Postnatal development of the central skull base: Normal variants

PURPOSE: To illustrate the normal variants and developmental anomalies of the skull base on computed tomographic (CT) scans. MATERIALS AND METHODS: One hundred eighty-nine children (age range, newborn to 18 years; median age, 4.0 years) without skull base deformity were referred for cranial CT. Normal developmental variants in the sphenoid and occipital bones were characterized. RESULTS: Sixteen normal variants of central skull base development were identified including anterior foramen in the presphenoid, remnant of the craniopharyngeal canal in the anterior portion of the postsphenoid, rounded defects in the central sphenoid, clefts and fissures along the basiocciput and basisphenoid, basioticum variants, notochordal remnant in the midline of the basiocciput, and fusion variants of the Kerckring ossicle with the supraoccipital portion of the occipital bone. CONCLUSION: The location and CT appearance of the 16 variants and anomalies are related to the known embryologic origin of this region. Recognition of such variants may prove necessary in evaluation of patients with skeletal dysplasias and disorders of skull base development.