0:00

This was another woman who had right-sided visual loss.

0:05

We're looking at the axial T2-weighted scans that

0:08

went through the orbits, as well as the coronal

0:11

post-gadolinium-enhanced scans.

0:13

These were done as part of a multiple sclerosis evaluation,

0:17

and therefore, you will have T2-weighted scans,

0:20

FLAIR scans, as well as post-gadolinium-enhanced scans.

0:24

And generally, in this situation,

0:26

the cervical thoracic spine is also evaluated

0:29

for the potential for spinal lesions.

0:32

As we scroll the T2-weighted scan, we identify an area

0:35

of abnormal signal intensity within the optic nerve.

0:40

Again, we are able to see the optic nerve sheath with the

0:42

bright CSF, as well as the optic nerve with the area

0:47

of abnormal signal intensity on the right side.

0:51

Be careful about partial volume averaging of CSF,

0:54

which could simulate demyelination of the optic nerve.

0:58

We also note that the optic nerve is not enlarged in size,

1:04

and this is typical of patients with optic neuritis.

1:07

Occasionally, they will have optic nerve enlargement,

1:09

but generally, not to the same extent

1:11

that we consider a neoplasm.

1:14

As we move to the coronal post-gadolinium

1:17

fat-suppressed scan,

1:18

we see the abnormal optic nerve

1:21

showing contrast enhancement.

1:23

We contrast this with the normal optic nerve on

1:27

the left side, showing absence of enhancement.

1:30

Let's scroll through these images, as well.

1:33

We follow the optic nerve posteriorly, and we see

1:37

that it is showing diffuse enhancement, and yet,

1:40

does not appear to be particularly enlarged.

1:43

It does appear that the cerebrospinal fluid,

1:46

within the optic nerve sheath complex,

1:49

is also showing contrast enhancement.

1:51

And this is what some people would call perioptic neuritis,

1:56

inflammation of the sheath with the gadolinium-enhanced sequence.

2:01

Note, however, that on the contralateral side, you also see some

2:06

element of faint enhancement of the optic nerve sheath

2:10

without affecting the optic nerve.

2:13

Continuing to scroll more posteriorly,

2:15

we follow it to the optic canal.

2:19

How do we identify the optic canal?

2:22

Usually, the optic canal is best identified by seeing the

2:25

anterior clinoid process. You see the cortex,

2:28

the dark signal intensity of the anterior clinoid

2:31

process, and the bright signal intensity

2:33

of the bone marrow, in this instance.

2:35

Here we have the cortex of the anterior

2:37

clinoid process as well.

2:39

The optic nerve canal is medial to the anterior

2:43

clinoid process, and we are identifying the optic nerve,

2:48

showing contrast enhancement on the right side,

2:51

as opposed to the left side.

2:54

As we scroll further posteriorly,

2:57

we're going to come to the prechiasmal optic nerve,

3:00

and then the optic chiasm.

3:02

These do not show contrast enhancement.

3:08

As I said, this patient was being evaluated

3:11

with known multiple sclerosis,

3:13

and therefore, we want to look

3:14

at the images of the brain.

3:17

I'm going to pull down the FLAIR scan,

3:20

which is the most sensitive for demyelination

3:22

in the brain.

3:24

In a woman in the 30s,

3:26

we would not expect to see white matter lesions.

3:30

And as you can see in this patient,

3:32

we immediately identified two lesions in the white matter,

3:37

juxtacortical in location on the right side.

3:44

As we continue to scroll,

3:45

we are looking for periventricular white matter lesions.

3:49

The reason for this is that to make the

3:51

diagnosis of multiple sclerosis,

3:53

the McDonald criteria require us to identify

3:57

demyelinating plaques in two of four locations,

4:01

those being juxtacortical, periventricular,

4:06

infratentorial, and in the posterior fossa or in the spine.

4:10

As of right now,

4:12

we have identified juxtacortical white matter lesions,

4:15

but the periventricular white matter looks clean.

4:20

For the evaluation of the posterior fossa,

4:23

we generally say that T2-weighted imaging is

4:26

superior to FLAIR imaging for identifying

4:29

demyelinating plaques.

4:32

So, let's pull down the T2-weighted scan

4:36

and look at the posterior fossa.

4:38

So I'm magnifying to the posterior fossa,

4:40

and we look at the brainstem and the cerebellum,

4:43

and we see there are no demyelinating

4:46

plaques in the posterior fossa.

4:48

So we cannot make the diagnosis of multiple sclerosis yet,

4:51

because we've only fulfilled one of the four McDonald criteria,

4:55

the juxtacortical white matter lesions.

4:59

The next thing to do would be to scan

5:01

the cervical thoracic spine.

5:05

In general,

5:06

T2-weighted imaging or STIR imaging are the best

5:10

pulse sequences to identify demyelinating

5:13

plaques in the spinal cord.

5:16

I generally prefer the T2-weighted scans,

5:20

without STIR imaging, because of the relative absence of

5:25

phase ghosting artifacts on the traditional T2-weighted scan,

5:29

as opposed to the FLAIR scans.

5:32

However, the FLAIR scans offer very good contrast

5:35

as well for looking at demyelinating plaques.

5:39

What one sees on this STIR image is an area of

5:43

abnormal signal intensity at the C2 level

5:46

of the cervical spinal cord.

5:49

We want to confirm that on axial T2-weighted imaging.

5:54

We also want to perform post-gadolinium-enhanced scans,

5:57

to identify whether this plaque is

6:00

showing activity with breakdown of the blood-brain

6:03

barrier, or in this case, the blood-spinal barrier,

6:07

that might suggest that there is active

6:08

demyelination going on.

6:10

If there is, more likely that

6:12

the neurologist will treat the patient acutely.

6:15

So by virtue of identifying a lesion in the spinal cord,

6:19

we now have met the McDonald criteria

6:21

in two out of the four areas.

6:24

A word of note. If you are viewing this from Europe,

6:28

the Magnims Convention is to include optic neuritis

6:34

as one of the four criteria for making the diagnosis

6:39

of multiple sclerosis.

6:41

In America, we have not yet adopted optic neuritis

6:44

as one of the four McDonald criteria.