neural tube defects and craniosynostosis
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CNS – Neural Tube Defects and Craniosynostosis
Dr. Kalpana MallaMD Pediatrics
Manipal Teaching Hospital
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CONGENITAL ANOMALIES
• NTD – Spina Bifida Occulta Meningocele Meningomyelocele Encephalocele Anencephaly
CONGENITAL ANOMALIES• Defects of Neuronal Migration – Lissencephaly
Porencephaly Schizencephaly Holoprosencephaly
• Craniosynostosis • Agenesis of Corpus Callosum• Microcephaly• Hydrocephalus
MORPHOGENESIS
Abnormal Organisation Of Cells In Tissue
DYSPLASIA
Unusual Forces On Normal Tissue
DEFORMATION
Poor FormationOf Tissue From Begining
MALFORMATION
Breakdown OfNormal Tissue
DISRUPTION
Neural tube defects
• Neural tube defect - Failure of closure of Neural tubes
Neural tube defects - ETIOLOGY:
Folic acid deficiency:Drugs antagonizing folic acid:Valproic acid, CBZ, phenytoin, phenoba., alcohol,
thalidomide, irradiation, maternal diabetesSyndromal disorders: trisomy 18, 13,
Malnutrition – zn , folate def.
EMBRYOLOGY
Nelson.
A single sheet of cells – midline ectoderm
Ectodermal plate enlarges
Neural folds become elevated and fuse forming Neural tube
Fusion occurs in cervical region and proceed both caudally and cephalic, by secondary neuralization
Cephalic completed by 23rd dayCaudally completed by 28th day Thus neural tube formation completed by 4th week
EMBRYOLOGY
TYPES OF NTD
PRIMARY -95% of all NTD Primary failure of closure/disruption of NT
btw 18-28 days.
Eg. -Myelomeningocele Encephalocele
Anencephaly
TYPES OF NTDSECONDARY
-5% of all NTD. Abnormal deve. of lower sacral seg. during
secondary neuralisation• Skin is usually intact• Involves lumbo sacral regionEg. Spina Bifida Occulta Meningocele
Spina bifida occulta:
• Midline defect of vertebral bodies without protrusion of spinal cord / meninges.
• Asymptomatic , usually of no consequence• Presents as patch of hair, lipoma, dermal sinus
in low back – underlying spinal malf.• Level - L5 & S1.• May be associated with tethered cord.• May present as recurrent meningitis – look for
dermal sinus.
Meningocele
Sac + CSF + intact skin + No nervous tissue + usually no hydrocephalus-Small sac which increases on crying - Usually no neurological abnormality
Meningocele• Inv.-• CT HEAD – r/o hydro• MRI SPINE – R/O (i)Diastematomyelia – division of spinal
cord into two halves by projection of fibrocartilagenous or bony septum from post vertebral body
(ii) Tethered cord – slender threadlike filum terminale attached to coccyx conus here is below L2 instead L 1
• Treatment – • Skin intact – surgery in infancy• Skin lacerated – urgent treatment• Look for recto vaginal fistula
Meningomyelocele
Sac + CSF + neural element + discontinuous skin + hydroce(80%). TYPE – 94% of all NTD - Lumbo sacral- Area of well developed skin at periphery With thin apex covered by glistening arachnoid membrane- Usually CSF oozing +
Meningomyelocele
• Check for reflexes, muscle power of LL. Check for SPHINTER and ANAL reflexes
TREATMENT:• SURGERY• MULTIDIS. APPROACH• Look for other anomalies• Treat hydroceph, Club foot• Bladder and bowel care
LOBERS CRITERIA 1972 - FOR SELECTIVE SURGERY
SURGERY NOT DONE IF – • Severe praplegia below L3 with bladder
paralysis• Gross Hydrocephalus• ASSOCIATED LIFE THREATENING GROSS CONG.
MALFORMATION.
LOBERS CRITERIA 1972 - FOR SELECTIVE SURGERY
SURGERY NOT DONE IF – • Kyphosis• Associated gross congenital anomalies• Very large lesions• Infection of sac ormeningitis
Myelomeningocele
ANENCEPHALY• Failure of closure of rostral neuropore.• Large defect of calvarium, meninges, scalp
associated with rudimentary brain.• Cerebral hemisphere and cerebellum
usually absent• Associated anomalies-• In pregnancy – polyhydroamnios• Die at birth or few days• Etiology – genetic, environmental toxins,
nutrition
ENCEPHALOCELE• Contains sac + cerebral cortex +
cerebellum + brain stem• – OCCIPITAL region, Can also occur in
frontal or nasofrontal• ↑ risk of arnold chiari or dandy walker
malformation• ↑ risk of hydroceph.• Visual problems, microcephaly, mental
retardation, seizures associated features.
Diagnosis in pregnancy
Amniocentesis - to diagnose chromosomal disorders and open neural tube defects (ONTDs)
Alpha-fetoprotein screening
• Measures the level of AFP in mothers' blood during pregnancy.
• Abnormal levels of AFP - Open neural tube defects (ONTD) Down syndrome Other chromosomal abnormalities Defects in the abdominal wall of the fetus Twins - more than one fetus is making the
protein
Neural tube defects – prevention
Folic acid deficiency:If previous history of NTD in family :4mg – 1 month before preg. To 3 months
thereafter
Else for every other women of child bearing age :0.4mg – 1 month before conception till 12 weeks
gestation.
Defects of Neuronal Migration
• Lissencephaly – absence of cerebral convolution due to faulty neuroblast migration
• Porencephaly – cysts or cavities within the brain
Defects of Neuronal Migration
• Schizencephaly – uni or bilateral cleft within cerebral hemisphere
• Holoprosencephaly – defective cleavage of procencephalon – single ventricle,absent falx,fused basal ganglia
CRANIOSYNOSTOSIS
• Craniosynostosis – premature closing of sutures causing problems with normal brain and skull growth
Plagiocephaly - coronal synostosis
- Fusion of either rt or lt side of the coronal suture-Causes the normal forehead and the brow to stop growing-Produces flattening of the forehead and the brow on the affected side, with the forehead tending to be excessively prominent on the opposite side
SCAPHOCEPHALY/DOLICHOCEPHALY
Early closure or fusion of the sagittal suture
Fusion causes a long, narrow skull .Prominent occiput and forehead
Usually only craniosynstosis which is relatively harmless
TRIGONOCEPHALY Fusion of the metopic (forehead) suture
Fusion result in a prominent ridge running down the forehead -looks pointed, like a triangle, with closely placed eyes (hypotelorism).
• Turriencephaly – cone shaped head . Fusion of coronal and speno frontal or fronto
ethmoid sutures.• Brachycephaly – premature closure of coronal
suture expands skull parallel to coronal suture , thus broadening of forehead with short AP diameter. Eg – in many syndromes like Downs
TYPES OF CRANIOSYNOSTOSIS
Primary • Closure of sutures due to abnormality of skull
development. Eg – genetics.
Secondary • Occurs from failure of brain growth and
expansion. Therefore causing premature fusion.
CLINICAL
• Palpation of suture reveals prominent bony ridge.
• Fusion may be confirmed by x-ray skull• Associated syndromes – Crouzon , Alperts,
Carpenter,
TREATMENT
• Premature fusion of single suture rarely causes any neurological deficit . Thus, in this situation the only indication is cosmetics.
• 2 or more suture fusion – more complications eg. ↑ ICT, hydrocephalus,
optic atrophy, DNS, choanal atresia --- operative surgery essential – craniectomy with craniofacial correction.
• Usually good prognosis with non syndromic infants……………
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