0:01

We are proceeding with this patient who had a dense MCA

0:05

sign on the non-contrast CT scan and then had a CTA.

0:09

The CTA showed the occlusion of the M1 segment

0:14

of the left middle cerebral artery, as well

0:16

as a clot that was extending in the proximal

0:19

A1 segment of the middle cerebral artery.

0:22

Now, at that point, sometimes you will

0:24

have a CT perfusion study to see whether

0:28

the entire middle cerebral artery distribution is

0:31

infarcted, or you may just have the CTA, and they're

0:36

making a judgment about whether to proceed to

0:39

thrombectomy based on the patient's symptomatology.

0:44

In this case, the patient did not have a CT

0:46

perfusion but did go on to thrombectomy.

0:51

And that was considered successful.

0:54

Two days later, the patient had this

0:57

MRI scan that I'm about to show you.

1:00

Now, if the thrombectomy was successful, we would hope

1:05

that the speech areas would not have been infarcted,

1:11

and we would hope that the vast majority of the motor

1:15

cortex and the MCA distribution, again, would be spared.

1:20

And we can also make that assessment

1:22

based on the patient's symptomatology.

1:24

If the aphasia went away after the thrombectomy,

1:28

then there was good reperfusion. Nonetheless, in most

1:32

cases—not in the emergency room potentially, but as

1:36

an inpatient—the patient will have a follow-up MRI,

1:40

because diffusion-weighted imaging still, to this day,

1:43

is our gold standard for the imaging of a stroke.

1:47

It's not the gold standard for determining

1:49

whether the patient has neurologic deficits.

1:52

That's the patient, and that's the clinical examination.

1:55

However, for the imaging evaluation

1:56

of the volume of infarcted tissue,

2:00

it remains diffusion-weighted imaging.

2:02

And that's what I would start in any

2:04

case in which you are being asked about

2:07

the BAT team—Brain Attack Team—or,

2:10

uh, for an acute stroke. Go immediately

2:14

to your diffusion-weighted imaging to

2:16

see whether an acute stroke is there.

2:19

So that way, you can make that call much earlier

2:22

to the clinicians because time is brain, right?

2:26

So, if they can save some brain, uh,

2:29

then the patient has fewer neurologic

2:31

deficits and a better long-term prognosis.

2:34

So, here's an MRI scan when we scan the patient.

2:39

Particularly in this setting, the very first clinical

2:44

pulse sequence that we're going to do is going

2:47

to be the diffusion-weighted scanning after a scout

2:50

image to determine the location of those slices.

2:53

So, for example, if I just show you this, this is

2:56

the scout image—three images, basically—that take

2:59

about, you know, 10 seconds, and then the next

3:03

pulse sequence is going to be our diffusion-weighted

3:05

imaging. For the diffusion-weighted imaging,

3:08

remember that there is an initial B0 in which the

3:11

diffusion gradients have not been applied, and then

3:14

there is the B1000 in most clinical settings, where the

3:19

diffusion gradients have been applied.

3:22

And here we see the patient's diffusion-

3:25

weighted scan on diffusion-weighted imaging.

3:27

Imaging strokes are bright, so here

3:30

we have the patient who had that.

3:33

M1 segment occlusion and A1 segment thrombus.

3:37

And what we see is a stroke, which is limited to

3:40

the caudate nucleus and putamen on the left side.

3:45

All of the remainder of the middle

3:47

cerebral artery distribution on the left

3:50

side was saved by that thrombectomy.

3:54

So, there is an acute infarction here.

3:56

It's affecting the basal ganglia, which

3:58

likely will cause motor neurologic problems.

4:01

But the speech centers of Broca's area and Wernicke's

4:07

area have been spared, and therefore, one would suggest

4:11

that this is a successful case in which, although

4:15

a stroke was not avoided, the vast majority of the

4:18

middle cerebral artery distribution has been saved.

4:23

Now, after looking at this diffusion-weighted

4:25

imaging, I'm on the phone with a clinician saying,

4:28

"Hey, this patient has had an acute infarction.

4:31

It's involving the caudate and the putamen, predominantly

4:34

sparing the globus pallidus." So, you're on the phone

4:39

early to give that information as soon as possible.

4:43

The next thing they're going to ask you is,

4:45

"Is there any hemorrhage?"

4:48

So, the next pulse sequence that I would look at

4:50

is going to be our susceptibility-weighted scan.

4:53

The susceptibility-weighted scan is the scan

4:55

that is most sensitive to the presence of

4:58

hemorrhage. In this case, we see that

5:00

the globus pallidus region has low signal

5:04

intensity here, implying hemorrhagic products.

5:07

However, this is likely hemosiderin because

5:09

there's no edema surrounding it that I can see.

5:13

So, remember that the patient had had a prior

5:17

foraminal stroke, and this is probably hemorrhagic

5:21

hemosiderin blood products rather than acute

5:24

hemorrhage of deoxyhemoglobin.

5:26

In any case, it's limited to the basal

5:28

ganglia, not involving the distal middle

5:32

cerebral artery distribution tissue.

5:34

At that point, I would probably go to the FLAIR scans.

5:37

The FLAIR scans are going to be our global

5:39

view of what's going on in the brain.

5:42

It identifies for us the old injury

5:46

where there had been that craniotomy that

5:48

we had seen on a non-contrast CT scan.

5:50

So, this is gliosis.

5:51

This is not an acute infarction.

5:53

We know that because the DWI was negative.

5:56

Here, we have loss of volume in the

6:01

foraminal region from the prior stroke.

6:03

Here, we have another area where

6:04

there's cortical injury and scarring.

6:07

But once again, this was negative on the DWI.

6:09

So, let me just verify that for you

6:12

by putting side by side the DWI.

6:17

So, we're at the top of the ventricles here.

6:19

This is this area here.

5:07

However, this is likely hemosiderin because

5:09

there's no edema surrounding it that I can see.

5:13

So remember that the patient had had a prior

5:17

foraminal stroke, and this is probably hemorrhagic

5:21

hemosiderin blood products rather than acute

5:24

hemorrhage of deoxyhemoglobin.

5:26

In any case, it's limited to the basal

5:28

ganglia, not involving the distal middle

5:32

cerebral artery distribution tissue.

5:34

At that point, I would probably go to the FLAIR scans.

5:37

The FLAIR scans are going to be our global

5:39

view of what's going on in the brain.

5:42

It identifies for us the old injury

5:46

where there had been that craniotomy that

5:48

we had seen on a non-contrast CT scan.

5:50

So this is gliosis.

5:51

This is not an acute infarction.

5:53

We know that because the DWI was negative.

5:56

Here we have loss of volume in the

6:01

foraminal region from the prior stroke.

6:03

Here we have another area where

6:04

there's cortical injury and scarring.

6:07

But once again, this was negative on the DWI.

6:09

So let me just verify that for you

6:12

by putting side by side the DWI.

6:17

So we're at the top of the ventricles here.

6:19

This is this area here.

6:21

No bright signal on the DWIs.

6:22

This is an old injury.

6:24

Similarly, this is an old injury on the FLAIR scans.

6:27

The next thing I would look at is the T2-weighted scan.

6:30

The T2-weighted scan is our better assessment

6:33

of the posterior fossa structures.

6:36

So I look at the brainstem, I look at

6:37

the cerebellum, I look at the pons.

6:40

Here, I look at the middle cerebellar peduncles.

6:42

No injury in the posterior fossa on the T2-weighted scan.

6:47

Again, we see

6:49

the acute infarction as well as the old infarction.

6:54

This is this area over here where

6:57

there was a previous injury.

6:59

There is a little bit of a small area

7:01

going into the beam, but the vast majority

7:03

of this shows evidence of chronicity.

7:07

At this point, you may have an MRA.

7:12

Most of the time, if you've had a CTA in

7:14

advance of the MRA, there's really no need

7:18

to duplicate the neurovascular imaging.

7:21

You go with the CTA.

7:22

So in summary, for this case, the correct diagnosis is a

7:28

left middle cerebral artery M1 segment occlusion with a

7:33

proximal left A1 segment small area of clot as well,

7:40

associated with a basal ganglionic

7:43

infarct and older injuries to the brain

7:47

in the left frontal lobe and left putamen.

7:50

The thrombectomy avoided involvement of a large

7:55

portion of the middle cerebral artery with

7:57

preservation of Broca's motor speech area,

8:04

as well as Wernicke's receptive speech area

8:08

on the diffusion-weighted MRI scan.

8:11

So congratulations if you got all

8:13

that on your analysis of this case.