Neural Tube Defects and Hydrocephalus

Question 1

Women who require 5mg folic acid instead of 0.4mg

Answer 1

HOPED:

• haemolytic anaemia
• obese
• previous neural tube defect
• epilepsy medication/co-trimoxazole
• DM

Question 2

Detection of NTDs (3)

Answer 2

Bloods: raised AFP

Amniocentesis: raised AFP

USS at booking and 20wks

(NB CVS can’t detect NTDs)

Question 3

Features of anencephaly (4)

Answer 3

failure of development of most of brain

die in utero/shortly after birth

can be detected via USS

more common in females

Question 4

Features of encephalocele (2)

Answer 4

brain and meninges herniate through weakness in skull

can be surgically repaired but most have underlying cerebral defects

Question 5

Features of spina bifida (4)

Answer 5

failure of fusion of vertebral arch

sometimes not noticed till birth, if skin overlying is closed>MRI/USS

can have overlying skin lesion e.g. tuft of hair, lipoma, birth mark

as child grows>cord tethering>lower limb weakness and spasticity, incontinence, constipation etc

Question 6

Features of meningoceles and myelomeningoceles (3)

Answer 6

meningocele: protrusion of meninges through defect in skull or spine
myelomeningocele: open spinal cord w. meningeal cyst

good prognosis w. surgical repair

Question 7

Associations of meningoceles and myelomeningoceles (7)

Answer 7

variable weakness/paralysis/imbalance of legs

sensory loss

bladder denervation

neuropathic bowel

sexual dysfunction

Scoliosis

hydrocephalus from Arnold-Chiari malformation

Question 8

Hydrocephalus, pathology and subtypes (3)

Answer 8

obstruction of CSF flow>ventricular dilatation

communicating and non-communicating

Question 9

Features and causes of non-communicating hydrocephalus (3)

Answer 9

obstruction w/i ventricles

can be congenital:

• aqueduct stenosis
• atresia of outflow of 4th ventricle
• chiari malformation

can be acquired:

• posterior fossa neoplasm or vascular malformation
• intra-ventricular haemorrhage in preterm

Question 10

Features of communicating hydrocephalus (3)

Answer 10

obstruction at arachnoid villi-site of CSF absorption

caused by SAH and meningitis

Question 11

Presentation of hydrocephalus (3)

Answer 11

disproportionately large head circumference

separated sutures/bulging fontanelles

fixed downward gaze (setting sun sign)

Question 12

Ix for suspected hydrocephalus (3)

Answer 12

cranial USS

CT/MRI

monitor head circumference on growth chart

Question 13

Mx of hydrocephalus and risks (4)

Answer 13

insertion of ventriculoperitoneal shunt.

risks of shunt:

• infection via coagulase -ve staph (epidermidis)
• over drainage>low pressure headache

surgery to create a ventriculostomy is another option