Spina bifida

Last revised by Joshua Yap on 23 May 2023

Spina bifida is a type of neural tube defect/spinal dysraphism which can occur to varying degrees of severity. It is often considered the most common congenital CNS malformation.

Spina bifida in its strictest sense means defective fusion of the vertebral posterior elements, leading to a bifid osseous configuration of the spine 16. However, most commonly it is used as a synonym or subset of spinal dysraphism.

The estimated incidence is at 1:1000-2000 live births 2.

Associated anomalies can occur in up to 40% of cases (especially if detected antenatally). They include:

A constellation of features can occur and these depend on the severity of spina bifida and any associated CNS defects. Common symptoms include:

Spina bifida is failure of the normal development of the neural tube. The etiology is often multifactorial with both genetic and environmental factors considered to play a role. Intake of adequate amounts of folic acid plays a protective role. 

There are many ways of classifying a spina bifida. One method is according to the extent of the defect and is as:

Another method is based on the position, either anterior (ventral) or posterior (dorsal). The vast majority of cases are of dorsal spina bifida.

A spina bifida can also be subtyped as:

Specific types

While it can occur anywhere along the spine 14:

  • lumbosacral region (90%)

  • cervical region (2-3%)

Ultrasound generally has a high detection rate for spina bifida and may show dorsal ossification centers / lateral pedicles as being splayed apart (which can give a V-shaped appearance to the posterior elements).

Ancillary intracranial sonographic findings:

Notably, closed and skin covered spinal lesions typically do not have any associated cranial abnormality. A normal cranial ultrasound therefore does not exclude a neural tube defect.

The overall prognosis is variable depending on the type and extent. For an isolated spina bifida, the recurrence risk range for future pregnancies is thought to be around 0.3-5% 12,13. Maternal intake of folic acid in subsequent pregnancies may again reduce the risk significantly.

The term spina bifida derives from the Latin words: bifida = split and spina = spine.

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Cases and figures

  • Case 1
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  • Case 2: with lipomyelomeningocele
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  • Case 3
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  • Case 4
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  • Case 5: with hip dysplasia and dislocation
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  • Case 6
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  • Case 7: with knee Charcot arthropathy
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  • Case 8: occulta
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