Clinical characteristics of disabling attacks at onset in patients with neuromyelitis optica spectrum disorder

Background Individual attacks of neuromyelitis optica (NMO) are generally severe enough to cause disability even after the onset attack. We aimed to elucidate the clinical characteristics of disabling attacks at the onset of NMO. Methods We investigated the clinical characteristics at onset and at first relapse in patients with NMO or NMO spectrum disorder with seropositive for the anti-aquaporin-4 antibody. A disabling attack at onset (DAO) was defined as an onset attack in which, at best recovery (allowing up to one year), patients were unable to walk without assistance or were left functionally blind in at least one affected eye. Results Fifty-seven patients were enrolled (53 females; onset age, 41.9 ± 14.8 years). Ten patients (17.5%) had a DAO; four had become unable to walk without assistance following myelitis, and six had severe visual impairment following optic neuritis despite rescue treatments. Attack severity at nadir was the only clinical factor predicting a DAO (odds ratio, 2.120; 95% CI, 1.162–3.869; P = 0.014). The use of immunosuppressants delayed the interval to the first relapse (P = 0.003). Conclusion Our study showed characteristics of NMO onset attacks that caused severe disability. However, no clinically modifiable factors predicted disabling attacks, except attack severity.