Subacute sclerosing panencephalitis (SSPE) masquerading as acute disseminated encephalomyelitis (ADEM).

Subacute sclerosing panencephalitis (SSPE) is an uncommon, progressive, and deadly brain condition that develops as a late consequence of a measles virus infection in otherwise healthy individuals, especially in children and young adults. Due to a decrease in vaccination adherence, which has been exacerbated by the COVID-19 pandemic, its frequency has increased in recent years.A 2-year-old male child, previously normal, presented with regression of attained milestones along with drop attacks, which eventually increased in frequency along with behavioural concerns. On retrospection, he had a history of self-limiting febrile exanthem with similar complaints in his mother. This child was diagnosed with SSPE and managed accordingly.To conclude, SSPE can present with a rapidly deteriorating course mimicking acute disseminated encephalomyelitis (ADEM).Myoclonic jerks with periodic complexes on EEG along with cerebrospinal fluid IgM for measles antibodies help to delineate from ADEM and avoid immunosuppression, which could be fatal.