Is there a prodrome to NMOSD? An investigation of neurologic symptoms preceding the first NMOSD attack.

BACKGROUND It is unknown whether people with aquaporin-4 antibody positive (AQP4-IgG+) neuromyelitis optica spectrum disorder (NMOSD) experience a prodrome, although a few cases report AQP4 + serology up to 16 years before the first attack. OBJECTIVES To evaluate whether individuals with AQP4-IgG + NMOSD have prodromal neurologic symptoms preceding the first attack. METHODS We reviewed medical records of participants meeting the 2015 diagnostic criteria for AQP4-IgG + NMOSD from four demyelinating disease centres in the Canadian NMOSD cohort study CANOPTICS. We searched for neurologic symptoms occurring at least 30 days before the first attack. RESULTS Of 116 participants with NMOSD, 17 (14.7%) had prodromal neurologic symptoms. The median age was 48 years (range 25-83) at first attack; 16 (94.1%) were female. Participants presented with numbness/tingling (n = 9), neuropathic pain (n = 5), visual disturbance (n = 4), tonic spasms (n = 2), Lhermitte sign (n = 2), severe headache (n = 2), incoordination (n = 2), weakness (n = 1), psychosis (n = 1) or seizure (n = 1). Of eight who underwent magnetic resonance imaging (MRI) brain, orbits and/or spinal cord, five had T2 lesions. Within 1.5-245 months (median 14) from the onset of prodromal neurologic symptoms, participants experienced their first NMOSD attack. CONCLUSIONS One in seven people with NMOSD experienced neurologic symptoms before their first attack. Further investigation of a possible NMOSD prodrome is warranted.