Antibodies against aquaporin-4 in neuromyelitis optica: distinction between recurrent and monophasic patients.

The detection of antibodies against aquaporin-4 (AQP4) has improved the diagnosis of neuromyelitis optica (NMO). We evaluated a recently established cell-based anti-AQP4 assay in 273 patients with inflammatory CNS demyelination. The assay had a specificity of 99% and a sensitivity of 56% to detect all NMO patients and of 74% to detect the recurrent NMO patients, similar to the initial studies reported. AQP4 antibodies were absent in monophasic NMO patients, while samples in recurrent cases remained positive during follow-up. We conclude that the pathogenesis of monophasic NMO may be different from that of relapsing NMO.