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.

Can affect the brain (anencephaly, encephalocele) or any level of the spinal axis, most commonly the lumbosacral region.

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, tethered cord syndrome, 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.

Preventable with maternal folate supplementation or fortification.

Most neural tube defects are detected antenatally on ultrasound or clinically at birth.

Definitive treatment is surgical repair, carried out antenatally or postnatally. Supportive multidisciplinary care is essential across the patient's 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 a common incidental radiological finding, 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, as well as multiple migrational abnormalities of the cerebrum and abnormalities of the brainstem, dura, and skull). Hydrocephalus and the Chiari II malformation are often associated with non-verbal learning disability and executive dysfunction, although intelligence is typically not impaired.