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Brain and Behavior Exam 1 > Lec 12 CNS Malformations > Flashcards

Lec 12 CNS Malformations Flashcards

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1
Q

What is the most common type of malformation of the nervous system?

A
  • neural tube defect
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2
Q

What happens in neural tube defects [NTDs]?

A
  • failure of fusion of neural tube by 28th day [4th wk] post conception
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3
Q

When do disordered of neural tube defects occur?

A

3-4 wks gestation

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4
Q

What are the 2 most common neural tube defects [NTDs]?

A
  • anencephaly

- myelomeningocele

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5
Q

What are the two categories of NTDs [neural tube defects]?

A
  1. failure of anterior [rostral] closure –> anencephaly/ encephalocele
  2. failure of posterior [caudal] closure –> myelomeningocele
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6
Q

What preventable treatment is associated with NTDs?

A
  • low folic acid intake before conception and during pregnancy associated with neural tube defects
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7
Q

What is anencephaly?

A
  • complete failure of anterior neural tube closure in first 24 days
  • absence of forebrain
  • open calvarium “frog-like appearance”
  • almost always get spontaneous abortion or can be born with brainstem [suck/gag/breath] function and die within days
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8
Q

What confirmatory tests can you do to test for neural tube defects?

A
  • high alpha-fetoprotein [AFP] in amniotic fluid and maternal serum
  • high AChE [acetylcholinesterase] in amniotic fluid (b/c fetal AChE in CSF transudates across defect into amniotic fluid)
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9
Q

What are clinical findings in anencephaly?

A
  • high AFP [alpha fetoprotein] in amniotic fluid and maternal serum
  • polyhydramnios [no swallowing center in brain]
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10
Q

What is associated with increased risk of anencephaly?

A
  • maternal diabetes type I

- low maternal folate

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11
Q

What happens in encephalocele?

A
  • restricted failure of anterior neural tube closure [around day 26]
  • mengingeal +/- cortical tissue extending through a bony defect
  • protruding tissue may be normal brain or gliotic tissue with little/no function
  • 30% mortality
  • diagnosed prenatally by ultrasound in 80% of cases
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12
Q

How do you treat encephalocele?

A
  • usually surgically repaired unless massive, then you have severe microcephaly or other lethal anomally
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13
Q

What are the 3 types of encephalocele?

A
  • sincipital: outcome normal or near normal intelligence without major complications
  • basal: requires prompt surgery, risk of meningitis + CSF leak
  • occipital: most severe, may get hydrocephalus, 17% have normal mental and physical development, requires immediate surgery
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14
Q

What is a myelomeningocele [meningomyelocele, spina bifida aperta] ?

A
  • restricted failure of posterior neural tube closure
  • have absence of overlying skin, menginges
  • malformed spinal cord
  • impariment in spinal cord + brain, loss of motor control and sensory input from level of spinal lesion
  • compatible with life
  • more common in females
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15
Q

What are risk factors for meningomyeloceles?

A
  • more common in females

- risk factors: alcohol, medical exposure, folate deficiency, diabetes

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16
Q

How do yo you diagnose meningomyelocele?

A
  • elevated alpha-fetoprotein [AFP] between 15-20 wks

- ultrasound wk 12 –> irregularity of spine/ bulging back, lemon sign, banana sign

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17
Q

What What is chiari 2 malformation?

A
  • significant herniation of cerebellar tonsils through foramen magnum
  • elongation/thinning of upper medulla/pons
  • hydrocephalus [due to obstruction from chiari]
  • aqueductal stenosis
  • brainstem dysfunction –> apnea, dysphagia, cyanotic spells

often present with lumbosacral myelomeningocele and paralysis below defect

  • lesion above L2 cannot walk, lesions below S1 can walk
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18
Q

How ambulatory is pt with mengingomyelocele above L2? at L3-5? below S1?

A

above L2: minimal to no walking
L3-L5: walk with assistive devices
S1 and below: normal ambulation or with minor weakness

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19
Q

What happens with bowel and bladder in meningomyelocele?

A
  • higher risk of UTI
  • can have urinary reflux, hydronephrosis, renal failure

treat: use catheter, timed toileting and dight high in fiber

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20
Q

What is a meningocele? can you detect with AFP?

A

menginges [but not spinal cord] herniate through spinal canal defect

normal AFP so can’t use AFP to test

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21
Q

What happens in spina bifida occulta?

A
  • failure of bony spinal canal to close but no structural herniation
  • usually seen at lower vertebral levels
  • dura is intact
  • associated with tuft of hair or skin dimple at level of bony defect
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22
Q

What is syringomyelia?

A
  • associated wtih chiari 1 malformation
  • most common at C8-T1
  • cystic enlargement of central canal of spinal cord
  • crossing fibers of spinothalamic tract are damaged
  • get cape-like bilateral loss of pain and temperature sensation i upper extremities
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23
Q

Where is syringomyelia most common?

A

at C8-T1

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24
Q

What is normal process of prosencephalic development [3 stages]?

A
  • at wks 5-6
  • prosencephalon develops into telencephalon and diencephalon through 3 stages –> formation, cleave, midline development
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25
Q

What does the diencephalon normally become?

A
  • thalamus, hypothalamus, subthalamic nuclei
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26
Q

What does the telencephalon normally become?

A

cerebral hemispheres

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27
Q

What happens inholoprosencephaly? Cause?

A
  • failure of left and right hemispheres to separate

- due to mutations in sonic hedgehog [SHH] signalling pathway

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28
Q

What are 3 types of holoprosencephaly?

A
  • lobar: mid line distinct
  • semilobar: separation posteriorly, but frontal and parietal lobes fused
  • alobar: complete failure of forebrain to divide
29
Q

What is correlation between hemispheric separation and neuro disfunction?

A
  • the greater the hemispheric separation, the more mild the neurologic dysfunction
30
Q

What are symptoms of moderate vs severe holoprosencephaly?

A
  • moderate = cleft lip/palate
  • severe = cyclopia

can be pretty normal facial appearance or dramatically altered

31
Q

What is cause of holoprosencephaly?

A
  • may be related to mutations in sonic hedgehog

- maternal diabetes increases risk

32
Q

What are the 3 stages of cortical formation?

A
  • cell proliferation: 2-4 mos, neural and glial precursors generated
  • neuronal migration: 3-5 mos, neurons move into cortical mantle
  • cortical organization: neurons develop into 6 layers
33
Q

What is focal cortical dysplasia?

A
  • neurons exhibit immature or glial features
  • cortex has large dsyplastic neurons that are not orgnaized into typical layers and underlying white matter hypomyelinated

on image:

  • wider than normal gyri
  • blurred gray/white junction
  • often have epilepsy, requiring surgery

occurs 2-4 mos

34
Q

What are heterotopias?

A
  • disorder of neuron migration
  • have collections of neurons outside cortex
  • neurons are normal
  • cortex overlying heterotopias maybe thing with shallow sulci
35
Q

What is periventricular heterotopia?

A
  • periventricular nodules of neurons rest beneath otherwise normal cortex
  • most patients have normal intelligence
  • 1/4 of pts are asymptomatic but may have undiagnosed learning disability
  • epilepsy commonly develops in teen age
36
Q

What is lissencephaly? two types?

A
  • decreased pattern of gyri/sulci, brain appears smooth

type 1 [classical]: arrest of neuronal migration –> fewer number of abnormally broad/flat gyri
type 2[cobblestone]: overmigration beyond pia into subarachnoid space –> excessive number small cortical gyri

37
Q

What happens in classical lissencephaly?

A
  • brain has agyria and pachygyria
  • agyria = diminished white matter, shallow or absent sylvian fissure
  • pachygryia = fewer number of abnormally broad and flat gyri

due to disruption of platelet ativating factor which interacts with microtubules

38
Q

What is etiology of classical lissencephaly?

A
  • genetic = double cortin on X chromosome, males have more severe
39
Q

What is clinical presentation of classical lissencephaly?

A
  • depends on amount of agyria vs pachygyris [greater gyral simplification = greater impairement]
  • epilepsy
  • developmental delay
40
Q

What is etiology of cobblestone lissencephaly?

A
  • associated with several congenital muscular dystrophies
41
Q

What is dandy-walker? etiology?

A
  • hypoplasia or absence of cerebellar vermis
  • 4th ventricle transformed into large cystic cavity [failure of luschka and magendie to open]
  • posterior fossa is large and lateral sinuses and torcula are elevated
  • associated with hydrocephalus and spina bifida
    etiology: sporadic or due to mom taking isoretinoin [accutane] during pregnancy
42
Q

What are chiari malformations?

A
  • anatomic anomolies of cerebeullum, brainstem, craniocervical junction
  • downward displacement of cerebellum with or without lower medulla into spinal cord
43
Q

What is chiari 1?

A

abnormally shaped cerebellar tonsils displaced below foramen magnum

  • can be isolated radiologic finding
    symptoms: occipital/cough related headache, syringomyelia or lower cranial neruopathies

treat: suboccipital decompression

44
Q

What is chiari 2?

A
  • downwart displacemnt of vermis and tonsils, 4th ventricle, and brainstem through foramen magnum
  • 4th ventricle obstructed, hydrocephalus likely

most have spinal [lumbosacral] meningomyelocele

45
Q

What is tethered spinal cord?

A

spinal cord fixed to lower immobile structure

  • have progressive motor and sensory dysfunction with abnormal gait and bladder incontinence
46
Q

What is the most common type of craniofacial malformation?

A

cleft lip/palate

47
Q

What is distribution cleft lip vs palate vs both?

A

1/3 combined
1/3 isolated cleft lip
1/3 isolated cleft palate

48
Q

What happens in pts with cleft lip +/- palate?

A
  • 2/3 are nonsyndromic
49
Q

Who is most likely to get cleft lip +/- palate?

A

highest in asians/native americans, lowest in american blacks
more common in males

50
Q

What happens in pts with cleft lip?

A
  • 1/2 are nonsyndromic
51
Q

Who is most likely to get cleft palate?

A
  • more common in females

- no variance in ethnicity

52
Q

What is the etiology of cleft lip/palate?

A

genetic: complex, up to 20 genes interact
drugs: alcohol, cigarettes, methotrexate
environmental: folate deficiency, maternal obesity

53
Q

What is the embryology of cleft lip +/- palate?

A
  • failure of fusion of maxillary and medial nasal processes

- can produce unilateral/bilateral or median lip clefting

54
Q

What is embryology of isolated cleft palate?

A
  • lack of fusion of palatine processes/shelves
55
Q

What is treatment for cleft lip/palate?

A
  • may have airway issues and feeding problems, use special nipple for babies with cleft lip/palate
  • get primary lip repair at 3 mos old, palate repair at 6 mos
  • speech therapy
  • also may have higher rate ear infections and may have missing/crooked teeth
56
Q

What is cerebral palsy?

A
  • permanent disorder of movement and posture causes activity limitation
  • due to non-progressive disturbance that occured in fetal or infant brain
  • often accompanied by: disturbance of sensation/perception/cognition/communition, epilepsy, 2ndary MSK problems
57
Q

What is cause of cerebral palsy?

A
  • hermorrhagic or ischemic stroke [acquired/hereditary thrombophilia or placental issues
  • CNS malformations/infections
  • periventricular leukomalacia [white matter focal necrosis + cyst formation]
  • asphyxia in perinatal
58
Q

What are risk factors for cerebral palsy?

A
  • > 2 previous abortions
  • maternal menstrual regulation
  • bleeding during pregnancy
  • preeclampsia
  • placental infection
  • multiple births
  • maternal hypothyroidism
  • low birth weight
59
Q

What are spastic syndrome?

A
  • syndromes in which upper motor neuron signs include spasticity, weakness, increased reflexes
60
Q

What is hemiplegia?

A
  • weakness on one side of body

- most common form of cerebral palsy usually affecting term infants of normal birth weight

61
Q

What is most common etiology of inborn hemiplegia? signs?

A

usually vascular

signs: early – unilateral fisting, early handedness; late – delayed motor milestones, siezures in first 2 years
- intelligence often not affected

62
Q

What is quadriplegia? etiology?

A
  • all 4 limbs affected, delayed milestones, epilepsy, mental retardation, microcephaly
    etiology: low birth weight, intrauterine disease, cerebral malformation, asphyxia in full term infamt
63
Q

What is diplegia? etiology?

A

all 4 limbs affected but legs more than arms, can walk independently, normal intelligence

etiology: asphyxia or prematurity

64
Q

What is dyskinesia? who gets it? symptoms?

A
  • acute perinatal asphyxia affects basal ganglia and thalamus
  • usually term infants

symptoms:
- early hypotonia [decreased muscle tone followed by abnormal movement around age 2

65
Q

What is ataxia? who gets it? symptoms?

A
  • due to prenatal injury to cerebellum
  • usually in children born to term
  • show hypotonia early on, delayed motor and language development
  • speech typically jerky/slow
  • ataxia improves with time
66
Q

What are clues for diagosis of cerebral palsy?

A
  • history of motor delay but without loss of skills
  • early handedness
  • persisting primitive reflexes
  • lack of development protective reflexes
67
Q

What health problems are associated with cerebral palsy?

A
  • epilepsy in 40%
  • scoliosis
  • prolonged puberty in nonambulatory girls
  • pain in hips
  • visual impairment in 1/3
68
Q

What is treatment for cerebral palsy spasticity and dyskinesias?

A
  • oral medicine
  • botox for spasticity/dystonia
  • selective dorsal rhizotomy

Brain and Behavior Exam 1 (15 decks)

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