AQP4 and neuromyelitis optica: Previously limited to opticospinal involvement and seropositivity of anti-Aquaporin 4 (AQP4) or NMO IgG antibody, NMOSD also includes clinical syndromes and MRI findings related to the area postrema, other brainstem, diencephalic, or cerebral presentations in addition to seronegative opticospinal cases with optic chiasmal involvement and longitudinally extensive spinal cord lesions (LESCLs) [5].