U-shaped fiber, why on earth are you affected?

In the past N years, at the case analysis meeting, I can hear that "U-shaped fibers" are involved and can identify certain diseases, but why and how to identify them? Whenever you encounter this problem, you can search for various public accounts in WeChat.
But did not find the answer
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This question seems to be too simple, or is this a unique secret that only experts know? Author: Chen Xiaohui This article is published by Yimaitong authorized by the author, please do not reprint without authorization
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What is U-shaped fiber? In short, U-shaped fibers are short fibers that connect the cortex and the cortex, and are bow-shaped, sometimes called "bow-shaped fibers
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The normal process of myelin formation and development follows a process from inside to outside and from back to front; the U-shaped fibers under the cortex form the latest
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The screenshot is from https:// How to see if it is affected? Look like the picture below.
Reproduced from https://radiopaedia.
org/play/3472/entry/42861/slide/30425?lang=us What are the conditions that are easily affected? (1) Because the metabolism of the myelin sheath of the U-shaped fiber is slow, the U-shaped fiber may not be involved in the disease that affects the metabolism of the myelin
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(2) Diseases that directly affect oligodendrocytes.
U-shaped fibers are often early involved (for example, progressive multifocal leukoencephalopathy associated with HIV infection; multiple sclerosis [MS]), and mainly affect astrocytes (HIV encephalopathy; NMOSD) demyelinating disease U-shaped fibers are not involved; in some studies, isolated U-shaped fiber involvement is believed to be similar to Dawson’s finger sign, suggesting MS rather than NMOSD
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There are also some studies that do not support it.
You can make clinical observations yourself
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(3) The subcortical blood supply is abundant, and the U-shaped fibers of vascular white matter disease are not affected in the early stage (but may be affected in severe cases)
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Table 1 U-type fibers can be affected/early not involved in the disease abbreviations: MS, multiple sclerosis; ADEM, acute disseminated encephalomyelitis; NMOSD, optic neuromyelitis spectrum disease; PML, progressive multifocal leukoencephalopathy
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 Practice is the standard for testing truth (1) Early U-shaped fibers of vascular white matter hyperintensity are not involved, but severe cases can be affected.
[1] (2) Progressive multifocal leukoencephalopathy is pathologically characterized by JC virus infection in oligodendrocytes.
The lesions are asymmetrical and present a marginal distribution compared with HIV encephalopathy.
U-shaped fibers are affected early; HIV encephalopathy mainly involves astrocytes, and the lesions are symmetrical and distributed around the ventricle.
U-shaped fibers are not affected [2](3) Isolated U Type fiber involvement suggests MS, which can be used as a reference to identify NMOSD[3]MS(4) Leukodystrophy (Adrenal Leukodystrophy, Metachromatic Leukodystrophy) Early U-shaped Fiber Involvement[4], Alexander’s Disease, Cavana disease (spongiform leukodystrophy) early involvement of U-shaped fibers [5] (5) Because U-shaped fibers are metabolized slowly, most metabolic toxic white matter lesions do not involve U-shaped fibers, but it is not absolutely written at the end Whether U-shaped fibers are involved is related to the course of the disease, is relative, and related to the severity of the disease, and does not have absolute diagnostic value
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But now that the reason is known, a little attention when reading the film in the future may bring new gains
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 References: [1]https://radiopaedia.
org/play/3472/entry/42877/case/30361/studies/31003?lang=us[2] Sarbu N, Shih RY, Jones RV, Horkayne-Szakaly I, Oleaga L, Smirniotopoulos JG.
White Matter Diseases with Radiologic-Pathologic Correlation.
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Evaluation of brain lesion distribution criteria at disease onset in differentiating MS from NMOSD and MOG-IgG-associated encephalomyelitis.
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[4 ] https://radiopaedia.
org/articles/x-linked-adrenoleukodystrophy-1?lang=us[5] Messing A, Brenner M, Feany MB, Nedergaard M, Goldman JE.
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[6] Keogh CF, Andrews GT, Spacey SD, Forkheim KE, Graeb DA.
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