After a great @CPSolvers #VMR on PML the other day, I found myself in the dark about U-fibers. Thanks to some nice #SpacedRepetition by @haematognomist I took a deeper dive.
They are affected differently bc they are among the last parts of the brain to myelinate, as late as the third or fourth decade
They have very slow myelin turnover and thus are affected last in diseases in which the abnormality is one of myelin metabolism/turnover like CADASIL
Just bc they are spared initially, over time they can become involved
Diseases in which the damage is direct to oligodendroglial cells, then no such relative sparing will be seen
And because JCV has tropism to oligodendrocytes, the pathology is seen!
Subcortical U-fibers are also protected from chronic small vessel ischemia
This is bc white matter receives dualblood supply, from penetrating arteries & deeper vessels ascending from perforators
Thus, the white matter closest to either source of blood should be least affected
Asymmetric multifocal bilateral confluent supratentorial lobar white matter involvement is the most common manifestation
The parietal lobe is most commonly involved
But there may be only 1 lesion restricted to subcortical U-fibers, ajnr.org/content/31/9/1…
Share this Scrolly Tale with your friends.
A Scrolly Tale is a new way to read Twitter threads with a more visually immersive experience.
Discover more beautiful Scrolly Tales like this.