OMG and neuromyelitis optica: MS needs to be differentially diagnosed from rare MS variants; Acute Disseminated Encephalomyelitis (ADEM); the range of Neuromyelitis Optica Spectrum Disorders (NMOSDs); Myelin Oligodendrocyte Glycoprotein (MOG) antibody disease; other inflammatory diseases such as primary angiitis of the CNS, systemic lupus erythematosus, Behcet’s disease and neurosarcoidosis; several infectious diseases of the CNS such as Lyme neuroborreliosis and viral CNS-associated diseases; and neoplastic pathologies such as primary CNS lymphoma and solid tumours [45].