What is the appropriate workup for spinal cord demyelination?

Workup for Spinal Cord Demyelination

Obtain MRI of both the brain AND entire spinal cord (cervical, thoracic, and lumbar) at minimum 1.5T field strength with T2-weighted sequences, T1 post-gadolinium sequences, and consider FLAIR sequences—spinal cord MRI is mandatory when spinal cord symptoms are present to exclude non-demyelinating pathology and establish the diagnosis. 1

Essential Imaging Protocol

MRI Technical Requirements

• Field strength: Minimum 1.5T (3.0T offers no additional diagnostic value for spinal cord imaging, unlike brain imaging) 1
• Sequences required:
  • T2-weighted sequences (detects >90% of MS cord abnormalities)
  • T1 post-gadolinium (0.1 mmol/kg body weight, minimum 5-minute delay after injection) 1
  • FLAIR sequences for brain imaging 2
  • Use 3D acquisitions or 2D with 3mm thick slices, no gap between slices 2

Critical Imaging Coverage

• Complete spinal cord imaging: Cervical, thoracic, AND lumbar spine must all be imaged—brain MRI alone is grossly inadequate, detecting critical spinal cord lesions in only 4.6% of cases 3
• Brain MRI: Essential for establishing dissemination in space and time
• Fat-suppressed optic nerve MRI: Consider in atypical cases to rule out alternative diagnoses 2

Clinical Context Matters

When Spinal Cord MRI is Mandatory

• Any patient presenting with spinal cord symptoms at disease onset 1
• Primary purpose: exclude non-demyelinating pathology (compressive lesions, vascular malformations, tumors)

When Spinal Cord MRI is Helpful

• Brain MRI results are equivocal (e.g., vascular changes, migraine-related white matter abnormalities) 1
• Brain MRI shows lesions typical of MS but insufficient to fulfill diagnostic criteria for dissemination in space 1
• Patients >50 years or with vascular risk factors require more stringent evaluation 2

Key Diagnostic Features to Document

Lesion Characteristics

• Number and location: T2 hyperintense and gadolinium-enhancing T1 lesions
• Topography and size: Spinal cord lesions are typically:
  • Short and peripheral in MS (≤2 vertebral segments)
  • Longitudinally extensive in NMOSD (≥3 vertebral segments) 4
• Enhancement patterns: Distinguish active inflammatory lesions from chronic plaques 4

Important Prevalence Data

• Asymptomatic cord lesions found in 30-40% of patients with clinically isolated syndrome 1
• Unlike brain, spinal cord rarely shows incidental MS-like abnormalities even in older patients 1

Laboratory Workup

While not explicitly detailed in the imaging guidelines, comprehensive workup should include:

• Serum testing: Aquaporin-4 antibodies (NMOSD), MOG antibodies (MOGAD) 5, 4
• CSF analysis: When diagnosis remains uncertain
• Vitamin B12 levels: To exclude subacute combined degeneration 6

Common Pitfalls to Avoid

1. Technical artifacts: Spinal cord imaging is challenging due to ghosting artifacts from breathing, blood/CSF pulsation, and truncation artifacts—minimize with spatial presaturation slabs and fast imaging sequences with spinal phase-array coils 1

2. Incomplete imaging: Brain MRI alone misses 95.4% of critical spinal cord lesions 3—always image the entire cord when demyelination is suspected

3. Age considerations: In patients >50 years, require higher number of periventricular lesions abutting lateral ventricles for diagnosis 2

4. Confirmation on multiple planes: Essential to avoid false positives from artifacts and false negatives 2

Advanced Imaging Considerations

Emerging techniques showing promise but not yet standard:

• Central vein sign: Improves MS diagnosis accuracy to 94% at 3T 4
• Diffusion tensor imaging (DTI) and magnetization transfer imaging (MTI): Correlate with demyelination extent and clinical disability 7, 8
• Paramagnetic rim lesions: Enhance diagnostic specificity 4