Spina bifida and neural tube defects result from abnormal neurulation during the first 4 weeks of embryogenesis. They are caused by interaction of genetic and environmental factors.
Preventable with maternal folate supplementation or fortification.
Can affect the brain (anencephaly, encephalocele) or any level of the spinal axis, although most commonly involves the lumbosacral region. Not to be confused with spina bifida occulta, a fusion defect that affects the vertebral arches only and is a clinically insignificant radiological finding in 10% of the general population.
Defects of the spinal cord are classified as open (not covered by skin) or closed (covered by skin). Open defects include myelomeningocele, when both the spinal cord and the meninges are exposed, or meningocele, when only the meninges are exposed. Closed spina bifida is a diverse group of lesions that includes fatty tumours within the spine (lipomeningocele) or intraspinal cartilage or bone (diastematomyelia).
Results in variable paralysis and sensory loss in the legs, orthopaedic deformities, scoliosis, neurogenic bowel and bladder, hydrocephalus, and Chiari II malformation. Often associated with non-verbal learning disability and executive dysfunction, although intelligence is typically not impaired.
Most neural tube defects are detected antenatally on ultrasound or clinically at birth.
Antenatal treatment in selected cases involves repair of the defect at an experienced fetal surgery centre. More typically, cele repair is performed within 1 to 3 days of term delivery.
A multi-disciplinary approach to care is important across the lifespan.
Neural tube defects are a spectrum of disorders that can affect the brain or the spinal cord.
They are caused by interaction of genetic and environmental factors, and are prevented with folate supplementation.
The most common neural tube defects include anencephaly, which affects brain and skull development and is incompatible with life, and spina bifida, which means 'split spine'. This split may be limited to the vertebral arches, known as spina bifida occulta (clinically insignificant and common, affecting 10% of the population), or associated with spine anomalies such as myelomeningocele.
Spina bifida presents clinically with variable paralysis and sensory loss in the legs, orthopaedic deformities, neurogenic bowel and bladder, hydrocephalus, and Chiari II malformation (caudal displacement of the cerebellar tonsils and vermis, caudal medulla, and occasionally the fourth ventricle, into the cervical spinal canal). Hydrocephalus and the Chiari II malformation are often associated with non-verbal learning disability and executive dysfunction, although intelligence is typically not impaired.
This Best Practice topic encompasses a lifespan approach to care.
History and exam
Key diagnostic factors
- maternal risk factors for child with spina bifida
- history of elevated triple or quadruple screening test during antenatal assessment
- history of abnormality on antenatal ultrasound
- open spina bifida lesion: myelomeningocele, myeloschisis, meningocele
- closed spina bifida lesion: asymmetrical gluteal fold or dimple, haemangioma, hairy patch, or other cutaneous markings
- bulging fontanelle
- rapid head growth
- abnormal urinary voiding
- leakage of meconium or stool
- mid-line congenital anomalies: cleft lip or palate, cardiac murmur
- arching of neck
Other diagnostic factors
- absence of anal wink/rectal tone
- downward deviation of the eyes (sundowning)
- upward and lateral deviation of eyes
- abnormal cry
- breathing abnormalities: apnoea, inspiratory stridor, snoring
- facial asymmetry
- asymmetry of spontaneous arm and leg movement
- difficulty with changing nappies or dressing
- abnormal muscle tone and bulk in arms and legs
- decreased sensation
- hip subluxation or dislocation
- club foot (equinovarus deformity)
- vertical talus deformity
- hip and knee flexion contractures
- feeding difficulties
- congenital scoliosis
- congenital kyphosis
- inadequate maternal folate intake
- previous pregnancy affected by spina bifida or other neural tube defect
- maternal history of spina bifida or other neural tube defect
- Hispanic ancestry or ethnicity
- trisomy 18 or trisomy 13
- antenatal exposure to valproic acid, carbamazepine, isotretinoin, or methotrexate
- inadequate maternal vitamin B12 intake
- maternal obesity
- maternal diabetes
- female sex of infant
- 22q deletion syndrome
- low socioeconomic status
- elevated maternal core body temperature during first trimester
1st investigations to order
- antenatal triple/quadruple test
- antenatal ultrasound
- fetal MRI
- cranial ultrasound
- spinal ultrasound
- CT head
- urine culture
- serum urea and creatinine
- renal ultrasound
- urodynamic study
- voiding cystourethrogram (VCUG)
Investigations to consider
- antenatal amniocentesis or postnatal chromosomal analysis
- fluorescence in situ hybridisation (FISH) testing
- MRI brain and spine
- hip ultrasound
- hip x-ray
- fetal echocardiography
neonate or infant
- Spine segmental dysgenesis
- Caudal regression syndrome (sacral agenesis)
- Multiple vertebral segmentation disorder
- Prevention, screening, diagnosis, and pregnancy management for fetal neural tube defects
- Antenatal care
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