Purpose of review: Longitudinally extensive transverse myelitis (LETM) is a frequently devastating clinical syndrome which has come into focus for its association with neuromyelitis optica (NMO). Recent advances in the diagnosis of NMO have led to very sensitive and specific tests and advances in therapy for this disorder. LETM is not pathognomonic of NMO, therefore it is important to investigate for other causes of myelopathy in these patients. This review aims to discuss recent advances in NMO diagnosis and treatment, and to discuss the differential diagnosis in patients presenting with LETM.
Recent findings: Fluorescence-activated cell sorting and cell binding assays for NMO-IgG are the most sensitive for detecting NMO spectrum disorders. Patients who have a clinical presentation of NMO, who have been tested with older ELISA or immunofluorescence assay and been found to be negative, should be retested with a fluorescence-activated cell sorting assay when available, particularly in the presence of recurrent LETM. Novel therapeutic strategies for LETM in the context of NMO include eculizumab, which could be considered in patients with active disease who have failed azathioprine and rituximab. Thorough investigation of patients with LETM who are negative for NMO-IgG may lead to an alternate cause for myelopathy.
Summary: LETM is a heterogeneous condition. Novel treatment strategies are available for NMO, but other causes need to be excluded in NMO-IgG-seronegative patients.