Neurologic involvement in atypical hemolytic uremic syndrome and successful treatment with eculizumab

Atypical hemolytic uremic syndrome (aHUS) is associated with defective regulation of the complement pathway. Neurological involvement is the most common extrarenal complication and represents a major cause of mortality and morbidity. Two girls aged 11 and 6 years, respectively, developed aHUS and were treated immediately with plasma exchange (PE) and fresh frozen plasma infusion (PI). Although initial improvement in renal function was seen in both cases, the first patient showed progressing thrombotic microangiopathy (TMA) despite daily PE, and neurological manifestations (seizures, vision loss, loss of balance, and confusion) developed after 1 month. The second patient developed cerebral TMA (seizures, vision loss, and nystagmus) 6 days after initial presentation and remained unresponsive to PE/PI. Neurological symptoms were similar in both patients, even though they had different complement protein mutations. Treatment with eculizumab achieved complete control of neurological symptoms within 24 h and gradually normalized hematological and renal parameters in both children. Based on our two cases, we conclude that eculizumab is a rapid-acting, effective, and life-saving treatment for pediatric patients with aHUS and severe neurological involvement, which works by inhibiting complement-mediated TMA in the kidney and other organs, such as the brain.