Multiple sclerosis

  • 40-50 years age
  • Relapsing-remitting type 85%
  • Primary-progressive type 15%
  • Characteristic abnormality – demyelinating plaques
  • Location of plaques – middle cerebellar peduncle, callososeptal interface, periventricular white matter, juxtacortical
  • Callososeptal interface involvement – pathognomonic
  • Plaque character
    • Initial stages: acute, with surrounding edema
    • Remyelination may occur: resulting in target lesions in pathology
    • Eventually, chronic stage: axon loss, fluid accumulation, gliosis
  • Periventricular lesions
    • White matter surrounding corpus callosum
    • Perpendicular to ventricular margin due to clustering around deep matter veins
  • Juxtacortical lesions
    • Adjacent to cortex with no intervening white matter
  • Infratentorial lesions
    • Cerebellar white matter
    • Cerebellar peduncles
    • Brain stem white matter tracts
  • Spinal cord lesions
    • Centrally or eccentrically within cord
    • Eccentric lesions best picked in axial T2 imaging
  • Tumefactive lesions
    • Large, swollen lesions
    • Target appearance, bright central T2, with lighter surrounding T2 hyperintensity
    • Multiple targets may be seen in one lesion – Balo’s concentric sclerosis
    • Incomplete ring enhancement is highly suggestive
  • Contrast: identifies activity of lesions
  • Incomplete enhancement, mild perfusion elevation and mild diffusion restriction favor MS rather than a neoplasm
  • Imaging criteria:
    • Dissemination in space: at least one lesion in two of the four typical locations
    • Dissemination in time: mix of enhancing and non enhancing lesions in one scan or appearance of new lesion in follow up scan suggests dissemination in time
Differential diagnosis
  • Virchow-Robin spaces
  • Ageing brain
  • Ependymitis granularis
  • Terminal zones of myelination