Demyelinating disease

A demyelinating disease refers to any disease affecting the nervous system where the myelin sheath surrounding neurons is damaged. This damage disrupts the transmission of signals through the affected nerves, resulting in a decrease in their conduction ability. Consequently, this reduction in conduction can lead to deficiencies in sensation, movement, cognition, or other functions depending on the nerves affected. Various factors can contribute to the development of demyelinating diseases, including genetic predisposition, infectious agents, autoimmune reactions, and other unknown factors. Proposed causes of demyelination include genetic predisposition, environmental factors such as viral infections or exposure to certain chemicals. Additionally, exposure to commercial insecticides like sheep dip, weed killers, and flea treatment preparations for pets, which contain organophosphates, can also lead to nerve demyelination. Chronic exposure to neuroleptic medications may also cause demyelination. Furthermore, deficiencies in vitamin B12 can result in dysmyelination. Demyelinating diseases are traditionally classified into two types: demyelinating myelinoclastic diseases and demyelinating leukodystrophic diseases. In the first group, a healthy and normal myelin is destroyed by toxic substances, chemicals, or autoimmune reactions. In the second group, the myelin is inherently abnormal and undergoes degeneration. The Poser criteria named this second group dysmyelinating diseases. In the most well-known demyelinating disease, multiple sclerosis, evidence suggests that the body's immune system plays a significant role. Acquired immune system cells, specifically T-cells, are found at the site of lesions. Other immune system cells, such as macrophages (and possibly mast cells), also contribute to the damage. Symptoms and signs that present in demyelinating diseases are different for each condition.