Q. My sister-in-law has been told that her nerve fibers are demyelinating. What does that mean in plain English?

A. Demyelinating is a term used to describe the opposite process from myelination. Multiple sclerosis is an example. It is thought to be an autoimmune condition where the body turns against part of itself. In this case, it involves destruction of the myelin sheath. Something triggers the stripping away or the destruction of the insulation. Depending on the location of the affected nervous tissue, a variety of symptoms can ensue, involving enervation of muscle tissue and the conscious control of bodily functions.