Acute motor axonal neuropathy during intensive immunosuppressive therapy for macrophage activation syndrome

We describe a 2-year-old girl with refractory macrophage activation syndrome (MAS), which is a serious complication of inflammatory disorders associated with rheumatic disease in children. Although she was treated with intensive immunosuppressive therapies such as immunoglobulin, plasma exchange, dexamethasone, methotrexate, cyclosporine, and etoposide, she subsequently developed motor deficit with the abolition of deep tendon reflexes. Since nerve conduction study revealed low-amplitude compound muscle action potentials and motor conduction slowing, she was diagnosed as having acute motor axonal neuropathy (AMAN) associated with refractory MAS. This is the first report of AMAN occurring during immunosuppressive therapy for extremely refractory MAS, suggesting that hypercytokinemia or activated macrophages may have played a critical role in the pathogenesis of AMAN in this patient.