Transitional medicine for an adult patient with MuSK–positive juvenile myasthenia gravis

Abstract

A four–year–old boy with oculobulbar symptoms visited our hospital and was diagnosed with anti–MuSK positive antibodies. He had been prednisolone (PSL) dependent (0.5–2mg/kg/day) with tacrolimus and been worsened gradually. When he was referred to the adult neurological department at the age of 19, with a prescription of PSL of 40 mg/48 hours, he presented with chronic muscle power deterioration and atrophy even without fatigue. Symptoms were significant in the trunk and limbs with his drophead and type 2 respiratory failure with the forced vital capacity (FCV) of 0.68 L. He was not able to stay in the chair to study or to sleep in a spine position. He also showed the complications of steroids : the moon face, glaucoma, hypertension, and hyperglycemia. At age of 19, the fast–acting treatment (FT) with plasma exchanges and repeated intravenous immune globulin (IVIg) improved his symptoms in activities of daily living with the FVC of 1.7 L. Repeated IVIg in one to two months and Efgartigimod infusions showed the therapeutic effects as maintenance and allowed the decrease of oral PSL to 15 mg/day. Although there is little evidence regarding the treatment of juvenile myasthenia gravis and the transitional medicine to adults, FT can possibly play a role in various stages, including transitions of MG treatment.