AUTHOR=Zhao Sijia , Yan Xu , Ding Jiaqi , Ren Kaixi , Sun Shuyu , Lu Jiarui , Zhang Chao , Zhang Kai , Li Zhuyi , Guo Jun 

TITLE=Lack of Immunotherapy as the Only Predictor of Secondary Generalization in Very-Late-Onset Myasthenia Gravis With Pure Ocular Onset

JOURNAL=Frontiers in Neurology

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2022.857402

DOI=10.3389/fneur.2022.857402

ISSN=1664-2295

ABSTRACT=During the past two decades, an increasing number of very-late-onset myasthenia gravis (v-LOMG) patients with an onset age of 65 years or older have been identified. However, few studies explore the predictors of secondary generalization in v-LOMG patients with pure ocular onset. In this retrospective cohort study, 69 v-LOMG patients were divided into ocular MG (OMG) and generalized MG (GMG), and the clinical characteristics and outcomes were compared. Cox regression analysis was performed to explore predictors of generalization. The average onset age of the study population was (73.1 ± 4.2) years and the median disease duration was 48.0 months (interquartile range, 32.5−64.5 months). Serum AChR antibody was detected in up to 86% of patients and concomitant diseases in approximately half of the patients. Male predominance was seen in OMG while female predominance in GMG (P = 0.043). OMG patients showed a lower positive rate of repetitive nerve stimulation (RNS) than GMG (P = 0.014), and favorable outcomes were obtained in more OMG patients than GMG (P < 0.001). Of the 51 patients with pure ocular onset, 25 (49.0%) underwent secondary generalization. A higher probability of generalization was found in patients with positive RNS results and without immunotherapy (P = 0.018 and < 0.001). Upon Cox regression analysis, immunotherapy was negatively associated with secondary generalization (HR 0.077, 95%CI 0.024−0.247, P < 0.001). Altogether, compared to very-late-onset GMG patients, the OMG counterparts exhibit a significantly higher female predominance and a lower positive rate of RNS tests especially on facial and accessory nerves. Lack of immunotherapy is the only predictor of secondary generalization in those with pure ocular onset.