Polioencephalitis, commonly known as inflammation of the grey matter of the brain, can be used interchangeably with several synonyms. Such synonyms include encephalomyelitis, which refers to inflammation of both the brain and spinal cord; myeloencephalitis, which indicates inflammation of the brainstem and spinal cord; and rhombencephalitis, which pertains to inflammation of the hindbrain. Additionally, terms like leukoencephalitis, panencephalitis, and necrotizing encephalitis can also be applied, depending on the specific type and extent of inflammation present. These synonyms serve as a broad range of descriptors that can help medical professionals more precisely identify and treat the condition.