Established childhood MOG antibody associated demyelination syndromes include monophasic/ multiphasic Acute Disseminated Encephalomyelitis (ADEM/MDEM), Chronic relapsing inflammatory optic neuropathy (CRION), NMO-IgG negative Neuromyelitis Optica (NMO) and acute transverse myelitis (ATM). They are not seen in multiple sclerosis (MS). Prolonged fever at presentation has not been described.

We describe 12 children (8 male) with prolonged fever at presentation with only 2 having neurological deficits. Six presented as subacute aseptic meningitis with fever (mean 27 days), headache/ vomiting / seizures but without neurological deficits. Four presented as prolonged fever without focus without symptoms referable to the CNS. CSF / MRI were done several weeks / months into the illness when neurological symptoms appeared. Two had an acute neurological syndrome (ATM & ON) followed by fever lasting 1 month or more.

12/12 had leukocytosis, 10/11 elevated ESR and/or CRP ; 10/12 had CSF pleocytosis. Positive serum anti-MOG antibodies and demyelinating lesions on MRI confirmed MOG Antibody associated demyelination syndrome in all.

Prolonged immunotherapy (Pulse methylprednisolone + oral steroids and/or IVIG) was followed by complete recovery in 11/12; The child with ATM has persistent bladder issues. Recurrent demyelinating episodes were noted either prior to diagnosis (2) or on follow up (4) in 6 patients requiring repeat / prolonged immunotherapy.

Conclusion:  MOG antibody associated demyelination syndromes can present with prolonged fever without focus or subacute aseptic meningitis and must be actively looked for in these clinical syndromes.