OB - Fall - ch. 59 Fetal Neural Axis
*meningocele
*cranial __________ describes the herniation of ONLY meninges.
*anencephaly
*failure of closure of the neural tube at the cranial end is ____________.
alobar
__________ holoprosencephaly is characterized by a monoventricle; brain tissue that is small and may have a cup, ball, or pancake configuration; fusion of the thalamus; and absence of the interhemispheric fissure, cavum septum, corpus callosum, optic tracts, and olfactory bulbs.
semilobar
__________ holoprosencephaly presents with a single ventricular cavity with partial formation of the occipital horns, partial or complete fusion of the thalamus, a rudimentary flex and interhemispheric fissure, and absent corpus callosum, cavum septum, and olfactory bulbs.
aqueductal stenosis
________________ results from obstruction, atresia, or stenosis of the aqueduct of sylvius, causing ventriculomegaly.
corpus callosum
a fibrous tract that connects the cerebral hems and aids in learning and memory is the ____________.
cephalocele
a neural tube defect in which the meninges alone or the meninges and brain, herniate through a defect in the calvarium is a(n) _____________.
list the sonographic features of DWM:
a posterior fossa cyst that can vary considerably in size; splaying of the cerebellar hems as a result of complete or partial agenesis of the cerebellar vermis; an enlarged cisterna magna caused by the cerebellar vermis anomaly and posterior fossa cyst; and ventriculomegaly.
schizencephaly
a rare disorder characterized by clefts in the cerebral cortex is _____________.
10
a ventricle is considered dilated when its diameter exceeds ____ mm.
ventriculomegaly
abnormal accum. of CSF w/in the cerebral ventricles leading to dilatation of the ventricles; compression of developing brain tissue and brain damage.
list sonogrpahic featurs of anencephaly:
absence of brain and cranial vault, rudimentary brain tissue characterized as the cerebrovasculosa; and bulging fetal orbits, giving the fetus a "frog-like" appearance.
list the sonographic features of agenesis of the corpus callosum:
absence of the corpus callosum; elevation and dialtion of the third ventricle; widely separated lateral ventricular frontal horns with medial indentation of the medial walls; dilated occipital horns (colpocephaly), giving the lateral ventricles a teardrop shape; and absence of the cavum septum pellucidi.
lobar
almost complete division of the ventricles is seen with a corpus callosum that may be normal, hypoplastic, or absent, although the cavum septum will still be absent in _______ holoprosencephaly.
anomaly
an abnormality or congenital malformation.
spina bifida occulta
closed defect of the spine without protrusion of meninges or spinal cord.
acrania
condition assoc. w/ anencephaly in which there is complete or partial absence of the cranial bones.
hydranencephaly
congenital absence of the cerebral hems caused by occlusion of the carotid arteries; midbrain structures are present, and fluid replaces cerebral tissue.
macrocephaly
enlargement of the fetal cranium as a result of ventriculomegaly.
obstruction
enlargement of the ventricles occurs with _______ of CSF flow.
occipital, frontal
fetal ventriculomegaly typically progresses from the _______ horns into the temporal and then to the ________ ventricular horns.
Chiari type II
fetuses with myelomeningoceles often present with the cranial defects assoctaited with the _________ malformation, which is identified in 90% of patients.
cebocephaly
form of holoprosencephaly characterized by a common ventricle , hypotelorism, and a nose with a single nostril.
cystic hygroma
increase in size of the jugular lymphatic sacs caused by abnormal development.
alobar holoprosencephaly
most severe form of holoprosencephaly characterized by a single common ventricle and a malformed brain.
anencephaly
neural tube defect characterized by lack of development of the cerebral and cerebellar hems and cranial vault; this abnormality is incompatible with life.
spina bifida
neural tube defect of the spine in which the dorsal vertebrae fail to fuse together, allowing the protrusion of meninges and/or spinal cord through the defect.
meningomyelocele
open spinal defect characterized by protrusion of meninges and spinal cord through the defect, usually within a meningeal sac.
meningocele
open spinal defect characterized by protrusion of the spinal meninges.
porencephalic
porencephaly or _____________ cysts are cysts filled with CSF.
holoprosencephaly
range of abnormalities resulting from abnormal cleavage of the forebrain.
cyclopia
severe form of holoprosencephaly characterized by a common ventricle, fusion of the orbits with one or two eyes present, and a proboscis.
list the sonographic features of spina bifida:
splaying of the posterior ossification centers with a V or U configuration; protrusion of saclike structure that may be anechoic (meningocele) or conatin neural elements (myelomeningocele); a cleft in the skin; and ventriculomegaly.
forebrain, spinal
the cephalic neural plate develops into the _______, and the caudal end forms the _______ cord.
prosencephalon, mesencephalon, rhombencephalon
the forebrain will continue to develop into the ___________, this midbrain will become the __________, and the hindbrain will form the ____________.
list the sonographic features of acrania:
the presence of brain tissue without the presence of a calvarium; disorganization of brain tissue; and prominent sulcal markings.
encephalocele
the term used to describe herniation of the meninges and brain through the defect is ___________.
hydrocephalus
ventriculomegaly in the neonate; abnormal accumulation of cerebrospinal fluid within the cerebral ventricles resulting in compression and, frequently, destruction of brain tissue.
