Type I split cord malformation with an usual bony morphology.

Variations in the configuration of the bony septum found in patients with split cord malformations are rare. We report the seemingly rare occurrence of a midline bony septum that ended posteriorly as a fully formed bony spinous process. We speculate that this variation is due to misplaced mesodermal cells associated with the primitive endomesenchymal tract during approximately the third week of foetal life. The clinician that manages these patients may wish to consider this rare morphology and avoid excessive manipulation of such a process, which could potentially injure an underlying hemicord.