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

Apr 25
1/Have some confusion about tumor perfusion?

Do you go into a coma looking at scans for glioma?

Never fear!

Read on for this month's @theAJNR SCANtastic for what you need to know on the latest in brain tumor imaging!

ajnr.org/content/45/4/4…
Image
@TheAJNR 2/Since the prehistoric days of medicine (1979!), we knew that some brain tumor patients treated w/radiation (XRT) initially declined, but then get better.

Today, we see this on imaging, where it looks worse early, but then gets better.

Now we call this pseudoprogression. Image
@TheAJNR 3/Why does this happen?

XRT induces a lot of inflammatory changes—from initiating the complement cascade to opening the blood brain barrier (BBB)

It’s these inflammatory changes that make the imaging look worse. Image
Read 21 tweets
Apr 19
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
Apr 18
1/”That’s a ninja turtle looking at me!” I exclaimed.

My fellow rolled his eyes, “Why do I feel I’m going to see this on X or twitter soon…”

He was right!

A thread about one of my favorite imaging findings & pathology behind it ! Image
2/Now the ninja turtle isn’t an actual sign—yet!

But I am hoping to make it go viral as one.

To understand what this ninja turtle is, you first have to know the anatomy in this region.

I have always thought the medulla looks like a 3 leaf clover in this region. Image
3/ The most medial bump of the clover is the medullary pyramid (motor fibers).

Next to it is the inferior olivary nucleus (ION), & finally, the last largest leaf is the inferior cerebellar peduncle.

Now you can see that the ninja turtle eyes correspond to the ION. Image
Read 11 tweets
Apr 17
1/CSF leaks are controversial!

Some say they're overdiagnosed, others underdiagnosed

How can YOU make sure you aren’t under or overdiagnosing?

Are you BERN-ing to know when to suspect CSF leak?

Here’s a 🧵about the CSF leak Bern score so you don’t get BERN-ed by CSF leaks Image
2/In CSF leaks, everyone knows about brain sagging.

But this can happen w/other diseases, ie Chiari 1.

Other findings can be seen on brain MRI in CSF leaks.

But what are these findings & are some findings more suggestive than others?

Do⬆️findings = ⬆️suspicion? Image
3/The Bern group looked at 9 quantitative & 7 qualitative signs seen on brain MRI in CSF leaks to see which are most important.

Depending on type & # of findings, they developed a score to indicate what level of suspicion you should have for a leak. Image
Read 15 tweets
Apr 15
1/Is remembering cerebellar anatomy making you dizzy?

Need help telling your flocculus from your nodule?

How much cerebellar anatomy do YOU know?

Here’s some help w/an anatomy thread on the 9 lobules of the vermis! Image
2/Coming from anterior, the first lobule is the lingula

It sticks out from the front of the vermis & is connected to the superior cerebellar peduncle (SCP)

I remember this bc of its very appropriate name—lingula—it looks like a tongue sticking out of the vermis to lick the SCP Image
3/Moving clockwise, next is the central lobule

I remember this bc it's positioned exactly how a central lobule should be positioned, in the driver’s seat!

It's where the front driver position would be if the vermis was a car—up front, looking out a windshield over the lingula Image
Read 12 tweets
Apr 12
1/Time is brain! But what time is it?

If you don’t know the time of stroke onset, are you able to deduce it from imaging?

Here’s a thread to help you date a stroke on MRI! Image
2/In ~25% of acute stroke patients, the time of last known well is well, not known.

Then it’s important to use the stroke’s MR imaging features to help date its timing.

Is it hyperacute? Acute? Subacute? Or are the “stroke” symptoms from a seizure from their chronic infarct? Image
3/Strokes evolve, or grow old, the same way people evolve or grow old.

Appearance of stroke on imaging mirrors the life stages of a person—you just have to change days for a stroke into years for a person.

So 15 day old stroke has features of a 15 year old person, etc. Image
Read 22 tweets

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