The split notochord syndrome (SNS) is a rare form of spinal dysraphism.


Synonym: posterior spina bifida, combined spina bifida, neurenteric fistula, dorsal enteric fistula


Basis: A persistent connection between the endoderm and ectoderm results in a splitting of the notochord. In the most extreme cases there is communication from the GI tract to the spinal canal to the skin of the back. In less extreme cases growth of tissue may obliterate parts of the communication leaving various remnants.


Essential components:

(1) vertebral anomalies (anterior and posterior spina bifida, butterfly vertebrae)

(2) central nervous system (CNS) abnormalities (myelomeningocele, diplomyelia, diastematomyelia, hydrocephalus)

(3) intestinal anomalies (enteric cyst, fistula, dermal sinus tract, diverticula, duplication, anorectal malformations, other). In more severe cases intestinal segments may be exteriorized.



• If the thoracic region is involved then anomalies involve the foregut or midgut.

• If the lumbosacral region is involved then anomalies involve the hindgut.


Additional findings may include:

(1) posterior mediastinal mass (teratoma, other)

(2) talipes equinovarus


Extreme cases can be identified at birth. Subtle forms may not be recognized until the patient is an adult.


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