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What I'd like to do now is talk to you about the

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consensus nomenclature for distinguishing between

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a disc bulge and a disc herniation.

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Before I do that,

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I just want to emphasize the fact that a disc

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bulge in the appropriate location may indent or

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displace a nerve root and be symptomatic.

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And a disc herniation may be non-compressive and

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be present, but not be doing anything to

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the thecal sac or to the nerve root.

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So the presence or the terms that we use,

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whether it be bulge, herniation, and within the

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herniation, we'll talk about the different varieties.

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It may not be as important to the pathology

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or the patient's symptomatology as what it's doing

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to either the thecal sac or the intrathecal

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nerve root, or the exiting nerve root.

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So let's talk about that distinction, however.

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So a disc bulge is disc material that is still confined

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by the annulus that is beyond

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the edge of the vertebra.

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The key word that I use with referring to

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disc bulge is it's a diffuse process.

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A disc herniation is a more localized extension of

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disc material beyond the intravertebral space.

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And these are the terms that are

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used by the nomenclature group.

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But the important term that I use for that

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is it's something that's focal.

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So if when you are describing the disc,

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you're sort of doing something like this.

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Well, here's the disc, like that,

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you're usually referring to a disc bulge.

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Whereas, if you can put your cursor right on something,

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it's more likely that you're dealing with a herniation.

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It's something focal rather than diffuse.

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Within the herniations,

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the nomenclature group defines three separate varieties.

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One is the protrusion.

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Two is the extrusion.

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And three is the sequestrated disc.

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The sequestrated disc is a free fragment that is

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no longer communicating with the parent disc,

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if you will.

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It's important that you understand that the

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term that they utilize is sequestrated,

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not sequestered.

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So some people will talk about a sequestered disc.

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That has not been accepted,

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the term that should be used is a sequestrated disc.

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So we're going to start by looking at disc

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protrusions and disc bulges,

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and distinguishing between them.

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And then we will go on to disc extrusions.

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So, here we have five separate diagrams on the distinction,

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on the nomenclature between bulges

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and disc herniations.

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On the top left, we have what's referred to as

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an asymmetric bulging disc. This is seen as

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this area of the disc which is diffuse and

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extending to the left side without a focal area.

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So this diffuse nature to it is going to be the

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key to referring to this as a disc bulge.

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On the bottom left,

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I've diagrammed a focal herniation.

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This focal herniation, as you can see,

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has a wider base with the parent disc than its

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more distal portion. And therefore, this

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is going to be termed a protrusion.

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So, wider at the connection with the host disc or

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the parent disc than it is at any point in

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the distal portion. This is a herniation.

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Now, in the revision of the nomenclature,

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a disc herniation has to only be within 25% of

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the circumference of a disc.

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So a protrusion

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that extended greater than 25% of the overall

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circumference of a disc is considered a bulge and

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not a herniation. So again, must be 25% or less.

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If you're thinking about it in terms of degrees,

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it would be 90 degrees or less.

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Here in the center we have patient who has

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a herniation, which is less than 25%.

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However, we note that the connection with the parent disc

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is narrower than an area in the distal portion of the disc.

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This, by definition, is going to be an extrusion.

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So the difference between protrusion and extrusion

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is the connection with the parent disc is wider

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at its base for protrusion than

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any place more distal.

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Whereas for an extrusion, the connection

4:58

to the parent disc is narrower

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than a portion of the disc in its most...

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in its distal portion. On the bottom right,

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we have that demonstration of what previously, in

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the first edition, was termed a broad based herniation.

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This has been eliminated now and herniations

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must be 25% or less.

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So this term has been eliminated in the revision

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to the first edition of the nomenclature.

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Intervertebral herniations are what we refer to

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sometimes as Schmorl's node.

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So this is a diagram showing the sagittal plane in

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which there is an introvertebral disc

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herniation into the endplate.

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So let's just say that this is anterior and this is posterior.

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And you see one going into the inferior endplate,

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you see one going to the superior

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endplate of the vertebral body.

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And these are, again, Schmorl's nodes,

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also referred to as intervertebral herniations.

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As I said, in the 2011 revision,

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this term of broad based herniation involving more

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than 90 degrees or 25% of the disc

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circumference was eliminated.

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And it's now...

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the appropriate term is just asymmetric bulge,

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as you see over in the top left corner.

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Here is a patient in which we have the diagram

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to the left and on the right hand side,

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a T2-weighted scan showing a symmetrically bulging disc.

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It's actually in contact with the thecal sac.

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This would be better seen on the sagittal scan to

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define the endplates as extending

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beyond the endplate.

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But everything you see here is nice and smooth

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and diffuse. So we would call it a bulge.

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Here we have, labeled for us with arrows,

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a protrusion. So again,

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a protrusion is a type of disc herniation.

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There are in the nomenclature three different

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varieties of disc herniations, protrusions,

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extrusions, and sequestrated discs or

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free fragments. In this situation,

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as you can see on the left hand axial scan,

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the connection with the parent disc,

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the base of the disc, is wider than any portion

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more distally.

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As I said in my opening remarks about

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disc herniations versus bulge,

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I spend a lot more time focusing on

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what it's doing to nerve roots,

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rather than worrying as much about whether it's

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a protrusion or extrusion or disc bulge,

7:43

because this herniated disc is abutting on the

7:49

nerve root and we are at the L4-L5 level.

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This is the intrathecal L5 nerve root.

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So my report is going to talk about the disc

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herniation and what it's doing to the thecal sac,

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compressing the thecal sac and abutting on the

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intrathecal L5 nerve root.

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In order to demonstrate that, I believe this is likely to cause

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a radiculopathy in the L5 distribution.

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Here on the sagittal plane,

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it's a little more difficult with regard to the

8:18

description of the protrusions versus extrusion

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on the sagittal plane. However,

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the concept is the same,

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and that is that if the portion of the disc

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connected to the parent disc at the base is wider

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at the connection than it is

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in a distal-most portion,

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then we're going to use the term protrusion.

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I'll talk in a moment about the location of discs.

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But right now, we're just trying to make that distinction

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between protrusions versus extrusions.

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Here is another patient.

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We're at the L5-S1 level,

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axial T2-weighted scan.

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You note that for these demonstration

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of disc herniations, in general,

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they're better demonstrated on the T2-weighted scan.

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Why is that?

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That's because the thecal sac on a T1-weighted scan

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is dark in signal intensity and sometimes it will

9:09

have the same signal intensity

9:11

as the disc herniation.

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Whereas on a T2-weighted scan, you have bright CSF.

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And so you see the thecal sac very well.

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You see the nerve roots outlined by the CSF.

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And that's why, in general,

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we emphasize the T2-weighted scan for distinguishing

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disc herniations from disc bulges and what it's

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doing to the thecal sac and to

9:30

the exiting nerve root.

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This protrusion, as you can see,

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is to the left side

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and it is extending also into the lateral recess,

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as well as the proximal left neural foramen.

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That, in and of itself, is a good use of the

9:53

description of the disc herniation.

9:55

However, the emphasis that I want to put to

9:59

the student, is what is it doing to nerve roots?

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So within this single scan,

10:07

what I am seeing is the intrathecal L5 nerve

10:12

root is being displaced compared to the

10:15

contralateral right, L5 nerve root.

10:19

So in describing this disc herniation,

10:21

I will say the protrusion is causing compression

10:26

or displacement of the intrathecal

10:30

left L5 nerve root.

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The next thing I look at is the neural foramina.

10:35

We note that we have nerve roots within

10:37

the neural pharamina as well.

10:39

And so I want to talk about what this disc

10:44

herniation is doing to the pherominal

10:46

nerve root as well. In this case,

10:49

the position of this nerve root is similar to the

10:52

position of this foraminal nerve root on the

10:56

right side. So if we are at the L4-L5. level,

11:01

the nerve root in the foramen

11:03

is the L4 nerve root.

11:05

So my description of this disc herniation

11:07

would say that this disc is abutting,

11:11

but not displacing the foraminal L4 nerve root.

11:17

So, again,

11:18

instead of worrying as much about whether it's

11:21

a bulge or a herniation, or

11:22

a protrusion, or extrusion,

11:24

try to emphasize what it's doing to the nerve roots.

11:27

So that way,

11:27

if the patient does indeed have an L4

11:30

radiculopathy or an L5 radiculopathy,

11:32

it will correlate well with the patient's symptomatology.