This article reports on the presence of an anatomic feature of the extracranial skull base that may result in internal carotid artery injury if secure and complete pterygomaxillary separation is not achieved before maxillary downfracture in the Le Fort I osteotomy. The extracranial skull base of 129 adult skulls and 10 pediatric skulls was examined in the region near the foramen lacerum. This region was inspected for the presence or absence of a bony protrusion that projected posteriorly from the base of the sphenoid, lying inferior to the foramen lacerum. The bony protrusion was present bilaterally in 71% of the adult skulls and 60% of the pediatric skulls. The protrusion was a bony "spike" that pointed posteriorly and was located inferior to the foramen lacerum on the extracranial skull base. Due to its size, shape, and location, the bony protrusion described in this study poses considerable risk to the internal carotid artery if the protrusion is displaced superiorly through the foramen lacerum. In the Le Fort I osteotomy, secure and complete pterygomaxillary separation is crucial to avoid injury to the internal carotid artery during maxillary downfracture.
Keywords: Le Fort I osteotomy; anterior skull base; foramen lacerum; internal carotid artery; maxillary downfracture; pterygomaxillary separation.