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M M conference 10/18/02

• Andrea Balazs M.D.
• Dept. of Pediatrics

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Neural Tube Defects

• Neurulation
• Brain and sp.cord formation
• on the dorsal aspect of the embryo
• 3rd 4th w of pregnancy
• Mesoderm induce the formation of the neural plate
  from the ectoderm 18th days of gest. neural
  tube - ant. closure 24th day post.closure 26th
  day

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• Caudal neural tube formation 28-32nd day
• from caudal cell mass - vacuoles - coalesc
  contact with the central canal - canalization
• and differentation

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Neural tube defects

• Craniorachischisis
• Anencephaly
• Encephalocele
• Myelomeningocele

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• Craniorachischisis totalis
• Total failure of neurulation
• Neural plate like structure, no overlying
• skeleton or skin, occurs on 20-22nd day
• abortion

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Anencephaly

• Failure of the anterior neural tube closure
• Degenarated mass of neurons, glia, vessels
• Froglike appearance
• Occurs on 24th day
• Polyhydramnion
• 75 stillborn or die during the neonatal period
• Rates of occurrence 0.2/1000 live births

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Anencephaly

• 4x as frequent in females than in males
• Expl.neurulation takes longer, longer vulnerable
  period

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Encephalocele

• Herniation of the brain tissue
• Location occipital 70-80, frontal / temporal
  / parietal less common
• Protruding mass - occipital lobe / cerebellum
• 50 complicated with hydrocephalus
• low occipital or high cervical EC combined with
  vertebra, skull base and lower brain stem anomaly
  compose Arnold - Chiari III

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Encephalocele

• Partial or complete agenesis of corpus callosum
• Venous drainage anomaly
• Occures before 26th day
• EC associated with visual problem,microcephaly,
  MR and seizure

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• Meningocele 10 - 20, no neural
  element,usually no neurologic deficit
• Outcome more favorable in anterior EC (mortality
  0 vs 45, nl.outcome 42 vs 14)
• Thx surgery

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Myelomeningocele

• Failure of the posterior neural tube closure
• 80 in the lumbar region
• variable dermal covering
• dorsal displacement of the neural tissue, CSF
  leakage, sac formation
• neural plate or neural tube-like structure,
  raw,velvety,flat
• ventral part of the cord less affected
• Axial skeleton deficiency lack of fusion or
  absence of the vertebral arches, widened spinal
  canal

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Myelomeningocele

• Onset no later than 26th days
• Overall incidence 11000 live births 89
• Risk of recurrence 3 after one affected child,
  10 with 2 previous abnormal pregnancies

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Myelomeningocele

• Clinical features
• Lesion itself
• disturbances of neurological function pending on
  the level (motor, sensory, and sphincter
  function)
• Low sacral lesions bowel and bladder
  incontinence and anesthesia in the perineal area
• Lesions below S1 able to walk unaided
• Lesion above L2 wheelchair, later scoliosis, as
  well

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Myelomeningocele

• Intermediate/midlumbar lesion L3 L4 or L5
• Flaccid paralysis of the LEs, absence of deep
  tendon reflexes
• Lack of response to touch and pain
• Clubfeet, hip subluxation
• Continuous urinary dribbling and relaxed anal
  sphincter
• ambulatory or primarily ambulatory with braces
  or cruthces

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Myelomeningocele

• Deterioriation to a lower level of ambulatory
  function than that expected from segmental level
  over time
• Hydrocephalus incidence 60 vs 90
• HC 90 ventriculomegaly in 95
• AF, sutures status
• S/s of hydrocephalus is overt by 2-3 weeks of
  life

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• Arnold Chiari II malformation
• accompanies thoracolumbar - lumbosacral MMC
  
• Sequence of events
• MMC - CSF leakage - lack of normal
  distension
• of the ventricles - small posterior fossa -
  inferior displacement of the medulla, IV th
  ventricle and cerebellum
• elongation, thinning of the medulla and pons
  
• kinking of the cervical cord
• obstructed CSF flow - aquaeductus sten. and
  hydrocephalus

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• Clinical features associated with A-C II
• malformation
• brain stem dysfunction feeding disturbances
  (reflux, aspiration), dysphagia, apnoe, stridor,
  cyanotic spells
• onset at 3.2 months
• causes brain stem malformation and displacement
  affects the cranial nerves and nuclei
• these structures under compression from the
  hydrocephalus and the increased ICP ischemic
  and hemorrhagic necrosis of the brain stem from
  the disturbed arterial architecture and caudally
  displaced vertebrobasilar circulation

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• Other anomalies of the CNS associated with
• MMC
• Abnormal cortical development
• Microgyria 55-95
• intellectual deficits and seizures
• Impaired neuronal migration
• Falx cerebri hypoplasia, septum pellucidum
• Anomalies
• Cerebellar dysplasia

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Management

• Prevention
• Prenatal therapy
• Human fetal surgery
• Optimal means of delivery of the affected infants
  -c/s vs vag. - paralysis level 3.3 segments
  below the anatomical level of the lesion to
  compare with 1.1 for babies delivered vag. -
  amb. or wheelch.
• Postnatal surgery - early closure - proph. Abx
  VP shunt placement

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Management

• Team approach specialties
• PE
• Correlate the functional level (motor, sensory
  and sphincter function and reflexes ) to the
  level of anatomic lesion
• Neurologic dysfunction correlates with the level
  of the spinal cord lesion
• Presence of anal wink and anal sphincter tone
  suggest functioning sacral spinal segments,
  prognostically important
• evaluate for other malformation

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• Hydrocephalus VP shunt IQ better preserved
• Earlier shunt placement improves the cognitive
  outcome - degree of ventriculomegaly in utero or
  the size of the cerebral mantle during the 1st
  week correlates with the subsequent intelligence
• Shunt complications - deleterious effect on
  intellectual outcome
• Mean IQ MMC infected VP shunt 73 / vs MMC
  VP shunt w/o infection 95
• MMC w/out hydrocephalus mean IQ 102

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Rare VP shunt complication

• Migration of the VP shunt tip through the
  patent processus vaginalis resulting in scrotal
  hydrocele

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Complications in MMC

• Orthopedic problems
• Lower extremities lack innervation atrophied
  foot, knee, hip and spine deformities result
  from muscle imbalance, abn. In utero positioning
• Hip dislocation/subluxation in 1 year mostly
  with midlumbar MMC
• contractures

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Complications in MMC

• Urinary tract abnormalities
• Major cause of death after the 1st year
• 85 MMC located above S2 associated with
  neurogenic bladder
• Urinary incontinence and ureteral reflux
• Hydronephrosis, chronic pyelonephritis with renal
  scarring and destruction, urosepsis
• Renal anomalies agenesis, horseshoe k.,ureter
  duplication

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Spina bifida occulta

• Neural lesions
• Myelocystocele cystic dilatation of the central
  canal of the caudal neural tube
• Diastematomyelia diplomyelia spinal cord is
  bifid, occassionally separated by fibrous or bony
  septum originating from the vertebra
• Lipomeningocele
• Epidermoid/dermoid sinus
• Tethered cord
• Meningocele (anterior, too)
• Agenesis of distal spinal cord

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Complications in MMC

• Outcome of cortical function pending on the level
  of lesion
• Lumbar MMC nl. range of intelligence
• Reading and spelling o.k.
• Greatest deficit in arithmetic achievement and
  visual motor integration
• IQ 80 with lesion below S1
• IQ 80 in 50 of pt. with thoracolumbar lesion

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Spina bifida occulta

• Caudal locus L5-S1
• Covered by skin
• No neurological deficit
• Undetected for years
• Abnormal conus med. (prolonged) and filum
  terminale (thickened)
• Tetherd or fixed at their caudal end by
  fibrous bands,lipoma, dermal sinus

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Spina bifida occulta

• Vertebra abnormality 85-90
• laminar defects over several segments
• Widened spinal canal and sacral deformities
• Skin lesion 80 - hair tufts, dimples or tracts,
  hemangioma, skin tag, cutis aplasia, pigmented
  macula, sc. Mass, lipoma, dermal sinus
  (epidermoid,dermoid cyst)
• 15-20 infants of diabetic mothers

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Spina bifida occulta

• Clinical aspect
• Neurological deficits appear later in infancy
• Delay in development of sphincter control, in
  walking, asymmetry of legs or abn. feet
• Pain in the back or lower extremities
• Recurrent meningitis
• In older child gait disturbance, foot deformity,
  scoliosis, abnormal sphincter f.

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Spina bifida occulta

• Management
• spine x ray
• spine US
• if both nl. And no sy - only clinical F/U
• if abn. - MRI
• thx. surgery in neonatal period to prevent
  neuro.deficits

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New things

• Fetal surgery
• Goal to prevent damage to the cord and prevent
  complications related to the primary anomaly, to
  restore or preserve neurologic function
• Done 28-30 w , via hysterotomy
• Theoretical advantage of FS greater potential
  for healing and regeneration in the fetus
• Results no improvement in motor function
• Definite improvement in the cerebellar herniation
  A-C III regressed, less likely to require VP
  shunt nl.CSF circulation

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New things

• Fetal surgery
• 2 pt. at risk
• Induction of early labor, preterm delivery,
  infection, death
• MMC is not lethal lesion
• Iatrogenic dermoid inclusion cyst in infancy
• Progressive neur. deterioriation for spinal cord
  tethering
• Unknown, unforseen complication

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• Thank you for your attention
• And
• Than you for your help
• Dr. Levin
• Dr.Quattromani