1. LETM refers to transverse myelitis (TM) that extends over 3 or more vertebral segments. It has many potential causes including inflammatory, infectious, metabolic, vascular and neoplastic etiologies. 2. Neuromyelitis optica (NMO), an autoimmune condition where antibodies attack astrocytes, is an important consideration as a cause of LETM. Diagnostic criteria for NMO include involvement of the optic nerve and spinal cord. 3. Other conditions like Sjogren's syndrome, systemic lupus erythematosus, Behcet's disease and sarcoidosis can also present with LETM and involve both autoimmune and inflammatory mechanisms. Accur

1. Differential diagnosis of LETM in adults Christopher Eckstein, Stephanie syc, Shiv saidha, John hopkins university,Baltimore European Neurological journal,Oct,2010