Congenital Malformations of the Central Nervous System

Neural Tube DefectsDr. Dhaval ShuklaAssociate Professor

Department of NeurosurgeryNIMHANS, 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 proneMeticulous 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 exercisesPerform 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 antibioticsExpressing 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