Acute disseminated encephalomyelopathy and Guillain-Barré syndrome are both immunologically mediated para-infectious demyelinating disorders, the former affecting the central nervous system and the latter affecting the peripheral nervous system. The term encephalo-myelo-radiculo-neuropathy was introduced to describe cases in which major involvement of one system, most commonly the peripheral, was associated with mild involvement of the other. We present a case of acute severe demyelination simultaneously affecting both the central and the peripheral nervous systems in a 10-year-old female. This clinical picture combines acute disseminated encephalomyelopathy and Guillain-Barré syndrome, both of which are extremely severe.