Spinal dysraphism

Last revised by Frank Gaillard on 15 Jun 2024

Spinal dysraphisms refer to a broad group of malformations affecting the spine and/or surrounding structures in the dorsum of the embryo. They are a form of neural tube defect.

The term dysraphism implies that the cause of the abnormality is due to anomalous midline fusion and should not be used interchangeably with the term tethered cord, which refers to a constellation of clinical deficits, often but not invariably caused by spinal dysraphism 11.

The overall prevalence of spinal dysraphism varies somewhat between different populations but is generally approximately 1/1000 pregnancies 12. The prevalence at birth is lower, primarily influenced by regional and cultural differences in termination rates 12.

Established risk factors include 12:

  • maternal obesity

  • maternal pregestational diabetes

  • maternal use of various drugs (e.g. carbamazepine, valproic acid)

  • maternal hyperthermia (e.g. fever) 13

Folic acid supplementation is protective 12.

The neural tube is formed by the lengthwise closure of the neural plate, in the dorsum of the embryo.

The upper part of the neural tube forms the forebrain, midbrain and hindbrain. The lower part of the neural tube forms the spinal canal. Dysraphism results when the neural plate does not fuse completely in its lower section.

Although spinal dysraphism can be classified in a variety of ways, most commonly it is broadly divided into two different clinicoradiological entities based on whether or not the skin is intact (closed) or the abnormality communicates through a cutaneous defect (open) with associated loss of CSF 8,9,14:

Associated abnormalities of mesenchymal development occur often. Hence, lipomas and/or teratomas may be associated with any type.

Spianl dysraphism is also associated with many other syndromes including 12:

Dysraphism is formed from the Greek root raphe which means ridge or seam.

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