2022 Volume 54 Issue 6 Pages 443-447
Myasthenia gravis (MG), an autoimmune disease of the neuromuscular junction, have an increased risk for complicating autoimmune thyroid diseases (AITD) such as Basedow disease (BD). We herein report a case of MG complicated by BD, treated with mechanical ventilation (MV). A 5-year-old boy with bilateral ptosis and diplopia was diagnosed with BD associated with MG by blood test and edrophonium test (day 0). He had received thiamazole, and thereafter BD symptoms improved. MG symptom was ocular manifestation, and evoked electromyography revealed no waning ; therefore, we initiated pyridostigmine therapy on day 4. However, ocular manifestation did not improve, concurrent with bulbar palsy symptoms appearing. Therefore, prednisolone (PSL) was initiated on day 21, while he suffered from aspiration-induced respiratory failure eventually requiring MV on day 22. He had received intravenous methyl-PSL pulse therapy and immunoglobulin therapy, subsequently, he could successfully wean from MV. Afterward, tacrolimus was added on day 28. Combining the therapy of PSL and tacrolimus successfully improved his symptoms. Oral intake was resumed on day 49, while ocular manifestation was almost completely resolved on day 57. He was finally discharged on day 81. Reports show that 6.0% of patients with BD are accompanied by MG. MG concomitant with AITD presents with milder symptoms than those in MG alone. However, some studies report there is no difference in the frequency of occurrence of MG crisis. Complications of AITD such as BD should be considered in cases of MG. Patients with AITD associated with MG show a mild course ; however, a severe presentation is possible, as observed in this case. It is necessary to pay attention to changes in symptoms and select an appropriate treatment.
