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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More from @teachplaygrub

Jun 27
1/Blast from the past!

Sometimes to be next gen, you gotta to go old school!

Cutting edge pituitary imaging must be MRI, right?

Or can we go back to the future w/CT?

Here’s the latest in pituitary imaging in this month’s @theAJNR SCANtastic!

2/Pituitary imaging is actually very difficult.

First challenge is the small size of the gland & even smaller adenomas, requiring high resolution.

And the difference between adenomas & the gland is subtle—both enhance, but adenomas enhance SLIGHTLY less Image
3/The difference in enhancement is transient & ends quickly

So pituitary imaging must be done dynamically to catch this small window of difference

So we have to do very high resolution imaging very quickly—the worst of both worlds! Image
Read 12 tweets
Jun 21
1/”I LOVE spinal cord syndromes!” is a phrase that has NEVER, EVER been said by anyone.

Do you become paralyzed when you see cord signal abnormality?

Never fear—here is a thread on all the incomplete spinal cord syndromes to get you moving again! Image
2/Spinal cord anatomy can be complex.

On imaging, we can see the ant & post nerve roots.

We can also see the gray & white matter.

Hidden w/in the white matter, however, are numerous efferent & afferent tracts—enough to make your head spin. Image
3/Lucky for you, for the incomplete cord syndromes, all you need to know is gray matter & 3 main tracts

Anterolaterally, spinothalamic tract (pain & temp). Posteriorly, dorsal columns (vibration, proprioception, & light touch), & next to it, corticospinal tracts—providing motor Image
Read 20 tweets
Jun 19
1/”Tell me where it hurts.”

How back pain radiates can tell you where the lesion is—if you know where to look!

Remembering lumbar radicular pain distributions can be back breaking work--but here's a thread to help you! Image
2/Let’s start with L1.

L1 radiates to the groin.

I remember that b/c the number 1 is, well, um…phallic.

So the phallic number 1 radiates to the groin. Image
3/Let’s skip to L3 for a second.

I remember L3 is to the knee—easy, it rhymes! Image
Read 8 tweets
Jun 10
1/Do you know all the aspects of, well, ASPECTS?

Many know the anterior circulation stroke system—but posterior circulation (pc) ASPECTS is often left behind

25% of infarcts are posterior circulation

Do you know pc-ASPECTS?!

Here’s a thread to help you 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:
3/But it’s only useful for the anterior circulation.

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 pts Image
Read 8 tweets
May 29
1/Waving the white flag when it comes to white matter anatomy?

Turns out white matter anatomy isn’t black & white!

This months @theAJNR SCANtastic is the white knight you need to rescue you!

Here’s the white matter anatomy you NEED to know!

2/Gray matter or cortical functional anatomy is well known.

Everyone knows the motor & sensory strips. Most know Broca’s & Wernicke’s

But most forget that white matter has similar functional topography & just bc it’s white matter doesn’t mean it doesn’t have function! Image
3/But too often we don’t refer to this white matter functional anatomy.

Instead we use general terms like “corona radiata”

But that’s the equivalent of using the word “body.”

Just like the body has many different systems in it, so does the corona radiata! Image
Read 12 tweets
May 21
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! Image
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
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 21 tweets

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