Multiple neural tube defects: rare developmental anomaly with an elusive embryological explanation

Neural tube defect is a congenital anomaly resulting from the failure of fusion of the neural folds in the midline which occurs in the third and the fourth week of embryonic development. These defects can occur at any of the three embryological stages-gastrulation, primary neurulation and secondary neurulation. Presence of neural tube defects at multiple (two or more) sites along the craniospinal axis is an extremely rare anomaly and the management depends on clinical as well as imaging findings. These multiple defects are not well explained by the "Zipper closure" theory and can be better explained by the "Multisite closure theory", which will be highlighted in this manuscript. Few of these multiple site anomalies cannot be fully explained even by the multisite closure theory and more research is needed to decipher this entity.