The myelin sheath is normally found in the nerves of human nervous system, and is believed to be involved in saltatory conduction or the rapid conduction of action potential along the nerve fiber. If the myelin sheath is damaged, this results in the slowing down of the impulse conduction. Individuals suffering from this disease are expected to show impairment in sensation, movement, cognition, and other functions related to the affected nerves.
Examples of demyelinating diseases of the central nervous system are: multiple sclerosis, transverse myelitis, optic neuritis, leukodystrophies, etc. Demyelinating diseases of the peripheral nervous system are Guillain-Barre syndrome, Charcot-Marie-Tooth disease, etc.
See also: demyelination