Given the wide range of illnesses covered by NMOSD and the anomalous presence of AQP4 described in the CSF in cases of hydrocephalus, bacterial meningitis, and diseases with inflammatory phenomena of the central nervous system [5, 26], the presence of AQP4 in the CSF is probably due to ependymal disruption phenomena. This evidence concerns the gene AQP4 and Hydrocephalus.