Multiple sclerosis

Introduction

• 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

Imaging

• 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