0:00

Let's seize our way into this posterior fossa lesion

0:03

in a middle-aged to slightly elderly woman.

0:07

who has a left-sided mass. Initially,

0:10

as you've said all along,

0:11

the most important thing is to decide

0:13

is it intra or extra-axial?

0:15

This one is sharply marginated,

0:17

it pushes the gray and white matter inward,

0:20

it's got an attachment to the dura,

0:22

so it's an extra-axial lesion.

0:25

It's pretty smooth and gray.

0:26

It's most likely a meningioma, it is a meningioma.

0:29

and we know meningiomas,

0:30

omen occur more frequently in females.

0:31

This is a female. I think the ratio is about 57:00.

0:34

rare and kids unless it's syndromic.

0:37

and typically in kids.

0:38

the location is gonna be a typical.

0:40

the peak.

0:40

age for those you've been taking exams 50 years of age.

0:43

so 21:00 is the is kind of the range.

0:47

uh, individuals can develop meningioma secondarily.

0:50

to uh XRT low-grade radiation.

0:53

and they could also develop or enhance.

0:55

or exacerbate their meningioma with estrogen.

0:58

secretion or exogenous estrogen administration.

1:02

because these tumors do have.

1:04

progesterone and estrogen receptors.

1:07

and then the other cause of meningioma.

1:09

when as long as we're talking.

1:10

demographics is syndromic and genetic.

1:13

so the genetic one everybody is familiar with is NF2.

1:16

found on chromosome 22.

1:18

Everybody knows that to take an examination.

1:21

Um, it's also associated with other tumors in NF2.

1:23

NF2 that we will.

1:24

Talk about right now.

1:25

remember with the meningeal mesenchyme.

1:28

then we've also got other syndromes.

1:29

it causes of an injury.

1:30

I'll rattle them off pretty fast

1:32

uh, nevoid basal cell syndrome,

1:34

multiple endocrine adenomatosis type one BAP one tumor

1:39

uh, predisposition syndrome,

1:41

Cowden syndrome or multiple hamartoma syndrome

1:45

Werner syndrome,

1:46

Rubenstein-Taybi syndrome,

1:48

and then familial

1:50

meningiomatosis which can be unilateral or bilateral.

1:53

Frequently they're everywhere

1:55

and this is a germ line mutation of

1:57

SMARCB1 and SMARCE1

2:00

so as we as we discuss the posterior fossa

2:04

meningioma, let's talk about locations for these.

2:07

What's the most common location

2:09

most common location would be the cerebellopontine angle,

2:11

sure right around here,

2:13

and what would you say

2:14

would it be the second most or second or 3rd

2:16

most common,

2:17

probably long the tentorium,

2:19

followed by jugular tubercle yeah,

2:21

so tentorium cerebelli anywhere?

2:23

There is a meningeal cap cells and then

2:24

along the jugular tubercle,

2:26

but sometimes you'll pick up in the coronal projection.

2:28

I'm intentionally not gonna magnify it

2:30

so you can get your bearings on the anatomy.

2:33

So here you've got your uh jugular tubercle right here

2:35

so you may see

2:36

I'm an meningioma draped right over this area

2:39

and it'll it'll appear as a very firm

2:41

gray adherent structure

2:44

and they even see it go down

2:46

into the jugular vein and go all the way down

2:48

into the neck

2:49

as a meningioma

2:51

and I've seen them get removed

2:52

and individuals have their carotid artery.

2:54

Cut which is is rather unpleasant.

2:57

Another location from an meningioma.

2:59

I'll blow this up a little bit

3:01

when it isn't talked about.

3:02

A lot is the uh

3:03

foramen magnum,

3:04

the falco tentorial interface right here

3:07

so you can see them right near the pineal gland,

3:10

and that falco tentorial location

3:12

uh can simulate a pineal region mass.

3:16

Occasionally

3:16

when they're down close to the dural venous sinuses,

3:19

they will compress those sinuses,

3:21

but they usually don't get occluded

3:23

and why is that

3:24

they don't get occluded?

3:25

Because meningiomas are typically

3:27

extremely slow growing and they

3:30

over time the body forms collaterals which will

3:33

essentially

3:35

exclude a venous infarction?

3:36

Yeah, so these you don't invade,

3:38

they usually just compress

3:39

and I don't remember ever seeing

3:41

meningioma,

3:42

only even a big one with a venous infarction.

3:45

So posterior fossa meningioma

3:47

typical locations for you

3:48

board and test takers

3:50

the C.

3:51

P angle number one and then you've got the tentorium,

3:53

the jugular tubercle, the falco tentorial region.

3:57

Don't forget to look at

3:58

the surrounding vascular structures,

3:59

the dural venous sinuses,

4:01

and also when you whenever you have a posterior fossa mass

4:02

because it's a smaller space,

4:04

you always have to be very sensitive about

4:05

compressive obstruction

4:08

cause that can be a medical emergency.

4:09

This patient doesn't have it,

4:11

but if you residents out there

4:12

beware of the posterior fossa

4:14

even when you have a small lesion

4:16

cause that may be the time you.

4:17

Have to make a phone call if there's

4:19

sudden or acute herniation.

4:20

Let's move on, shall we?