Intramedullary Lesion, Diffuse/Ill-Defined Enhancement

Jeffrey S. Ross, MD

DIFFERENTIAL DIAGNOSIS

Common

Less Common

Rare but Important

ESSENTIAL INFORMATION

Helpful Clues for Common Diagnoses

Multiple Sclerosis
- Patchy or confluent enhancement
- Cervical > thoracic
- Small focal areas of T2 signal abnormality
- Dorsal cord at C1-2 common location
Transverse Myelitis (ATM)
- Can be secondary to known cause (e.g., MS, ADEM, cord ischemia)
- Can be idiopathic (unknown cause) 15%
- Thoracic > cervical
- Imaging normal in up to 50%
ADEM
- Immune-mediated, inflammatory white matter disorder
  - Para/post-infectious
  - Post-immunization
- Typically monophasic illness
- Any age (more common in child, young adult)
- Brain affected more than spinal cord
- Can be multifocal, patchy, or confluent
- Check brain for multifocal white matter lesions with relatively little mass effect
Viral Myelitis
- Acute/subacute viral infection (e.g., HIV, enteroviruses, HHSV6)
- Usually multisegmental
- Variable enhancement from subtle to profound
Neuromyelitis Optica (NMO)
- Autoimmune, inflammatory disorder involving myelin of optic nerves and spinal cord
- Longitudinally extensive (> 3 vertebral segments) T2 hyperintensity within cord
- Presence of brain WM lesions does not exclude NMO
- May reflect autoimmune targeting of Aquaporin-4 transmembrane channel proteins
- Respiratory failure due to extensive cervical involvement in up to 1/3 cases (very uncommon in MS)
- Radicular pain in 35% (uncommon in MS)
- Lhermitte symptom common in MS and NMO

Helpful Clues for Less Common Diagnoses

Helpful Clues for Rare Diagnoses

Radiation Myelopathy
- Spindle-shaped cord swelling with irregular, focal rind of enhancement
- Typically with doses over 50 Grey (Gy)
- Demyelination in lateral, dorsal tracts
- Concurrent chemotherapy may be a predisposing factor, especially if intrathecal
Parasitic or Bacterial Infections
- Typical is well-defined, ring-enhancing mass within cord, with appropriate clinical history of inflammation/infection
- More uncommon ill-defined or patchy enhancement
- Schistosomiasis ill-defined punctate enhancement of conus

Other Essential Information

Long (multisegmental) cord enlargement with edema, patchy enhancement favors infection/inflammation over neoplasm
Do sagittal FLAIR or T2WI of brain in patients with unexplained myelopathy, cord lesions!
- MS, ADEM usually have coexisting brain lesions

Alternative Differential Approaches