0:01

This is yet another patient who

0:02

presented with fever and seizures.

0:08

Remarkably,

0:09

patients who have herpes encephalitis

0:11

have fever in about 90% of cases and

0:15

show seizures in about 80% of the cases.

0:18

In this case, we have a diffusion-weighted scan, which is

0:22

pretty dramatic in the medial hippocampal region and

0:26

uncus bilaterally, but worse on the right side. You can

0:30

see that as bright signal intensity on the DWI here.

0:34

A little less dramatic on the left side, but the

0:36

amygdala here is showing high signal intensity.

0:40

On the FLAIR scan,

0:42

again, what we see is bright signal intensity in

0:45

the medial hippocampal structures, the uncus-amygdala

0:49

region, worse on the right side than the left side.

0:53

In addition to findings that we would typically see in

0:58

patients who are elderly with small vessel

1:01

white matter changes, age-appropriate.

1:03

So this was a patient who did indeed

1:06

have herpes encephalitis but also had

1:09

lung cancer. In patients who have cancers,

1:13

the differential diagnosis, in addition

1:15

to the herpes, is a paraneoplastic syndrome.

1:20

Paraneoplastic syndromes can cause

1:22

a limbic encephalitis, and the

1:25

hippocampal formation is part of the limbic system.

1:28

Remember, the limbic system will also include

1:31

the fornix columns and the cingulum, in addition

1:35

to the amygdala and medial hippocampus.

1:39

So in this situation, um, with the presence of

1:43

fever, it's more likely to be an infectious etiology.

1:47

Those patients who have limbic encephalitis

1:49

from paraneoplastic syndromes

1:51

are less likely to show a fever.

1:53

Nonetheless, you may want to recommend, in those patients

1:57

who do not have fevers, that they screen for such

2:01

paraneoplastic antigens, as the Li, or Hue, or Ra

2:09

type of antigens that are associated with,

2:13

for example, ovarian cancer, lung cancer, and certain thymomas,

2:18

as well as testicular cancers.

2:21

In this case, it was a herpes encephalitis case,

2:24

and there was no evidence of abnormal contrast

2:29

enhancement, as opposed to that more fulminant case

2:33

of herpes encephalitis that I showed previously.

Case: Herpes Encephalitis in a Lung Cancer Patient on MRI

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