Minimally Invasive Thymectomy Shows Promise for Ocular MG

Minimally invasive treatment and earlier surgical consideration for thymectomy led the way as potential treatments for patients with ocular myasthenia gravis (OMG) in a new investigation, due to positive outcomes that include a higher rate of complete stable remission (CSR) and their lower perioperative neurological risk.

Writing in the Journal of Clinical Medicine, the authors noted, “The prognosis of OMG is generally favorable in patients achieving sustained symptom control with low-dose pharmacologic therapy…. However, [thymectomy’s] role in OMG remains controversial.”¹

They explained that evidence until now has been inconclusive about thymectomy’s benefits in purely ocular disease, having been extracted primarily from retrospective and heterogeneous investigations. Therefore, they conducted a multicenter, retrospective, observational study of patients living with OMG who underwent a thymectomy before and after secondary generalization. Medical records from January 2000 through January 2023 were used to gather patient data for this investigation.

Included patients needed to have a confirmed OMG diagnosis and 3 months of isolated ocular symptoms before surgery, a history of thymectomy, an R0 resection because of thymoma, and a minimum postop follow-up of 2 years. Diagnosis was confirmed via abnormal repetitive nerve stimulation, positive response to edrophonium chloride or pyridostigmine, or positive response to anti-acetylcholine receptor antibodies (anti-AChR-Ab).

Of the 174 patients, 53.4% (n = 93) were male patients, and their mean (SD) age at surgery was 42.28 (12.96). Ages at disease onset were 37.78 (13.74) years in the OMG cohort (n = 112) and 39.07 (14.63) years in the generalized OMG (g-OMG) cohort (n = 62), and at surgery, 42.99 (12.94) years and 41.05 (14.10) years, respectively. Diplopia, or double vision,² was present in 78.6% and 67.7% (P = .310), and 62.5% and 70.9% (P = .179) were positive for anti-AChR-Ab.

The most common preoperative medications by far were cholinesterase inhibitors (66.1%, OMG cohort; 77.4%, g-OMG cohort; P = .225) and corticosteroids (59.8% and 66.1%; P = .168). However, it was the least-used medication that had the greatest difference in use: azathioprine was reported by 3.6% and 16.1% (P = .015), which the authors deemed significant. Overall results for thymic histology were deemed significant, too (P = .006), with thymoma being predominant in the g-OMG cohort (37.9% vs 25.0%) and thymic hyperplasia in the OMG cohort (56.3% vs 30.6%).

“These findings may indicate distinct pathophysiological backgrounds between early and late generalization,” the study authors wrote.

Over a mean follow-up of 54.49 (29.21) months, 18.9% of participants were able to achieve CSR, but the outcome was seen in significantly more of the OMG cohort vs the g-OMG cohort, at 23.2% vs 11.3% (P = .036), and there were no postop myasthenic crises in the former compared with 5 events (8.1%; P = .004) seen in the latter.

Per Kaplan-Meier analysis, estimated 5-year CSR probability also was significantly higher in the OMG vs the OMG group (43% vs 22%; P = .017), and following multivariable analysis, the only independent predictor of overall CSR was preoperative use of cholinesterase inhibitors (HR, 31.776; 95% CI, 4.188-241.111; P = .001). Other factors considered for this were male sex, age, diplopia, presence of anti-AChR Ab, open surgery, thymoma histology, steroids before surgery, and azathioprine before surgery.

A subgroup analysis conducted among patients with nonthymomatous MG showed a higher 5-year estimated CSR in the OMG group vs the g-OMG group: 41% vs 17% (P = .010), and cholinesterase inhibitors again were the only significant predictor of CSR (HR, 19.746; 95% CI, 2.518-154.849; P = .005).

The authors noted that timing of surgery was a major outcome determinant, as the rate of CSR was more than twice as high in the OMG group as it was in the g-OMG group, and postop myasthenic crises only occurred in the patients with g-OMG, “underscoring the dual disadvantage of operating after generalization: reduced long-term remission potential and heightened perioperative neurological risk.”

Still, there are limitations to their results: its retrospective design may have introduced selection and information biases, it was not possible to control for all confounding variables, and interinstitutional heterogeneity was likely present in diagnostic work-up and perioperative management.

References

1. Nachira D, Congedo MT, Kuzmych K, et al. Thymectomy in ocular myasthenia gravis: results before and after generalization and prognostic predictors of outcomes. J Clin Med. 2025;14(21):7840. doi:10.3390/jcm14217840
2. Diplopia (double vision) University of Michigan Health. Accessed December 4, 2025. https://www.uofmhealth.org/our-care/specialties-services/diplopia-double-vision