1
Q
What is the common theme in Holoprosencephaly (HPE)?
A
Some element of abnormal central fusion
HPE is characterized by a failure to perform normal midline cleaving.
2
Q
In normal embryology, what does the term cleavage refer to?
A
The process of separating lateral hemispheres
Cleavage occurs back to front, opposite to the formation of the corpus callosum.
3
Q
What are the three forms of Holoprosencephaly based on severity?
A
- Lobar
- Semi-Lobar
- Alobar
These forms represent a spectrum of severity in midline fusion abnormalities.
4
Q
In the Alobar form of HPE, what is the condition of the cerebral hemispheres?
A
Cerebral hemispheres are fused with a single midline ventricle
This is the most severe form of HPE.
5
Q
What is the shape of the brain in the Lobar form of HPE?
A
Pancake / Cup Shape
The frontal lobes may show varying degrees of fusion.
6
Q
True or false: In HPE, the posterior cortex is typically normal in milder forms.
A
TRUE
The anterior cortex is fused while the posterior cortex remains normal.
7
Q
What is a possible buzzword associated with the HPE spectrum?
A
- Monster Cyclops Eyes
- Cleft lips / Palates
- Solitary Median Maxillary Incisor
These terms are often used to describe physical manifestations of HPE.
8
Q
What does the Septum Pellucidum refer to in the context of HPE?
A
A structure that may be partially or completely fused
Its condition varies across different forms of HPE.
9
Q
What is the outcome for individuals with Cleft Lip / Palate in HPE?
A
Survive into adulthood, but may have significant challenges
Their cognitive abilities can vary widely.
10
Q
Fill in the blank: The anterior interhemispheric fissure is associated with which condition?
A
Holoprosencephaly
This structure may be affected in varying degrees of HPE.
11
Q
What is Arhinencephaly characterized by?
A
- Minor HPE expression
- Absent midline olfactory bulbs/tracts
- Clinical buzzword: ‘Can’t Smell’
Could be tested as Kallmann Syndrome, which also has hypogonadism and mental retardation.
12
Q
What is the classic triad of Meckel-Gruber Syndrome?
A
- Occipital Encephalocoele
- Multiple Renal Cysts
- Polydactyly
Also strongly associated with Holoprosencephaly.
13
Q
What is another name for Septo Optic Dysplasia?
A
de Morsier Syndrome
The classic findings include absent Septum Pellucidum and hypoplastic optic structures.
14
Q
What are the classic findings in Septo Optic Dysplasia?
A
- Absent Septum Pellucidum
- Hypoplastic optic structures (Optic Chiasma and Optic Nerves)
Associated with Schizencephaly.
15
Q
What is an Azygos ACA?
A
A common trunk of the anterior cerebral arteries
This is rare but associated with Septo Optic Dysplasia and lobar Holoprosencephaly.
16
Q
What is the failure to migrate/proliferate associated with?
A
Lissencephaly-Pachygyria Spectrum
Understanding this complex pathology requires a rapid review of embryologic neuronal cortex formation.
17
Q
What is hemimegalencephaly characterized by?
A
- Enlargement of all or part of one cerebral hemisphere
- Failure in normal neuronal differentiation
- Abnormal mixture of normal tissues (hamartoma)
This condition often coexists with other migration errors like polymicrogyria, pachygyria, and heterotopia.
18
Q
What are the two key features that can confuse hemimegalencephaly with destructive pathologies?
A
- Dilated ventricle
- Mismatched hemisphere size
The side of the dilated ventricle helps differentiate between conditions.
19
Q
In hemimegalencephaly, if the big side has a big ventricle, what does this indicate?
A
Hemimegalencephaly
This indicates an overgrowth of part of a cerebral hemisphere due to differentiation/migration failure.
20
Q
In hemimegalencephaly, if the small side has a big ventricle, what does this indicate?
A
Atrophy
The shrunken half is atrophic, resulting in an ar vacuo dilation of the ventricle.
21
Q
What is Rasmussen’s encephalitis?
A
A zebra viral (or maybe autoimmune) disease that annihilates half the brain
This condition typically affects children and can lead to severe neurological deficits.
22
Q
What are the characteristics of Dyke-Davidoff-Masson syndrome?
A
- Unilateral skull thickening
- Expanded sinuses
- Superior sagittal sinus and fissure moved across the midline
It is supposedly caused by an in utero or childhood stroke.
23
Q
What is a common cause of refractory extra-temporal epilepsy in kids?
A
Failure to migrate
Treatment usually involves surgical resection.
24
Q
What is the most common subtype of failure to migrate seen in kids?
A
Type II
There is significant overlap between the various subtypes.
25
What are general features on MRI for failure to migrate?
* Cortical/subcortical T2/FLAIR hyperintensity
* Focal cortical thickening
* Blurry grey-white interface
* Transmantle sign
## Footnote
The Transmantle sign is a linear FLAIR hyperintense band radiating from the ventricle to the subcortex/cortex.
26
What does the **Transmantle sign** indicate?
Linear FLAIR hyperintense band radiating from ventricle to subcortex/cortex
## Footnote
This sign is associated with failure to migrate.
27
What is the **spectrum** of pathologies related to abnormal migration?
* Agyria
* Pachygyria
* Band heterotopias
## Footnote
These conditions range from no gyri to flat gyri and abnormal brain structures.
28
Define **Lissencephaly**.
A condition characterized by a smooth brain surface due to abnormal neuronal migration
## Footnote
It can be classified into different types, including Classic Type 1 and Cobblestone Type 2.
29
What is the **classic** type of Lissencephaly also known as?
Type 1
## Footnote
This type is associated with a double cortex appearance and seizure disorders.
30
What does **Colpocephaly** refer to?
A condition characterized by a 'Figure 8' shaped brain due to shallow, vertical Sylvian fissures
## Footnote
It is commonly associated with Lissencephaly.
31
What is the result of **undermigration** in neuronal migration?
Failure to migrate adequately, leading to disorganized layers of cortical neurons
## Footnote
This results in a classic 'double cortex' appearance and is considered the mildest form of Classic Lissencephaly.
32
What is the **gyral pattern** in undermigration?
Normal or mildly simplified
## Footnote
The cortical folding process does not take place due to inadequate migration.
33
What is the inheritance pattern for **Lissencephaly**?
* Autosomal Inheritance (M=F)
* X-Linked Inheritance (F>M)
## Footnote
These patterns indicate how the condition may be passed down through generations.
34
What is **overmigration** in the context of neuronal migration?
An excessive migration of neurons resulting in additional layers of cortex
## Footnote
This condition is associated with congenital muscular dystrophy and retinal detachment.
35
What are **nodular gray matter** deposits associated with?
Failed migration of neurons in the periventricular region
## Footnote
This results in nodular gray matter deposition along the ventricle borders.
36
What distinguishes **heterotopias** from other gray matter conditions?
They follow gray matter on all sequences and do NOT enhance
## Footnote
In contrast, subependymal tubers of TS may appear brighter on T2 relative to gray matter.
37
What is the **hallmark finding** of Polymicrogyria (PMG)?
Excessive number of small folds
## Footnote
This occurs due to the obliteration of layer 5 after normal migration, causing superficial layers to overfold and fuse.
38
What is the **classic look** of Polymicrogyria?
Fine undulating / bumpy cortex
## Footnote
This anomaly can vary in shape and size, being unilateral, bilateral, small, large, symmetric, or asymmetric.
39
Where is the most common location for Polymicrogyria to occur?
Adjacent to the Sylvian fissure bilaterally
## Footnote
This is a typical presentation of PMG.
40
What is the most common cause of **Polymicrogyria** in Brazil and South America?
Zika Virus
## Footnote
This viral infection has been linked to the development of PMG.
41
What does **schizencephaly** literally mean?
Split brain
## Footnote
The defining feature is a cleft lined with grey matter connecting CSF spaces with the ventricular system.
42
What is a popular theory regarding the cause of **schizencephaly**?
Vascular insult
## Footnote
This damages the radial glial fibers responsible for guiding neuron migration.
43
What percentage of patients with **schizencephaly** also have non-CNS vascular stigmata?
30%
## Footnote
An example of this is gastroschisis, which is thought to occur from a vascular insult.
44
What are the two types of **schizencephaly** clefts?
* Closed Lip (20%)
* Open Lip (80%)
## Footnote
Closed Lip is less common and less severe, while Open Lip is more common and more severe.
45
What is a defining feature of **Closed Lip** schizencephaly?
The 'Lip' appears closed without a CSF filled cleft
## Footnote
To identify it, look for grey matter running across the corona radiata.
46
What is a defining feature of **Open Lip** schizencephaly?
CSF-filled cleft lined with grey matter
## Footnote
This cleft extends from the ventricle to the pial surface.
47
What are some **associations** with schizencephaly?
* Absent Septum Pellucidum (70%)
* Focally Thinned Corpus Callosum
* Optic Nerve Hypoplasia (30%)
* Epilepsy
## Footnote
These associations highlight the complexity of the condition.
48
What are the **two conditions** discussed that mimic developmental failure?
* Hydranencephaly
* Porencephalic Cyst
## Footnote
These conditions can be thought of along a spectrum of severity.
49
In terms of severity, which condition is considered **least severe**?
Porencephalic Cyst
## Footnote
Hydranencephaly is considered more severe.
50
What is the underlying mechanism for **Hydranencephaly** and **Porencephalic Cyst**?
Acquired conditions due to a vascular insult or anything causing encephalomalacia
## Footnote
Encephalomalacia is focal necrosis of both gray matter and white matter with eventual cystic degeneration.
51
What happens to the brain in **Hydranencephaly**?
Almost the entire brain is destroyed, leaving only the cerebellum, midbrain, and falx
## Footnote
This condition results in significant loss of brain tissue.
52
What is a key finding in the brain associated with **Porencephalic Cyst**?
Absence of a gray matter lining along the defect
## Footnote
This absence is a significant indicator of the condition.
53
What does the term **encephalomalacia** refer to?
Focal necrosis of both gray matter and white matter
## Footnote
It can lead to cystic degeneration in the brain.
54
What is the difference between **open lip** and **closed lip** in the context of **Schizencephaly**?
* Open Lip: Cleft communicates with the Subarachnoid Space
* Closed Lip: Cleft communicates only with the ventricular system
## Footnote
This distinction is important for diagnosis.
55
What typically remains in the brain after **bilateral ICA occlusion**?
* Cerebellum
* Midbrain
* Falx
## Footnote
This condition causes massive destruction of both cerebral hemispheres.
56
What are some **in utero infections** that can lead to conditions like Hydranencephaly?
* Herpes
* Toxoplasmosis (toxo)
* Cytomegalovirus (CMV)
## Footnote
These infections are classic causes of brain damage during fetal development.
57
What is the appearance of a **cleft** in the brain associated with **Porencephalic Cyst**?
CSF-filled cleft extending from the ventricle to the pial surface
## Footnote
The cleft is lined with gray matter.
58
True or false: In **Hydranencephaly**, the brain is normally formed but appears developmental due to massive insult.
FALSE
## Footnote
Hydranencephaly involves significant loss of brain tissue, not normal formation.
59
What is the **first question** to determine the condition of the brain?
Is the **Cortical Mantle** (outside of brain) present or gone fishing?
## Footnote
This question helps narrow down the choices for diagnosis.
60
If the **Cortical Mantle** is present, what is the **second question** to ask?
Look for the **falx cerebri**.
## Footnote
The presence of the falx cerebri can indicate specific conditions.
61
What condition is indicated if the **Cortical Mantle** is still present but the **falx cerebri** is not?
**Hydranencephaly**
## Footnote
This condition involves the absence of the cerebral hemispheres.
62
What condition is indicated if the **Cortical Mantle** is still present and the **falx cerebri** is present?
**Severe Hydrocephalus**
## Footnote
This condition involves an accumulation of cerebrospinal fluid in the brain.
63
What condition is indicated if the **Cortical Mantle** is present but the **falx cerebri** is missing?
**Holoprosencephaly - Alobar**
## Footnote
This condition is characterized by the failure of the brain to properly divide into two hemispheres.
64
In the case of **Holoprosencephaly**, what is usually missing in the semi-lobar form?
**Anterior falx**
## Footnote
The anterior falx is typically absent in this subtype.
65
In the **mild subtype** of **Holoprosencephaly**, what should still be present?
**Falx cerebri**
## Footnote
This indicates that even in mild cases, some structures may remain intact.
66
What is the definition of **Cephalocele**?
**Herniation of the cranial contents through a defect in the skull**
## Footnote
Sub-classified based on location and contents of the herniation sac.
67
List the **locations** where Cephaloceles can occur.
* Parietal
* Frontal
* Ethmoid
* Trans-sphenoidal
* Occipital
## Footnote
These locations determine the classification of the cephalocele.
68
What are the **contents** that can be found in a herniation sac of a Cephalocele?
* CSF & Meninges (Meningocele)
* CSF, Meninges, and Brain (Encephalocele)
## Footnote
Meningoencephaloceles are sometimes referred to as Encephaloceles.
69
What is a **Cystocele**?
**CSF, Meninges, Brain, and Ventricle**
## Footnote
Cystocele is a type of herniation that includes these specific contents.
70
What does a **Myelocele** contain?
**Spinal Cord**
## Footnote
Myelocele refers specifically to herniation involving the spinal cord.
71
What is the shared finding of **Chiari malformations**?
**Downward displacement of the cerebellum**
## Footnote
Chiari malformations are categorized into several numbered sub-types.
72
What are the **subtypes** of Chiari malformations?
* Type I
* Type II
* Type III
* Type IV
* Type 1.5
## Footnote
Each subtype has distinct features and clinical implications.
73
What is a characteristic feature of **Type I Chiari malformation**?
**Tonsillar herniation (more than 5 mm)**
## Footnote
Type I is relatively less severe compared to Type II.
74
What is a classic association with **Chiari malformations**?
* Syrinx (cervical cord)
* Low lying torcula
* Tectal beaking
* Hydrocephalus
* Clival hypoplasia
## Footnote
These features may not always be present but are commonly associated.
75
What does **Type 1.5 Chiari malformation** describe?
**Conditions with features of both Type 1 and Type 2**
## Footnote
Not associated with neural tube defects despite significant downward movement of the tonsils and brain stem.
76
True or false: **Type IV Chiari malformation** is historically used to describe severe cerebellar hypoplasia without herniation.
TRUE
## Footnote
The term has fallen out of favor in the current nomenclature.
77
What is **Chiari Type I** defined as?
1 or both tonsils > 5mm below the level of the Basion - Opisthion
## Footnote
Classically associated with a syrinx.
78
What is the **classic mechanism** of Chiari Type I?
Congenital underdevelopment of the posterior fossa, leading to overcrowding and downward displacement
## Footnote
Non-classic can be post-traumatic deformity acquired later in life.
79
What are the **clinical symptoms** of Chiari Type I?
* Occipital headache from pressure of the cerebellar tonsils, worse with sneezing
* Weakness, spasticity, and loss of proprioception from pressure on the cord
## Footnote
Symptoms can vary in presentation.
80
What is a **classic association** with Chiari Type I?
Syrinx of the cervical cord
## Footnote
Not always present but commonly associated.
81
What is a **less classic association** with Chiari Type I?
Klippel-Feil Syndrome (congenital C-spine fusion)
## Footnote
This condition is not associated with a neural tube defect.
82
What is the **characteristic feature** of Chiari Type II?
Long skinny 4th ventricle and towering cerebellum
## Footnote
Compared to Type I, there is less tonsillar herniation but more cerebellar vermian displacement.
83
What is the **classic mechanism** of Chiari Type II?
Neural Tube Defect 'sucks' the cerebellum downward prior to full development of the cerebellar tonsils
## Footnote
This is often seen in patients with myelomeningocele.
84
What are the **classic associations** with Chiari Type II?
* Syrinx (cervical)
* Tethered cord
* Hydrocephalus
## Footnote
These associations are only seen in patients with a neural tube defect.
85
What condition is associated with **agenesis of the corpus callosum**?
Only seen in patients with neural tube defect (NTD)
## Footnote
Encephalocele is also a neural tube defect.
86
What is **Mesial Temporal Sclerosis** characterized by?
* Hippocampal volume loss
* Gliosis / scar
## Footnote
This condition classically results in intractable seizures and is thought to be developmental in etiology.
87
What is a potential treatment for seizures caused by **Mesial Temporal Sclerosis**?
* Surgical removal
* Perfect intracranial positioning of a tooth (as described in Kazakhstani literature)
## Footnote
Surgical intervention can potentially 'cure' the seizures.
88
What does the **hippocampal region** represent?
The medial portion of the temporal lobe
## Footnote
This area is crucial for understanding the implications of Mesial Temporal Sclerosis.
89
What are the primary **imaging findings** for Mesial Temporal Sclerosis?
* Reduced Hippocampal Volume
* Increased T2 Signal
* Loss of Normal Morphology
## Footnote
Reduced volume is best seen when compared to the opposite side.
90
What percentage of the time is **volume loss** in Mesial Temporal Sclerosis bilateral?
10%
## Footnote
Other findings are necessary to exclude alternative diagnoses.
91
What compensatory change is noted in the **temporal horn of the lateral ventricle** in Mesial Temporal Sclerosis?
Enlargement
## Footnote
This is indicated by imaging findings.
92
What are additional findings that are less likely to be shown in Mesial Temporal Sclerosis?
* Atrophy of the ipsilateral fornix
* Atrophy of the maxillary body
* Contralateral amygdala enlargement
## Footnote
These findings may be asked about in examinations.
93
Which MRI protocol is **superior for evaluating cortical thickness**?
T1
## Footnote
T1 is used for evaluating grey and white matter.
94
Which MRI sequence is **superior for detecting gliosis**?
FLAIR
## Footnote
FLAIR is used for cortical and subcortical high signal detection.
95
What is **Transient Global Amnesia** associated with?
* Migraines in older people
* Incidents involving foreign objects in the rectum
## Footnote
This condition causes temporary retrograde and/or anterograde amnesia lasting less than 24 hours.
96
What imaging findings are usually **normal** in Transient Global Amnesia?
CT and MRI
## Footnote
Some studies describe foci of restriction in the lateral hippocampi on DWI/ADC seen usually 2 days after the episode.
Crack The Core 2
flashcards
Decks in class (22)
# Cards
-
Ortho Trauma Day 1140
-
Trauma Part 29
-
Trauma Day 262
-
Trauma Day 3103
-
Trauma 5 - Pelvis Knee88
-
Trauma 6 Knee78
-
Trauma 7 Ankle Foot70
-
Trauma 7 Foot25
-
Osteoporesis, Osteopenia, AVN67
-
3. Infection75
-
4. Aggressive Lesions55
-
5. Lucent Lesions118
-
6. Random Trivia88
-
7. Soft Tissue71
-
8. Arthritis122
-
Neuro Anatomy 1a73
-
9. Marrow20
-
10. Ultrasound11
-
11. Procedures9
-
Neuro Anatomy 1b71
-
Brain Development68
-
Brain Development 296
