Malformations and Developmental Diseases Flashcards

1
Q

How is a malformation caused?

A

intrinsic malformation

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2
Q

How is a deformation caused?

A

external force acts upon

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3
Q

How is a disruption caused?

A

a destructive force acts upon

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4
Q

When is the neurulation phase?

A

3-4wks

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5
Q

When is the prosencephalic phase?

A

2-3 mos

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6
Q

When is the neuronal proliferation phase?

A

3-4 mo

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7
Q

When is the neural migration phase?

A

3-5 mo

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8
Q

When is the organization phase?

A

5-postnatal years

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9
Q

When does myelination occur?

A

birth-postnatal years

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10
Q

When does neural tube closure occur?

A

28 days

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11
Q

What is the definition of a neural tube defect?

A

disurbance of formation of neuroectodermal and/or overlynig mesodermal structures or reopening or secondary rupture of closed tube

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12
Q

How can neural tube defects be detected?

A

prenatal folate supplement

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13
Q

What are the 3 main types of neural tube defects?

A

spina bifida
anencephaly
encephalocele

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14
Q

Which type of spina bifida causes neural defects?

A

myelomeningocoele

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15
Q

What drug can cause neural tube defects in 1-2% of pregnancies?

A

valproic acid

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16
Q

What are potential complications of myelomeningocoele?

A

hydrocephalus (type II chiari defect 80%)
meningitis
pneumonia

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17
Q

What is a chiari crisis?

A

downward herniation of the medulla and cerebellar tonsils

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18
Q

What is typically missing in anencephaly?

A

cerebral and cerebellar hemispheres

calvarium, meninges and scalp

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19
Q

What is an encephalocele?

A

broad-based pedunculated masses of cerebral tissue & dura protruding through cranial defect, covered by skin

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20
Q

Where is the most common site for an encephalocele?

A

occupital region, frontal/nasal location also common

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21
Q

What is meckel-gruber syndrome?

A

AR condition
occipital encephalocoele, cleft lip or palate, microcencephaly, micropthalmia, abnormal genitalia, polycystic kidneys and polydactyly

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22
Q

What is polymicrogyria?

A

too many irregular small fused gyri

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23
Q

What casues polymicrogyria?

A

results from the disordered organization of the neurons in the cortex at the time of migration

24
Q

What is agyria?

A

absence of gyri

25
Q

What are pachygyria?

A

decreased numbers of broad coarse gyri, brain is small

26
Q

When does agyria or pachygyria occur?

A

4th month gestation

27
Q

What chromosomes are associated with agyria or pachygyria?

A

17 & X

28
Q

What are sx of a/pachy-gyria?

A
failure to thrive
microcephaly
marked developmental delay
severe seizure disorder
hypoplasia of the optic nerve
microphthalmia
29
Q

What is miller dieker syndrome?

A

prominent forehead, bitemporal hollowing, nteverted nostrils, prominent upper lip, micrognathia

30
Q

What is schizencephaly?

A

unilateral or bilateral clefts within the cerebral hemispheres due to an abnormality of morphogenesis
cleft may be fused or unfused, and is usually surrounded by abnormal brain, microgyria

31
Q

What are sx of schizencephaly?

A

severe MR
intractable seizures
microcephaly
spastic quadriplegia when clefts are bilateral

32
Q

What is arrhinencephaly?

A

disorders of cleavage of forebrain

ie/holoprosencephaly & olfactory aplasia

33
Q

What are signs/sx of holoprosencephaly?

A

profound MR, seizures, rigidity, apnea, temperature imbalance, hydrocephalus, facial abnormalities

34
Q

What causes agenesis of the corpus callosum?

A

an insult to the commissural plate during embryogenesis

35
Q

What are signs/sx of agenesis of the corpus callosum?

A

usually asymptomatic , margination defects (heterotopia, microgyria, pachygyria)
may present with MR, microcephaly, hemiparesis, diplegia and seizures

36
Q

What do you see on CT/MRI for agenesis of the corpus callosum?

A

widely separated frontal horns with an abnormally high position of the 3rd ventricle

37
Q

What is aicardi syndrome?

A

severe MR, intractable seizures w/onset between birth and 4 mo age, chorioretinal lacunae
hemivertebrae and costovertebral anomalies are common
independent activity from both hemispheres as a result of the absence of the corpus callosum

38
Q

What is a type 1 chiari malformation?

A

chronic tonsillar herniation

assoc w/hydrocephalus, sudden death, cranial nerve palsies, ataxia, long tract signs, syringomyelia

39
Q

What is another name for a type 2 chiari malformation?

A

arnold chiari malformation

40
Q

What is a type 2 chiari malformation?

A

herniated cerebellar tissue through foramen magnum with displacement of dorsal medulla causing a hump or Z-shape in brainstem/spinal cord

41
Q

What are signs/sx of a type 2 chiari malformation?

A

lower cranial nerve defects

arm weakness, spasticity, hydrocephalus sx

42
Q

What is a dandy walker malformation?

A

agenesis of vermis
cystic dilatation of the 4th ventricle
enlargement of posterior fossa
hydrocephalus is frequently present

43
Q

What are signs/sx of dandy walker malformation?

A

motor retardation, spasticity and resp failure

44
Q

What is a risk factor for dandy walker malformation?

A

isotretinoin use during pregnancy

45
Q

What is a syringomyelia?

A

fluid filled cleft like cavity in spinal cord

assoc w/chiari type 1 malformation and post traumatic

46
Q

What are signs/sx of syringomyelia?

A

loss of pain/temp, retention of position and vibration senses & motor function
onset of symptoms in 2nd and 3rd decades, progressive

47
Q

What happens with perinatal hypoxia/ischemia of white matter? White and gray matter?

A

white matter necrosis (periventricular leukomalacia)

multicystic encephalopathy

48
Q

What happens with perinatal hemorrhagic lesions?

A

subependymal germinal plate/matrix hemorrhage

49
Q

What causes cerebral palsy?

A

perinatal insults

50
Q

What is cerebral palsy?

A

non-progressive neurologic motor deficit

-spasticity, dystonia, ataxia/athetosis, paresis

51
Q

What does periventricular leukomalacia look like?

A

sharply defined foci of necrosis in white matter
selectively vulnerable oligodendrocytes lost
histology: central zone of necrosis, surrounding mineralization of axons

52
Q

What does multicystic encephalopathy look like?

A

sponge-like glial lined cysts post destruction of both gray and white matter in 3rd trimester

53
Q

Where do most subependymal germinal matrix hemorrhages originate/

A

germinal zone overlying head of caudate and thalamus

frequently break through into ventricular system or underlying parenchyma

54
Q

What usually precipitates subependymal germinal matrix hemorrhage?

A

extreme physical distress/prematurity

perinatal occurrence, hemodrynamic instability, mechanical ventilation, hyaline membrane disease

55
Q

Where do grades 1-4 of subependymal hemorrhages invade?

A

1-confined to germinal matrix
2-germinal matrix & lateral ventricle, no ventricular dilation
3-germina matrix & lateral ventricle, with acute ventricular distention
4- grade 3 plus extension into adjacent brain parenchyma