Chapter 11: Lumbar Spine: Disc Disease & Stenosis *complete*

Front 1

What does a degenerated disk look like on MR?

Back 1

Loss of signal on T2

Front 2

A broad-based disk bulge=

Back 2

A bulging annulus fibrosus

Front 3

A focal disk bulge=

Back 3

Herniated nucleus pulposus

Front 4

What does disruption of the annular fibers look like on MR?

Back 4

High signal on T2— “high intensity zone”

Front 5

Most common cause of failed back surgery?

Back 5

Missed free fragment disk protrusion

Front 6

What is a free fragment?

Back 6

Disk protrusion that has broken off from the parent disk

Front 7

What does a free fragment look like?

Back 7

-On CT: soft tissue density with a higher attenuation than that of the thecal sac, located away from the disk space
-On MR: disk material that has moved away from the disk space
-No documented preference for cephalad vs. caudal location.

Front 8

What entities can look similar to a free fragment?

Back 8

-Conjoined root
-Tarlov cyst

Front 9

What is a conjoined root?

Back 9

-Normal variant
-Two nerve roots exiting the thecal sac together
-Has attenuation similar to the thecal sac

Front 10

What is a Tarlov cyst?

Back 10

-Normal variant
-Dilated nerve root sleeve
-Has attenuation similar to the thecal sac

Front 11

Why is a free fragment important to surgeons?

Back 11

It means they have to explore more cephalad or caudally during surgery to remove the free fragment

Front 12

Which spinal nerve gets stretched by a lateral disk protrusion?

Back 12

-The nerve that has already exited the central canal
-Symptoms mimic disk protrusion one level cephalad

Front 13

Define spinal stenosis:

Back 13

Encroachment of the bony or soft tissue structures in the spine on one or more of the neural elements

Front 14

Define central canal stenosis:

Back 14

-Compression of the thecal sac
-Described as mild, moderate, or severe

Front 15

Most common cause of central canal stenosis?

Back 15

-Degenerative disease of the facets with associated bony hypertrophy that encroaches on the central canal
-When facets are degenerative, they often have some slippage, which results in buckling of the ligamentum flavum, termed ligamentum flavum hypertrophy

Front 16

Less common causes of canal stenosis?

Back 16

Paget disease, achondroplasia, posttraumatic changes, severe spondylolisthesis

Front 17

Causes of neuroforaminal stenosis:

Back 17

-Facet hypertrophy (most common)
-Free disk fragments
-Post-operative scar
-Lateral disk protrusion

Front 18

Is the exiting nerve above or below the disk space?

Back 18

It’s above

Front 19

Where are the lateral recesses?

Back 19

They are the bony canals in which the nerve roots lie after they leave the thecal sac and before they enter the neuroforamen

Front 20

Define spondylolysis:

Back 20

Defects in the bony pars interarticularis

Front 21

What does it look like?

Back 21

Seen better on CT
Identified on axial images through the midvertebral body as a break in the normally intact bony ring of the laminae

Front 22

Causes of spondylolisthesis:

Back 22

-Slippage of vertebral bodies due to bilateral spondylolysis (can be severe)
-DJD of the facets with slippage (usually minimal)

Front 23

How can you tell post-op scar tissue from disk material?

Back 23

Scar tissue enhances, disk material only has peripheral enhancement (presumably due to inflammation)

Front 24

Describe type 1 bony changes in DJD:

Back 24

T1: low signal bands that parallel the endplates
T2: these bands get brighter

Front 25

Causes of type 1 bony changes?

Back 25

-They represent inflammatory or granulomatous response to degenerative disk disease
-Fibrovascular marrow replacement

Front 26

Describe type 2 bony changes in DJD:

Back 26

T1: high signal bands that parallel the endplates
T2: these bands remain high signal

Front 27

Causes of type 2 bony changes?

Back 27

They represent fatty marrow conversion

Front 28

How do you distinguish type 2 changes from disk space infection?

Back 28

In disk space infection, the disk should be bright on T2
A degenerative disk is not bright on T2

Front 29

Describe type 3 bony changes in DJD:

Back 29

Parallel bands of low signal adjacent to the endplates on both T1 and T2

Front 30

Causes of type 3 bony changes in DJD?

Back 30

They represent bony sclerosis with little residual marrow

Front 31

Back 31

1

Front 32

Back 32

2

Front 33

Back 33

3

Front 34

Back 34

4

Front 35

Back 35

5

Front 36

Back 36

6

Front 37

Back 37

7

Front 38

Back 38

8

Front 39

Back 39

9

Front 40

Back 40

10

Front 41

Back 41

11

Front 42

Back 42

12

Front 43

Back 43

13

Front 44

Back 44

14

Front 45

Back 45

15

Front 46

Back 46

16

Front 47

Back 47

17