0:01

These are four different patients manifesting

0:04

posterior reversible encephalopathy

0:07

syndrome, or what we call PRES.

0:10

In the top images, you see on the FLAIR scan,

0:14

high signal intensity in the subcortical white matter,

0:17

which is extending to involve the gray matter.

0:20

Although most of the time, we think of

0:22

PRES as more of a leukoencephalopathy

0:24

rather than a gray matter disorder.

0:27

Here is a more characteristic feature in

0:29

which you see the white matter high signal

0:32

intensity extending to the subcortical regions

0:35

bilaterally in the medial parietal lobes.

0:39

On post-gadolinium enhanced scan,

0:40

this is a different patient,

0:42

again showing a predominantly white matter

0:44

pattern without evidence of enhancement of the

0:48

white matter nor the underlying gray matter.

0:51

Here is a patient who has PRES that is extending

0:55

more anteriorly than the classic appearance,

0:59

but also affecting the brainstem, with the pons,

1:03

as well as deep gray matter here affecting the thalamus.

1:07

So these are four different patients, all with

1:10

posterior reversible encephalopathy syndrome.

1:13

Encephalopathy.

1:15

Therefore, the patient has mental status changes, AMS.

1:19

And this is one of the entities that you should

1:22

consider when you're looking at patients

1:24

who have a change in mental status or

1:27

are found down from the emergency department.

1:30

With respect to posterior reversible encephalopathy

1:33

syndrome, there are a number of etiologies.

1:37

The most common is fluctuations

1:40

in the patient's blood pressure.

1:42

While we typically think of PRES as showing high

1:45

blood pressure in the 200 range or 190 range

1:49

with a diastolic in the 100 to 120 range.

1:53

It may be that there is just wide

1:56

variation in the patient's blood pressure.

1:59

So sometimes we'll have patients come from

2:01

the dialysis unit with encephalopathy.

2:04

And what has happened is, because of the fluid dynamics

2:06

during dialysis, their blood pressure has gone

2:09

from a baseline of 120 over 70 up to 170 over 95.

2:15

That type of change in the blood pressure may lead

2:18

to posterior reversible encephalopathy syndrome.

2:22

Another situation is when we

2:23

have patients who are on cocaine.

2:26

After using the cocaine, blood pressure may go

2:28

very high, sort of like a methamphetamine effect.

2:31

Blood pressure goes very high.

2:33

By the time they get to the emergency room, their

2:35

blood pressure is normal, but they had that big

2:38

spike in their blood pressure, and that led to

2:42

posterior reversible encephalopathy syndrome.

2:44

The other scenario is in eclampsia and preeclampsia

2:47

in patients who are prepartum or postpartum and

2:51

have elevated blood pressure, as well as the, uh,

2:55

coagulopathy that we sometimes will see with eclampsia.

2:58

Finally, we have the medications, and

3:00

there are a lot of different medications,

3:02

mostly chemotherapeutic agents or

3:05

immunosuppressives that can cause posterior

3:08

reversible encephalopathy syndrome.

3:10

All these are causing a vasoregulatory problem,

3:15

that is more sensitive in the posterior

3:18

white matter and occipital and parietal

3:21

lobes rather than in the frontal regions.

3:25

And it usually does not cause a lot of mass effect.

3:30

So here are other etiologies for posterior

3:34

reversible encephalopathy syndrome.

3:37

Acute kidney injury, sepsis.

3:40

Now, with sepsis, you may have a very

3:42

low blood pressure, hypotension,

3:44

and then you return to normal blood pressure.

3:47

Those swings in the blood pressure

3:49

may be what is the common feature of posterior

3:53

reversible encephalopathy syndrome.

3:54

Autoimmune disorders.

3:56

I've talked about immunosuppressive drugs.

3:58

Tacrolimus is one of the drugs that is used

4:00

for multiple sclerosis, and there is that risk

4:04

of PRES in patients with multiple sclerosis.

4:08

Cyclosporine, we talked about.

4:10

FK 506, et cetera.

4:13

Illicit drugs, we talked about

4:15

cocaine, organ transplantation,

4:17

chronic kidney disease,

4:18

hepatorenal disease, another cause,

4:21

and dialysis.