AQP4 and neuromyelitis optica: Periependymal inflammation has been observed in MRI studies and is included in the international diagnosis criteria for NMO.1,18,19 Moreover, a histopathological study of post-mortem tissues showed granulocyte infiltration, microglial reactivity, sub-ependymal gliosis, ependymal cell loss and morphological alteration in NMO patients.20 In this study, 56% of NMO patients presented with loss of AQP4 in the ependyma and 38% presented with complement deposition.