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

Jul 23
1/My hardest thread yet! Are you up for the challenge?

How stroke perfusion imaging works!

Ever wonder why it’s Tmax & not Tmin?

Do you not question & let RAPID read the perfusion for you? Not anymore! Image
2/Perfusion imaging is based on one principle: When you inject CT or MR intravenous contrast, the contrast flows w/blood & so contrast can be a surrogate marker for blood.

This is key, b/c we can track contrast—it changes CT density or MR signal so we can see where it goes. Image
3/So if we can track how contrast gets to the tissue (by changes in CT density or MR signal), then we can approximate how BLOOD is getting to the tissue.

And how much blood is getting to the tissue is what perfusion imaging is all about. Image
Read 18 tweets
Jul 21
1/Do you know all the aspects of, well, ASPECTS?

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

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
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 ptsImage
Read 12 tweets
Jul 2
1/The medulla is anything but DULL!

Does seeing an infarct in the medulla cause your heart to skip a beat?

Does medullary anatomy send you into respiratory arrest?

Never fear, here is a thread on the major medullary syndromes! Image
2/The medulla is like a toll road.

Everything going down into the cord must pass through the medulla & everything from the cord going back up to the brain must too.

That’s a lot of tracts for a very small territory. Luckily you don’t need to know every tract Image
3/Medulla has 4 main vascular territories, spread out like a fan: anteromedial, anterolateral, lateral, and posterior.

You don’t need to remember their names, just the territory they cover—and I’ll show you how Image
Read 18 tweets
Jun 30
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/Strokes evolve, or grow old, the same way people evolve or grow old.

The 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
3/Initially (less than 4-6 hrs), the only finding is restriction (brightness) on diffusion imaging (DWI).

You can remember this bc in the first few months, a baby does nothing but be swaddled or restricted. So early/newly born stroke is like a baby, only restricted Image
Read 10 tweets
Jun 27
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 23
1/Do you get a Broca’s aphasia trying remember the location of Broca's area?

Does trying to remember inferior frontal gyrus anatomy leave you speechless?

Don't be at a loss for words when it comes to Broca's area

Here’s a 🧵to help you remember the anatomy of this key region! Image
2/Anatomy of the inferior frontal gyrus (IFG) is best seen on the sagittal images, where it looks like the McDonald’s arches.

So, to find this area on MR, I open the sagittal images & scroll until I see the arches. When it comes to this method of finding the IFG, i’m lovin it. Image
3/Inferior frontal gyrus also looks like a sideways 3, if you prefer. This 3 is helpful bc the inferior frontal gyrus has 3 parts—called pars Image
Read 13 tweets

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