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

Sep 12
1/Do you feel there’s a back-log of findings in a spine MRI report?

Everyone talks about discs & facets, but not everyone talks about the endplates

Do you?

Do you need to talk about degenerative changes (Modic changes) of the endplates?

Here’s thread w/all you need to know! Image
2/Over 30 years ago, Modic et al. found there were 3 types of degenerative endplate changes:

(1) T2 bright changes (indicating edema, Modic 1)
(2) T1 bright changes (indicating fat, Modic 2)
(3) T1 & T2 dark changes (indicating sclerosis, Modic 3)

But what do they mean? Image
3/Let’s start w/Modic 1.

These are bright on T2, indicating edema

On pathology, it’s what you’d expect w/edema: inflammation, vascular granulation tissue, & high cellular turnover

Vascular granulation tissue means these can enhance on post contrast images—mimicking discitis! Image
Read 18 tweets
Sep 10
1/Are you FISHING for a way to better evaluate subarachnoid hemorrhage?

Are you hungry for a way to classify these patients?

Donut you worry!

Here’s a short thread to help you remember the modified Fisher scale for classifying subarachnoid hemorrhage. Image
2/Just think of the brain as a donut. Like a donut, it’s a bunch of stuff around a hole in the middle.

Ventricles are the hole in the middle of the brain just like there’s a hole in the middle of the dough in a donut.

Just don’t quote me to your neuroanatomy professor…. Image
3/Subarachnoid hemorrhage (SAH) added to the brain makes it less healthy, the same way adding toppings to a donut makes it less healthy.

Increasing severity of SAH is like increasingly unhealthy donut toppings. Fisher scale quantifies the vasospasm risk for increasing SAH Image
Read 8 tweets
Sep 8
1/Talk about twisting your back!

Do spine vascular lesions make your brain feel as tangled as the dilated vessels you see?

Want some more information on malformations?

Here’s a thread on spine vascular anatomy to give you durable knowledge on dural arteriovenous fistulas (dAVF)Image
2/To understand spinal dural AVFs, you need to understand basic spinal vascular anatomy.

The spine is LONG—to get blood from the top to the bottom is like going through the length of a marathon course Image
3/So we will need to tackle it like you tackle running a marathon.

When you run a marathon, you replenish yourself at aid/water stations along the way so you can make it all the way through.

Same w/spinal arterial vasculature—it needs to be replenished on the way down. Image
Read 19 tweets
Sep 3
1/Does the work up for dizziness make your head spin?

Wondering what to look for on an MR for dizziness

This month’s @theAJNR SCANtastic will tell you all you need about imaging Meniere’s disease!

ajnr.org/content/46/8/1…Image
@TheAJNR 2/The etiology for dizziness can have very diverse causes—each with very different treatments.

So it is important to try to differentiate

Meniere’s is a common cause & we can help diagnose it w/imaging! Image
@TheAJNR 3/To understand Meniere’s disease, you must know labyrinth anatomy

It has layers, like Russian nesting dolls. Outer doll is the bony labyrinth, holding perilymph & a second doll—membranous labyrinth.

Inside the membranous labyrinth is endolymph Image
Read 13 tweets
Aug 1
1/They say form follows function!

Brain MRI anatomy is best understood in terms of both form & function.

Here’s a short thread to help you to remember important functional brain anatomy--so you truly can clinically correlate! Image
2/Let’s start at the top. At the vertex is the superior frontal gyrus. This is easy to remember, bc it’s at the top—and being at the top is superior. It’s like the superior king at the top of the vertex. Image
3/It is also easy to recognize on imaging. It looks like a big thumb pointing straight up out of the brain. I always look for that thumbs up when I am looking for the superior frontal gyrus (SFG) Image
Read 12 tweets
Jul 29
1/Talk about bad blood!

Do you know when a hematoma is going to expand?

Read on for month’s @theAJNR SCANtastic on all you need to know about imaging intracranial hemorrhage!

ajnr.org/content/46/7/1…Image
@TheAJNR 2/Everyone knows about the spot sign for intracranial hemorrhage

It’s when arterial contrast is seen within a hematoma on CTA, indicating active
extravasation of contrast into the hematoma.

But what if you want to know before the CTA? Image
@TheAJNR 3/Turns out there are non-contrast head CT signs that a hematoma may expand that perform similarly to the spot sign—and together can be very accurate.

How can you remember what they are? Image
Read 9 tweets

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