Neural Tube Defect

Question 1

What are the risk factors for neural tube defects?

Answer 1

(MODA)
Maternal hyperthermia
MTHFR deficiency - C677T in some populations
Obesity
Diabetes
Aneuploidy - T13, T18, triploidy, 22q11
Antiepileptic medication - valproic acid, carbamazepine

Question 2

Describe ultrasound characteristics of fetal neural tube defects.

Answer 2

Lemon head - scolloping of frontal bones
Bananna cerebellum - gravity pull on the cerebellum
Obliteration of cisterna magna
Ventriculomegaly /hydrocephalus
Scoliosis, kyphosis
Sagittal view of spine - defect in skin line
Transverse view of spine - u/v configuration of the neural arch
Coronal view of spine - splaying of the spine, lack of parallel configuration

Question 3

What is the recurrence risk for neural tube defects?

Answer 3

0.5% - second degree relative
3%
6% if 2 siblings are affected

Question 4

How effective is preconception folic acid in reducing the risk of neural tube defects?

Answer 4

Protective effect is 72%
Spina bifida by 23%
NTD decreases by 19%
Anencephaly by 11%

Question 5

If lumbosacral neural tube defect is identified on mid trimester ultrasound, how do you counsel the patient?

Answer 5

Expectant management with or without intrauterine surgery repair and pregnancy termination

Question 6

If lumbosacral neural tube defect is identified on mid trimester ultrasound, what work-up do you do?

Answer 6

Detailed anatomic survey and fetal growth
Fetal echocardiogram
Amniocentesis (AFAFP, ACH, Karyotype)
+/- MRI

Question 7

What genetic conditions are associated with neural tube defects

Answer 7

T13
T18
Triploidy
22q11
Waardenburg syndrome (pigmentation/hearing abnormality)

Question 8

What is the likelihood of identifying chromosomal abnormality in neural tube defect?

Answer 8

2-16%

Question 9

Do you recommend amniocentesis for patients with a fetal neural tube defect?

Answer 9

Yes. It can help with confirmation of diagnosis and assess karyotype (also needed for eligibility for MMC repair)

Question 10

What patients may be considered candidates for the inutero repair of a fetal neural tube defect?

Answer 10

Singleton pregnancy
Less than 25 weeks and 6 days (19 weeks and 25 weeks)
Normal karyotype and isolated
No history of uterine surgery
No history of preterm delivery or with short cervical length
Maternal BMI less than 35 with no comorbidities
Kyphosis less than 30 degrees
Lesion between T1 - S1

Question 11

How do you counsel a patient regarding the risks of in utero repair of a fetal neural tube defect?

Answer 11

Uterine rupture 
Premature birth 
Chorion amnion seperation 
Abruption 
Anemia and maternal transfusion 
Need for cesarean delivery

Question 12

How do you counsel a patient regarding the benefits of in utero repair of a fetal neural tube defect?

Answer 12

• Decreases the need for shunts by decreasing risk for hydrocephalus
• Preserve nerve function
• Decreases fetal death

Question 13

How do you follow a patient in utero repair of a fetal neural tube defect?

Answer 13

• Administer nifedipine until 36 weeks and 6 days, can add magnesium with contractions
• Weekly antenatal follow-up

Question 14

When do you recommend delivery following in utero repair of a fetal neural tube defect?

Answer 14

37 weeks

Question 15

Do you recommend cesarean delivery or vaginal delivery following in utero repair of a fetal neural tube defect?

Answer 15

Cesarean section for open repair

Vaginal can be attempted for laparoscopic repair

Question 16

What is the likelihood of uterine rupture in labor following in utero repair of fetal Neuro tube defect?

Answer 16

Assuming open repair, then 12.5%

Question 17

Management of Myelomeningocele (MoMs) trial:

Answer 17

Trial was stopped early (at 183 instead of 200 planned)

Outcome measure: fetal/neonatal death and shunt placement at 12 months

Outcome experienced less in the treatment group (68%) verses no surgery group (98%)

30 month composite of mental development in favor of repair