Evaluation a child with encephalitis is difficult due to the similarities in the clinical, imaging and laboratory findings of many forms of autoimmune and infectious encephalitis. Presentation of autoimmune encephalitis in childhood is often subacute, with varied clinical manifestation [1]. However, as it takes time to get the results of antibody tests for autoimmune encephalitis, immunosuppression is often started with a presumed diagnosis of AE. Due to increasing awareness of AE, many primary-care physicians are diagnosing it and starting immunomodulation, which may be detrimental at times.

In past few months, two children presented to us in vegetative state. Both children were diagnosed as AE based on their presentation with fever, behavioral changes and myoclonic jerks/focal seizures. Pulse methylprednisolone was administered to the children with presumed diagnosis of autoimmune encephalitis. There was no improvement on immunotherapy and children deteriorated to vegetative state in next 2-3 weeks. There was no history of measles in these children, and they were vaccinated (one dose of measles vaccine at 9 months). Fundus examination showed hyperemic disc, large whitish subretinal patch over posterior-pole with satellite lesions, and magnetic resonance imaging (MRI) of brain showed subtle asymmetrical hyper-intensities in peri-ventricular white-matter. Based on these findings, Subacute sclerosing panencephalitis (SSPE) was suspected, and subsequently confirmed by raised (1:625) titers of IgG measles antibodies detected by enzyme-linked immunosorbent assay in CSF. Both children died over next one month.

In regions where SSPE is still common, we should be cautious before using immunomodulation in presumed autoimmune encephalitis. Diagnosis of SSPE is mainly based on clinical presentation, supported by elevated CSF measles antibody titers [2]. Autoimmune encephalitis clinically manifests with alteration of consciousness and/or behavioral changes, which may be associated with seizures, movement abnormalities and/or focal neurological deûcits. While in SSPE, the initial symptoms are usually subtle, include mild intellectual deterioration and behavioral changes without any apparent neurological signs; this is followed by steady motor decline and myoclonus [1-3]. However, some cases of SSPE have an acute presentation with death occurring in few weeks. Retina-, EEG- and MRI findings help to distinguish SSPE from AE. The most characteristic ophthalmic findings in SSPE are optic nerve head edema, retinal pigment epithelial changes, active or scarred chorioretinitis, and optic atrophy [4]. Periodic EEG complexes are pathognomonic features of SSPE but are not seen in all individuals [2]. In the early stages, MRI findings are normal, or cortical/subcortical asymmetrical hyperintense lesions may be observed in the posterior parts of the brain. As the disease progresses, the lesions disappear and new lesions occur symmetrically in the periventricular white-matter in association with mild cortical atrophy [2]. Apart from these findings, CSF examination for antibody provides definite diagnosis of both SSPE and AE.

To conclude, when in doubt it is better to withhold immunosuppression with methylprednisolone till we get the confirmation of a diagnosis of autoimmune encephalitis.

1. BrentonJ, Goodkin H. Antibody-mediated autoimmune encephalitis in childhood. Pediatr Neurol. 2016;60:13-23.

2. Gutierrez J, Issacson R, Koppel B. Subacute sclerosing panencephalitis: An update. Dev Med Child Neurol. 2010;52:901-7.

3. Graus F, Titulaer M, Balu R, Benseler S, Bien C, Cellucci T, et al. A clinical approach to diagnosis of autoimmune encephalitis. Lancet Neurol. 2016;15: 391-404.