Diagnosis of longitudinally extensive transverse myelitis.

Longitudinally extensive transverse myelitis (LETM) is a neurological condition characterised by a contiguous inflammatory lesion of the spinal cord. LETM is often associated with the autoimmune central nervous system disease neuromyelitis optica (NMO) and rarely with multiple sclerosis. The discovery of the NMO-IgG antibody, provides a useful serological marker of LETM associated with the NMO disease spectrum (LETM and/or optic neuritis). Here, the authors report two cases of LETM, which differ in disease severity and NMO-IgG antibody serological status.