Immune-Mediated Encephalidities

Encephalitis accounted for hospitalizations in 5.2/100,000 population between 1994 and 2008 in Canada [1]. While 50% of these cases had unknown etiologies at the time [1], it has recently become clear that a large number of encephalidities of unknown etiology may be inflammatory. For example, one population-based study found that 21% of cases of encephalitis were identified as being due to immune-mediated processes [2]. In children, the frequency of immune-mediated encephalitis has been estimated to be approximately 34% in a retrospective single-center cohort study, surpassing that of infectious etiologies [3].