Neuromyelitis optica in children

Neuromyelitis optica (NMO; also known historically as Devic disease) is a rare inflammatory, demyelinating disease of the central nervous system (CNS) that has a predilection for the optic nerves and spinal cord [1]. Disease attacks are usually severe, often resulting in blindness and paraplegia [1]. Although the median age of onset of NMO is 39 years [2], cases have been observed across all age groups, including children and the elderly [3–6]. Clinical, serological, immunological, and pathological data which have emerged in the past 15 years has indicated that NMO is a disease distinct from multiple sclerosis (MS). In particular, the discovery of a disease-specific IgG antibody biomarker, NMO-IgG [7], has revolutionized the classification of demyelinating disorders of childhood [3–5]. Recent studies of NMO in children have provided new insights into idiopathic demyelinating CNS disorders in that age group. While radiological brain abnormalities are common in adults with NMO, symptomatic disease is rare [1,8]. In children, symptomatic brain attacks are distinctly common, occurring in nearly half [4]. In light of these novel clinical findings and the emergence of aquaporin-4 (AQP4; the most abundant water channel in the CNS [9]) as the target autoantigen of NMO-IgG [10], a new previously unrecognized entity has emerged of an astrocytic AQP4 autoimmune channelopathy of the CNS [11].