Surgical removal of the thymus before the development of generalized myasthenia gravis is associated with higher remission rates in people with ocular myasthenia gravis (OMG) compared with patients who underwent the surgery after their disease generalized, a new study suggests.
The study, titled “Thymectomy in ocular myasthenia gravis before generalization results in a higher remission rate,” was published in the European Journal of Cardio-Thoracic Surgery.
OMG is myasthenia gravis that affects only the muscles that control the eye and eyelid. For about 60% of people with OMG, the condition eventually progresses to generalized MG, affecting different parts of the body.
Thymectomy — surgery to remove the thymus — has been shown to significantly improve MG symptoms. Waiting until OMG has progressed to the more severe, generalized form of MG before performing surgery would seem logical since surgery is an invasive procedure. However, postponing surgery may carry its own risks.
In the study, researchers set out to investigate the outcomes of patients with OMG who underwent thymectomy before generalization with the outcomes of those who had the surgery after their disease generalized.
They reviewed medical records of OMG patients who underwent thymectomy at Charité University Hospital Berlin in Germany. Two groups were created: one group included people with OMG who underwent thymectomy before their disorder progressed to generalization, and the other group who received the surgery after generalization.
Both groups (165 people in each) were similar in terms of age at disease onset (average of 41 years), sex (about two-thirds female), and clinical characteristics, including the presence of detectable autoantibodies and tissue-level abnormalities in the thymus. After excluding possible bias, a total of 130 patients were included in further analyses (65 patients in each group).
The researchers compared the percentage of people who achieved complete stable remission — no MG symptoms and no MG-related treatment for at least a year — in both groups. Those who received surgery prior to generalization had a significantly higher rate of complete remission (50.8% vs. 27.7% in the group who underwent surgery after generalization).
Additional statistical modeling further suggested that thymectomy prior to generalization was associated with a significantly higher likelihood of achieving complete remission at five years (49.5%) than surgery after generalization (33.4%). Complete remission was also significantly associated with a younger age at onset (40 years or younger) and with the thymus being enlarged.
“Our results suggest that thymectomy before generalization of OMG is likely to result in a higher rate of [complete remission] than thymectomy after generalization of OMG. Hence, thymectomy may be a first-choice treatment for patients with OMG,” the researchers said.