EMBRYOLOGY A single sheet of cells – midline ectoderm Ectodermal plate enlargesNeural folds become elevated and fuse forming Neural tubeFusion occurs in cervical region and proceedboth caudally and cephalic, by secondaryneuralization Cephalic completed by 23rd day Caudally completed by 28th day Thus neural tube formation completed by 4th week Nelson.
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 NTD SECONDARY -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.
MeningoceleSac + CSF + intact skin + No nervoustissue + 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
MeningomyeloceleSac + CSF + neural element + discontinuous skin +hydroce(80%). TYPE – 94% of all NTD - Lumbo sacral- Area of well developed skin at periphery Withthin apex covered by glistening arachnoidmembrane- Usually CSF oozing +
Meningomyelocele• Check for reflexes, muscle power of LL. Check for SPHINTER and ANAL reflexesTREATMENT:• SURGERY• MULTIDIS. APPROACH• Look for other anomalies• Treat hydroceph, Club foot• Bladder and bowel care
LOBERS CRITERIA 1972 - FOR SELECTIVE SURGERYSURGERY NOT DONE IF –• Severe praplegia below L3 with bladder paralysis• Gross Hydrocephalus• ASSOCIATED LIFE THREATENING GROSS CONG. MALFORMATION.
LOBERS CRITERIA 1972 - FOR SELECTIVE SURGERYSURGERY NOT DONE IF –• Kyphosis• Associated gross congenital anomalies• Very large lesions• Infection of sac ormeningitis
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 pregnancyAmniocentesis - to diagnosechromosomal disorders andopen 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 syndromeOther chromosomal abnormalitiesDefects in the abdominal wall of the fetusTwins - more than one fetus is making the protein
Neural tube defects – preventionFolic acid deficiency:If previous history of NTD in family :4mg – 1 month before preg. To 3 months thereafterElse 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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