myelin-, myelino- +
(Greek: lipoid substance (containing or resembling fat) sheathing certain nerve fibers; lipoid substance found in body tissue)
Central demyelination occurs within the central nervous system (for example, the demyelination seen with multiple sclerosis); peripheral demyelination affects the peripheral nervous system.
One group of diseases is named according to whether primarily white matter or gray matter is affected; another group is defined by whether there is coexistent disease of the meninges (meningomyelitis) or the brain (encephalomyelitis). In practice, the term is also used to denote noninflammatory lesions of the spinal cord.
2. Inflammation of the bone marrow.
It is characterized clinically by fever, sore throat, headache, and vomiting; often with stiffness of the neck and back.
In the minor illness (abortive poliomyelitis) these may be the only symptoms. The major illness, which may or may not be preceded by the minor illness, is characterized by involvement of the central nervous system, stiff neck, pleocytosis in the spinal fluid, and sometimes paralysis.
There may be subsequent atrophy of groups of muscles, ending in contraction and permanent deformity.