Travis Smith, DO Profile picture
Jun 3, 2020 5 tweets 2 min read Read on X
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…

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May 30, 2021
Some cool #Syphilis Pearls from an article that @k_vaishnani shared ncbi.nlm.nih.gov/pmc/articles/P… Primary syphilis first manifests into a painless chancre at the site of inoculation 1 to 6 weeks later…
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curiousclinicians.com/2020/09/30/why…

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A Teal pain in the neck:

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