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Wk 4, Case 1 - Review

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0:00

It was a pretty straightforward case of vestibular schwannoma. Yeah, I mean,

0:05

it was a kind of a,

0:06

just a sort of a straightforward case with the left c p angle mass with a little

0:10

bit extending into the lateral aspect of the left po acoustics. So, um,

0:15

this to me was sort of a, an, an easier one.

0:19

This case will be fine.

0:20

So the main thing is to look at the widening of the porous cost discuss.

0:27

Yeah, I think, um, I would say th this way. So with vestibular schwannomas,

0:32

you know, they can either,

0:33

the most common location where they arise is actually in,

0:37

let me magnify this up.

0:40

It's felt to arise from the superior vestibular nerve.

0:44

And the majority of vestibular schwannomas are actually gonna arise a little bit

0:47

more distal. In this particular case,

0:50

this one arose from the more laterally at the CCP angle and extend it through

0:54

the pore acoustics.

0:56

So the reason why I showed this one is to kind of bring up the diagnosis of what

1:00

else can cause a CP angle mass and why this is not a meningioma.

1:04

So the differential diagnosis really would be between, um,

1:07

vestibular schwannoma and men meningioma. Um, the reason why this favors, uh,

1:12

vestibular schwannoma is that it's more oval. It doesn't have a dural tail,

1:17

it's not plaque like. And there is, you know,

1:20

a small component in this case that extends through the pores acoustics. Um,

1:25

I didn't, uh,

1:25

I didn't want to give you the classic one involved in the I E C 'cause that's

1:28

just too easy, but, um, mm-hmm. The key thing here is to,

1:32

to notice that it's not, um,

1:35

it doesn't have the dural tail and it's not plaque line.

1:38

Any other questions on this one?

1:40

I think this one probably shows a little bit better.

1:42

That little lip right here extending into the, um,

1:46

force acoustics into the I A C. See this area right here?

1:51

Yeah. Okay,

1:52

Good.

1:52

So, mening usually won't extend into I a C,

1:56

You know, occasionally it can extend into the I E C,

1:58

so I don't wanna say never is never, yes. But from my experience,

2:01

what ends up happening is that when you have a meningo in this location,

2:05

it's a little bit more broad based because it's arising from the dura.

2:09

So it's a little bit more oblique, where the, this is more grounded,

2:12

more shaped like a golf ball.

Report

Patient History
Left CP angle mass.

Findings
Pre- and postcontrast MR was performed of the brain and internal auditory canal.

Brain: Sagittal T1-weighted images demonstrate corpus callosum to be intact. No evidence of Chiari malformation. No abnormal pineal region masses. Pituitary gland is not enlarged. Diffusion imaging demonstrates no evidence of recent infarct. Axial FLAIR and T2-weighted images demonstrate mild prominence of the sulci and ventricles. Multiple punctate areas of increased FLAIR and T2 signal are seen in the juxtacortical, centrum semiovale, and periventricular white matter. These findings are likely due to microvascular angiopathy. No evidence of vasogenic edema or mass effect. Contrast-enhanced T1-weighted images show no abnormal intraaxial enhancing masses.

Internal Auditory Canals: Pre- and postcontrast images were performed through the internal auditory canals. Study demonstrates a likely low left-sided vestibular schwannoma that extends from the left cerebellopontine angle into the porous acusticus and involves the proximal two-thirds of the left internal auditory canal. The lesion does not extend into the fundus of the internal auditory canal. The lesion is isointense to brain on T1 and avidly enhances with contrast with heterogeneous T2 signal suggesting the diagnosis of vestibular schwannoma. There is mass effect on the underlying left middle cerebellar peduncle with mild effacement of the 4th ventricle. The posterior fossa component of the lesion measures approximately 1.8cm x 1.5cm in the transverse plane and approximately 2cm in the craniocaudad plane. The lesion extends into and widens the adjacent porous acusticus.

Thin-section T2 DRIVE sequences demonstrate mass effect with compression of the individual nerves of the left 7th and 8th nerve complex within the internal auditory canal. The contrast-enhanced T1-weighted images suggest some possible subtle enhancement of the nerves. There is no evidence of extension into the cochlear canal to involve the modiolus. Bilateral cochlea appear to have 2-1/2 turns. Basilar membrane is visualized. Modiolus is intact. No obvious evidence of congenital inner-ear malformation is identified. No evidence of enlarged vestibular aqueduct.

Conclusions
1. 1.8cm x 1.5cm x 2cm left vestibular schwannoma with both posterior fossa and internal auditory canal components as described above.
2. Punctate areas of increased FLAIR and T2 signal involving the white matter likely due to microvascular angiopathy.

Case Discussion

Faculty

David M Yousem, MD, MBA

Professor of Radiology, Vice Chairman and Associate Dean

Johns Hopkins University

Suresh K Mukherji, MD, FACR, MBA

Clinical Professor, University of Illinois & Rutgers University. Faculty, Michigan State University. Director Head & Neck Radiology, ProScan Imaging

Tags

Neuroradiology

MRI

Head and Neck