Very Late Onset Neuromyelitis Optica Spectrum Disorders

Background and purpose Neuromyelitis optica spectrum disorder (NMOSD) often presents in the elderly with an insidious onset of symptoms and aggressive progression. There have been anecdotal cases of very late onset (VLO)-NMOSD, but case series reports are rare. The aim of this retrospective study was to clarify the clinical features of VLO-NMOSD.Methods According to the age at onset, we classified patients with NMOSD into three subgroups: <= 49 years, early onset NMOSD (EO-NMOSD); 50-69 years, late onset NMOSD (LO-NMOSD); and >= 70 years, VLO-NMOSD. We evaluated the clinical characteristics, magnetic resonance imaging (MRI) findings, laboratory data, and immunotherapies of the groups.Results Overall, 12 men and 64 women with a median (interquartile range) age at onset and duration of disease of 42.0 (29.0-55.8) years and 70.0 (16.3-143.0) months, respectively, were included. Eight (11%) patients had VLO-NMOSD, 22 (29%) had LO-NMOSD, and 46 (61%) had EO-NMOSD. Patients with EO-NMOSD had a significantly longer interval between episodes as well as time between the first symptom and diagnosis of NMOSD than did those with VLO-NMOSD and LO-NMOSD (p = 0.046). Optic neuritis and nerve lesions on MRI were significantly less frequent in patients with VLO-NMOSD than in those with LO-NMOSD and EO-NMOSD (p = 0.002 and p = 0.028, respectively). In contrast, patients with VLO-NMOSD had higher nadir Expanded Disability Status Scale and Nurick scale scores and a significantly longer spinal lesion length than did those with LO-NMOSD and EO-NMOSD (p = 0.029, p = 0.049, and p = 0.032, respectively).Conclusions Patients with VLO-NMOSD tend to develop severe myelitis with long cord lesions but not optic neuritis.