Pathol.
a chronic degenerative, often episodic disease of the central nervous system marked by patchy destruction of the myelin that surrounds and insulates nerve fibers, usually appearing in young adulthood and manifested by one or more mild to severe neural and muscular impairments, as spastic weakness in one or more limbs, local sensory losses, bladder dysfunction, or visual disturbances.
[ 1880-85 ]