0:00

Stroke intervention is something that has been changing

0:05

very rapidly over the course of the last 10 years.

0:09

Largely because of some very large trials that have

0:12

shown amazing benefit in doing mechanical thrombectomy,

0:17

removing the clot from the vessel.

0:20

These are the 2018 American Heart Association

0:23

guidelines that we are now working under, again,

0:27

adopted also by the American Stroke Association.

0:31

However, this is 2021.

0:33

By the end of 2021, you don't know; there may

0:36

be new guidelines about how to treat stroke.

0:40

But currently, here's what we talk about.

0:41

The early window is less than six hours.

0:44

Remember that six hours is a good time frame for

0:47

MRI because a stroke within the first six hours,

0:52

theoretically, is going to be bright on diffusion-

0:55

weighted imaging but negative on FLAIR imaging.

0:58

So we can date the stroke to less than six hours.

1:02

In the period of zero to four and a half hours, current

1:05

treatment guidelines are intravenous thrombolysis,

1:09

with imaging with a non-contrast CT scan.

1:12

Most people, were they to see a dense MCA, would

1:17

probably still go on for mechanical thrombectomy.

1:22

In the period between zero to six hours, treatment

1:25

is thrombectomy with imaging, including the CTA

1:30

or the MRA, in order to define where the clot might be.

1:35

So, thrombectomy.

1:38

Extended window, which has been adopted,

1:42

suggests that even at 6 to 24 hours after

1:46

the initial presentation with a neurologic

1:49

deficit, patients may benefit from thrombectomy.

1:55

However, more and more interventionalists

1:59

are utilizing CT or MR perfusion in order

2:04

to identify whether the patient has tissue

2:07

at risk or whether it is a completed stroke.

2:10

If there is that mismatch, a volume greater than 1.2,

2:14

then that patient has tissue at risk that

2:18

might benefit from mechanical thrombectomy.

2:22

So we are now in a situation where, by virtue of the

2:27

different hours of presentation, the patient may get a

2:30

non-contrast CT, CTA, or CT perfusion—or, if you have

2:36

it in your armamentarium, an MR, MRA, and MR perfusion.

2:42

This is what we are working with currently as we start 2021.

2:47

Here, for example, is a patient

2:49

who has new left-sided weakness.

2:50

The CT scan was read as showing chronic changes.

2:55

The FLAIR images suggested abnormal changes

3:00

that were commensurate with those on the CT scan.

3:03

But when we did diffusion-weighted imaging,

3:07

we noticed that there was bright signal intensity on

3:10

the DWI and, on the ADC map, dark signal intensity.

3:15

Low ADC that was not present on the FLAIR scan.

3:21

This suggests that this area of abnormality

3:25

is less than six hours old—negative

3:28

on FLAIR, but positive on DWI and ADC.

3:33

So if we go backward, we're in this timeframe,

3:37

at least based on our imaging criteria.

3:40

Now, if we know when the patient's symptoms

3:43

developed, we might be more accurate clinically.

3:48

Again, here's a patient.

3:50

CT, CT with contrast—no stroke that I would see.

3:55

Nice insular ribbon, nice separation of the

3:58

caudate from the putamen with the intervening

4:00

internal capsule—anterior limb and posterior limb.

4:04

I'm calling this negative.

4:05

Here is the patient's CT perfusion—a large

4:10

right middle cerebral artery perfusion.

4:13

Again, depending upon the timing,

4:15

this may be treated with mechanical

4:17

thrombectomy if present on the CTA.

4:21

Same thing with MRI scanning.

4:23

You can have the same area of

4:26

perfusion abnormality on an MRP,

4:29

in this case, commensurate with a diffusion-weighted

4:33

imaging that shows the same area of infarction.

4:37

Here's the back edge of it.

4:38

Here's the ADC map showing dark signal intensity.

4:41

The basal ganglia is involved,

4:43

and it goes out to the frontal lobe.

4:45

So in this case, a diffusion

4:48

weighted scan shows the infarction.

4:51

Final example—here we have the MRI scan

4:55

showing an area of infarction on the DWI,

4:59

less than 70 cc's, a clot in the right M1 segment,

5:05

and perfusion deficits that show a mismatch

5:10

volume, which is far greater than 1.2

5:14

compared to the diffusion-weighted infarct.

5:17

This is another patient who, based on the

5:20

timing, would benefit from intravenous

5:23

thrombolysis and/or mechanical thrombectomy.