0:01

Remember that in addition to the focal neurologic

0:04

deficits that I've described previously, one of the

0:07

presentations of a stroke is dizziness or vertigo.

0:14

Again, this is a pretty nondescript,

0:17

uh, clinical presentation.

0:19

It can be Ménière's disease, it can be just

0:22

dehydration, but the concern by the clinicians

0:26

is, could this be vertebrobasilar artery

0:29

insufficiency? You'll see VBI (vertebrobasilar artery

0:33

insufficiency) or a brainstem stroke, for example.

0:38

So, this was a patient who had just those symptoms.

0:42

Again, the vast majority of

0:43

these are going to be negative.

0:45

This patient, as we look at the non-contrast CT scan,

0:49

we come into a basilar artery, which seems more dense

0:54

than the internal carotid arteries nearby at the

0:58

tip of the basilar artery.

1:00

And that is this density here.

1:02

Now, once again, I would be reflecting

1:05

more on the thin section images.

1:07

Here is the 347-slice portion.

1:11

And we see that the basilar artery seems to be

1:15

overly bright on multiple sections of this CT scan.

1:20

Assessing for the density of the basilar artery

1:22

when you're surrounded by basal cisterns,

1:25

which are dark, is somewhat more difficult than,

1:28

for example, the M1 segment, which is usually

1:31

with a comparison to the contralateral side.

1:33

With the basilar artery, obviously,

1:35

we only have one of them.

1:37

So, there is a suspicion here.

1:39

Again, when evaluating the patient for stroke,

1:42

the first thing I would do is get an overview of

1:44

the whole patient on the thick section images,

1:48

make sure that there is no hemorrhage,

1:50

which is going to require immediate assessment.

1:53

And then move from there to our

1:55

CTA and our thin section images.

1:58

So, once again, I'm going to show the CTA with the

2:02

thick section images initially, purely for the

2:06

purpose of getting through the case a little bit faster.

2:10

So, here we are down at the aorta, and we'll rapidly

2:15

look at the common carotid arteries together.

2:18

The carotid bifurcations together, they look good.

2:22

There was a little bit of calcification

2:24

here, but no high-grade stenosis.

2:27

And then we have our petrous internal carotid arteries

2:31

looking good, and our cavernous carotid arteries

2:34

with calcified plaque, but no high-grade stenosis.

2:38

On the other hand, let's look at our vertebral arteries.

2:42

So, here's the origin of the right vertebral

2:45

artery, the origin of the left vertebral artery.

2:47

Those look good.

2:48

Their V1 segment, prior to entering

2:51

the spinal canal, looks good.

2:53

The V2 segment within the spinal canal.

2:56

Looks good bilaterally, as it comes out of

3:00

the vertebral bodies and proximal to entering

3:04

the intracranial compartment, our V3 segment.

3:07

Little bit of narrowing here, but nothing high-grade.

3:11

Here we have the intracranial V4

3:13

segment of both vertebral arteries.

3:16

They come together.

3:17

Here is our basilar artery, and whoop!

3:20

Where did the basilar artery flow go?

3:22

This is exactly where we saw the

3:25

hyperdensity of the basilar artery.

3:28

Let me see whether I can just hit my 2

3:30

here and go back to the area where we

3:35

saw that high density was right in here.

3:39

And that's where this vessel

3:42

is no longer showing contrast.

3:45

Here's the basilar, pretty much at the midline.

3:48

Here it is again at the midline.

3:50

Dense on the non-contrast because of a clot.

3:55

Absence of flow because of that clot

3:58

in the mid to distal basilar artery.

4:01

And here we have the posterior cerebral arteries.

4:05

They may be getting flows from posterior

4:07

communicating artery collateral flow.

4:10

So let's look at this on our coronal MIP.

4:13

Again, my favorite, MIP.

4:15

I get to see both of the anterior

4:17

cerebral arteries nicely.

4:19

I get to see the A1 segments and the M1

4:23

segments nicely of the internal carotid artery.

4:26

Here's the distal internal carotid artery.

4:28

Distal internal carotid artery.

4:30

And, uh, uh, I have a segment missing here.

4:35

Left vertebral, right vertebral,

4:37

proximal basilar artery.

4:39

Segment missing before it gets to the basilar tip.

4:43

Here's the posterior cerebral,

4:45

posterior cerebral, superior cerebellar.

4:47

But where is this section right here?

4:51

That's where the clot is.

4:53

Let's look at that on the sagittal recon.

4:57

We have the basilar tip.

4:59

We have an outline of a clot.

5:02

We have the proximal basilar, but we have

5:04

a segment missing in the basilar artery.

5:09

This is an emergency because, obviously,

5:11

the basilar artery supplies the brainstem.

5:13

The brainstem runs breathing and cardiac function,

5:19

as well as lots of ocular motor function and cranial

5:23

nerve function, but we're missing that segment.

5:26

Let's look quickly at the CT perfusion.

5:29

Again, I'm on the phone telling the clinician,

5:33

"Hey, you've got a clot in the basilar artery.

5:36

Call the interventionist if they're not

5:38

already there as part of the BAT team."

5:40

This is the cerebral blood volume.

5:44

This is the

5:47

cerebral blood flow map, and what you're seeing

5:52

is within the brainstem and bilateral cerebellum.

5:56

This blue is not good.

5:59

You want it to be more on the red side.

6:02

And on the TMAX, you have all this.

6:07

Remember the TMAX, we have a six-second.

6:09

So anything longer than six seconds,

6:12

which is delayed, is abnormal.

6:14

In this case, bilateral cerebellar and brainstem

6:19

tissue is in the red zone.

6:21

We don't want that.

6:23

And it also affects some of—these

6:26

are the medial occipital lobes.

6:28

This is the normal signal on the

6:31

TMAX, as you can see in the MCA.

6:33

We want it to be blue and light blue.

6:35

Anything below six seconds is our threshold here.

6:38

In this case, we have all this tissue in the

6:42

vertebrobasilar artery distribution, the

6:44

basilar artery distribution, which is abnormal.

6:47

Now let me see whether I have my analysis.

6:50

So, this analysis package gives us the volume of the

6:53

penumbra, the volume of the infarction, and the amount

6:57

of tissue that is salvageable still after intervention.

7:04

So, this is an excellent example of going

7:07

outside the typical middle cerebral artery or

7:09

internal—the anterior circulation infarcts.

7:12

In this case, we have a posterior circulation

7:15

infarct in a patient presenting with dizziness,

7:18

represented by a clot in the mid to distal basilar

7:23

artery with associated perfusion abnormality in the

7:27

cerebellum and in the brainstem from that clot.