fetal face and neck and neural axis 2
Terms
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- a defect that may have varying degrees of severity; abnormality of ventricular system because of a posterior fossa cyst
- dandy walker malformation
- it manifests with agenesis of hypoplasia of the cerebellar vermis with resulting dilation on the fourth ventricle and therefore dilation of the third and lateral ventricle; occurs in two forms
- dandy walker malformation
- the mildest form of dandy walker malformation with dilation of the fourth ventricle only
- dandy walker variant
- assoc. with hydrocephalus, agenesis of the corpus callosum, aqueductal stenosis, microcephaly or macrocephaly, encephalocele, chromosomal anomalies 13, 18, 21, and meckel-gruber syndrome; prognosis depends on the presence or absence of assoc. anomalies.
- dandy-walker malformation
- sono appearance: posterior fossa cyst that can vary considerably in size; splaying of the cerebellar hemispheres as a result of the complete or partial agenesis of the cerebellar vermis; an enlarged cisterna magna caused by the cerebellar vermis anomaly;
- dandy walker malformation
- encompasses a range of abnormalities resulting from abnormal cleavage of the prosencephalon (forebrain); falx not there to separate the two brain hemispheres
- holoprosencephaly
- causes are usually sporadic, with a slight recurrence risk, but also genetic, teratogenic, and chromosomal assoc (13); prognosis is uniformly poor but depends on type
- holoprosencephaly
- what are the three types of holoprosencephaly (determined on amount of division)
- alobar (severe), semilobar (intermediate), lobar (mildest)
- characterized by a mono-ventricle, 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 pellucidum, corpus callosum, optic tracts, and olfactory bu
- alobar holoprosencephaly
- presents with a singular ventricular cavity with parital formation of the occipital horns, partial or complete fusion of the thalamus, a rudimentary falx and interhemispheric fissure, and absent corpus callosum, cavum septum pellucidum, and optic tracts a
- semilobar holoprosencephaly
- almost complete division of the ventricles with a corpus callosum that may be normal, hypoplastic, or absent, although the cavum septum pellucidum will be absent; almost complete hemispheric division
- lobar holoprosencephaly
- sono appearance: a common c-shaped ventricle may or may not be enlarged is seen; brain tissue with a horseshoe shape as it surrounds the mono-ventricle; fusion of the thalamus with the sbsence of the third ventricle; absence of IHF; a dorsal sac with exp
- holoprosencephaly
- develops from 12-20 weeks so diagnose until after 20 weeks
- holoprosencephaly
- often assoc with facial abnormalities, especially in the severe forms; cyclopia, hypotelorism, an absent nose, flattened nose with single nostril, and a proboscis; facial cleft may be present with median or bilateral clefting most commonly observed; also
- holoprosencephaly
- assoc. with renal cysts or dysplasia, omphalocele, cardiac defects, spina bifida, talipes, and GI anomalies
- holoprosencephaly
- describes a range of complete to partial absence of the callosal fibers that cross the midline, forming a connection between the two hemispheres; can't be diagnosed until after 20 weeks
- agenesis or dysgenesis of the corpus callosum
- the etiology is somewhat unclear but is thought to involve a vascular disruption or inflammatory lesion before 12 weeks; may be assoc with CNS malformations, and autosomal dominant, autosomal recessive,a nd x-linked syndromes, trisomy 13 and 18; prognosis
- agenesis or dygenesis of corpus callosum
- as an isolated event may be asymptomatic or associated with mental retardation and/or seizures
- agenesis or dysgenesis or corpus callosum
- sono appearance: absence of the corpus callosum, dilation of the third ventricle, widely separated ventricular frontal horns with medial indentation of the medial walls; dilated occipital horns (colpocephaly), givign the lateral ventricles a teardrop shap
- agenesis or dysgenesis or corpus callosum
- associated with holoprosencephaly, DWM, arnold-chiari malformation, hydrocephaly, encephalocele, porencephaly, and microcephaly; in addition cardiac malformations, diaphragmatic hernia, lung agenesis or dysplasia, and absent or dysplastic kidneys may be s
- agenesis or dysgenesis of corpus callosum
- results from the obstruction, atresia, or stenosis of the aqueduct of sylvius causing ventriculomegaly; the fourth ventricle, cisterna magna, and cerebellum appear normal but 3rd ventricle and everything prox. to it is dilated
- aqueductal stenosis (cerebral aqueduct between the third and fourth ventricle)
- usually a sporadic anomaly but also may result from TORCH; cranial masses and ventricular hemorrhage are also contributing factors or aquired obstruction; usually x-linked and has an autosomal-recessive inheritance
- aqueductal stenosis
- more common in male fetuses; the prognosis is considered poor and varies with assoc. anomalies; mental retardation are seen with x-linked disorders
- aqueductal stenosis
- sono appearance: ventricular enlargement of the lateral ventricles and third ventricular dilation; flexion and adduction of the thumb are seen in the x-linked form
- aqueductal stenosis
- an aneurysm of the vein of galen (brain is fed by circle of willis and drained by vein of galen); a rare arteriovenous malformation; the vein is enlarged and communicates with normal-appearing arteries
- vein of galen cyst/malformation
- is considered sporadic and has male predominance; usually don't see it until the third trimester; usually and isolted anomaly, although it has been assoc. with congenital heart defects, cystic hygromas, and hydrops
- vein galen cyst/malformation
- prognosis is generally poor, especially when assoc with hydrops and/or cardiac failure
- vein galen cyst/aneurysm/malformation
- sono appearance: cystic space that may be irregular in shape and is located midline and posterosuperior to the third ventricle; turbulent flow with doppler; cardiomegaly, nonimmune hydrops, ventriculomegaly with resultant macrocephaly also may develop; ma
- vein of galen cyst/malformation
- round or ovoid anechoic structures found within the choroid plexus; more commonly seen between 13-24 weeks adn then goes away; if it doesn't go away it might be linked to chromosomal problem; contain CSF adn usually an isolated finding without assoc. with
- choroid plexus cyst
- have been associated with aneuploidy, most commonly trisomy 18 and 21; sonographically is appears as a cyst within choroid plexus in size from 0.3-2 cm; completely round or oval; may be uni or bilateral; soliary or multiple, uni or multilocular, enlargeme
- choroid plexus cyst
- cysts filled with CSF that communicate with the ventricular system or subarachnoid space; form when there is degeneration of brain tissue usually next to and communicating with lateral ventricles; may result in hemorrhage, infarction, delivery trauma, or
- porencephalic cyst
- the affected brain parenchyma undergoes necrosis, brain tissue is resorbed, and a cystic lesion remains; there is no known assoc. anomalies with this anomaly
- porencephalic cyst
- sono appearance: cyst within the brain parenchyma wihtout mass effect; dilation of ventricle; communication of the cyst with the ventricle or subarachnoid space; if it doesn't communicate with lateral ventricle then can't be this; may be confused with ara
- porencephalic cyst
- a rare disorder characterized by clefts in the cerebral cortex; seen in parietal or temporal lobe; clefts may be uni or bilateral, open-lip (extends to lateral ventricles) or closed lip defects (in cortex only); result from abnormal migration of neurons
- schizencephaly cyst
- these clefts can extend from the outer surface to the ventricles of the brain and are lined with abnormal gray matter; the etiology remains unclear, although it has been linked with multiple assaults during pregnancy; assoc with congenital infections, dru
- schizencephaly cyst
- the prognosis varies, with mild to severe outcomes; closed lip might be repairable. open lip repairs often don't work; open lip lesions carry a worse prosnosis; hydrocephalus may be progressive and require shunt replacement
- schizencephaly cyst
- sono appearance: fluid-filled cleft in the cerebral cortex extending from the calvarium to the ventricular system; ventriculomegaly may be observed; also assoc with absence of septum pellucidum, microcephaly, and corpus callosum
- schizencephaly cyst
- destruction of the cerebral hemispheres by occlusion of the internal carotid arteries resulting in ischemia of the frontal lobe making water head
- hydranencephaly
- brian parenchyma is destroyed and is replaced by CSF; because the posterior communicating arteries are preserved, the midbrain and cerebellum are present, and the basal ganglia, choroid plexus, and thalamus may be spared, but everything anterior is gone
- hydranencephaly
- may be assoc with polydramnios, holoprosencephaly, and hydrocephaly; the etiology usually involved congenital infection or ischemia such as TORCH, maternal hypotension, twin-to-twin embolization, or vascular agenesis which can all occlude ICA
- hydrancephaly
- may occur later in pregnancy (late second or early third) and that brain structures intially may be normal
- hydrancephaly
- sono appearance: absence of normal brain tissue with almost complete replacement by CSF; an absent or partially absent falx, presence of the midbrain, basal ganglia, and cerebellum seen, and the choroid plexus may be identified; macrocephaly may occur; ma
- hydranencephaly
- dilation of ventricles in the brain; most common cranial abnormality; occurs when ventriculomegaly is coupled with enlargement of the fetal head
- hydrocephalus(ventriculomegaly)
- enlargement of the ventricles and thus hydrocephalus occurs with obstruction of cerebral spinal fluid. what are the three types of obstruction
- non-communicating, communicating, mass effect
- hydrocephalus: type that occurs within the choroid plexus such as a papilloma that caused CSF to overproduce is ___. type that occurs outside the ventricular system is called ___. the type that is caused by aqueductal stenosis or foramen of monroe is __
- mass, communicating, non-communicating
- physiologically when an obstruction occurs the ventricles dilate as the flow of CSF is blocked; this increases the pressure within the ventricular system, which leads to ventricular expansion; enlarged ventricles may exert pressure on the brain tissue, en
- hydrocephalus
- may be assoc with an anomaly or the cause may remain unknown; aqueductal stenosis, arachnoid cysts, vein of Galen aneurysms, spina bifida, encephaloceles, dandy-walker malformation, agenesis of the corpus callosum, schizencephaly, and holoprosencephaly ca
- hydrocephalus/ventriculomegaly
- ventriculomegaly is diagnosed when the lateral ventricles are greater than __ mm
- 10
- complete dilation of the ventricular system typically progresses from the __ horns into the temporal and then to the frontal venticular horns; the mortality rate is high with the outcome depending largely on the presence and severity of assoc anomalies;
- *occipital *half
- sono appearance: lateral ventricular enlargement greater than ten mm; a "dangling choroid sign" as the gravity-dependent choroid plexus fall into the increased ventricular space; possible dilation of third and fourth ventricles; fetal head enlargement; as
- hydrocephaly/ventriculomegaly
- an abnormally small head that falls 2 standard deviations (2 weeks) below the mean; it occurs because the brain is reduced in size; all parameters (HC, BPD, FL, AC) should always fall within two weeks of each other
- microcephaly
- may result from inheritance of either an autosomal-recessive or dominant pattern; if it's genetic link then prognosis is fine. bad prognosis occurs when teratogen-induced, congenital infections, maternal alcohol abuse, heroin addiction, mercury poisoning
- microcephaly
- sono appearance: small BPD and HC in comparison to other parameters; abnormal hc/ac and/or hc/fl ratios; disorganized brain tissue and ventriculomegaly, encephalocele, porencephaly, agenesis fo the corpus callosum, craniosynostosis (clover-leaf), holopros
- microcephaly