M5.1: Fetal Spinal Pathology Flashcards
Describe the 3 ossification centres of the spine
What do the 2 neural processes form
The central part is formed by the centrum
The 2 lateral neural processes form:
Peduncles Transverse processes Laminae Spinous process Posterolateral part of the vertebral body
When does ossification of the laminae occur
18 wks
When in wks could you possibly miss a small spinal bifida
Before 18 wks
Risks of and NTD increases with which factors
Valproic acid (medication for seizures) Maternal diabetes (type 1) Folic acid deficiency History of spinal defects -previous preg -family history
What is spinal bifida
NTD in the structure of the spinal canal that can lead to the herniation of its contents including possibly meninges, CSF and neural tissue
Describe spina bifida occulta
- involves only the deeper layers
- May only see a skin dimple or a path of hair on the back
- closed defect, not easily seen
think of a ‘cult’
Describe spina bifida aperta
- involves all layers from dura to skin
- open defect
- accounts for majority of cases
Aperta means open
What are the 2 types of spina bifida aperta
- meningocele- includes meninges and CSF
- completely cystic - Myelomeningocele- includes meninges, CSF and neural tissue/nerves
- not completely cystic
which type of spinal bifida aperta is more severe
Myelomeningocele
fetuses w/ a meningocele display what US appearances when scanning the head
Arnold Chiari type 2- lemon sign, banana sign, no cistena magna
When is the quad screen done
16 wks
When would AFP be elevated w/ an NTD?
When the defect is not covered by skin
where is AFP produced by the fetus
does it cross the placenta
liver
yes…. its important to consider gestational age and values will vary
What are the other causes of elevated MSAFP
Abdo wall defects (Omphalocele or Gastroschisis) multiple preg Fetal death Urinary obstruction Cystic hygroma Incorrect dates
NTD are associated w/ what syndromes
Meckel gruber syndrome
T18
Triploidy
What is spinal dysraphism
Abnormal closure of the spine/failure of fusion of vertebral arches
What is rachischisis
Another name for spinal dysraphism
What are the radiological landmarks for the spine
T-12; most distal rib
L5: superior margin of the iliac wing/crest
S4: most caudal ossification center in the 2nd trim
how are the legs effected by NTDs and why
Legs - Club foot and Hip dislocation (not seen on US)
Caused by an imbalance of muscular activity due to nerve involvement of the neural tube defect
How does a spinal NTD appear on US
- splayed laminae
- protruding mass or cyst
- also look for Arnold chiari and ventriculomegally
how do NTDs usually effect amniotic fluid levels
polyhydramnios
assessment of the spine is best done in which plane
TRX
What is the prognosis of spinal dysraphism
Depends on the location and extent of the neural tissue involved … more superior in the spine the greater the disability
What is iniencephaly
case of dysraphism involving the back of the cranium and c-spine…
… there are segmentation errors of the upper spine which shorten the neck and head into a dorsiflexed position (called the star gazing position)
What would you expect to see in the brain w/ iniencephaly
Hydrocephalus
iniencephaly is asociated w/ what other condition
anencephaly
What is scoliosis
Lateral curvature of the spine
What is kyphosis
Exaggerated curve of the spine in the sag
Scoliosis and kyphosis are associated w/ which conditions
Amniotic band syndrome
Skeletal dysphasia
VACTERL
Caudal regression syndrome
What is caudal regression
Range of anomalies of the spine…. includes absence of part of the sacrum, up to the absence of the lumbar spine
When do you have an increase risk of caudal regression
w/ Type 1 diabetes
what is Sirenomelia/Mermaid syndrome? what abonormailites does it cause
fetus lacks a sacrum and legs are fused
- rectal atresia
- renal agenesis
- oligohydramnios (no fetal bladder)
what is the prognosis for Sirenomelia/Mermaid syndrome?
fatal
what is the most severe form of caudal regression
Sirenomelia/Mermaid syndrome
What is the VACTERL sequence
Vertebral (dysraphism) Anal (atresia) Cardiovascular Tracheo-esophageal (fistula) Renal Limb (radial Ray)
You must have 3+ of these conditions to be VACTERL
What conditions are the VACTERL sequence associated w/
Caudal regression
spinal bifida
congenital scoliosis
hemi vertebrae
prognosis for VACTERL
depends on severity and extent of involvement
what is a sacrococcygeal teratoma
where can they arise in the body?
- rare mass that contains elements of many tissues
- sacrum, coccyx, brain or gonads
what are the 4 types of sacrococcygeal teratoma
- external mass predominant (most common)
- external mass w/ internal compounds
- internal mass predominant w/ smaller external components
- pre sacral mass (internal only)
how does a sacrococcygeal teratoma appear on US
- mass in rump area adjacent to the spine
- will displace pelvic structures and may compress ureters causing hydro
- can show signs of heart failure of theres Av shunting
describe the variable echo textures of a sacrococcygeal teratoma
how are they linked to bengin vs malignancy
- most are solid or mixed which have malignant tendencies
- cystic -benign tendencies
- may show calcifications
whats the prognosis of a sacrococcygeal teratoma
whats the DDX
depends on size and severity of structural displacements
rectal duplication, anterior myelomeningocele, sarcoma
if a sacrococcygeal teratoma is > what value will the baby have to be delivered by C section
> 4.5cm
