Benefits of FK 506 for refractory eye symptoms in a young child with ocular myasthenia gravis

Recently, there have been many reports on the efficacy and safety of tacrolimus (FK506) treatment for adult patients with intractable generalized myasthenia gravis (MG). There have also been a few reports of successful FK506 therapy in patients with severe childhood-onset generalized MG involving a myasthenic crisis. Herein, we report the efficacy of FK 506 for refractory ocular symptoms in a 3-year-old girl with ocular type MG. Ptosis and alternating strabismus had appeared at 10 months of age. No bulbar signs, respiratory failure or generalized muscle weakness had been seen during her course. Her ocular symptoms had persisted despite repeated steroid pulse therapy, high dose oral prednisolone and thymectomy. Adverse effects of steroids, including obesity, growth retardation, osteoporosis, cataracts and hyperlipidemia, gradually worsened. After obtaining written informed consent from her parents, we started oral tacrolimus at a dose of 0.5 mg/day and her symptoms resolved completely within 3 weeks at a maximum dose of 2.5 mg/day. No adverse effects, such as renal failure or glucose intolerance, were seen. FK506 treatment allowed the steroid dose to be reduced, eliminating its adverse effects. In patients with intractable childhood-onset MG with ocular manifestations, FK506 is an alternative to steroid therapy or thymectomy.