Editing Multiple sclerosis (section)

=== Lesions ===
[[File:MS Demyelinisation KB 10x.jpg|thumb|Demyelination in MS: On [[Klüver-Barrera]] myelin staining, decoloration in the area of the lesion can be appreciated.]]
The name multiple sclerosis refers to the scars (sclerae – better known as plaques or lesions) that form in the nervous system. These lesions most commonly affect the [[white matter]] in the [[optic nerve]], [[brain stem]], [[basal ganglia]], and [[spinal cord]], or white matter tracts close to the lateral [[Ventricular system|ventricles]].<ref name="pmid1897097722"/> The function of white matter cells is to carry signals between [[grey matter]] areas, where the processing is done, and the rest of the body. The [[peripheral nervous system]] is rarely involved.<ref name="pmid119555563"/>

[[File:MRI machine with patient (23423505123).jpg|thumb|MRI machine used as a tool for MS diagnosis]]

To be specific, MS involves the loss of [[oligodendrocyte]]s, the cells responsible for creating and maintaining a fatty layer—known as the [[myelin]] sheath—which helps the neurons carry [[Action potential|electrical signals]] (action potentials).<ref name="pmid1897097722"/> This results in a thinning or complete loss of myelin, and as the disease advances, the breakdown of the [[axons]] of neurons. When the myelin is lost, a neuron can no longer effectively conduct electrical signals.<ref name="pmid119555563"/> A repair process, called [[remyelination]], takes place in the early phases of the disease, but the oligodendrocytes are unable to completely rebuild the cell's myelin sheath.<ref name="pmid17531860">{{cite book | vauthors = Chari DM  |chapter=Remyelination in Multiple Sclerosis | veditors = Minagar A |title=The Neurobiology of Multiple Sclerosis |series=International Review of Neurobiology |date=2007 |volume=79 |pages=589–620 |pmid=17531860 |pmc=7112255 |isbn=978-0-12-373736-6 |doi=10.1016/S0074-7742(07)79026-8 }}</ref> Repeated attacks lead to successively less effective remyelinations, until a scar-like plaque is built up around the damaged axons.<ref name="pmid17531860" /> These scars are the origin of the symptoms and during an attack [[magnetic resonance imaging]] (MRI) often shows more than 10 new plaques.<ref name="pmid1897097722"/> This could indicate that some number of lesions exist, below which the brain is capable of repairing itself without producing noticeable consequences.<ref name="pmid1897097722"/> Another process involved in the creation of lesions is an abnormal [[astrocytosis|increase in the number of astrocytes]] due to the destruction of nearby neurons.<ref name="pmid1897097722"/> A number of [[pathophysiology of multiple sclerosis#Demyelination patterns|lesion patterns]] have been described.<ref name="pmid17351524">{{cite journal | vauthors = Pittock SJ, Lucchinetti CF | title = The pathology of MS: new insights and potential clinical applications | journal = The Neurologist | volume = 13 | issue = 2 | pages = 45–56 | date = March 2007 | pmid = 17351524 | doi = 10.1097/01.nrl.0000253065.31662.37 | s2cid = 2993523 }}</ref>