Very Late-onset Neuromyelitis Optica Spectrum Disorders.

Nakahara, Keiichi; Nakane, Shunya; Nagaishi, Akiko; Narita, Tomoko; Matsuo, Hidenori; Ando, Yukio

BACKGROUND 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, 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.