Bilateral choanal atresia associated with malformation of the anterior skull base: embryogenesis and clinical implications.

A number of craniofacial and systemic malformations have been described in association with choanal atresia. We report a case of bilateral choanal atresia associated with congenital absence of the cribriform plate, crista galli, and perpendicular plate of the ethmoid bone. The anterior skull base defect was detected by using high-resolution computed tomography with three-dimensional reconstructions. The findings support the mesodermal flow theory of choanal atresia, in which there is excess migration of neural crest cells into the developing nasal septum and posterior choanae. This occurs at the expense of cells that would otherwise form the rest of the ethmoid complex. Clinical implications include the need for adequate preoperative imaging of the anterior skull base and consideration of potential intracranial complications during surgical repair.