Chapter 60 Fetal Neural Axis Flashcards
1
Q
CNS arises from the ectodermal neural plate around _____
A
18 days gestation
2
Q
Cephalic neural plate develops into the
A
forebrain
3
Q
the caudal end forms the
A
spinal cord
4
Q
the forebrain develops into the
A
Prosencephalon
5
Q
the mesencephalon develops into the
A
midbrain
6
Q
the rhombencephalon develops into the
A
hindbrain
7
Q
by the end of the 3rd week, the cephalic end of the neural tube bends into a ____ shape
A
c-shape
8
Q
in the ____ week, the neural tube bends again
A
5th
9
Q
The prosenceohalon divides into the
A
Telencephalon and diencephalon
10
Q
Telencephalon becomes the
A
Cerebral hemispheres
11
Q
Diencephalon becomes the
A
Thalamus
12
Q
Rhombencephalon divides into the
A
Metencephalon and mylencephalon
13
Q
Metencephalon becomes
A
Cerebellum and pons
14
Q
Mylencephalon becomes
A
Medulla
15
Q
Neural function begins at
A
6 weeks gestation
16
Q
Between _____ the fetus can grip objects and is capable of weak respiratory movements
A
4-5 months
17
Q
Fetus displays sucking reflux at ____
A
6 months
18
Q
Most common neural tube defect
A
Anencephaly
19
Q
Absence of brain and skull
A
Anencephaly aka aprosencephaly/atencephaly
20
Q
Risk of anencephaly can be reduced by 50-70% with use of ______ supplements beginning 1 month before pregnancy
A
Folic acid
21
Q
Caused by failure of the neural tube at the cranial end. Resulting in absent cranial vault, complete/partial absence of forebrain
A
Anencephaly
22
Q
Prenatal diagnosis of anencephaly is often made with sonography, following a lab value of ___
A
Elevated AFP
23
Q
Causes for anencephaly:
A
Diabetes, Meckel-Gruber syndrome
24
Q
Sonographic findings of anencephaly:
A
Bulging fetal orbits—frog face appearance
25
Absence of skull
Acrania
26
Acrania is also known as
Exencephaly
27
Absence of cranial bones with the cerebral hemispheres still there(although abnormal)
Acrania
28
Acrania usually progresses to anencephaly because:
Brain slowly degenerates from exposure to amniotic fluid
29
How to distinguish acrania from anencephaly:
Presence of significant brain tissue and lack of frog-face appearance indicated acrania
30
Neural tube defect in which meninges alone or meninges and brain herniate through a defect in the skull
Cephalocele
31
Herniation of meninges AND brain through defect
Encephalocele
32
Herniation of only meninges through defect
Cranial meningocele
33
Cephalocele more commonly involves the _____ bone
Occipital
34
Sonographic features of cephalocele:
Extracranial mass
| Ventriculomegaly
35
Autosomal recessive disorder characterized by encephalocele, polydactyl, polycystic kidney disease
Meckel-Gruber syndrome
36
Cephalocele may be confused with
Cystic hygroma
37
Chromosomal anomalies and syndromes associated with cephaloceles
Trisomy 13
| Meckel-Gruber syndrome
38
Wide range of defects that result from failure of neural tube to close
Spina bifida
39
Spina bifida most commonly occurs along the ____ and ____ region
Lumbar and sacral
40
The term spina bifida means
There is an cleft/opening in the spine
41
Spina bifida occulta is extremely difficult to detect if
Defect is covered by skin
| AFP is normal
42
Spinal opening covered in skin, commonly with a tuft of hair
Spina Bifida Occulta
43
Sounds bifida term used when defect only involves the protrusion of meninges
Meningocele
44
Sounds bifida term used when both meninges & neural elements protrude through defect(more common)
Meningomyelocele
45
Sounds bifida term used when defect is very large and severe
Rashcischisis
46
Raschischisis is associated with increased
AFP
47
Most fetus(90%) with myelomeningocele present with cranial defects associated with
Arnold-Chiari 2 malformation
48
Arnold-Chianti 2 malformation is ____ shaped appearance of the cerebellum
Banana
49
Arnold-Chiari 2 malformation leads to obliteration of the
Cisterna magna
50
Due to increased intracranial pressure during spina bifida, the skull will be ____ shaped
Lemon shaped
51
The best plane to evaluate the spine for spina bifida is:
Transverse
52
Normal spine should be triangular or circular, with spina bifida (meningomyelocele) the splaying of the posterior ossification centers makes a
V or U shape
53
Intracranial findings with spina bifida
Ventriculomegaly
Banana shaped cerebellum
Lemon shaped skull
Cisterna magna obliteration
54
Spina bifida is associated with chromosomal anomalies and syndromes like:
Trisomy 18
55
Maternal risk factors for spina bifida:
Diabetes, obesity, folic acid deficiency, hyperthermia
56
Rare, occiput is fused to the cervical region
Iniencephaly
57
Defect in occiput involving the foramen magnum, retroflexion of spine causes fetus to look upward: ____ sign. This is ____
Stargazing sign
Iniencephaly
58
cerebellar lobes “go for a walk”
Dandy-Walker Malformation
59
Agenesis or hypoplasia of the cerebelar vermis, resulting in 4th ventrical dilation and enlargement of posterior fossa
Dandy-Walker Malformation
60
50% of the time, Dandy-Walker Malformation is associated with
Agenisis of the corpus collosum
61
Dandy Walker Malformation encompasses 3 types of posterior fossa malformations:
Elevated tentorium(tent of the cerebellum)
Dialation of 4th ventricle & hypoplasia of cerebellar vermis w/o enlargement of posterior fossa
Megacisterna magna(large Cisterna magna)
62
Diagnosis of agenesis or hypoplasia of vermis shouldnt be made until ____ week
18 weeks gestation
63
Vermis begins to develop during
9th week
64
4th ventricle and cisterna magna are complete:
18 weeks
65
Extracranial abnormalities associated with Dandy-Walker Malformation(DWM):
Cardiac anomalies
66
Sonographic features of DWM:
Large posterior fossa cyst
Enlarged cisterna magna, ventriculomegaly
67
How would you differentiate a posterior fossa cyst from a subarachnoid cyst
PFC communicates with the 4th ventricle
68
Holoprosencephaly results from abnormal cleavage of
Prosencephalon
69
3 forms of holoprosencephaly
1. Lobar(mild)
2. Semi-lobar(middle)
3. Alobar(worst)
70
Holoprosencephaly: Singular, monoventricle brain tissue that js small(may have cup, ball, pancake configuration). Absence of pretty much everything
Alobar
71
Alobar holoprosencephaly involves fusion of the ____
Thalamus
72
Holoprosencephaly: Singular ventricular cavity with partial formation of occipital horns, falx & interhemispheric fissure
Semi-lobar
73
Holoprosencephaly in which the corpus collosum may still be present
Lobar
74
Sonographic features of holoprosencephaly
C-shaped ventricle
Horseshoe shaped brain tissue surrounding that ventricle
Absent CSP
75
Facial clefts may be oresent with holoprosencephaly, most commonly they are
Medial or bilateral
76
Hypotelorism with normally placed nose with single nostril
Cebocephaly
77
Severe hypotelorism with probiscis superior to eyes
Ethmocephaly
78
Fibrous tract that connects the cerebral hemispheres that aids in learning and memory
Corpus collosum
79
Agenesis of the corpus callosum is thought to involve _____ or inflammatory lesions before 12 weeks
Vascular disruption
80
Maternal diseases contributing to a genesis of the corpus callosum
Diabetes
81
Sonographic features of agenesis of the corpus callosum
Teardrop shaped lateral ventricle
absent cavum septum pellucidum
82
Aqueductal stenosis results from obstruction or stenosis of the
Aqueduct of Sylvius
83
Sonographic features of aqueductal stenosis
Dilation of third ventricle, lateral ventricle enlargement
84
Rare arteriovenous malformation, predominantly occurs in males, associated with congenital heart defects
Vein of Galen Aneurysm
85
Vein of Galen aneurysm prognosis is especially poor when associated with
Hydrops or cardiac failure
86
Primary treatment for Vein of Galen aneurysm
Embolism
87
Vein of Galen aneurysm will show ____ flow with Doppler
Turbulent
88
Cystic space that may be a regularly shaped and located midline and posterosuperior to the third ventricle indicates:
Vein of Galen aneurysm
89
Choroid plexus cysts may be associated with
Trisomy 18
90
Cysts filled with CSF that communicate with the ventricular system or subarachnoid space. No known associated anomalies.
Porencephalic cysts/porencephaly
91
Post natal problems from porencephalic cysts/porencephaly may include
Seizures
92
Rare disorder characterized by clefts in the cerebral cortex
Schizencephaly
93
Schizencephaly is usually in the area of the _____
Sylvian fissure
94
Schizencephaly is linked with ___
Multiple assaults during pregnancy
95
In schizencephaly, _____ and ____ carry a wkrse prognosis
Open lip lesion and bilateral clefts
96
Sonographic features of schizencephaly
Ventriculomegaly
Fluid-filled cleft in cerebral cortex extending from ventricle to calvarium
97
Absent or reduced cerebral convolutions, brain lacks sulci and gyri, therefore is appears smooth
Lissencephaly
98
Diagnosis of lissencephaly cannot be made until
3rd trimester
99
Destruction of cerebral hemispheres by occlusion of the internal carotid arteries
Hydranencephaly
100
Coexisting chromosomal and stuctural anomalies associated with hydranencephaly
None
101
Hydranencephaly is associated with
Polyhydramnios
102
With hydranencephaly, brain ischemia may result from
Maternal hypotension
103
Sonographic features of hydranencephaly
Absense if normal brain tissue with almost complete replacement by CSF
Absent or partially absent falx
104
How do you differentiate hydranencephaly from hydrocephaly?
Look for the midline falx— if its gone it will be hydranencephaly
Hydranencephaly wont demonstrate the dangling choroid sign, hydrocephaly will
105
Dilation of the ventricles within the brain secondary to an increase in CSF volume
Ventriculomegaly/hydrocephalus
106
Ventriculomegaly/hydrocephalus can be either ____ or ______
Communicating or noncommunicating
107
Ventriculomegaly/hydrocephalus:
Obstruction cause by ventricular defect(aqueduct Sylvius):
Noncommunicating hydrocephalus
108
Ventriculomegaly/hydrocephalus:
Obstruction outside the ventricular system:
Communicating hydrocephalus
109
Associated abnormalities with ventriculomegaly/hydrocephalus:
Aqueductal stenosis
| Vein of Galen aneurysm
110
Common causes of ventriculomegaly/hydrocephalus:
Spina bifida
Encephaloceles
111
Sonographic features of hydrocephalus/ventriculomegaly
Dangling choroid sign
112
What differentiates hydrocephalus/ventriculomegaly from hydranencephaly and holoprosencephaly?
Presence of complete falx, choroid plexus, 3rd & 4th ventricles
113
Abnormally small head that falls 2 standard deviations below the mean
Microcephaly
114
Factors linked with microcephaly
Alcohol abuse, heroin addiction, mercury poisoning
115
Microcephaly is usually associated with ______
Neurological deficits
116
Sonographic features of microcephaly
Abnormal measurements
Cerebral calcifications with congenital infections
Clover-leaf skull
