AQP4 and neuromyelitis optica: Of the 26 AQP4-ab-positive patients with brain lesions, 17 (65%) had NMO-like brain lesions (i.e., periependymal areas, optic chiasm and area postrema) (Figure 4A), six (23%) patients had ADEM-like brain lesions, most of which were bilateral, asymmetric lesions in the supratentorial space without enhancements (Figure 4B), and three (12%) patients had nonspecific brain lesions.