Thymus Removal Is an Effective Myasthenia Gravis Treatment, Chinese Researchers Argue

Removing the thymus is an effective way to treat people with ocular myasthenia gravis, according to an analysis of previously published data that could resolve the controversy around the treatment.

The Chinese researchers’ conclusion applied to thymectomies — or surgical removal — of thymuses that do not contain tumors.

Myasthenia gravis is eliminated in a significant percentage of patients who have thymectomies, with particularly good results for children, according to the study in Neurological Sciences.

Previous research had reported conflicting outcomes for thymectomy in patients with no thymus tumors, researchers at the First Affiliated Hospital at Sun Yat-sen University had noticed.

They decided to analyze a number of studies together to get a better idea of whether the treatment is effective. Their analysis was titled  “Thymectomy is a beneficial therapy for patients with non-thymomatous ocular myasthenia gravis: a systematic review and meta-analysis.”

Scientists consider the approach they took, a meta-analysis, the highest level of research in medicine.

Myasthenia gravis is caused by autoimmune attacks on the connection between nerves and muscles. It  been linked to abnormal processes in the thymus, an organ in the chest where several types of immune cells mature.

Up to 70 percent of patients with myasthenia gravis have an enlarged thymus, and a tumor called a thymoma is found in about 10 percent.

The team’s review covered 26 articles on thymectomy involving a combined 640 patients.

About half the patients with no tumor achieved complete remission with the operation. The Chinese team noted that remission rates varied widely among studies, particularly those in their homeland.

Remission rates appeared to be better in children than adults, but results also varied more in children. Asians had somewhat lower remission rates than Europeans, Americans, and Pacific Islanders.

Researchers found evidence that the analyzed data may have been subject to publication bias, however. This occurs when researchers, for instance, publish only positive findings and leave out negative findings.

Because the risks and costs of surgery are higher than with other treatments for ocular myasthenia gravis, the team argued that more studies — particularly randomized clinical trials — should be done to verify their findings.