Spina bifida

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.

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

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

  • back pain
  • bladder or bowel incontinence
  • paraplegia
  • spinal or lower limb deformities

The aetiology 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.

Classification

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

Another method is based on position as being anterior (ventral) or posterior (dorsal). The vast majority of cases comprise of dorsal spina bifida.

A spina bifida can also be subtyped as:

Location

While it can occur anywhere along the spine 14:

  • lumbosacral region (90%)
  • cervical region (2-3%)
Markers
Associations

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

Antenatal ultrasound

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.

Complications

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


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Article Information

rID: 13416
Section: Pathology
Synonyms or Alternate Spellings:
  • Spina bifida: general

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