Neural Tube Defects NTDs

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Neural Tube DefectsNTDs

• Dr. Mohamed Abunada
• Pediatric Neurology Department
• Dr. Al rantisi Specialized children Hospital

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Definition

• A variety of neural tube, bone and skin defects
  that can include various neural elements.

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Spectrum of NTD

1. Spina bifida occulta
2. Meningocele
3. Myelomeningocele
4. Encephalocele
5. Anencephaly

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Spectrum of NTD
Spina Bifida - Types
Myelomeningocele
Spina Bifida Occulta
Lipoma
Meningocele
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Pathophysiology

• Some lesions may have skin covering the sac.
• The meningeal sac and contents bulge out.
• The sac may be intact or ruptured.
• The lesions may span one to many vertebrae in
  length, though most involve a single vertebrae.

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NTD EMBRYOLOGY

• The human embryo passes through 23 stages after
  conception, each occupying approximately 2-3
  days.
• Two different processes form the central nervous
  system.
• The first is primary neurulation, which refers to
  the formation of the neural structures into a
  tube, thereby forming the brain and spinal cord.
• Secondary neurulation refers to the formation of
  the lower spinal cord, which gives rise to the
  lumbar and sacral elements.

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• The neural plate is formed at stage 8 (days
  17-19), the neural fold occurs at stage 9 (days
  19-21), and the fusion of the neural folds occurs
  at stage 10 (days 22-23).
• Any disruption at stages 8-10 (when the neural
  plate begins its first fold and fuses to form the
  neural tube) can cause craniorachischisis, the
  most severe form of NTD.

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Craniorachischisis, the most severe form of NTD
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• Stage 11 (days 23-26) is when the closure of the
  rostral neuropore occurs. Failure at this point
  results in anencephaly.
• Myelomeningocele is a result of disruption of
  stage 12 (days 26-30), closure of the caudal
  neuropore.

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NTD GENETIC

• There may be genetic factors with the PAX-3
  gene. This gene is located on chromosome 2 and
  is involved in the control and function of the
  neural crest cells that help to form the central
  nervous system.
• Multifactorial
• Recurrence risk
• 1. The recurrence risk is 2-5 if parents have
  1 child with this defect.
• 2. There is a 10 risk of further recurrence
  if 2 children have been affected.
• 3. If a parent had a myelomeningocele, there
  is a 10 chance of the child having the lesion.

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Genetic (continued)

• Association with other syndromes and sequences.
• Trisomy 13
• Trisomy 18
• Single gene-Meckels Syndrome

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Incidence

• Overall 0.7 0.8/1,000 live
• United Kingdom 0.7- 2.5/1,000 live births
• U.S. 0.4- 1.43/1,000 live births

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CLINICAL PRESENTATIONSpina Bifida Occulta
Dermal sinus
Hair tuft
Sacral dimple
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Spina Bifida Occulta

• no herniation of the meninges is present
• the skin of the back is completely
  epithelialized, although always showing some
  abnormality such as a nevus, dermal sinus, and
  dimple (35), an underlying lipoma (29), or a
  hirsute area.
• Radiography reveal commonly
• widening of the spinal canal,
• fusion of the vertebral bodies,
• spina bifida, and sometimes,
• a midline bone mass within the spinal canal.
• These skin and bone abnormalities are indications
  that the cord and nerve roots are malformed also.

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Spina Bifida Occulta

• There may be
• a localized doubling of the cord (diplomyelia),
• a sagittal splitting of the cord
  (diastematomyelia),
• an intradural lipoma attached to the cord.
• These lesions must be recognized because they can
  cause progressive loss of neural functioning
  during the childhood growth spurt.
• In many cases, operative intervention to free the
  cord or nerves is indicated to prevent further
  damage or prophylactically to avoid such damage.

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Meningocele
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Cervical MC
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Meningocele

• herniation of only the meninges through the
  defective posterior arches the sac does not
  contain neural elements
• Meningoceles account for less than 5 of patients
  with spina bifida cystica
• MMC must be differentiated from meningocele
  because the prognoses are vastly different.
• An infant with a meningocele has little or no
  associated CNS malformation, rarely develops
  hydrocephalus, and usually has a normal
  neurologic examination.
• A MMC is differentiated from a meningocele only
  at the time of operative repair.

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Myelomeningocele MMC
Posterior MMC
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MeningomyeloceleSpina Bifida Cystica

• A lumbar or lumbosacral defect is most common
• 90 or more of lumbosacral myelomeningoceles are
  accompanied by Chiari type II malformations and
  hydrocephalus.
• when a patient has been selected for surgical
  treatment, the procedure should be undertaken
  within 24 hours of birth and no later than 1 week
  of age.

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If the neonate is to be treated

• If the neonate is to be treated, the sac is kept
  clean and moist before surgery by an under cover
  of gauze sponges wet with a povidone-iodine
  solution.
• To prevent colonization of the GIT and to keep
  the meconium sterile, the infant is not fed.
• Systemic broad-spectrum ABs, especially against
  Staphs and coliform organisms, are started when
  the infant arrives at the hospital and are
  continued for several days after closure of the
  sac.
• Postoperatively, the infant is kept prone for the
  first week to diminish the risk of urine or feces
  contaminating the wound.

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The course of follow-up examinations

• In the course of follow-up examinations, the head
  circumference and the appearance of the
  fontanelle are monitored, and imaging is used
  whenever the findings suggest increased
  intracranial pressure.
• As judged by imaging studies, more than 90 of
  infants with spina bifida cystica ultimately
  develop progressive hydrocephalus. Of these, 80
  do so within the first 6 months of life and
  require a shunting procedure.

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Site of Lesion of Spina Bifida Cystica 1387
patients
Number of Patients Level
51 Cervical
103 Thoracic
137 Thoracolumbar
583 Lumbar
382 Lumbosacral
119 Sacral
6 Anterior
3 Thoracic
3 Pelvic
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Neurologic Syndromes with Myelomeningoceles
1.Complete paraplegia and dermatomal para-anesthesia2.Bladder , rectal incontinence3.Nonambulatory Above L3
1.Same as for above L3 except preservation of hip flexors, hip adductors, knee extensors2.Ambulatory with aids, bracing, orthopedic surgery L4 and below
1.Same as for L4 and below except preservation of feet dorsiflexors and partial preservation of hip extensors and knee flexors2.Ambulatory with minimal aids S1 and below
Normal LL motor function, Variable bladder and rectal incontinence S3 and below
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Encephalocele
Ant. encephalocele
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Ant encephalocele
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Cranium Bifidum(cephalocele, encephalocele)

• The incidence of cranium bifidum is approximately
  1/10 that of spina bifida cystica.
• 85 of these lesions are dorsal defects involving
  the occipital bone. Parietal, frontal, or nasal
  encephaloceles are far less common.

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• Anencephaly

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Anencephaly

• Anencephaly is seen 37 times more frequently in
  female than in male newborns
• Anencephalic patients do not survive infancy.
• During their few weeks of life, they exhibit
  slow, stereotyped movements and frequent
  decerebrate posture
• The presence of anencephaly and other open neural
  tube defects can be predicted by measuring of
  alpha fetoprotein (AFP) in amniotic fluid or
  maternal serum.

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AFP

• Normal AFP in adult serum is less than 10 ng/mL.
• In normal maternal serum and amniotic fluid, it
  ranges from 15 to 500 ng/mL.
• At 15 to 20 weeks' gestation, an AFP
  concentration of 1,000 ng/mL or greater strongly
  suggests an open neural tube defect, and the
  current screening of serum detects 79 of cases
  of open spina bifida at 16 to 18 weeks
• Amniotic fluid AFP screening is more reliable,
  detecting 98 of open spina bifida cases,
  Amniotic fluid AFP obtained between 15 and 20
  weeks' gestation is most specific

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Complications of Neural Tube Defects
Neurosurgical Complications

• Hydrocephalus
• Clinical signs of progressive hydrocephalus
  accompanying a myelomeningocele include an
• abnormal increase in head circumference,
• full fontanelle,
• spreading of sutures,
• hyper-resonant calvarial percussion note,
• dilated scalp veins,
• deviation of the eyes below the horizontal
  (setting sun sign),
• strabismus, and
• irritability.

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Hydrocephalus

• Shunt required in 80 of patients
• Good shunt function necessary for good outcome

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Shunt Malfunction

• Increased head growth
• Tense anterior fontanel
• Lethargy, headache, vomiting, irritability
• Paralysis of sixth cranial nerve
• Strabismus
• Double Vision
• Paralysis of upward gage

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Shunt Malfunction (Continued)

• Shunt infection
• Fever and increased WBC
• Subtle signs
• Changes in personality
• School performance decline
• Weakness of arms or legs

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Neurosurgical Complications (Continued)

• Arnold Chiari Malformation-II
• 1. Caudal placement and elongation of
  medulla, pons, cerebellar tonsils cause
  obstruction of outflow of ventricle.
• 2. Symptoms
• 3. Management

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Arnold Chiari
Normal
Arnold Chiari
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Symptoms of Cord Compression

• Difficulty swallowing
• Choking
• Hoarseness
• Breath holding spells
• Apnea
• Vocal cord paralysis

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Orthopedic Deformities

• Contracture deformities of the lower limbs
  require physical therapy, leg braces, and
  stabilization of dislocated hips.
• Muscle or tendon transplants and joint
  arthrodeses might be necessary in the ambulating
  child.
• neuropathic fractures resulting from paralysis
  and prolonged immobility are common. They are
  best prevented by early active and passive
  range-of-motion exercises

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Treatment(Continued)

• Feet
• Calcaneus's deformity
• Serial casting with Achilles lengthening if
  flexion extension is compromised
• Further corrective surgery at 12 months of age

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Scoliosis

• Spine
• Scoliosis
• Kyphosis
• Kyphectomy

• Plain spine films to measure scoliosis

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Genitourinary tract

• The three fundamental urologic problems are
• infection,
• incontinence, and
• retrograde high pressure on the upper urinary
  tract, producing hydronephrosis and hydroureter.
• Therefore, early and constant monitoring of the
  urinary tract with
• IVP,
• cultures with colony counts, and
• MCUG is an essential part of any therapeutic
  program.
• To assess the efficacy of clean intermittent
  catheterization and to time appropriate surgical
  intervention for the prevention or arrest of
  upper urinary tract damage, more complex
  urodynamic studies are available.

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Genitourinary tract

• In lumbosacral spina bifida cystica, few children
  attain urinary continence
• They require urodynamic testing, including
  cystometrography, uroflometry, and EMG of the
  urinary sphincter
• Types of lesions
• 1. Keepers- UMN
• 2. Leakers- LMN
• According to results and consulting urologist
  patient may need intermittent catheterization,
  pharmacological agents, implantation of an
  artificial urinary sphincter or a combination.

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Bowel incontinence

• Bowel incontinence owing to a flaccid external
  sphincter, although not as serious a medical
  problem as bladder incontinence, poses a much
  greater social disability.
• Constipation and impaction of stool are major
  problems after the first few years of life.
• Routine enemas or suppositories have been used
  with some degree of success.
• Appendicovisicostomy, a relatively simple
  operation, the appendix is inserted into the
  anterior aspect of the cecum, and retrograde
  colonic enemas can be performed. The slow washing
  out of the colonic contents by injection of water
  through the appendicostomy may be needed only
  every 24 to 48 hours, leaving the child free to
  take part in normal activities for the remainder
  of the time. The procedure can be carried out by
  itself or in combination with surgery for urinary
  incontinence

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Bowel Complications

• Constipation
• Incontinence
• Management techniques
• -enemas -suppositories
• -habit training - digital stimulation
• -biofeedback -appendicostomy(ACE)

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Psychosocial Issues

• Developmental issues
• -social
• -cognitive
• School Issues
• -learning disabilities
• Vocation planning
• Independence
• Secondary conditions

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Prognosis

• Long term mortality can be as high as 35-50 by
  adulthood
• 75 have IQs higher than 80
• Among these 60 are learning disabled
• - Non verbal learning disability
• - Deficits in mathematics, sequencing,
  visual perceptual skills, problem solving

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Prognosis(continued)

• 89 of pre-adolescent are community ambulators
  when they receive aggressive multidisciplinary
  management
• Post-adolescence community ambulation decreases
  to approximately 50 because it is more energy
  efficient to use a wheelchair

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Prognosis(continued)

• 85 of school aged children acquire continence
  through regimented bowel and bladder programs
• Vocational issues remain significant concern with
  only 32 gainfully employed
• Transition to adult care clinicians and
  maintaining access to appropriate health care in
  adulthood is an increasing concern

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Prevention

• Historical aspects of use of prenatal vitamins
  (1964-England)
• Current research-folic acid
• Doses ranges .4mgm/day (Smithhells) to 4.0
  mgm/day (Wald)
• CDC recommendation 4.0 mgm should be taken by
  all mothers with prior history of a child with
  NTD
• Recent focus on NTD caused by enzymatic
  abnormality of metabolic pathways that require
  folate, not simply deficiency

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long-term care

• The of the patient with spina bifida cystica
  requires a multidisciplinary effort. In addition
  to continuing neurologic and neurosurgical
  evaluations, the infant also should be seen at
  regular intervals by orthopedic surgeons,
  urologists, physiotherapists, and nursing and
  social services.

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THANKS

• THANKS