Clinical characteristics and therapeutic effect of myasthenia gravis coexisting with thyroid eye disease

Introduction Here, we describe the clinical characteristics and therapeutic effects of myasthenia gravis (MG) coexisting with thyroid eye disease (TED). Methods We collated clinical data from MG patients in our hospital between 2012 and 2022 and analyzed the clinical characteristics of MG patients with hyperthyroidism, MG patients with TED and ocular myasthenia gravis (OMG) patients with TED. Results We recruited 62 MG patients with hyperthyroidism, including 13 MG patients with TED and 10 OMG patients with TED. There were 70 MG patients without hyperthyroidism; 29 of these were OMG. Compared with patients without hyperthyroidism, patients with hyperthyroidism had an earlier age at onset and milder clinical symptoms (P < 0.05). The incidence of thymus hyperplasia in patients with hyperthyroidism and TED was significantly lower than that in patients without TED (38.5% vs. 69.4%, P < 0.05); these patients also had a significantly lower antibody titer for the acetylcholine receptor [0.72 (0.27, 14.93) nmol/L vs. 2.38 (0.28, 49.51) nmol/L, P < 0.05]. Diplopia was significantly more frequent in OMG patients with TED than in patients with OMG (84.6% vs. 44.8%, P < 0.05), and the rate of diplopia in OMG patients with TED was significantly higher after treatment with bromostigmine and glucocorticoid (69.2% vs. 3.4%, P < 0.05). Conclusions MG patients with TED had a significantly lower incidence of thymus hyperplasia and a lower antibody titer for the acetylcholine receptor. Patients with OMG and TED are more likely to develop diplopia; it is very difficult to treat diplopia in these patients.