5/ The patient was significantly hypercarbic on the first ABG after intubation & continued to become apneic on SBT any time they slept.
This is due to the loss of respiration pattern generators in the lateral medulla (explained in more detail in the linked #tweetorial ⬆️)
6/ So, we have a suspected left lateral medullary stroke. The arterial supply is either the
🩸L vertebral artery or
🩸L PICA (usually a branch of the left vert)…
Back to the imaging:
The whole left side of the vertebral-basilar system is brighter than the right side. 🤔
7/ Here’s a source image.
You can see highlighted that left vert opacifies and the right doesn’t.
In a dissection, the side that is dissected loses/has diminished opacification due to tear/associated thrombus.
*Vert distribution* pathology is often ipsilateral to the tear.
8/ Said differently, in this case, the stroke localizes ipsilateral to the side that opacifies with contrast.
Another fun recon to emphasis this.
Left = opacified, right = not so much.
⬇️⬇️⬇️
9/ What is going on!?
Well, the big fact I left out in this case: the patient is in the CV-ICU on ECMO.
I know, I know. That’s really an important nugget of context! 😉 But for the fun of guessing...
10/ Next question: is why is the patient on ECMO?
Answer:
💔 Very advanced heart failure awaiting transplant
Which means the patient was on *VA-ECMO*
11/ In VA-ECMO the blood is removed from a venous cannula -> oxygenated -> returned to the arterial side to perfuse the rest of the body.
12/ There are a lot of models and configurations of ECMO. We do a fair number of consults with the CV-team, and I still find the different set-ups confusing.
BUT, if you take away nothing else, remember that it is so helpful to understand the setup when doing a stroke eval!
13/ In this case the patient had a sport configuration:
a left subclavian venous cannula sent blood to the ECMO and a left axillary arterial cannula returned the blood
ECMO set-up and native heart function affect where the mixing cloud is!
🔁Mixing cloud = where does the blood returning from the circuit meets the blood that has been pumped from the patient’s native heart.
15/ Can we see this with contrast?
1⃣st, how does contrast circulate if the patient is on ECMO?
Most contrast is removed via the venous cannula ➡️ circulates through ECMO ➡️flows to the arterial side ➡️ travels to the rest of the body. Review: tinyurl.com/2p92h29a
16/ So most contrast re-enters the circulation from the ECMO device!
A quick scroll down the CTA demonstrates the contrast-rich blood (from ECMO) mixes with the contrast-poor blood (from native heart) in the aortic arch between the left common carotid and the left subclavian.
17/
This is tricky to visualize, right?
Fortunately, Tammy Lin (@b3ta_lacTAM), CV-ICU fellow and illustrator extraordinary made a beautiful figure to illustrate this!!
Dark red = pumped from heart (*note* this blood is not hypoxic! Lungs were fine)
Light red = pumped from ECMO
18/ So! The difference in opacification reflects the difference in the source of perfusion: contrast-rich from ECMO versus contrast-poor from native heart.
19/ In this case the brachiocephalic & left common carotid got perfusion directly from the heart.
The left subclavian (and vert) received perfusion from the ECMO circuit.
Meaning that of the 4 vessels perfusing the brain, only the left vert received direct-from-ECMO blood!
20/
So... where did the lateral medullary stroke come from??
The ECMO circuit.
Here, a few days later, you can see that something seems off at the base of the brainstem on the left. MRI would be better.. but #ECMO.
21/ Finally, it’s hard to time a perfusion study for a patient on ECMO, so it may also be the perfusion is attenuated because of poor timing… but here is the CTP.
22/ So perfectly watershed-y, which fits with how the blood is traveling to the anterior circulation & right posterior circulation from a failing heart (seems plausible it would have delayed transit times). Notably, there is no green in the the L cerebellum.
Rads-- thoughts?
23/ Ultimately, this was a challenging case for many reasons.
But some takeaways are:
1⃣ Always look for pupil asymmetry in a pt with AMS
2⃣ Stroke consult? Ask the CV people to review the ECMO circuitry with you
3⃣ When possible find the contrast-mixing cloud
1/ 🥳Big News! This is the 1⃣0⃣0⃣th #CONTINUUMCASE!!
To celebrate? A must know dz, bc w/ this disease:
Time is Spine!
A 39 yo woman with Sjogren’s syndrome comes to the ED with sudden neck pain. Then arm weakness. Then leg weakness. All within 24 hours.
Now she can’t urinate
2/ On your exam, mental status=intact. But she has terrible vision in the right eye, which she reports is from a sjogrens attack.
She has 3/5 arm strength, 2/5 leg strength.
As shown above 🔼 she has a longitudinally extensive lesion w/ contrast at C2 and C3.
Is this Sjogrens?
3/ You complete a spinal tap.
‼️There are 120 WBC with a lymphocytic predominance‼️
A 58 yo woman with breast cancer on active chemo presented with shortness of breath.
She was just found to have (A).
Unfortunately, a head CT reveals (B).
They want to know – can she be a/c’ed? A #ContinuumCase
2/ Thoughts?
3/ Why does this feel like such a common conundrum? A few reasons.
1⃣incidence of brain mets may be 🔼 due to improved detection & better control of extracerebral dz
2⃣VTE is common in cancer patients & may also be 🔼 (more detection, longer life expectancy & novel treatments)
1/ A 35 yo M has lower limb weakness & painful hand & foot paresthesias.
EMG suggested axonal neuropathy and a presumed diagnosis of GBS was made.
After PLEX he was not better, instead he was becoming confused & ataxic.
How might a Thanksgiving Turkey solve this #ContinuumCase?
2/ Note: PLEX does not work immediately. In fact, many pts fail to have a response to immunotherapy during their hospitalization. Many continue to progress DESPITE treatment.
This does not mean that the treatment isn’t working. More is not better!
3/ Ok, off my soap box!
As you should for all confusing cases, you go back to the bedside and the patient tells you that over the last 2 months, he’s had increasing stress that resulted in an escalation of alcohol intake and reduced food intake.