Was it Rasmussen Encephalitis?

Introduction: We present a rare case of subacute sclerosing panencephalitis (SSPE) in a child mimicking Rasmussen encephalitis. Case Report: An 11-year-old boy with normal developmental milestones presented with left focal seizure to bilateral tonic-clonic seizure 1 month back and left focal motor status epilepticus for 20 days. Fever preceded seizure by a fortnight and child had cognitive decline for 2 months and left hemiparesis for 20 days. He had poor attention, a leftward gaze with nystagmus, reduced vocabulary, impaired recent memory, increased tone and reflexes, and 3/5 power on the left side with a hemiplegic gait. The brain magnetic resonance imaging showed right fronto-parieto-occipital T2/fluid-attenuated inversion recovery hyperintensity and electroencephalogram (EEG) suggested right focal onset seizure activity with left focal spillthrough. Suspecting Rasmussen encephalitis, we sent his autoantibodies like NMDA, AMPA-GluR1, AMPA-GluR2, GABA-B receptor antibody, LGI-1, and CASPR2 antibodies, which were negative. The patient developed myoclonic jerks following oxcarbazepine and suspecting SSPE, we sent cerebrospinal fluid measles index, which was positive (3.23). The patient’s repeat EEG suggested stage 2 of SSPE. We therefore started tablet isoprinosine and intrathecal interferon-α. The patient’s seizures decreased, his alertness improved, and he was discharged to be followed up after 1 month. Conclusion: The clinical and EEG of our patient initially resembled Rasmussen encephalitis and the only cue to the diagnosis of SSPE was the subsequent development of myoclonus. This signifies the importance of follow-up in patients with focal status epilepticus and keeping SSPE in the differential diagnosis, so as to start early treatment in such cases. Publication History Article published online: 15 July 2026 © 2026. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/) Thieme Medical and Scientific Publishers Private Limited A-13A, Graphix Tower 1, 6th floor, Sector 62, Noida 201309, Uttar Pradesh, India