AQP4 and neuromyelitis optica: According to Wingerchuk criteria in 2006, 71.43 % anti-AQP4 (+) patients (10/14) converted to NMO while only 11.76 % anti-AQP4 (-) ABS patients (2/17) converted to NMO within the follow-up after first-event brainstem symptoms (p < 0.01).