Transverse Myelitis Is Not Always Longitudinally Extensive in Neuromyelitis Optica

Longitudinally extensive transverse myelitis (LETM) is one of the defining features of neuromyelitis optica (NMO) and NMO spectrum disorders (NMOSD) and remains a key component in research criteria. However, the frequency of short transverse myelitis (STM) in patients with NMO or NMOSD is unknown. To identify this frequency, investigators retrospectively reviewed data from 176 patients who were aquaporin-4 antibody (AQP4 Ab) positive, presented with transverse myelitis, and had available spinal cord imaging.

A short lesion (<3 vertebral segments) was identified in 14% (25 patients). Short transverse myelitis (STM) at disease onset was typically a single lesion (72%), had a median length of one segment, was often enhancing (56%) and within th…