate of remission (53 percent) in contrast to the 35 patients whose glands were normal or atrophic. Remission rates for the over all groups ranged between 6 and 9.9 percent. (2)
The use of a thymectomy in the treatment of myasthenia gravis should be an integral consideration by both the physician and the patient to increase chances of a remission. As in most illnesses and diseases early diagnosis and treatment considerations will increase the success rate of the treatment protocols and decrease problems associated with the disease.
(1) Annals of Surgery: Effectso of Thymectomy in Myasthenia Gravis
(2) Annal of Thoracic Surgery: Thymectomy of Myasthenia Gravis
Myasthenia Gravis Foundation of America: Thymectomy
University of Maryland Medical Center: Myasthenia Gravis Center
Thorax: Thymectomy for Myasthenia Gravis