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

- Exclude compressive myelopathy. Talk to clinician, learn time course of symptom onset.
- Tumors cause heterogeneous focal cord enlargement.
- Inflammatory/infectious myelitis cause diffuse uniform cord enlargement.
- Avoid biopsy in inflammatory/demyelinating diseases and use brain MRI for differential.
- Maintain a high index of suspicion for vascular disease.

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.