Ch 12 Spine

Question 1

Are congenital spine anomalies common?

Answer 1

Yes - will see them in practice

Question 2

How does the spine look in TRV by the 16th week of gestation?

Answer 2

Looks like 3 echogenic ossification centers, surrounding the neural canal

(2 lie posterior to spinal canal within laminae + 1 is anterior within vertebral body)

Question 3

How does the TRV spine look at the cervical, thoracic, lumbar + sacral level?

Answer 3

C: posterior ossification centers have a quadrangular shape

T/L: inverted triangle shape with base towards dorsum of fetus

S: posterior ossification centers have a wider placement than upper vertebrae

Question 4

What is the classic spinal image?

Answer 4

Taken in SAG - often shows its entirety as a parallel structure ending in pointed sacrum

(parallel lines = represent 2 ossification centers: the vertebral body + posterior arch)

Question 5

The SAG spine images the neural tube in 1st trimester + what during the other trimesters?

Answer 5

Spinal cord

Question 6

In the 2nd/3rd trimesters, ____ images at the 2nd + 3rd lumbar spine levels?

Answer 6

The conus medullaris

Question 7

List 3 things that determine if the spine is normal?

Answer 7

-Intact neural canal
-Intact dorsal skin contour
-Normal location + shape of spinal ossification centers

(imaging the conus medullaris in SAG can increase confidence that spine is normal)

Question 8

How many planes do we image the spine in at minimum?

Answer 8

-SAG
-TRV (axial)

(imaging in coronal is good to do as well tho)

Question 9

What is the spine protocol we follow?

Answer 9

SAG + TRV: C, T, L + S spine
Coronal: S spine

Question 10

Is there always a bit of AFP in amniotic fluid?

Answer 10

Yes - if there are elevated levels that is abnormal

Question 11

The spine can be screened by what 2 things?

Answer 11

-U/s
-Biochemical testing

Question 12

MSAFP levels occur through diffusion across what?

Answer 12

The placenta + amnion

Question 13

What types of defects result in higher AFP levels entering the amniotic fluid?

Answer 13

Structural defects - like anencephaly or spina bifida

Question 14

What prevents AFP from escaping fetal circulation + results in a normal amniotic AFP level?

Answer 14

Skin covered or closed neural tube defects (NTDs)

Question 15

What forms the neural tube during the 3rd week of embryonic life?

Answer 15

Infolding of the slipper-shaped ectoderm of the neural plate

Question 16

What fuses to form the neural tube?

Answer 16

The neural groove - it begins midembryo + is completed at cranial + caudal neuropore

(is a 2 day process)

Question 17

What factors can cause closure failure of the neural tube at either end of it, demonstrating the connection b/w spina bifida + caudal defects?

Answer 17

A disruption to the 2 day process by infections, drugs or genetic factors

Question 18

What is spina bifida?

Answer 18

-NTD from incomplete closure of the bony elements of the spine (the lamina + spinous processes) posteriorly

Question 19

List the 2 types of spina bifida defects?

Answer 19

Ventral: involves vertebral body splitting + development of a neurogenic origin cystic structure

Dorsal (m/c): has subdivisions of open (not covered by skin) + closed (covered by skin) forms

Question 20

Where do ventral spina bifida lesions occur?

Answer 20

At lower cervical + upper thoracic spine (are uncommon)

Question 21

What is spina bifida occulta?

Answer 21

-Split vertebrae closed + covered by skin
-M/c at sacrolumbar level
-Not noticeable on surface, except for small tuft of hair or dermal lesion over affected area
-Incidental finding

Question 22

What is spina bifida aperta?

Answer 22

-Open + not covered by skin (exposing neural canal)
-Full thickness defect of skin, tissues + vertebral arches
-This lesion occurs in 85% of all spina bifida cases

Question 23

Differentiate a meningocele vs a myelomeningocele?

Answer 23

Meningocele: lesion has thin meningeal membrane that does NOT contain neural tissue

Myelomeningocele: neural tissue inside the protruding sac

Question 24

Is closed spina bifida aperta inconsequential?

Answer 24

Yes - b/c skin is covered it has minimal neural involvement

(15% of time this occurs)

Question 25

85% of spina bifida aperta is open or closed?

Answer 25

Open: 2 subdivisions -Meningocele (sac w/o spinal cord) -Myelominingocele (sac with spinal cord)

Question 26

What causes a NTD?

Answer 26

Genetics, nutritional factors, environmental factors, or a combo of things

Question 27

Are males or females m/c to have spina bifida?

Answer 27

Females

Question 28

NTDs have a high concordance rate in MZ or DZ twins?

Answer 28

MZ

Question 29

How to sonographically assess for spina bifida?

Answer 29

-Best seen in SAG -Use TRV to rule out smaller defects -Look for banana + lemon sign in head (it distorts the shape of brain + cerebellum)

Question 30

What is the only definitive way to make a diagnosis of spina bifida?

Answer 30

Viewing of a meningomyelocele

Question 31

How does spina bifida look in TRV?

Answer 31

-Vertebral segments has a "U" or "V" shape -Splays (widens) the posterior ossification centers

Question 32

What causes displacement of cranial structures into the foramen magnum + superior cervical canal with spina bifida?

Answer 32

CSF leakage

Question 33

If the cranium appears normal, does this exclude a myelomeningocele?

Answer 33

Yes

Question 34

The differentiation b/w open + closed forms of spina bifida are best shown by what?

Answer 34

Sonographic demonstration of abnormal or normal cranial anatomy

Question 35

What head anomaly occurs in the 2nd trimester when spina bifida aperta is present?

Answer 35

Hydrocephalus (70% of time)

Question 36

Spina bifida shows what type of lower extremity deformities?

Answer 36

-Bilateral clubfeet -Rocker bottom feet (curved bottom of feet) -Hip deformities

Question 37

What is kyphoscoliosis?

Answer 37

Combo of abnormal lateral + anterior curvature of spine

Question 38

How is scoliosis + kyphosis best imaged?

Answer 38

Scoliosis: coronal Kyphosis: SAG

Question 39

What is scoliosis?

Answer 39

Lateral displacement of anterior ossification centers

Question 40

Is scoliosis an isolated finding?

Answer 40

It can be isolated or seen with other findings

Question 41

During the 1st trimester, what 2 sonographic features indicate caudal regression syndrome?

Answer 41

-Short CRL -Abnormal YS

Question 42

What is caudal regression syndrome?

Answer 42

-Rare congenital anomaly affecting the caudal spine, spinal cord, hindgut, urogenital system + lower limbs -Ranges from agenesis of coccyx to absence of sacral, lumbar + lower thoracic vertebrae

Question 43

This factor increases the risk of caudal regression syndrome 250x?

Answer 43

Maternal diabetes

Question 44

SAG + TRV views of the spine with caudal regression syndrome uncover what?

Answer 44

-Absence of vertebrae -Fused iliac wings -Decreased femur head distance -Short femurs -Clubfeet

Question 45

What is the m/c location for teratomas to develop?

Answer 45

Caudal end (sacrococcygeal)

Question 46

What is the m/c neoplasm in the newborn?

Answer 46

Sacrococcygeal teratomas (m/c in females)

Question 47

Where can teratomas develop?

Answer 47

Gonads, umbilical cord, placenta, anywhere in neural tube + caudal end

Question 48

What is a sacrococcygeal teratoma?

Answer 48

Rare germ cell tumor that forms on fetus's tailbone/coccyx (usually benign) (male fetuses have increased chance of developing malignant form)

Question 49

Most sacrococcygeal teratomas are what type?

Answer 49

Type 1 or 2

Question 50

How do sacrococcygeal teratomas appear on u/s?

Answer 50

-Protrusion b/w anus + coccyx (some can develop in presacral space of pelvis) -Solid or complex with cystic parts -Choroid plexus secretes CSF within tumor, resulting in a cystic component

Question 51

Fetus's are at risk for developing what 2 things if they have a sacrococcygeal teratoma?

Answer 51

-Congestive heart failure -Hydrops

Question 52

Perinatal mortality + morbidity are related to what type of failure if they have a sacrococcygeal teratoma?

Answer 52

Related to high output cardiac failure - due to arteriovenous shunting within tumor, hydrops, polyhydramnios + preterm delivery

Question 53

What is fetal hydrops?

Answer 53

Condition in which large amounts of fluid build up in a baby's tissues and organs, causing extensive swelling (edema)

Question 54

T/F: Skin covered NTD lesions prevent a rise in MSAFP levels.

Answer 54

True

Question 55

The posterior elements of the spine seen on u/s are called what?

Answer 55

Laminae

Question 56

What are the 3 dots we see of the spine in TRV?

Answer 56

-2 posterior laminae -1 anterior body

Question 57

What are the 2 types of spina bifida called?

Answer 57

Occulta (closed) + aperta (open)