A differentiated approach to thymectomy in generalized form of myasthenia gravis

Objective. To identify clinical and morphological factors associated with favorable neurological outcomes after extended thymectomy in patients with generalized myasthenia gravis. Material and methods. A single-center retrospective study with prospective component included 103 patients with generalized myasthenia gravis who underwent extended thymectomy in 2009–2021. The primary endpoint was improvement in the Myasthenia Gravis Foundation of America (MGFA) Postintervention Status classification: sustained remission, pharmacological remission, or minimal manifestations. Potential predictors included thymus morphology, thymoma, period between manifestation and surgery, immunopathogenetic variant of myasthenia, preoperative QMG score, age, gender and characteristics of disease onset. Results. Improvement was achieved in 73 out of 103 patients (70.9%) after 3 years. Favorable outcome was more common in thymic hyperplasia compared to thymic involution (75.5% vs 66.0%), in patients without thymoma than in those with thymoma (73.3% vs 53.8%), as well as in case of surgery within 2 years after manifestation (76.7% vs 62.8%). Preoperative QMG cutoff of 26.5 identified patients with higher risk of no improvement (odds ratio 4.0; 95% CI 1.64–10.08; p = 0.02). Thymectomy efficacy was 74.5% in AChR-positive, 54.0% in MuSK-positive, and 33.0% in seronegative myasthenia gravis. Postoperative complications occurred in 4 patients (3.8%), conversion was required in 3 patients (2.9%), and no deaths or postoperative myasthenic crises were recorded. Conclusion. Preoperative stratification before thymectomy in generalized myasthenia gravis should integrate QMG score, disease time, thymoma status, and thymic morphology. QMG combined with clinical and morphological variables may be useful for predicting the expected benefit of surgery and for patient counseling.