What does demyelination mean?
Demyelination refers to the damage to or loss of myelin, the fatty substance that forms a protective sheath around nerve fibres and allows electrical signals to travel quickly and efficiently along them. When this sheath is stripped away — whether by an autoimmune attack, inflammation, infection, or metabolic failure — nerve impulses slow down or fail altogether, producing symptoms such as numbness, weakness, blurred vision, or impaired coordination. The word belongs chiefly to medical language: it appears constantly in discussions of neurological disorders, above all multiple sclerosis, in which the immune system mistakenly attacks myelin in the brain and spinal cord. Clinicians speak of focal, widespread, active, or chronic demyelination depending on where and how aggressively it occurs. The related terms 'demyelinate' (verb) and 'demyelinated' (adjective) describe the same process at work. Understanding demyelination matters because much modern neurology is concerned not only with stopping the damage but with promoting remyelination — the repair of the sheath once it has been lost.
nounThe loss or destruction of myelin, the fatty insulating sheath that surrounds nerve fibres, which impairs the transmission of electrical impulses along the affected nerves.
- The pathological loss of the myelin sheath surrounding nerve axons, impairing neural signal conduction.
"MRI scans revealed extensive demyelination in the patient's optic nerves, explaining her sudden loss of vision."
"Chronic demyelination in the spinal cord led to progressive weakness in his legs."
"Researchers studied whether early treatment could halt demyelination before permanent damage occurred."
Usually treated as an uncountable mass noun referring to a general pathological process. A plural form exists but is rare, used mainly when distinguishing separate instances or lesions of demyelination in different locations or patients.
"The autopsy revealed scattered demyelinations throughout the white matter."
In multiple sclerosis, the body's own immune system strips the insulation from its own nerve wiring — and scientists are still learning how to rewrap it.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of demyelination
Demyelination combines the privative prefix 'de-', indicating removal or loss, with 'myelin', the name of the fatty sheath around nerve fibres. The term 'myelin' itself was coined in the mid-19th century by the German pathologist Rudolf Virchow from Greek 'myelos', meaning marrow or spinal cord, since he observed the substance in nerve tissue and likened it to marrow. The derived word 'demyelination' emerged in late-19th- and early-20th-century medical literature as physicians sought precise terminology for the pathological changes seen in diseases now classified as demyelinating disorders. Its cognates share the Greek root 'myelos', including 'myelin' itself and medical compounds such as 'myelopathy'.
Related word forms
How demyelination is actually used
A technical term used almost exclusively in medical and scientific contexts; it is formal rather than colloquial. It carries a strongly clinical connotation and is most often encountered in discussions of neurological disease such as multiple sclerosis, Guillain–Barré syndrome, and certain leukodystrophies. The verb form 'demyelinate' and participial adjective 'demyelinated' are common in clinical writing.
Easily confused with demyelination
Myelin is the protective sheath around nerve fibres itself, whereas demyelination is the process of losing or destroying that sheath.