0:00

Let's review the intraconal orbital pathology.

0:04

Some of the cases of which we've seen and some of

0:07

which we will review just via the PowerPoint.

0:10

So, this is a list of the most common of the lesions

0:13

that occur in the intraconal space.

0:15

Far and away, the most common is going to be the

0:18

venous vascular malformation,

0:20

also known as the cavernous hemangioma.

0:24

Remember that the venous vascular malformation

0:26

is actually not a neoplasm, whereas,

0:28

infantile hemangiomas actually are neoplasms,

0:31

and I will demonstrate an example of that.

0:34

Then, we have the optic nerve sheath complex lesions which

0:37

include optic neuritis, optic nerve glioma,

0:40

optic nerve meningioma and pseudotumor,

0:43

also known as idiopathic orbital inflammation.

0:45

What we didn't talk about are some of the vascular

0:48

lesions and I'll describe them with PowerPoint,

0:52

and also schwannomas.

0:53

So the schwannomas are not going to be optic nerve

0:56

lesions but schwannomas of the cranial nerves,

1:00

which include three, four, six and five.

1:03

The understanding of vascular malformations has

1:07

really gained further prominence through

1:10

the Mulliken and Glowacki system,

1:12

and they've described the characteristics of the

1:15

various vascular malformations. The first of which,

1:18

we're going to talk about, is the true neoplasm,

1:20

which is the capillary hemangioma.

1:23

This is also known as hemangioendothelioma.

1:27

These lesions generally are extraconal in location,

1:30

as opposed to the venous vascular malformations,

1:33

which are intraconal.

1:34

Capillary hemangiomas may have a growth phase,

1:37

and then an involutional phase in

1:40

infants and in young children.

1:43

And we talk about those that are rapidly involuting,

1:47

and those that are non-involuting,

1:50

so-called rapidly involuting capillary hemangioma, or RICH,

1:54

versus the non-involuting capillary hemangiomas,

1:57

which are sometimes referred to as NICH.

1:59

In general, these lesions,

2:01

because they involute on their own,

2:04

they can be observed and not treated at all,

2:06

or you can propel it to involute more rapidly

2:10

through the use of steroids and/or interferon,

2:13

in general, and occasionally, laser therapy.

2:16

As you can see, this is an infant, a young patient.

2:20

And what one sees is an abnormality that is

2:23

associated with the lower lid of the orbit.

2:28

Here on the T1-weighted, T2-weighted coronal

2:31

images and axial T2-weighted scans, we see an

2:35

irregular lesion which is infiltrating the lower lid of the orbit.

2:39

As I mentioned,

2:40

these capillary hemangiomas are generally extraconal

2:43

lesions as opposed to the venous vascular

2:45

malformations although they can

2:47

occur intraconal as well.

2:49

One of the characteristic features of the capillary

2:51

hemangiomas is that you do see flow voids within

2:54

them and they usually will show contrast

2:57

enhancement rapidly on your dynamic scanning.

3:01

In this case,

3:01

you see that this is infiltrating the skin surface

3:04

as well as the subcutaneous tissue and discoloring it.

3:07

And this was obvious at the time of clinical evaluation.

3:12

The second lesion is what we again refer to as

3:15

the cavernous hemangioma but it

3:17

is actually not a neoplasm.

3:19

This is a venous vascular malformation and it's

3:23

an entity that usually occurs in adulthood, although it

3:26

may slowly increase in size from young

3:29

adulthood through to middle age.

3:32

This is the lesion that is generally intraconal and

3:35

has a characteristic feature of having phleboliths.

3:38

There are some syndromes that are associated with

3:41

venous vascular malformations including Maffucci

3:44

syndrome and blue rubber bleb syndrome.

3:47

Once again,

3:48

unless these lesions cause symptoms, they are usually

3:51

observed and not treated because of the potential

3:56

for damage to the orbit during surgery.

4:00

Here is a lesion which is seen within the intraconal

4:04

space. Our inferior rectus muscle is located here.

4:07

Here's our medial rectus muscle.

4:09

See a little bit of the lateral rectus muscle

4:11

and superior rectus muscle.

4:13

And within the intraconal space, we have an irregular

4:16

mass that shows a small area of calcification

4:20

on the CT scan representing a phlebolith.

4:23

This would be an excellent example of

4:26

a venous vascular malformation.

4:28

Here is a more classic-looking hemangioma of

4:32

the orbit or venous vascular malformation.

4:35

It is generally bright in signal intensity on T2-weighted imaging.

4:40

It is usually well-defined

4:43

and it shows progressive enhancement from the initial

4:47

post-contrast scan to the final

4:49

post-contrast scan over time.

4:53

Again, we recognize this as an intraconal lesion.

4:55

We have the lateral rectus muscle and the medial rectus muscle

5:00

and the optic nerve seen coursing around the lesion.

5:03

The optic nerve is seen on the T2-weighted

5:06

scan as being separate from the lesion.

5:08

So the most common mass in the intraconal space is

5:12

going to be an orbital venous vascular malformation

5:15

or so-called cavernous hemangioma.

5:19

The final of the vascular malformations that we

5:22

refer to in the orbit is the lymphatic malformation.

5:26

Now, this may have a component that is venous as well,

5:30

in which case we would use the term venolymphatic malformations.

5:35

These lesions also occur generally in childhood,

5:38

as you see 60% before the age of 16.

5:41

Lymphatic malformations are characterized by the

5:45

presence of fluid-fluid levels within them.

5:49

Now, this fluid within them may contain

5:51

different stages of hemorrhage.

5:53

It may be lymphatic material with hemorrhage or

5:56

it can be proteinaceous material.

5:59

But we do see these fluid-fluid levels as characteristic

6:02

of lymphatic malformations.

6:04

It's not so common when one has a combined venolymphatic malformation.

6:10

Another of the important imaging features that

6:13

distinguishes lymphatic malformations is that

6:15

they do not show contrast enhancement.

6:18

If one has a venolymphatic malformation,

6:21

the venous portion will show contrast enhancement,

6:24

but the lymphatic portion does not.

6:28

Here we have a patient whom we are seeing the T1-weighted

6:32

as well as the T2-weighted scans.

6:35

We note that this lesion appears to

6:37

be multicompartmental. That is,

6:39

we have a component anteriorly which is extraconal.

6:43

We have a component which is intraconal,

6:47

and we have a component which shows contrast

6:50

enhancement and a component which does

6:52

not show contrast enhancement.

6:54

We also have what appears to be a fluid-fluid level.

6:57

On the axial scans, we look at the T2-weighted scan,

7:01

and again, this lesion is multicompartmental,

7:04

including a portion which is above the superior rectus muscle,

7:08

as well as components which are intraconal.

7:11

This is characteristic of a venolymphatic malformation

7:15

in that it has the fluid-fluid levels,

7:18

it has portions that are showing contrast enhancement,

7:21

and it also has both intraconal as well as extraconal components.

7:27

The final entities that we should describe with

7:30

regard to orbital vascular lesions are the orbital

7:33

varix, the arteriovenous fistula, and the dural AVM.

7:36

An orbital varix is essentially a varicosity

7:40

of the superior ophthalmic vein.

7:42

Now, it may occur involving the inferior ophthalmic vein.

7:46

Its characteristic feature is that it enlarges

7:49

when one performs a Valsalva maneuver.

7:52

And the classic story of a venous varix is a patient

7:58

who complains about unilateral proptosis while

8:02

straining on the toilet in the bathroom.

8:06

That is, when the Valsalva maneuver is performed,

8:09

the varix will enlarge dramatically from its normal

8:13

size vein and then propels the globe anteriorly,

8:20

causing intermittent proptosis. This

8:23

can also occur when one sneezes.

8:27

The orbital varix is a source of spontaneous

8:30

orbital hemorrhage in young adulthood.

8:33

These varices can enlarge dramatically,

8:36

as you saw in the last case.

8:38

The risk is that they may lead to thrombosis.

8:42

And if the superior ophthalmic vein thromboses,

8:45

remember that it drains into the cavernous sinus.

8:48

Cavernous sinus thrombosis can lead to problems with

8:52

the cranial nerves that course through the cavernous

8:55

sinus, including portions of III, IV, VI, and V.

8:59

The final lesion to describe in the vascular intraconal

9:03

lesions is the cavernous carotid fistula.

9:06

Cavernous carotid fistulas can occur

9:09

post-traumatic or de novo.

9:12

They are usually characterized by enlargement

9:15

of the veins in the orbit.

9:17

So we look at the left superior ophthalmic vein

9:22

and its course going from lateral

9:24

to medial as it runs anteriorly,

9:27

and we contrast that with the contralateral side

9:30

where the vein is much enlarged and showing

9:33

greater contrast enhancement.

9:34

There's an additional vein that is seen more posteriorly.

9:39

This is a patient who has a cavernous carotid fistula.

9:43

There are four different varieties of cavernous carotid fistulas.

9:48

These include those that have a single opening

9:51

between the internal carotid artery and the cavernous sinus,

9:56

those that have a branch of the internal carotid

9:59

artery opening to the cavernous sinus,

10:01

those that have a branch of the external carotid

10:04

artery opening to the cavernous sinus, and those that

10:07

actually represent arterial venous malformations

10:11

of the cavernous sinus and the carotid artery.

10:14

When we look at these patients,

10:16

we generally focus additionally on the cavernous

10:20

sinus to see whether we see any abnormalities in

10:23

there, either potentially an aneurysm that might be

10:26

visualizing to the cavernous sinus or additional

10:29

blood vessels that might suggest an arterial venous malformation.