Unusual prodromal manifestation of neuromyelitis optica with prolonged seizures, fever, CSF pleocytosis and encephalopathic EEG-pattern

Introduction: Neuromyelitis optica (NMO) is a demyelinating CNS-disorder, confirmed with the 2 major criteria optic neuritis (ON) and myelitis ≥3 vertebral segments. The NMO-IgG-seropositivity as additional diagnostic criteria is rarely detected in children. Encephalopathy and seizures are further and less circumscribed symptoms of NMO.

Case report: We present the case of a 5-year-old Tamil boy with a first, generalized seizure during a febrile respiratory infection. One week later, after a second prolonged seizure, EEG showed encephalopathic changes. CSF revealed pleocytosis, and cMRI was normal. Detailed investigations could not demonstrate an infectious, causing agent. After the following 3 weeks with recurrent fever episodes and fatigue, the boy developed painful eye movements and loss of vision within 2 days, demonstrating ON in the right eye and disc swelling in the left optic nerve. In addition, he presented symmetrical hyperreflexia and bilateral Babinski signs. Cranial MRI then showed prominent signal abnormality of the optic nerve on the right more than on left, and a small, subcortical white matter lesion. Spinal imaging demonstrated T2 hyperintensity consistent with longitudinally extensive transverse myelitis from segment C2 to C5, fulfilling criteria for NMO despite negative NMO-Ig-G and negative oligoclonal bands in CSF. After high-dose steroid treatment, the visual acuity improved from < 10% to 100% within 4 weeks.

Conclusion: In children with bilateral ON, NMO should always be considered and spinal imaging consequently should be performed. NMO can present with a broad spectrum, including encephalopathy and seizures, sometimes weeks prior to the first attack as in our patient. Absence of NMO-Ig-G does not rule out NMO in most pediatric patients.

Recent literature has demonstrated better clinical outcome in monophasic cases that have negative NMO-Ig-G. As such, the patient is being watched conservatively and is not on long-term-immunosuppression.