demyelinating disease

[dē-mīə-lə-nā′tĭng]
n.
  1. Any of a group of diseases of unknown cause in which there is extensive loss of the myelin sheaths of nerve fibers, as in multiple sclerosis.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.