0:01

Since we are early in this course on

0:03

lumbar spine degenerative disc disease,

0:06

I will go through this next case with

0:08

pretty much a thorough evaluation of

0:11

the entire case. So, as I said,

0:13

I begin with looking at the scout images,

0:16

in part to look and see whether there is

0:18

any scoliosis and/or any abdominal

0:21

pelvic pathology.

0:23

The top left image is the scout image.

0:25

You see that it's both in the sagittal plane,

0:27

coronal plane. And on this sequence,

0:32

I'm struck by a process that's going on

0:34

in the upper pole of the left kidney.

0:38

Now, this is going to be the only place where

0:40

we'll actually be seeing the kidneys

0:42

on this particular scan.

0:44

And so, if there is an abdominal pelvic

0:47

CT that is in the patient's archive,

0:50

I'll probably look at that and see

0:52

whether there's any change,

0:53

or I will make a referral to either

0:56

ultrasound or CT for follow up of this renal process.

1:00

But that's one of the purposes of the

1:02

scout images in part to see whether

1:04

there's abdominal pelvic pathology that

1:06

might explain the patient's back pain,

1:09

if you will.

1:10

So the next thing is to look at the

1:12

sagittal T2-weighted images.

1:16

And this is the sagittal fast spin echo

1:19

sequence, in which we can look very

1:21

nicely at the conus medullaris and make

1:23

a determination as to whether there's

1:24

any cord pathology. This is, again,

1:27

a blind spot or a potential medical legal

1:31

blind area where you could get into

1:33

problems if you were to miss a tumor in the spinal cord

1:37

on a study performed for degenerative change.

1:40

Next thing I'm going to comment on in

1:42

this case is the amount of signal loss

1:46

that is occurring within the discs.

1:49

And if I use my magic pen here,

1:52

you can see that the signal intensity of

1:54

the L3-L4 and the L4-L5,

1:55

and the L5-S1 discs is slightly diminished compared

2:00

to the L1-L2 and L2-L3 disc.

2:02

And this is part of that degenerative

2:05

process where the discs lose some of their water content.

2:09

I'll also comment at this point on the

2:11

alignment of the vertebral bodies which looks normal.

2:14

At this juncture,

2:15

we're also seeing some of the pathology

2:18

that's going to be present,

2:19

particularly at the L4-L5 level.

2:21

And the other thing to comment on,

2:24

which I would discuss in a moment,

2:25

is about the endplate degenerative changes.

2:29

As you can see, at the L3-L4 level,

2:33

there is an area in which there is

2:35

bright signal intensity in the posterior

2:38

portion of the endplate at the L3

2:42

and L4 levels, in the inferior

2:44

endplate of L3 and the superior endplate of L4.

2:48

If you look at the corresponding T1-weighted scan,

2:51

which is just to the right,

2:54

you see that the patient has bright

2:57

signal intensity in the

3:00

inferior endplate of L3 and the

3:02

superior endplate of L4,

3:04

which corresponds with the bright areas

3:06

on the T2-weighted scans as well.

3:08

This is what is referred to as Modic Type II changes.

3:12

So modic type II changes...

3:14

type II are bright in signal intensity

3:17

on T1-weighted images and they're

3:19

bright in signal intensity on T2-weighted images.

3:22

Modic Type I change is dark in signal

3:26

intensity on T1-weighted image and

3:29

bright in signal intensity on T2-weighted image,

3:31

and modic type II, type III change is dark and dark.

3:36

So we will discuss the modic changes.

3:38

But for now, I would make a comment about

3:41

the modic type II changes in the

3:44

endplates on either side of the L3-L4 disc.

3:48

At this juncture, I would look at the

3:51

sagittal STIR images for any areas in

3:53

which there is bone edema, and also

3:56

looking at the conus medullaris, as well

4:00

as a quick scan of the facet joints

4:05

for any bright signal intensity within

4:06

the facet joints that might be

4:08

indicative of synovial inflammation.

4:12

Let's move now to the T2-weighted scans.

4:14

So this is, in the center here, we have bright CSF,

4:17

and we're going to go from the top to the bottom.

4:19

On the T2-weighted scan,

4:20

you see just to the, on the left hand side

4:24

of the the abdomen, that this may

4:28

just be a very large cyst that's

4:30

occurring associated with the kidney.

4:32

That will have to be evaluated with abdominal imaging.

4:36

As we scroll through the axial scans,

4:39

I'm going to put the cursor on

4:41

to see where I am on the

4:44

sagittal plane.

4:46

And we have a very normal looking

4:49

disc at...

4:50

five, four, three, two.

4:51

The L1-L2 level.

4:52

As we go to the L2-L3 level, again,

4:56

looks pretty much normal.

4:57

There's no bulge. There's no compression of thecal sac.

5:01

There's no compression of nerve roots.

5:03

So, I would pretty much dispense with

5:05

this as saying, at the L1-L2 level,

5:08

the appearance is normal.

5:09

At the L2-L3 level, no pathology is seen or

5:12

normal appearance.

5:14

As we scroll down to the L3-L4 level,

5:18

we have a little bit more of a

5:19

flattening of the thecal sac by

5:21

a non-compressive disc bulge.

5:24

And I note also that there is

5:26

ligamentum flavum thickening bilaterally

5:29

with mild degenerative change in the facet joints.

5:33

This is non-compressive disease.

5:36

As we continue down to the L4-L5 level,

5:41

we see that the patient has something

5:44

that is compressing the thecal sac.

5:46

So in assessing this disc disease, we note

5:51

that the attachment of the disc to the

5:55

parent disc is wider than any portion of its distal

6:00

extent, identifying this as a disc protrusion.

6:03

Now, if you just use the term disc herniation,

6:06

there's nothing wrong with that.

6:08

If you want to gild the lily or be a

6:10

little bit more specific as far as the

6:12

appearance of the disc herniation,

6:14

you would use the term protrusion.

6:17

So on this scan, we have the focal area.

6:21

So this is focal and therefore a herniation,

6:23

with a disc protrusion at the L4-L5 level.

6:26

We continue to show evidence of

6:28

ligamentum flavum thickening bilaterally

6:31

with degenerative facet joint disease,

6:33

and a little bit of bright signal

6:35

intensity synovium at the right

6:38

side L4-L5 facet joint.

6:42

This disc herniation is located

6:45

centrally, and therefore it would be

6:47

termed a central disc protrusion

6:49

with compression of the thecal sac,

6:52

as well as compression of the intrathecal

6:55

L5 nerve root.

6:59

So, if we compare the left side with the right side,

7:02

we see that the intrathecal L5 nerve root on the left

7:08

is being displaced slightly posterior compared

7:11

with that on the right side.

7:14

The size of disc herniations

7:17

is divided into

7:20

percentages of the spinal canal.

7:22

And the way the size has been laid out,

7:26

is that if it is one third of the spinal

7:29

canal width or less, it's considered a

7:32

small disc herniation,

7:33

causing mild canal stenosis.

7:37

If it's from one third to two thirds of the width,

7:41

we would call it a moderate size disc herniation

7:44

or moderate canal stenosis.

7:47

And if it encroaches on greater than two

7:49

thirds of the spinal canal,

7:52

we would call it a large disc herniation or

7:55

severe spinal stenosis.

7:58

So, it's graded in terms of one third,

8:00

one third, one third.

8:03

One third or less, mild.

8:05

One third to two thirds, moderate.

8:07

Greater than two thirds, severe.

8:10

So, continuing to scroll through this,

8:12

we see that this disc herniation then

8:14

migrates to the left side into the

8:17

lateral recess. This is, again,

8:19

the L5 nerve root on the left side

8:22

with the disc material abutting

8:23

on that nerve root.

8:25

However, within the thecal sac,

8:26

it's compressing the intrathecal nerve roots.

8:33

So, again, on this slice, if we use our marker,

8:38

we can see that we're at the pedicle level,

8:40

which is the lateral recess level.

8:41

We have the L5 nerve root in the

8:44

lateral recess being displaced slightly

8:46

to the right...

8:47

I'm sorry,

8:47

slightly laterally compared to the contralateral nerve root.

8:51

However, even within the thecal sac, we have S1

8:55

nerve root being displaced posteriorly.

8:57

So relatively,

9:00

prominent disc herniation.

9:02

At this juncture, we would measure,

9:05

or imagine if we will,

9:06

the distance from here to here.

9:08

So this is the size of the disc

9:10

herniation and this is the spinal canal.

9:13

And it looks to me like it's within

9:15

about 60% of the overall dimension of the spinal canal,

9:20

making it a moderate size disc

9:22

herniation with moderate canal stenosis.

9:25

So by convention,

9:26

that would be moderate sized.

9:29

And then continuing to scroll,

9:31

we come down to the L5-S1 level,

9:33

which shows a mild disc bulge

9:35

without compression of nerve roots.

9:39

For those of you who are looking

9:40

a little bit more laterally,

9:42

we notice that there does appear to be a

9:45

discrepancy in the size of the psoas

9:48

musculature from right to left.

9:50

Now, this may be positional the way the

9:52

patient's legs are in the spinal canal...

9:55

I'm sorry, in the scanner. However,

9:58

this gross discrepancy between the size

10:01

suggests that there may either be hypertrophy

10:04

on the left side, or atrophy on the right side.

10:09

And for this,

10:10

you'd look at the T1-weighted scan,

10:12

note that there is more fat in the right

10:16

psoas muscle than the left psoas muscle,

10:19

suggesting that there is an element of atrophy.

10:22

Now, I don't see the cause of that atrophy

10:25

on this lumbar spine MRI scan.