Aquaporin-4–neuromyelitis optica spectrum disorder is not a progressive disease

Whether there is central nervous system (CNS) damage outside of relapses in patients with aquaporin-4 (AQP4)–neuromyelitis optica spectrum disorder (NMOSD) has been a matter of debate. Lu et al analyse this question by searching retina atrophy unrelated to optic neuritis (ON) relapses.1 Most of the evidence so far indicates that, contrary to the case of multiple sclerosis (MS), all damage is due to the acute inflammatory injury during the relapses. AQP4-NMOSD is due to pathogenic anti-AQP-4 IgG1 antibodies that damage astrocytes, which are preferentially located in the inner retina, and retina’s Muller cells.2 For this reason, AQP4-NMOSD is described as an astrocytopathy in which demyelination and axonal …