Term
| In normal brain development, the Prosencephalon (forebrain) develops in the ___ week. |
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Definition
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Term
| What is the term for a severe defect/incomplete cleavage of forebrain into two hemispheres? |
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Definition
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Term
| How rare is Holoprosencephaly? |
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Definition
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Term
| If the forebrain does not divide to form both hemispheres, it causes defects in the development of the ___ and ____ structure and function. |
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Definition
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Term
| What is the most common cause of Holoprosencephaly? |
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Definition
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Term
| Other than idiopathy, what are some other causes of Holoprosencephaly? |
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Definition
Chromosomal: Strong assoc. with Trisomy 13 (Patau Syndrome)
Teratogens: drugs, severe chemical exposure |
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Term
| What are the three types of Holoprosencephaly? |
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Definition
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Term
| What is the most severe form of Holoprosencephaly? |
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Definition
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Term
| Describe the brain anatomy involved with alobar holoprosencephaly. |
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Definition
Monoventricle with minimal amount of surrounding cerebral tissue
fused thalami
absent third ventricle, falx, CSP, and corpus callosum |
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Term
| What facial abnormalities are associated with alobar? |
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Definition
| hypotelorism, cyclopia, proboscis, midline facial clefts (absent nose) |
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Term
| What is the term for close-set eyes? |
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Definition
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Term
| What is the most severe facial defect associated with alobar holoprosencephaly? |
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Definition
| cyclopia - 2 orbits fused into one eye |
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Term
| What is the "false nose" visualized above the level of the eyes called? |
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Definition
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Term
| T/F. Alobar holopresencephaly presents with normal lateral ventricles. |
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Definition
False - there are NO lateral ventricles
Instead, there is a monoventricle (horseshow shaped). |
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Term
| What is the prognosis for alobar? |
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Definition
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Term
| How do the lateral ventricles and brain mantle appear in alobar vs semilobar? |
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Definition
very similar, both have:
-monoventricle (no lateral ventricles)
-cortex displaced/flattened
Semilobar may have a dorsal cyst
[image] |
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Term
| How does the size of the head appear in alobar and semilobar? |
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Definition
| variable - microcephaly, normal, or large |
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Term
| This type of holoprosencephaly presents with more cortex and partial fusion of thalami. |
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Definition
| Semilobar Holoprosencephaly |
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Term
| Name the abnormal brain anatomy in semilobar holoprosencephaly. |
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Definition
resembles alobar
-missing midline structures
-variable development of falx/interhemispheric fissure
-more cortex
-partial fusion of thalamus
-absent 3rd ventricle |
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Term
| What type of holoprosencephaly can be associated with a dorsal cyst? |
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Definition
Semilobar
Dorsal cyst is the extension of a ventricle posterior |
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Term
| What facial defects are more common in semilobar? |
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Definition
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Term
| What is the least severe type of holoprosencephaly? |
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Definition
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Term
| Describe the abnormal brain anatomy associated with lobar. |
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Definition
-fully developed cortex
-partial falx (2 hemispheres present)
-absent CSP
-absent/hypoplastic corpus callosum
-normal separation of thalamus
-normal 3rd ventricle
-separate lateral ventricles |
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Term
| What facial abnormalities are associated with lobar holoprosencephaly? |
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Definition
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Term
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Definition
1) lobar
2) alobar
3) normal
4) semilobar |
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Term
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Definition
| proboscis - assoc. with alobar |
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Term
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Definition
| monoventricle - assoc. with lobar & semilobar |
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Term
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Definition
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Term
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Definition
| hypotelorism - close-set eyes |
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Term
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Definition
| cleft nose and cyclopia - assoc. with alobar |
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Term
| What is the bridge of tissue located within the midline of the brain that connects the cerebral hemispheres? |
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Definition
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Term
| The corpus callosum forms the roof of the ________ ________. |
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Definition
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Term
| In normal development, the corpus callosum is completely formed at ___ weeks. |
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Definition
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Term
The corpus callosum lies to CSP and lateral ventricles.
a. lateral
b. inferior
c. medial
d. superior |
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Definition
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Term
| ______________ is defined as the congenital lack of the corpus callosum. |
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Definition
| Agenesis of the Corpus Callosum (ACC) |
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Term
| T/F. ACC includes both partial and complete absence of corpus callosum. |
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Definition
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Term
| Why is an absent CC worrying? |
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Definition
allows the ventricles to ride up and become displaced and misshapen
associated with as many as 50-200 syndromes:
-Trisomy 18 & 13
-Dandy walker
-Holoprosencephaly |
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Term
| Why does Agenesis of the Corpus Callosum result in an absent Cavum Septum Pellucida? |
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Definition
| CC and CSP are formed at the same time |
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Term
| This is a disorder that refers to disproportionate enlargement of the occipital horns of the lateral ventricles. |
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Definition
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Term
| Is Colpocephaly is associated with partial or complete ACC? |
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Definition
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Term
| Describe the appearance of partial ACC. |
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Definition
Anterior portion is present
Posterior portion is absent |
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Term
| What is the prognosis of ACC? |
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Definition
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Term
| Agenesis of the corpus callosum may be suspected by the absence of the ____ and the ‘teardrop’ shape of the _____. |
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Definition
absence of CSP
teardrop shape of lateral ventricles
[image] |
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Term
| ACC is demonstrated in what view of the brain? |
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Definition
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Term
| The "sunburst" or "spokeswheel" sign refers to what brain anatomy in ACC? |
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Definition
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Term
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Definition
| sulci & gyri "sunburst" or "spokeswheel" sign |
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Term
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Definition
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Term
| Name some sonographic signs of Agenesis of the CC. |
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Definition
-Lateral displacement of lateral ventricular walls
-Widely separated lateral ventricular frontal horns
-Tear drop shaped lateral vents
-Absent CSP
-Colpocephaly: small frontal horns and enlarged occipital horns
-Elevated and dilated 3rd ventricle |
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Term
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Definition
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Term
| _______ events: Abnormalities related to vascular infarction or agenesis. |
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Definition
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Term
| Name the four types of Ischemic Events. |
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Definition
Porencephaly
Schizencephaly
Lissencephaly
Hydranencephaly |
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Term
| What is the congenital disorder that results in “softening of the brain” and formation of cysts filled with CSF? |
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Definition
Porencephaly (Porencephalic Cysts)
-Cyst communicates with the ventricular system
-Caused by infection/trauma-hemorrhage within one or both of the cerebral hemispheres |
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Term
[image]
Identify the abnormality and prognosis. |
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Definition
Porencephaly (Porencephalic Cysts)
Prognosis: Neurological deficits (cerebral palsy) |
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Term
| Describe the US appearance of Porencephaly. |
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Definition
Head size = OFTEN NORMAL (CAN be large or small sometimes)
Cystic mass that communicates with lateral ventricle in the brain parenchyma
Most often unilateral
Other cranial anatomy = Well Developed
Face = NORMAL |
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Term
[image]
This cyst is filled with CSF and communicates with the lateral ventricles. |
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Definition
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Term
| Due to unknown cause, this destructive process creates a cleft in the cerebral cortex. |
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Definition
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Term
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Definition
Seizures
developmental delay
mental retardation
motor impairment |
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Term
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Definition
US Appearance of Schizencephaly
Cerebrum containing clefts filled with anechoic CSF
May be associated with agenesis of the CSP and Corpus callosum |
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Term
[image]
You can think of this as creating clefts while ice skating. |
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Definition
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Term
| Brain surface is smooth with no sulci and gyri; Means “smooth brain” |
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Definition
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Term
| US Appearance of Lissencephaly |
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Definition
Difficult to diagnose until 3rd trimester when you can visualize sulci and gyri
Sometimes ventriculomegaly |
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Term
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Definition
Hydranencephaly
Most or all of the cerebrum is absent and the cranium is filled with fluid |
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Term
| Causes of Hydranencephaly |
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Definition
-Bilateral occlusion of the Carotid arteries causing destruction of the cerebral hemispheres
-Infections: (Intrauterine) Herpes virus, cytomegalovirus, toxoplasmosis, cocaine abuse
-Trauma |
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Term
| A severe brain abnormality where normal tissue is destroyed and replaced with fluid. |
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Definition
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Term
| What structures of the brain are absent in Hydranencephaly? |
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Definition
Almost all structures above the brain stem and midbrain are absent
Cerebrum: ABSENT
CSP: ABSENT OR PARTIAL
Falx: ABSENT OR PARTIAL
3rd Ventricle: ABSENT
Thalamus: PARTIAL OR PRESERVED |
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Term
| What part of the brain is normal with Hydranencephaly? |
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Definition
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Term
| Hydranencephaly US Appearance |
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Definition
Enlarged head size (Macrocephaly)
Fluid-filled cranium
Absent or hypoplastic midline structures
No identifiable cerebral cortex
[image] |
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