Evaluation and management of longitudinally extensive transverse myelitis: a guide for radiologists

Longitudinal extensive transverse myelitis (LETM) is defined as an intramedullary spinal cord T2 signal abnormality extending craniocaudally over at least three vertebral bodies on an MRI study. Timely and appropriate diagnosis greatly facilitates patient management. The radiologist should review the relevant clinical information and determine the patient demographics and acuity of symptoms. Herein, we review the spectrum of diseases causing LETM and propose interpretation to guide the radiologist when presented with the MRI finding of LETM.