Spina bifida and neural tube defects

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.[Figure caption and citation for the preceding image starts]: Neonate with myelomeningoceleFrom the collection of Dr Greg Liptak; used with permission [Citation ends].[Figure caption and citation for the preceding image starts]: MyelomeningoceleFrom the collection of Dr Greg Liptak; used with permission [Citation ends].[Figure caption and citation for the preceding image starts]: Brain MRI scan showing Chiari malformationFrom the collection of Dr Nienke P. Dosa; used with permission [Citation ends].