AQP4 and Encephalopathy: In 2015, new international diagnostic criteria for NMOSD were proposed.[3] According to this criterion, a diagnosis of NMOSD is made if a patient tests positive for anti-AQP4 antibody and presents with one of the major clinical signs (such as ON, myelitis, and encephalopathy).[3] However, our patient did accurately meet the 2015 criteria for NMOSD.[3] On the other hand, there have been many anti-MOG antibody positivity reports in cases that have symptoms similar to those of NMOSD but do not meet this criterion.