Flashcards in CH17 - Central Nervous System Pathology Deck (315)
What are the developmental anomolies?
1) neural tube defects 2) cerebral aqueduct stenosis 3) Dandy Walker Malformation 4) Arnold Chiari Malformation
What do neural tube defects arise from?
They arise from incomplete closure of the neural tube
What happens to the neural plate early in gestation?
It invaginates to form the neural tube, which runs along the cranial caudal axis of the embryo
Regarding the neural plate, what forms the central nervous system?
The wall of the neural tube forms central nervous system tissue,
In the neural tube, what does the hollow lumen form?
the ventricles and spinal cord canal, and the neural crest forms the peripheral nervous system.
What are neural tube defects associated with?
low folate levels prior to conception
When are neural tube defects detected?
during prenatal care by elevated alpha-fetoprotein (AFP) levels in the amniotic fluid and maternal blood
What is anencephaly?
it is the absence of the skull and brain (disruption of the cranial end of the neural tube)
What does anencephaly lead to?
a frog like appearance of the fetus
What does anencephaly result in?
maternal polyhydramnios since fetal swallowing of amniotic fluid is impaired
What is spina bifida?
It is failure of the posterior vertebral arch to close, resulting in a vertebral defect (disruption of the caudal end of the neural tube).
How does Spina bifida occulta present?
as a dimple or patch of hair overlying the vertebral defect.
How does Spina bifida present?
with cystic protrusion of the underlying tissue through the vertebral defect
What is a meningocele?
protrusion of meninges
What is meningomyelocele?
protrusion of meninges and spinal cord
What is cerebral aqueduct stenosis?
congenital stenosis of the channel that drains cerebrospinal fluid (CSF) from the 3rd ventricle into the 4th ventricle
What does cerebral aqueduct stenosis lead to?
accumulation of CSF in the ventricular space; most common cause of hydrocephalus in newborns
What is the most common cause of hydrocephalus in newborns?
Cerebral aqueduct stenosis
What produces the CSF?
It is produced by the choroid plexus lining the ventricles
Decribe the flow of CSF?
from the lateral ventricles into the 3rd ventricle via the interventricular foramen of Monro, Flows from the 3rd ventricle into the 4th ventricle via the cerebral aqueduct, Flows from the 4th ventricle into the subarachnoid space via the foramina of Magendie and Luschka
What is the cerebral aqueduct?
Allows for the flow from the 3rd ventricle into the 4th ventricle
What allows the CSF to flow from the 4th ventricle into the subarachnoid space?
Via the foramina of Magendie and Luschka
What is the foramen of monro?
Allows for the flow of CSF from the lateral ventricles into the 3rd ventricle
What does cerebral aqueduct stenosis present with?
enlarging head circumference due to dilation of the ventricles (cranial suture lines are not fused)
What is a dandy walker malformation?
Congenital failure of the cerebellar vermis to develop
How does a dandy walker malformation present?
as a massively dilated 4th ventricle (posterior fossa) with an absent cerebellum; often accompanied by hydrocephalus
What is an Arnold chiari malformation?
Congenital extension of cerebellar tonsils through the foramen magnum
What might Arnold Chiari malformation result in?
Obstruction of CSF flow can result in hydrocephalus
What might Arnold chiari malformation occur in association with?
meningomyelocele and syringomyelia