Caudal Dysplasia Sequence

Caudal Dysplasia Sequence

CR – Lumbosacral reduction anomaly.

MR – Blunt termination of the conus medullaris and clumping of ventral and dorsal nerve roots.

Caudal dysplasia sequence or caudal regression syndrome is a sporadic defect with partial genetic contribution. Caudal dysplasia sequence occurs in up to 1% of pregnancies of women with diabetes (up to 22% of cases are associated with either type I or type II diabetes mellitus in the mother, with hyperglycemia the likely teratogen).

Caudal dysplasia sequence is thought to arise from a defect in induction of caudal elements of the embryo before the 7th week of gestation and may be related to defective primitive streak migration, neurulation, or differentiation. The proximity to the developing caudal cord, spine, hindgut, and mesonephric elements result in the collateral deficits.

It was previously thought that caudal dysplasia sequence and sirenomelia were manifestations of the same syndrome. Sirenomelia is thought to result from a vascular steal phenomenon that causes severe ischemia of the caudal portion of the fetus. In sirenomelia, an aberrant vessel derived from the vitelline artery shunts blood from the high abdominal aorta directly through the umbilical cord resulting in severe hypoperfusion of structures caudally.

Smith AS, Grable I, Levine D. Caudal Regression Syndrome in the Fetus of a Diabetic Mother. Radiology (2004); 230:229-233.