A T2-bright cord lesion with or without enhancement: its length, axial position and enhancement pattern separate MS, NMOSD, MOGAD, infection, sarcoid, spinal cord infarct and dural fistula — and a compressive cause must be excluded first.
Orient first
- Short (< 2 segments), peripheral, dorsal or lateral: MS.
- Long (≥ 3 segments), central: NMOSD, MOGAD, infection; H-sign in grey matter: MOGAD.
- Dorsal subpial enhancement with a central canal sign: sarcoid ("trident"); owl-eye anterior horns with sudden onset: infarct; flow voids on the dorsal surface: dural AV fistula.
Acquire the study
- MRI whole spine: sagittal T2, STIR, axial T2 through the lesion, DWI (for infarct), post-gadolinium sagittal and axial T1; brain MRI for demyelination.
The manoeuvre
- Sagittal T2/STIR: lesion length in vertebral segments; cord swelling.
- Axial T2: central vs peripheral; grey matter (H or owl eyes) vs white matter.
- Post-gadolinium T1: pattern (ring, patchy, subpial dorsal, none).
- DWI: restricted diffusion in acute infarct.
- Dorsal cord surface on sagittal T2: serpiginous flow voids = dural AV fistula (with venous congestion oedema).
- Exclude compression: disc, tumour, abscess.
What confirms it
- An intramedullary T2 lesion with a pattern concordant with serology, CSF and clinical course.
What licenses you to exclude it
- A normal whole-spine MRI with contrast excludes a structural myelitis at the time of imaging.
The classic misread
- Treating a dural fistula as myelitis with steroids — look for the flow voids.