Neuromyelitis optica-IgG in childhood inflammatory demyelinating CNS disorders.

OBJECTIVE To determine seroprevalence of neuromyelitis optica (NMO)-IgG in childhood CNS inflammatory demyelinating disorders. METHODS We analyzed demographic, clinical, and radiologic data in a blinded fashion and assessed serum NMO-IgG status for 87 children: 41 with relapsing-remitting multiple sclerosis (RRMS), 17 with NMO, 13 with monophasic/recurrent optic neuritis (ON), 13 with transverse myelitis, of whom 10 were longitudinally extensive on MRI spine (LETM), and another 3 with LETM in the context of acute disseminated encephalomyelitis (ADEM). RESULTS Ten of the 87 children (11%) were seropositive. Eight of 17 with NMO (47%) were seropositive (7 of 9 with relapsing NMO [78%], 1 of 8 with monophasic NMO [12.5%]). Two other children were seropositive: 1 of 5 with recurrent ON and one child with recurrent LETM. No seropositive case was identified among 41 with RRMS (14% of whom had LETM at some point in their clinical course), 8 with monophasic ON, 9 with monophasic LETM, or 3 with LETM in the context of ADEM. CONCLUSIONS The similar frequency of neuromyelitis optica (NMO)-IgG in both childhood and adult cases of NMO, and its rarity in relapsing-remitting multiple sclerosis, supports the concept that these diseases have a similar pathogenesis in childhood and adulthood. It is noteworthy that none of nine children with monophasic longitudinally extensive transverse myelitis (LETM) was NMO-IgG-seropositive. Furthermore, LETM does not appear to be as predictive of an NMO spectrum disorder in children as it is in adults. Longitudinal studies of larger pediatric LETM cohorts are required to ascertain whether the absence of NMO-IgG is a negative predictor for relapse in this childhood entity.