An accessory sphenoidal foramen of the middle cranial fossa detected on computed tomography.

Background: The skull base depicts significant morphological variability, which is frequently described due to its neurosurgical significance. The middle cranial fossa's accessory foramen has rarely been described.

Materials: A 53-year-old female patient's computed tomography (CT) scan was further investigated for its unusual morphology.

Results: On the left-sided middle cranial fossa, an accessory sphenoidal foramen (ASF) was observed, located 3.3 mm posterior to the foramen rotundum (FR) and 5.5 mm anterior to the foramen ovale (FO). Extracranially, the ASF opened into the infratemporal fossa and coexisted with another sphenoidal emissary foramen (SEF), anteromedially to the FO. On the right side, two SEF were located anteromedially to the FO.

Conclusions: Similar to the current case, ASF of the middle cranial fossa were reported in a previous study with a prevalence of 0.20%. The unconstraint well described accessory foramina are the emissary foramina that transmit emissary veins, and are of interest for anatomists, radiologists and neurosurgeons.