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