Chapter 60 fetal neural axis
List sonographic features of anencephaly
-Absence of the brain and cranial vault -frog like appearance (bulging of fetal orbits) -cerebrovasculosa (rudimentary brain tissue) -detected between 10-14weeks of gestation
List the sonographic features of agenesis of the corpus callosum
-absence of corpus callosum -elevation and dilation of third ventricle -widely separated lateral ventricle horns -dilated occipital horns (tear drop shaped) -absence of cavum septum pellucidum
List sonographic features of Dandy-Walker malformation
-posterior fossa cyst, varying in size -splaying of cerebellar hemisphere -partial/complete agenesis of vermis -enlarged cisterna magnum -ventriculomegaly
List the sonographic features of acrania
-presence of brain tissue w/o presence of calvarium -disorganization of brain tissue -prominent sulcal markings
List the sonographic features of spina bifida
-slaying of the posterior ossification centers with a "v" or "u"configuration -protrusion of a sac-like structure that maybe anechoic or contain elements. -a cleft in the skin
A ventricle is considered dilated when it's diameter exceeds ____________ mm
10
____________ holoprosencephaly is characterized by a monoventricle, brain tissue that is small ams may have a cup ball or pancake configuration
Alobar
Fetuses with myelomeningoceles often present with cranial defects associated with the _______ malformation which is identified in 90% of cases.
Arnold Chiari syndrome
A neural tube defect in which the meninges alone or the meninges and brain herniate through a defect in the calvarium is a ____________
Cephalocele
The term used to describe herniation of the meninges and the brain through the defect is ____________
Encephalocele
Cephalic neural plate develops into the ____________ and the caudal end forms the ____________ cord
Forebrain, spinal
Almost complete division of the ventricles is seen with a corpus callosum that may be normal, hypoplastic or absent, although the cavum septum pellucidi will still be absent in ____________ holoprosencephaly
Lobar
Cranial ____________ describes the herniation of only meninges.
Meningocele
anecephaly
Neural tube defect caused by folate deficiency. Fatal congenital malformation that results in lack of formation of brain and skull.
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.
Enlargement of the ventricles occurs with ____________ of the CSF flow.
Obstruction
Fetal ventriculomegaly typically progresses from the ____________ horns into the temporal and then to the ____________ ventricular horns
Occipital, frontal
Porencephaly or ____________ cysts are cysts filled with CSF
Porencephalic
A rare disorder characterized by clefts in the cerebral cortex is ____________
Schizencephaly
____________ holoprosencephaly presents with a single ventricular cavity with partial formation of the occipital horns, partial or complete fusion of thalamus
Semilobar
hyrocephalus
Ventriculomegaly in the neonate, abnormal accumulation of CSF within the cerebral ventricles resulting in compression and destruction of brain tissue
Ventriculomegaly
abnormal accumulation of cerebrospinal fluid within the cerebral ventricles leading to dilation of the ventricles; compression of the developing brain tissue and brain damage may result; commonly associated with additional fetal anomalies
anomaly
abnormality or congenital malformation
____________ results from obstruction, atresia or stenosis of the aqueduct of Sylvius causing ventriculomegaly
aqueductal stenosis
spina bifida occulta
closed defect of the spine without protrusion of meninges or spinal cord
Acrania
condition associated with anencephaly in which there is complete or partial absence of the cranial bones
Hydranencephaly
congenital absence of the cerebral hemispheres caused by occlusion of the carotid arteries; midbrain structures are present, and fluid replaces cerebral tissue
a fibrous tract that connects the cerebral hemispheres and aids in learning and memory
corpus callosum
Macrocephaly
enlargement of the fetal cranium as a result of ventriculomegaly
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
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
The forebrain will develop into the _____, midbrain will become the _____, and the hindbrain will form the ________.
prosencephalon, mesencephalon, rhombencephalon
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
