Immune-mediated pediatric epilepsies

Apart from Rasmussen encephalitis, other immune-mediated brain disorders have emerged that are frequently associated with recurrent epileptic seizures: (1) limbic encephalitis, (2) anti-N-methyl-D-aspartate-receptor (NMDAR) encephalitis, and (3) steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT, formerly called Hashimoto encephalopathy). Limbic encephalitis mainly affects the mediotemporal aspect of the cortex giving rise to temporal lobe seizures and memory and affective disturbances. It can occur as a paraneoplastic or, even more frequently, a nonparaneoplastic condition. Detection of specific autoantibodies may suggest underlying cancer (onconeural antibodies) and may give hints regarding the long-term prognosis. VGKC-complex or GAD antibodies have been identified in children. Anti-NMDAR encephalitis is a disorder mainly of female adolescents and young adults. Patients present with seizures in around one-third of cases, and 80% of patients develop recurrent, mainly extratemporal seizures at some stage of their disorder. The clinical course is that of a mostly monophasic, but sometimes multiphasic, severe cortico-subcortical encephalopathy. Ovarian teratomas underlie the disorder in 30-60% of adult cases but are rare in young children. Tumor removal and early intense immunotherapy are predictors for a favorable outcome. SREAT is not a disorder with definite pathogenesis but rather a "catch all" for encephalopathic immune-mediated brain diseases (often with seizures) which have in common thyroid antibodies and a good response to steroid therapy.