A recurrent longitudinally extensive transverse myelitis with Aquaporin-4(AQP4) antibody after herpes zoster.

Longitudinally extensive transverse myelitis (LETM) is a syndrome that involves three or more vertebral segments in the spinal cord lesion, and it is one of the characteristic features of neuromyelitis optica (NMO) differentiating it from multiple sclerosis. Many studies proved the importance of aquaporin-4 (AQP4) antibody, which plays a vital role in the pathogenesis of NMO. Recent reports suggest that recurrent LETM patients with positive anti-AQP4 antibody titers have a higher chance of converting to NMO, and they are now termed as NMO spectrum disorders (NMOSD). The specific role of AQP4 antibody in NMO is yet to be elucidated but there are reports to bring up the pathogenesis in relation with infectious events. Interestingly, parainfectious NMOSD tends to spare the optic nerve unlike classic NMOSD. Here we report a young woman who was once diagnosed as herpes zoster-related LETM, but later developed as recurrent LETM with positive AQP4 antibody titers, which renders the diagnosis of parainfectious LETM without optic neuritis.