Lea Alhilali, MD Profile picture
Mar 15, 2023 8 tweets 5 min read Read on X
1/I call the skullbase “homebase” bc you can’t make an anatomy homerun without it!

Most know the arteries of the skullbase, but few know the veins. Do you?

Here’s a🧵to help you remember #skullbase venous #anatomy!
#medtwitter #meded #neurorad #radtwitter #neurosurgery #radres Image
2/When I look at the skullbase veins, I see an angry Santa yelling at me. His eyebrows are raised, his mouth is open, & he has a mustache w/a big beard hanging down.

Each I look at the skullbase, I look for this Santa—bc each part of him is an important venous structure. Image
3/So let’s start w/Santa’s eyes. The eyes are actually not a venous structure, but an important landmark—foramen ovale, where the V3 trigeminal nerve exit.

I remember ovale is Santa's eyes bc eyes are OVAL, so his eyes are OVALE Image
4/Next are Santa’s angry raised eyebrows. These are the sphenoparietal sinuses.

I remember these are the eyebrows bc I call them “seen”-oparietal sinuses & you see w/your eyes.

These have this “eyebrow” shape bc they are following the curve of the greater sphenoid wing Image
5/Sphenoparietal sinuses meet in the middle at the cavernous sinus—like your eyebrows meet in the middle at your nose.

I remember the cavernous sinus & intracavernous sinuses are Santa’s nose bc you dig in a cavern. And where do all kids like to go digging? Their nose! 🤢 Image
6/Right below Santa’s nose is his mustache & this is the basilar plexus, right below the cavernous sinus.

You can remember this bc mustaches are made of a base & handlebars—and the BASE of Santa’s mustache is the BASilar plexus Image
7/Extending from Santa’s mustache is his beard. These are the petrosal sinuses (inferior & superior), important in many neurosurgical approaches.

You can remember that the PETROsal sinuses make up sides of the beard bc you use PETROleum to smooth the sides of your beard Image
8/Finally, Santa’s mouth is the marginal sinus. I remember this bc the word marginal sounds like “Aaaargh”—the sound pirates make from their mouth. I call it the Maaaargh—inal sinus

So hopefully this thread has given you some ELF-confidence when it comes to skullbase anatomy! Image

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More from @teachplaygrub

Jun 4
1/Having trouble remembering what to look for in vascular dementia on imaging?

Almost everyone w/memory loss has infarcts. Which are important?

The latest @theajnr SCANtastic has what you need to know:

ajnr.org/content/46/5/1…Image
@TheAJNR 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 Image
@TheAJNR 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? Image
Read 20 tweets
Jun 2
1/Having trouble remembering how to differentiate dementias on imaging?

Is looking at dementia PET scans one of your PET peeves?

Here’s a thread to show you how to remember the imaging findings in dementia & never forget! Image
2/The most common functional imaging used in dementia is FDG PET. And the most common dementia is Alzheimer’s disease (AD).

On PET, AD demonstrates a typical Nike swoosh pattern—with decreased metabolism in the parietal & temporal regions Image
3/The swoosh rapidly tapers anteriorly—& so does hypometabolism in AD in the temporal lobe. It usually spares the anterior temporal poles.

So in AD look for a rapidly tapering Nike swoosh, w/hypometabolism in the parietal/temporal regions—sparing the anterior temporal pole Image
Read 16 tweets
May 27
1/Feel perplexed by the lumbosacral plexus??

This plexus doesn’t have to be so complex-us

Here’s what you need to know from this month’s @Radiographics!



@cookyscan1 @RadG_editor doi.org/10.1148/rg.240…Image
@RadioGraphics @cookyscan1 @RadG_Editor 2/The lumbosacral plexus is like a love story

The lumbar & sacral plexuses met & fell in love

They loved each other so much they came together to create the nerves to the lower extremities! Image
@RadioGraphics @cookyscan1 @RadG_Editor 3/Lumbosacral plexus is essentially formed by the nerves from L1-S4 (with some other small contributions)

Remember this bc the plexus is to the lower extremitieis and L & 1 look legs and S & 4 look like feet! Image
Read 12 tweets
May 6
1/Have disagreements between radiologists on the degree of cervical canal stenosis become a pain in the neck?

Worried about sticking your neck out & calling severe cervical stenosis?

This month’s @theAJNR SCANtastic has the latest about Cspine MRI!

ajnr.org/content/46/4/7…Image
@TheAJNR 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 Image
@TheAJNR 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 Image
Read 16 tweets
May 2
1/Do radiologists sound like they are speaking a different language when they talk about MRI?

T1 shortening what? T2 prolongation who?

Here’s a translation w/an introductory thread to MRI. Image
2/Let’s start w/T1—it is #1 after all! T1 is for anatomy

Since it’s anatomic, brain structures will reflect the same color as real life

So gray matter is gray on T1 & white matter is white on T1

So if you see an image where gray is gray & white is white—you know it’s a T1 Image
3/T1 is also for contrast

Contrast material helps us to see masses

Contrast can’t get into normal brain & spine bc of the blood brain barrier—but masses don’t have a blood brain barrier, so when you give contrast, masses will take it up & light up, making them easier to see. Image
Read 20 tweets
Apr 28
1/Asking “How old are you?” can be dicey—both in real life & on MRI! Do you know how to tell the age of blood on MRI?

Here’s a thread on how to date blood on MRI so that the next time you see a hemorrhage, your guess on when it happened will always be in the right vein! Image
2/If you ask someone how to date blood on MRI, they’ll spit out a crazy mnemonic about babies that tells you what signal blood should be on T1 & T2 imaging by age.

But mnemonics are crutch—they help you memorize, but not understand. If you understand, you don’t need to memorizeImage
3/If you look at the mnemonic, you will notice one thing—the T1 signal is all you need to tell if blood is acute, subacute or chronic.

T2 signal will tell if it is early or late in each of those time periods—but that type of detail isn’t needed in real life

So let’s look at T1Image
Read 20 tweets

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