Subacute sclerosing panencephalitis (SSPE) is a chronic progressive encephalitis of childhood and young adults due to persistent measles virus infection. The usual age of onset is between 5 and 15 years. There are wide varieties of presentations of SSPE described in the literatures. Variable clinical presentations may lead to diagnostic dilemma and unnecessary investigations especially in developing countries, where the measles is quite endemic and vaccination status is not up to the mark because of poor literacy and socioeconomic status. Good clinical correlations, neuroimaging findings, EEG and cerebrospinal fluid (CSF) marker for SSPE yield the clue to diagnosis. This case illustrates a 13-year-old boy presented with short history of intellectual decline, headache, papilloedema, cranial nerve palsy, myoclonus with suggestive neuroimaging mimicking acute disseminated encephalomyelitis (ADEM) and pseudotumour cerebri. Subsequently he was diagnosed to be a case of SSPE on the basis of CSF and serum measles antibody titer.