0:01

This was a patient who presented

0:02

with worst headache of life.

0:05

On the non-contrast CT scan, we can see that

0:09

there is some effacement of the sulci

0:13

on the right side compared with the left side.

0:16

And, point of fact, some of this area here

0:19

that we see represents blood products in the sulci.

0:24

So, sometimes delayed subarachnoid hemorrhage

0:28

will look isodense to the gray matter, very

0:30

similar to an isodense subdural hematoma.

0:33

In this case, it's isodense blood products

0:36

in the subarachnoid space laterally here,

0:40

filling in the cerebrospinal fluid with

0:44

isodense hemorrhage to gray matter.

0:48

This patient presented with the worst

0:49

headache of life, so we would be concerned

0:51

about the potential for an aneurysm.

0:54

And I'm not sure whether this case was

0:55

confirmed or not with lumbar puncture.

0:58

However, the patient went on for CT angiography.

1:02

And although I don't have the reconstructed

1:04

images, I think that this is instructional in

1:08

and of itself, in that as you go out to the

1:11

area where there is the subarachnoid hemorrhage,

1:15

you see this round ball here. So, there's the

1:18

little round ball of a peripheral aneurysm.

1:25

So, here we have the area.

1:27

Now, why is this not just hemorrhage and bleeding?

1:31

As you can see, it's very, very well-defined,

1:33

and we did not see it on the non-contrast scan.

1:37

So, this is a peripheral aneurysm, and when we have

1:41

aneurysms in the periphery, we are more likely

1:44

to suggest that this is a mycotic aneurysm.

1:48

Now, the term "mycotic" usually implies

1:53

fungal disease in other scenarios.

1:56

In the scenario of describing aneurysms,

2:00

it just means an infected aneurysm,

2:02

rather than implying a specific pathogen.

2:06

In this, when we have mycotic aneurysms out in the

2:09

periphery, number one, they are more likely to bleed

2:12

into the parenchyma than Circle of Willis aneurysms.

2:17

They are more likely to be associated with subacute

2:21

bacterial endocarditis as an embolic phenomenon that goes

2:27

into the blood vessel and then leads to the blood vessel

2:29

deterioration and aneurysm formation or pseudoaneurysm

2:34

formation as the blood vessel is, uh, destroyed.

2:37

So, these aneurysms, as you might expect, are kind

2:40

of difficult to treat because they're so far in

2:44

the periphery that getting there endovascularly

2:47

is much more complicated, sort of like more

2:49

of a peripheral arteriovenous malformation.

2:52

In some cases, when it's clearly infected,

2:55

the patient will benefit from antibiotics,

2:59

and sometimes that blood vessel heals up,

3:01

so you don't even see the aneurysm anymore.

3:04

That is, uh, another potential strategy

3:07

for treatment of mycotic aneurysm.

3:10

So, the lesson here is when you see subarachnoid

3:14

hemorrhage in the periphery, not in the basal cisterns,

3:18

we have a higher suspicion for mycotic aneurysms.

3:22

We still do a CTA first.

3:25

And with the identification of a mycotic aneurysm,

3:30

there is a discussion about what the potential

3:32

therapeutic options for the patient are, as far as

3:36

treating with antibiotics and doing a follow-up

3:40

CTA to see whether it goes away or decreases in

3:43

size versus going with an endovascular approach.

3:47

Understanding that it is a much

3:49

harder, uh, uh, aneurysm to treat.