Lea Alhilali, MD Profile picture
Aug 26, 2022 12 tweets 6 min read Read on X
1/”Now your mouth will drop when you see the cord compression we caused,” I said to my fellow looking at our targeted #bloodpatch CT, “But take a deep breath—that’s actually what we want.”
A #tweetorial about CSF leaks & blood patches! #medtwitter #CSFleak #neurotwitter #neurorad Image
2/Epidural blood patches (EBPs) have been around since the 60s. Blood was first injected in the epidural space to try to plug the leak in post-dural puncture HA. It has now been expanded to other CSF leaks. However, controlled studies are lacking & therefore methods vary greatly Image
3/No one is sure of how EBPs work. Some believe blood directly plugs the leak site. Other believe it’s a pressure effect--injected blood increases epidural pressure, squeezing the thecal sac like a stress ball, elevating subarachnoid CSF pressure to relieve low pressure HA. Image
4/In reality, it is probably both mechanisms. The pressure effect is likely what provides the immediate relief from the low pressure HA but the direct plug of the leak is likely what provides the long lasting effectiveness. Image
5/Since direct plugging likely gives long term relief, it’s important to patch the leak site, to increase the likelihood the blood will reach the defect. Finding the leak site could fill a whole other tweetorial. Today we will focus on how to treat the site after it’s found. Image
6/Leaks occur at 3 main sites: (1) Ventrally, usually from an osteophyte spike tearing the dura (2) At the nerve root sleeve, likely related to a leak from a leaking/torn nerve root sleeve diverticulum (3) Dorsally, usually related to a lumbar puncture or spinal intervention Image
7/To get a targeted patch for a ventral leak, a transforaminal approach w/a 22g spinal needle is used to access the ventral epidural space. Care should be taken to avoid the nerve root in the foramen. Both fibrin glue & blood are given to maximize the chance of plugging the leak Image
8/For a leak at the nerve root sleeve, a similar approach for a targeted patch is used, except the needle is stopped short in the foramen and blood/fibrin is given in this region. Image
9/For a nerve root sleeve leak targeted patch, one should see epidural reflux of contrast, to indicate the whole nerve root sleeve has been coated by the patch. For ventral leaks, it is important to confirm that blood has spread across the ventral epidural space to cover the leak Image
10/For a dorsal leak, the traditional interlaminar approach to the epidural space is used. This can be achieved using either fluoroscopy or CT depending on the site.

Choice of injection material/volume can and do vary for all these EBPs depending on the proceduralist Image
11/A significant volume should be given—bc the patch will shrink. I give at least 4cc fibrin & 5-10cc blood—depending on pt tolerance--this guides you. So cord compression is fine, as long as the toes can move. Patch will shrink—like this patch imaged on myelography 3 days later Image
12/Here is a 3D rendering of targeted EBPs/fibrin at 2 levels punctured during spinal stimulator insertion. You can see that over half the canal is filled by the patch. I always tell my fellows a little rhyme: Remember thecal sac compression will lead to symptom regression! Image

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Mar 14
1/The 90s called & wants its carotid imaging back!

It’s been 30 years--why are you still just quoting NASCET?

Do you feel vulnerable when it comes to identifying plaque vulnerability?

Here’s a thread to help you identify high risk plaques with carotid plaque imaging Image
2/Everyone knows the NASCET criteria:

If the patient is symptomatic & the greatest stenosis from the plaque is >70% of the diameter of normal distal lumen, patient will likely benefit from carotid endarterectomy.

But that doesn’t mean the remaining patients are just fine! Image
3/Yes, carotid plaques resulting in high grade stenosis are high risk.

But assuming that stenosis is the only mechanism by which a carotid plaque is high risk is like assuming that the only way to kill someone is by strangulation. Image
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1/Do you know all the aspects of, well, ASPECTS?

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25% of infarcts are posterior circulation

Do you know pc-ASPECTS?!

Here’s how to remember pc-ASPECTS! Image
2/Many know anterior circulation ASPECTS.

It uses a 10-point scoring system to semi-quantitation the amount of the MCA territory infarcted on non-contrast head CT

If you need a review: here’s my thread on ASPECTS: Image
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Posterior circulation accounts for ~25% of infarcts.

Even w/recanalization, many of these pts do poorly bc of the extent of already infarcted tissue.

So there’s a need to quantitate the amount of infarcted tissue in these ptsImage
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Mar 10
1/I always say you can tell a bad read on a spine MR if it doesn’t talk about lateral recesses.

What will I think when I see your read? Do you rate lateral recess stenosis?

Here’s a thread on lateral recess anatomy & a grading system for lateral recess stenosis Image
2/First anatomy.

Thecal sac is like a highway, carrying the nerve roots down the lumbar spine.

Lateral recess is part of the lateral lumbar canal, which is essentially the exit for spinal nerve roots to get off the thecal sac highway & head out into the rest of the body Image
3/Exits have 3 main parts.

First is the deceleration lane, where the car slows down as it starts the process of exiting.

Then there is the off ramp itself, and this leads into the service road which takes the car to the roads that it needs to get to its destination Image
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Mar 3
1/Does PTERYGOPALATINE FOSSA anatomy feel as confusing as its spelling?

Does it seem to have as many openings as letters in its name?

Are you pterrified of the pterygopalatine fossa (PPF)?

Let this thread on PPF anatomy help you out. Image
2/The PPF is a crossroads between the skullbase & the extracranial head and neck

There are 4 main regions that meet here:

(1) Skullbase itself posteriorly, (2) nasal cavity medially, (3) infratemporal fossa laterally, and (4) orbit anteriorly. Image
3/At its most basic, you can think of the PPF as a room with 4 doors opening to each of these regions: one posteriorly to the skullbase, one medially to the nasal cavity, one laterally to the infratemporal fossa, and one anteriorly to the orbit Image
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Feb 28
1/Feel like a fish out of water when it comes to water on the brain?

Read on for this month’s @Radiographics summary of what you need to know about hydrocephalus!!



@cookyscan1 @RadG_editor #RGphx doi.org/10.1148/rg.240…Image
2/To understand hydrocephalus, think of CSF like the flow of traffic

3 main ways traffic backs up:

(1) Obstruction on the road:
For hydrocephalus, this is an obstruction along CSF in the ventricle Image
3/

(2) Obstruction of an off ramp
For hydrocephalus=obstruction at its off ramp into the venous system

(3) Rush hour
For hydrocephalus=over production Image
Read 8 tweets
Feb 27
1/Do scans for dizziness make your head spin?

Need to know what to look for?

Just hear me out!

This month’s @theAJNR SCANtastic will show what to look for:

ajnr.org/content/46/2/3…Image
2/I always remember the rhyme of the big three for dizz-ee!

First, are vestibular schwannomas

These give an ice cream cone shape in the internal auditory canal! So scoop up that finding! Image
3/Next is labyrinthitis

Labyrinthitis can look like night & day, depending on the timing

Late labyrinthitis is dark—loss of bright fluid signal on FIESTA

Early labyrinthitis is bright—enhances on post-contrast Image
Read 12 tweets

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