Developmental Anomalies Flashcards
How are neural tube defects caused and how are they detected?
Associated with low folate levels prior to conception. Detected during prenatal care by elevated levels of alpha-fetoprotein (AFP) in the amniotic fluid and maternal blood.
What portion of the neural tube forms the central nervous system tissue? The ventricles and spinal cord canal? The peripheral nervous system?
The wall forms CNS, the hollow lumen forms ventricles and spinal cord canal, the neural crest forms the PNS.
What is anencephaly and what causes it? What does it result in?
It is the absence of the skull and brain due to disruption of the cranial end of the neural tube. Results in maternal polyhydraminos since fetal swallowing of amniotic fluid is impaired.
How does spinabifida occulta present?
Presents as a dimple or patch of hair overlying the vertebral defect.
How does spinabifida present?
Presents with cystic protrusion of the underlying tissue through the vertebral defect. Meningocele - protrusion of meninges. Meningioma eloped - protrusion of meninges and spinal cord.
What is cerebral aqueduct stenosis and how does it present?
Congenital stenosis of the cerebral aqueduct that drains CSF from the 3rd to the 4th ventricle and leads to its accumulation in the ventricular space. Presents with enlarging head circumference due to dilation of the ventricles. (Cranial suture lines are not fused).
You are working as a neuro consult and you see a patient who on imaging presents with a massively dilated 4th ventricle with an absent cerebellum. You also notice a hydrocephalus. What does your patient have?
He has a dandy-walker malformation which is a congenital failure of the cerebellar vermis to develop.
What is Arnold-Chiari malformation?
It is a congenital downward displacement of cerebellar vermis and tonsils through the foramen magnum. Obstruction of CSF flow commonly results in hydrocephalus and is often associated with meningomyelocele.
