We describe a case of an unusually early and severe manifestation of an Aquaporin-4 (AQP-4) positive Neuromyelitis Optica Spectrum Disorder (NMOSD) in a young child with refractory disease course despite aggressive immunotherapy.

NMOSD is an autoimmune condition primarily involving the optic nerve and spinal cord. It typically presents in the fourth decade of life. However, approximately 3 percent of cases are seen in children with mean onset in the pediatric group reported around 10-12 years of age. Clinical presenting features in pediatric patients include optic neuritis and myelitis, and can include fevers, malaise, narcolepsy, and seizures as well.

A 2-year-old girl who came in with 2 days of progressive left hand weakness and abnormal gait, following a week of flu symptoms. Her neuroimaging was notable for abnormalities in the dorsal medulla and longitudinally extensive myelitis (from high cervical to T8) with normal optic nerves. Her CSF was significant for elevated protein with normal oligoclonal bands and IGG index. She was started on a 5 days course of methylprednisolone and her gait and hand weakness improved. Further investigation revealed her serum AQP-4 antibody to be at 1:100,000. She has since had multiple exacerbations, including bilateral optic neuritis, optic chiasm and hypothalamus involvement, brain lesions, and cord edema despite being on rituximab and mycophenolate mofetil. Deficits from each attack responded favorably to corticosteroids and PLEX. We are now planning to add on tocilizumab to mycophenolate mofetil in hopes of controlling her very active disease.

Our case highlights the challenges in establishing and managing AQP-4 NMOSD in the very young child. As the bulk of disability related to the disease is accrued from incomplete recovery from relapses, it is imperative to recognize and intervene at the earliest manifestations of disease, both with acute therapies and long-term immunosuppressive regimens to prevent further exacerbations.