Neuropathology

Question 1

Neural tube defects - time

Answer 1

22-26 days

Question 2

The most severe form of neural tube defect - complete failure of primary neurulation

Answer 2

Cranioraschisis totalis

Question 3

failure of rostral neuropore to close

Answer 3

anencephaly

Question 4

defect in skull with protrusion of the leptomeninges +/- brain…maintain epidermal covering over the cranial neural tube closure defect

Answer 4

encephalocele

Question 5

failure of closure of the posterior neuropore - seen in chiari II

Answer 5

Myelomeningocele

Question 6

How is the primitive streak formed?

Answer 6

cells of the caudal half of the epiblast thicken, converge in the midline to form the primitive streak

Question 7

What happens at the cranial end of the primitive streak?

Answer 7

cranial end thickens to form the primitive (Hensen’s Node)

Question 8

What forms in the middle of the primitive streak?

Answer 8

Primitive groove

Question 9

When does the primitive streak form?

Answer 9

14-16 days

Question 10

Gastrulation

Answer 10

formation of three germ layers

Question 11

With regard to neurogenesis what happens during gastrulation?

Answer 11

cells from Hensen’s node begin migrating cranially toward the buccopharyngeal membrane (prochondral plate) FORMING THE NOTOCHORDAL process

Question 12

Once the notochord is formed what happens around day 18?

Answer 12

Neural plate morphogenesis - neuroectoderm - wide end lies rostrally
bilateral symmetry
regionalization

Question 13

what occurs during primary neurluation

Answer 13

neural tube folds
- first folds occur caudally at 22 days 
- closure proceeds bidirectionally 
- not simple zipper
takes 4-6 days, keeps paces with somites

Question 14

secondary neurulation

Answer 14

caudal cells mass coalesces and fuses with area where posterior neuropore has closed to form sacral spinal cord (s3)

Question 15

Which neural tube defects are also associated wtih tethering of spinal cord?

Answer 15

myelomeningocele
lipomyelomeningocele
dermal sinus tract
spina bifita oculta

Question 16

time-line anencephaly

Answer 16

23-25 days

Question 17

site of final closure of anterior neuropore

Answer 17

commissural plate - which is immediately anterior to the lamina terinalis at the site of the future anteiror commissure

Question 18

encepholocele distinguished from anencephaly?

Answer 18

have an epidermal covering over the cranial neural tube closure defect

Question 19

myelomeningocele

Answer 19

failure of the posterior neuropore closure

Question 20

time - myelomeningocele

Answer 20

25-27

Question 21

a skin covered CSF filled mass that is continuous with the CSF in the spinal canal

Answer 21

meningocele

Question 22

lipomyelomeningocele

Answer 22

lipoma extends from subcutaneous tissue to the dorsal aspect fo the corde and tethering the cord inferiorly

this process reflects a premature separation of the cutaneous ectoderm druing the process of neurulation that allows mesenchyme to enter the unclosed neural tube and differentiate into fat

Question 23

dorsal dermal sinus tract

Answer 23

ectoderm lined tracts that can transgress the dura and allow communication between the skin and CSF - can also cause tethering

Question 24

spina bifita oculta

Answer 24

at L5-S1 common incidental fidning - failure of verterbral arch to encricle appropriately

Question 25

where is conus medullaris in typical newborn and where should it not be below in adult

Answer 25

L3 not below L2 Usually between L1-2

Question 26

Consequence of neural tube tethering

Answer 26

Common incontinence due to UMN issues

Question 27

caudal cerebellar tonsillar ectopia, below the foramen magnum, associated with chronic tonsillar herniation with syringomyelia

Answer 27

chiari I

Question 28

complex malformation - myelominigocele, hydrocephalus, hindbrain and spina abrnomalities

Answer 28

chiari II

Question 29

Which of the chiari malformations is associated with neural tueb closure defects

Answer 29

II

Question 30

Universal symptoms of chiari type II

Answer 30

``` hydrocephalus meningomyelocele small posterior fossa with kinking of brainstem herniation of cerebellum - vermis synonymous with Arnold-Chiari ```

Question 31

chiari type I can be associated with

Answer 31

syringomyelia

Question 32

What is syringomyelia?

Answer 32

low lying cerebellar tonsils in chiari I can obstruct the aperture that allows CSF to exit the canal of the spinal cord into the subarachnoid space - leading to accumulation of CSF within the central canal - the CSF filled cyst can break out of the central canal and dissect into substance of the cord

Question 33

When is the prosencephalon developing

Answer 33

peak period 2-3 months gestation

Question 34

How does prosencephalic development occur

Answer 34

by inductive interations between the notochord/prechordal mesoderm and forebrain. This occurs ventrally at the rostral end of the embryo - ventral induction

Question 35

what does prosencephalic induction effect?

Answer 35

face and brain

Question 36

3 cleavages in prosencephalic development occur at 5-6 weeks gestation

Answer 36

horizontally transversely sagitally

Question 37

when a single centricle that exists in teh early embryonic forebrain fails to form properly into two lateral ventricles and one third ventricle

Answer 37

holoprosencephaly

Question 38

no evidence of division of cerebral cortex

Answer 38

alobar holoprosencephaly - most severe

Question 39

only partial cleavage with the cerebral hemisphere fused at the frontal region only

Answer 39

semilobar -

Question 40

cerebral hemispheres are separated anteriorly and posterioly with modest fustion of structures

Answer 40

lobar holoprosencephaly -

Question 41

common cause of holoposencephaly

Answer 41

SHH gene mutations

Question 42

when does the external granular layer develo

Answer 42

12 weeks :)

Question 43

Embryology of cerebellum - what happens with the cerebellum and 4th ventricle?

Answer 43

in early gestation the small cerebellum is found on top of the very large 4th ventricle - in time the cerebellum grows caudally and completely enfolds the cavity of the 4th ventricle

Question 44

Key features of Dandy Walker Malformation

Answer 44

``` enlarged posterior fossa high tentorium hypoplasia or agenesis of vermis cystic dilatation of 4th ventricle that fills the posterior fossa hydrocephalus ```

Question 45

What type of migration do we see in the cortex?

Answer 45

radial migration | - successive waves of neurogenesis migration past previously born neurons - inside out pattern

Question 46

3 causes of malformations of cortical development

Answer 46

abnormal neural/glia proliferation abnormal cortical migration abnromal organization

Question 47

micro and macro cephaly are disorders of

Answer 47

abrnomal proliferation

Question 48

agyria (lissencephaly) polymicrogyra hetertopia are disorders of

Answer 48

neuronal migration adn gyral formaiton

Question 49

proencephaly hydraencephaly schizencephaly are disorders of

Answer 49

late destructive gestational lesions

Question 50

what is schizencephaly

Answer 50

dysplastic gray matter lined clefts extending from the ependymal lining of the lateral ventricles to the pial covering of the cortex both genetic and acquired causes

Question 51

what are three causes of fine structural abnromalities of myelin or dentrictic branching

Answer 51

downs malnutrition metabolic disorders

Question 52

principle cause of stroke in children

Answer 52

genetic malformation of heart or blood vessels

Question 53

childhood stroke hemorrhagic vs ischemic

Answer 53

55% ischemic

Question 54

strok in perinatal period in term infants

Answer 54

Ulegyria (mushroom gyri) is a result of perinatal watershed infarcts with subsequent growth of non-damaged parts of gyri

Question 55

Stroke in perinatal period in preterm infants

Answer 55

germinal matrix hemorrhages (subependymal hemorrhages) are major cause of morbidity and mortality GMH occurs in preterm infats less than 32-34 weeks

Question 56

risk factors for GMH

Answer 56

immaturity of lungs hypercapnia low birth weight acidosis