1/Sometimes the tiniest thing can be the biggest pain—that’s microvascular compression of the trigeminal nerve! But seeing such a tiny finding can be hard!
2/The most important thing to remember is that the nerve is 3D so you have to look for compression in all 3 planes. Let’s start w/the axial plane. On a normal axial, the trigeminal nerves should look like the arms of an alien sticking out of the pons.
3/Compression in the axial plane usually will deviate the nerve laterally—making it so that the Alien looks like he is flexing one of his arms. So if you see the Alien trying to show his guns—that’s microvascular compression!
4/In the sagittal plane, the nerve looks like an elephant’s trunk coming out of the pons. It should have a smooth curve up and over before it enters Meckel’s cave, just like the way an elephant’s trunk curves.
5/If the trunk is flattened, like it’s balancing ball or is curved downwards—that’s microvascular compression in the sagittal plane. If the nerve is pressed downward, you could miss this in the axial plane—bc the movement is parallel to the axial plane. You need a sagittal view
6/In the coronal plane, the nerves look like two gun barrels pointed at you, by a very potty bellied cowboy that is the pons.
7/If the nerves lose their gun barrel shape, and looks more like a boomerang—in any direction—that is microvascular compression. Coronal is usually the most helpful view, bc you can see movement both up and down and left to right.
8/So now you know what the normal trigeminal nerve looks like in all 3 planes—and you can now check for microvascular compression in three dimensions. Remember, images may be 2D, but life—and pathology—are 3D!
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1/Having trouble remembering what you should look for in vascular dementia on imaging?
Almost everyone worked up for dementia has infarcts. Which ones are important?
Here’s a thread on the key findings in vascular dementia!
2/Vascular cognitive impairment, or its most serious form, vascular dementia, used to be called multi-infarct dementia.
It was thought dementia directly resulted from brain volume loss from infarcts, w/the thought that 50-100cc of infarcted related volume loss caused dementia
3/But that’s now outdated. We now know vascular dementia results from diverse pathologies that all share a common vascular origin.
It’s possible to lose little volume from infarct & still result in dementia.
So if infarcts are common—which contribute to vascular dementia?
1/ I always say, "Anyone can see the bright spot on diffusion images—what sets you apart is if you can tell them why it’s there!”
If you don't why a stroke happened, you can't prevent the next one!
Can YOU tell a stroke’s etiology from an MRI?
Here’s a thread to show you how!
2/First a review of the vascular territories.
I think the vascular territories look a butterfly—w/the ACA as the head/body, PCA as the butt/tail, and MCA territories spreading out like a butterfly wings.
3/Of course, it’s more complicated than that.
Medially, there are also small vessel territories—the lenticulostriates & anterior choroidal.
I think they look like little legs, coming out from between the ACA body & PCA tail.
1/Have disagreements between radiologists on the degree of cervical canal stenosis become a pain in the neck?!
Worried about sticking your neck out and calling severe cervical stenosis?
Here’s a thread on cervical stenosis grading that’s easy, reproducible & evidence based!
2/In the lumbar spine, it is all about the degree of canal narrowing & room for nerve roots.
In the cervical spine, we have another factor to think about—the cord.
Cord integrity is key. No matter the degree of stenosis, if the cord isn’t happy, the patient won’t be either
3/Cord flattening, even w/o canal stenosis, can cause myelopathy.
No one is quite sure why.
Some say it’s b/c mass effect on static imaging may be much worse dynamically, some say repetitive microtrauma, & some say micro-ischemia from compression of perforators