CNS: Developmental Anomalies Flashcards
Neural plate forms what
neural tube
Along what axis does the neural tube run
cranial-caudal axis of embryo
what does the wall of the neural rube form
central nervous system tissue
The hollow lumen of the neural tube forms what
ventricles and spinal cord canal
What does the neural crest form
peripheral nervous system
Neural tube defects arise from what
- incomplete closure of neural tube
- low folate levels prior to conception
How are neural tube defects detected
- during prenatal care
- elevated alpha-fetoprotein (AFP) in amniotic fluid and maternal blood
What is anencephaly
absence of skull and brain
-disruption of cranial end of neural tube
What does an anencephaly child look like
‘frog-like’ appearance
What gets disrupted during pregnancy in anencephaly
- maternal polyhydramnios
- fetal swallowing of amniotic fluid is impaired
What is spina bifida
failure of the posterior vertebral arch to close
- vertebral defect
- disruption of caudal end of neural tube
How does spina bifida occulta present clinically
dimple or patch of hair overlying the vertebral defect
Meningocele
protrusion of meninges
Meningomyelocele
protrusion of meninges and spinal cord
What is the most common cause of hydrocephalus in newborns
cerebral aqueduct stenosis
What is cerebral aqueduct stenosis
- congenital stenosis of channel that drains cerebrospinal fluid from 3rd ventricle into 4th ventricle
- accumulation of CSF in ventricular space
Where is CSF produced
choroid plexus lining the ventricles
what is the flow of CSF fluid
- lateral ventricles to 3rd ventricle via interventricular foramen of Monro
- 3rd ventricle into 4th ventricle via cerebral aqueduct
- 4th ventricle into subarachnoid space via foramina of Magendie and Luschka
clinical presentation for cerebral aqueduct stenosis
enlarging head circumference due to dilation of ventricles
- cranial suture lines are not fused
Dandy Walker Malformation
- congenital failure of cerebellar vermis to develop
- dilated 4th ventricle (posterior fossa) with an absent cerebellum
What other abnormality does Dandy Walker Malformation usually accompany
hydrocephalus
What is Arnold-Chiari Malformation (Type II)
Congenital downward displacement of cerebellar vermis and tonsil through the foramen magnum
Obstruction of CSF flow commonly results in what for Arnold-Chiari malformation (Type II)
hydrocephalus
- occlusion of 4th ventricle
Arnold-Chiari malformation (Type II) is associated with what
- Meningomyelocele
- Syringomyelia
