Module 5.1 : Fetal Spinal Pathology Flashcards
Development of spine
- each vertebrae develop from 3 ossification centers
- centrum
- neural processes
What does the centrum form
- central portion of vertebral body
What does the neural processes form
- pedicles
- transverse processes
- laminae
- spinous process
- posterolateral part of vertebral body
when is Ossification complete
- ossification is not complete in than laminae until 18 weeks
- can potentially miss a small spina bifida before the
Risk of NTD increase with
- valproic acid (meds for seizures)
- maternal diabetes
+ type 1 or 2 - folic acid deficiency
- history of spinal defects
+ previous pregnancy
+ family history
what is Spina bifida
- defect in bones structure of spinal canal that may result in Bernita ion of its content
- a neural tube defect
what are the contents of the spine that might herniate in a spina bifida
- meninges
- CSF
- neural tissue
2 Other NTD
- encephalocele
+ brain herniation - anencephaly
+ missing all = brain and and skull
2 Variations of spina bifida
Spina bifida occulta
Spina bifida Alperta
Spina bifida Occulta
- involves only the deeper layers
- may only see a skin dimple or patch of hair on the skin
- closed defect
- less common
Spina bifida aperta
- involves all layers from dura to skin
- open defect
- more often
- two types
+ meningocele
+ myelomeningocele
Spina bifida aperta - meningocele
- contains meninges and CSF
Spina bifida aperta - myelomeningocele
- contains meninges, CSF, and neural tissue
- more common
Screening for NTD - MS AFP
- quad screen at 16 weeks
- maternal serum alpha fetal protein
- AFP produced by liver
- crosses placenta and varies with gestational age
- AFP is elevated with NTD not covered by skin
6 Other causes of elevated AFP
- abdominal wall defects \+ omphalocele \+ gastrodchisis (bowel outside) - twins - fetal death - urinary obstruction - cystic hygroma - incorrect dates
where do NTDs usually occur
- in the lumbosacral spine
NTD in lumbar spine is associated with
- Meckel Gruber syndrome \+ encephalocele \+ polycystic kidneys \+ polydactyly - T18 - triploidy
what is a NTD caused by
- spinal dysraphism
what is spinal dysphism
- abnormal closure of the spine
- aka rachischisis
- failure of fusion of the vertebral arches
NTD landmarks correspond to what
- level of defect
three NTD landmarks
- T-12 most distal rib
- L-5 superior margin of iliac wing
- S-4 most caudal ossification center int eh 2nd trimester
Other system affected by NTD
- legs
+ club foot
+ hip dislocation (not seen on US) - causes by imbalance of muscular activity due to nerve involvement of NTD
- nerves exposed to amniotic fluid get damages
does a higher a lower NTD have a worse prognosis
- the higher the NTD the worse off the baby is
Spinal NTD on US
- splayed laminae
- protruding mass or cyst
- look for associated Arnold Chiari II and ventriculomegaly
What plane is assessment on spine done best in
Transverse
Prognosis of NTD
- depends on location and extent of neural tissue involved
- more superior the worse off
characteristics of Ineincephaly
- special case of dyraphism involving back of cranium and c spine
- Inein refers to name of neck
- segmentation errors of upper spine shortens neck and head becomes drosifelxed
- known as star gazing position
ineincephaly is associated with what other NTD
- anencephaly
what would you expect to see in the brain with ineincephaly
- hydrocephaly from ventricles not being able to drain
what is Scoliosis
- lateral curvature of spine
Kyphosis
- exaggerates curvature of spine in sagittal Plane
Scoliosis and kyphosis associated with
- amniotic band syndrome
- skeletal dysplasia
- VACTERL
- caudal regression syndrome
what is Caudal regression
- range of abnormalities of the spine
+ absence of part of sacrum up to absence of lumbar spine
what maternal disease increases risk of caudal regression
- increased risk with
+ type 1 maternal diabetes and insulin dependant diabetes (IDDM)
characteristics of Sirenomelia (mermaid syndrome)
- absence of sacrum
- fusion of legs
- re tail atresia
- renal dysgenisis or agenisis
- oligohydroamnious (no kidneys no urine)
prognosis of sirenomelia
- very poor all die in infancy
what is the most sever form of caudal regression
- sirenomelia
VACTERL sequence
- Vertebral (dysraphism)
- Anal (atresia)
- Cardiovascular
- Tacheo-Esophageal (fistula or atresia)
- renal
- Limb (radial Ray)
VACTERL is often associated with what 4 other anomalies
- caudal regression \+ sirenomelia - spina bifida - congenital scoliosis - hemi vertebrae
prognosis of VACTERL
- depends on severity and extent of involvement
what is a Sacroccygeal teratoma
- contains elements of many tissue
- 4 types
what three structures can teratomas can arise form
- sacrum or coccyx
- brain
- gonads
the four types of teratomas
- I external mass predominant (most common)
- II external mass with internal components
- III internal mass predominant with smaller external component (least common)
- IV presacral mass (internal only) (second least common) MOST MISSED
Teratomas on US
- mass on rum area adjacent to spine
- most are solid or mixed = malignant
- cystic = benign
- May see calcification
- displaces pelvic structures may compress ureters = hydronephrosis
- if AV shunting May see heart failure
Teratoma prognosis
- depends on size of mass and severity of structure displacement
- solid mass more malignant
- if > 4.5 cm cesarean done
DDX of teratoma
- rectal duplication
- anterior myelomeningocele
- sarcoma
