Malformations & Developmental Diseases Part 1 Flashcards Preview

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Flashcards in Malformations & Developmental Diseases Part 1 Deck (33):
1

The anatomic pattern of malformation reflects ________ ____ ___________ at time of injury.  

______ or ______ insults may cause failure of development and/or tissue destruction. 

_______ & _______ are contributing factors to malformations. 

Stage of brain formation 

Prenatal, perinatal 

Genetics, environment

2

Definitions

  • Malformation
  • Deformation
  • Disruption 

  • Malformation – intrinsic abnormality
  • Deformation – extrinsic force
  • Disruption – destructive force 

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3

What is the deformation sequence of renal agenesis?

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4

What are the steps to normal development of the CNS? (5)

  • Induction
  • Neural tube formation
  • Regionalization & specification
  • Proliferation & migration
  • Connection & selection 

5

Major Events in Human Brain Development 

*fill in the blanks*

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6

What stages are pictures A, B & C?

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A. Late presomite & early neural plate stage

B. Early somite & neural groove stage 

C. Eight-somite & early neural tube stage 

7

Gestation

When/where does neural tube closure occur?

What happens with failure of closure?

  • Neural tube closure occurs early in gestation
    • 28 days
  • Closure occurs at several sites along neuraxis
  • Failure of closure at these sites results in defects (anencephaly, spina bifida

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8

Sulcation of the Brain

*how many months?*

  • Major fissures
  • Secondary sulci 
  • Tertiary sulci 

  • Major fissures – 5 months
  • Secondary sulci – 7 months
  • Tertiary sulci – 9 months 

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9

What is the pattern of cerebral myelination?

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10

What is this?

 

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Cytoarchitecture of the Cerebral Cortex 

11

What is the definition of a neural tube defect?

  • Most common category of CNS malformations
  • Disturbance of formation of neuroectodermal and/or overlying mesodermal structures

12

What is the etiology of neural tube defects?

  • Genetics
    • Trisomy 13, 18
  • “Environment” during pregnancy
    • Folic acid deficiency
    • Maternal DM
    • Hyperthermia
    • Alcohol
    • Valproic acid (anti-seizure drug) 

13

What is the pathogenesis of neural tube defects?

  • Failure of closure of neural tube
    • Primary failure of neuroectoderm or mesoderm
  • Reopening or secondary rupture of closed tube 

14

What are the 3 main categories of neural tube defects?

  • Spina bifida
  • Anencephaly
  • Encephalocele 

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15

Neural Tube Defects

Detection

Diagnosis

Prevention

  • Failure of closure of the neural tube allows excretion of fetal substances (AFP, acetylcholinesterase) into the amniotic fluid
  • Diagnosable by ultrasound and/or prenatal screening of maternal serum for AFP at 16-18 week GA
  • Maternal periconceptional use of folic acid supplementation reduces the incidence of NT defects by at least 50% 

16

Spina Bifida

Definition

Types

  • Combined malformations of vertebral column & spinal cord
  • Types
    • Spina bifida occulta (least severe form)
    • Spina bifida cystica (80-90% lumbosacral)
      • Meningocele (less common – 10-20%)
      • Myelomeningocele (more common – 80-90%) 

17

Spina Bifida Occulta 

Definition

Clinical Presentation

  • Non-closed vertebral arches w/o visible lesion (externally)
  • Most often lumbosacral
  • Often asymptomatic
    • May be foot & gait abnormalities
    • Patches of hair, lipoma, discoloration of skin or dermal sinus 

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18

How is spina bifida occulta diagnosed?

  • Spine X-ray
    • Defect in closure of the posterior vertebral arches & laminae (usually L5 & S1)
  • May be associated w/ syringomyelia, diastematomyelia & tethered cord
  • Recurrent meningitis of occult origin should prompt careful exam for dermal sinus tract 

19

What is the definition of a meningocele

 

  • Cyst lined w/ meninges & dura (but no spinal cord)
  • Herniated through vertebral defect
  • Spinal cord may be normal, or may present w/ tethering, syringomyelia, or diastematomyelia
  • Most are lumbosacral 

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20

What are the symptoms of a Meningocele?

  • Little or no neurological defect
  • Anterior Meningocele may project into the pelvis through a defect in the sacrum causing symptoms of constipation & bladder dysfunction
  • Female patients may have associated anomalies of the genital tract (rectovaginal fistula, vaginal septa) 

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21

Meningocele

Diagnosis

Treatment 

  • Diagnostic testing
    • Plain X-ray
    • MRI (spine)
    • CT of head to rule out HCP
  • Treatment approaches
    • Asymptomatic children w/ no neuro findings & full-thickness skin may have surgery delayed
    • Patients w/ leaking CSF or thin skin covering should undergo immediate repair to prevent meningitis

22

Myelomeningocele

Definition

Cord abnormalities 

Location

  • Both meninges & spinal cord herniated through vertebral defect
  • Usually broad-based
  • Cyst (“cele”) often ruptures & skin covering absent
  • Variable cord abnormalities
    • Complete disorganization & flattening
    • Slight midline opening
  • Most (75%) are lumbosacral
  • *exposure of neurons to amniotic fluid damaging 

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23

What are the risk factors for a Myelomeningocele?

  • ~1/4,000 live births
  • Risk of recurrence after 1 affected child increases to 3-4% & increases to 10% w/ 2 previous abnormal pregnancies
  • Certain drugs that antagonize folic acid (TMP, AEDs: CBZ, PHY, Pb, Primidone) increase the risk of Myelomeningocele
  • Valproic acid causes NT defects in ~1-2% of pregnancies 

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24

What are the symptoms of a Myelomeningocele?

Complications?

  • Extent & degree of neuro deficit depend on location
  • CM
    • Flaccid paralysis
    • Absent DTRs
    • Sensory deficit below the affected level
    • Postural abn of the LE (clubfeet, subluxation of the hips)
    • Constant urinary dribbling & relaxed anal sphincter
  • Weakness or flaccid paralysis, sensory loss, bowel/bladder dysfunction
  • Complications: meningitis, hydrocephalus, pneumonia 

25

What are the complications of a Myelomeningocele?

What is a Chiari crisis?

  • HCP in associated w/ type II Chiari defect (80%)
  • Infants w/ HCP & Chiari II: symptoms of hindbrain dysfunction
    • Difficulty feeding
    • Choking, stridor, apnea
    • VC paralysis
    • Pooling of secretions
    • Spasticity of UEs
  • Chiari crisis
    • Downward herniation of the medullar & cerebellar tonsils 

26

How is a Myelomeningocele treated?

  • Multidisciplinary approach: surgeon, therapist, pediatrician
  • Surgery: repair & shunting, orthopedic procedure, urologic evaluation
  • GUT: regular catheterization to prevent UTI & reflux (PN & hydronephrosis), urine cult, serum elec, creatinine, renal scan, IV pyelogram, Utz
  • Rehab: functional ambulation (sacral or LS lesion) 

27

What is the prognosis for a Myelomeningocele?

  • MR: 10-15%
  • Most deaths occur before 4 YO
  • 70% normal intelligence
    • Learning problems & seizures common
  • History of meningitis or ventriculitis adversely affect the ultimate IQ

28

Anencephaly

Definition

Diagnosis

Prognosis 

  • Large defect of the calvarium, meninges & scalp associated w/ a rudimentary brain (failure of closure of the rostral neuropore)
  • Diagnosis: increased AFP in amniotic fluid
  • Primitive brain: connective tissue + vessels + neuroglia
  • Cerebral & cerebellar hemispheres usually absent
  • Only residue of brainstem identified (eyes & CNs V-XIII intact)
  • Die w/i several days of birth
  • 1/1000 live births
  • Recurrence risk: 4% --> 10% w/ 2 previously affected pregnancies 

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29

What is this?

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Anencephaly 

30

Encephalocele

Definition

Location

  • Broad-based pedunculated masses of cerebral tissue & dura protruding through cranial defect, covered by skin
  • Occipital region most common site
  • Frontal/nasal locations more common in some countries
  • Tissue mass attached by pedicle
  • Ethmoidal location: “nasal glioma
  • Disorganization of remaining brain in cranial cavity 

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31

How is Encephalocele diagnosed?

  • Plain X-ray of the skull & cervical spine
  • Cranial utz
  • In utero: AFP, biparietal diameter 

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32

What is the prognosis of an Encephalocele?

  • Encephalocoele: at risk for visual problems, microcephaly, MR, seizures
  • Meckel-Gruber syndrome: AR condition, occipital encephalocoele, cleft lip or palate, microcephaly, microphthalmia, abnormal genitalia, polycystic kidneys, polydactyly 

33

What is this?

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Encephalocele

wavy cortical architecture