A<unk>  is any<unk>  of the nervous system in which the myelin sheath of neurons is damaged. This damage impairs the conduction of signals in the affected nerves. In turn, the reduction in conduction ability causes deficiency in sensation, movement, cognition, or other functions depending on which nerves are involved.<unk> s can be caused by genetics, infectious agents, autoimmune reactions, and other unknown factors. Proposed causes for demyelination include genetics and environmental factors such as being triggered by a viral infection or chemical exposure. Organophosphate poisoning by commercial insecticides such as sheep dip, weed killers, and flea treatment preparations for pets, can also result in nerve demyelination. Chronic neuroleptic exposure may cause demyelination. Vitamin B12 deficiency may also result in dysmyelination.<unk> s are traditionally classified in two kinds: demyelinating myelinoclastic<unk> s and demyelinating leukodystrophic<unk> s. In the first group, a normal and healthy myelin is destroyed by a toxic, chemical, or autoimmune substance. In the second group, myelin is abnormal and degenerates. The second group was denominated dysmyelinating<unk> s by Poser. In the most well known example of<unk> , multiple sclerosis, evidence has shown that the body's own immune system is at least partially responsible. Acquired immune system cells called T-cells are known to be present at the site of lesions. Other immune-system cells called macrophages (and possibly mast cells) also contribute to the damage.
Demyelinating disease
Paraneoplastic cerebellar degeneration
Vascular myelopathy
Malignant multiple sclerosis
Hereditary CNS demyelinating disease
CMV polyradiculomyelopathy
Neurolathyrism
Neurocristopathy