Risk factors of attacks in neuromyelitis optica spectrum disorders.

Predisposing factors before the onset of neuromyelitis optica spectrum disorders (NMOSD) have not been systematically evaluated by now. We investigated the detailed pre-onset history in consecutive NMOSD patients. Thirteen of the enrolled 53 NMOSD patients (24.5%) had accompanying autoimmune diseases, such as Sjögren's syndrome. History of malignancy was seen in 8 of the 53 patients (15.1%). Recent history of non-neurological clinical episodes, such as systemic allergic reaction, systemic infection, surgical operation, or traumatic injury, was seen in 23 of the 53 patients (43.4%). NMOSD patients are likely to have pre-onset history of other autoimmune diseases, malignancy, or recent non-neurological systemic conditions, which may predispose or trigger the onset of NMOSD.