Congenital Malformations of the
Central Nervous System
Neural Tube Defects
Dr. Dhaval Shukla
Associate Professor
Department of Neurosurgery
NIMHANS, Bangalore.
Epidemiology
• 1/3rd of all congenital malformations
• 75% of fetal deaths
• 40% of deaths during the first year of life
• Cause not known in 75%
Epidemiology
• Most fetuses with major malformations are stillborn or die
during the neonatal period
• Survivors are seriously incapacitated, ranging from
unresponsiveness throughout their entire life to profound
mental retardation, muteness, severe motor deficits, and
seizures
• Minor anomalies manifest with mental retardation,
behavioral changes, motor disorders, and seizures.
Etiology
Development
Major Developmental Events
Major Developmental Events
Normal and abnormal
spinal cord
Normal and abnormal
spinal cord
Neural Tube Defects
• 0.5 to 2 per 1,000 births
• Genetic risk factors, maternal diabetes mellitus,
and the use of the anticonvulsants valproic acid
and carbamazepine
• Brain or the spinal cord, or both, with their
coverings
Classification
Cutaneous manifestations
Cutaneous manifestations
Spina bifida occulta
• Sacral or lumbosacral is commonest
• Requires no treatment at birth
• Potential for the spinal cord to become fixed
(tethered) at the site of the lesion during
growth of child
Meningocele
• Neurological function outcome is usually more
favorable
• Surgery to close the lesion
• Long-term needs will depend on the extent of
neurological deficits and level of involvement
Myelomeningocele
• Apparent at birth
• Legs, bladder and bowel are usually affected
• Hydrocephalus is usually present
Preoperative care
• Prevent infection
–
–
–
–
At the site of the lesion
Meningitis
Ventriculitis
Urinary infections
• Avoid drying and injury
• Dressing
– Clear Film
– Non-abrasive
– Non-adherent
Nurse prone
Meticulous nappy care
Surgery for open defects
• Within 24 hours of birth if no other life
threatening malformations
• Dissecting the neural tissue
• Covering the tissue with fibrous dura
• Skin graft may be necessary
• Shunt may be inserted
Postoperative care
• Maintaining the airway and providing adequate
oxygenation
• Maintaining adequate circulatory fluid volumes
and replacing blood loss
• Ensuring hypoprothrombinaemia is minimized by
giving vitamin K preoperatively
Postoperative care
• Ensuring the environment minimizes heat loss
• Monitoring and preventing metabolic
abnormalities such as hypoglycaemia,
hypocalcaemia or acidosis
• Maintaining strict precautions to minimize the
risk of infections
Postoperative care
• Nurse the infant prone
• The wound must be observed for CSF leak and
signs of infection
• Nylon sutures are removed after 10–14 days
• Hydrocephalus is likely to develop within 10
days
Neurological care
• Correct positioning of the limbs
• Observation of the skin for any signs of pressure
damage
• Regular position changes
• Regular passive exercises
Perform above with other routines such as
feeding and nappy care
Bladder care
• Continuous urine leakage or full bladder after voiding
• Regular renal ultrasound scans
• Intermittent catheterization
• Prophylactic antibiotics
Expressing the bladder by applying pressure over the lower
abdomen during nappy changes may increase the risk of
urinary reflux into the ureters
Care of parents
• Future predictions relating to the potential
physical and cognitive outcomes
Antenatal Detection
• Maternal ultrasound examination
• High α – fetoproteins in amniotic fluid
– Maternal serum - 12 weeks
– 30 per cent chance of a false-positive
• Amniocentesis is offered at 16–18 weeks for chromosomal
aberrations by karyotyping
• DNA studies on chorionic villi - 8 weeks
• Magnetic resonance imaging (MRI)
Prevention
Before and during pregnancy
• Folic acid (0.4mg daily)
• Increase to 5mg daily for high risk women
• Avoid smoking and alcohol intake
• Avoid aminopterin, methotrexate, trimethoprim,
valproic acid, carbamazepine, and phenobarbitone
If you are not taking contraceptives take FOLIC ACID