White matter disorders

White matter diseases are a group of conditions that predominantly or significantly affect the white matter of the brain. They comprise a vast heterogeneous group and have a variety of appearances and presentations. They cause disease by altering the process of normal myelination. 

Useful groupings

White matter disease can be broadly grouped into:

• demyelinating disorders
  • damage and/or destruction of previously normally myelinated structures
  • e.g. multiple sclerosis, ADEM
• dysmyelinating disorders 
  • abnormal structure and function of myelin, usually secondary to a hereditary disorder
  • e.g. leukodystrophies (note, however, that many leukodystrophies have a demyelinating component)
• hypomyelinating disorders
  • reduction in the amount of otherwise normal myelin
  • e.g. hypomyelination of prematurity