Adult-onset Rasmussen's encephalitis with anti-AMPA receptor antibodies.

A woman aged 49 years developed focal seizures, with right hemispheric focal slowing on electroencephalograph and right hemisphere focal cortical hyperintensities with subtle atrophy on MR brain scan. Cerebrospinal fluid identified anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor auto-antibodies, but her condition did not respond to immunotherapy for AMPA receptor encephalitis. Subsequent MR brain scan showed striking progressive unihemispheric atrophy, consistent with Rasmussen's encephalitis; she made a good functional recovery with cyclophosphamide. This case highlights the diagnostic and treatment challenges surrounding adult-onset Rasmussen's encephalitis. The unusual co-occurrence of anti-AMPA receptor autoantibody positivity emphasises the need for careful interpretation of such associations. It is important to think of Rasmussen's encephalitis as a spectrum of diseases with shared T-cell-mediated neuronal loss pathways but varying humoral components to understand this complex disease better.