A rare anatomical variation in foramen of Vesalius: A useful guide for maxillofacial surgeons

Background: Foramen of vesalius is an inconstant foramen that gives passage to an emissary vein that connects pterygoid venous plexus with cavernous sinus. It lies in the anteromedial side of the foramen ovale. Foramen ovale allows the passage for the mandibular branch of trigeminal nerve, the main site for the trigeminal rhizotomy. The presence and description of anatomical variations about the foramen of Vesalius is important during the surgical procedure on the trigeminal nerve which may injure the emissary vein in the foramen leading to intracranial bleeding. Objectives: The aim of the present study is to report the presence and to enlighten the anatomical variations of foramen vesalius which may serve as a guideline for surgeons. Methods: The study was conducted on 100 dry adult human skulls collected from the department of anatomy at Panimalar medical college hospital & research institute Chennai. The skulls were viewed both extracranially and intracranially to identify the presence of foramen of vesalius. The presence and variation of the foramen was noted and discussed. Result: A total of about 200 sides of 100 skulls were studied. Among them 20% of the skull showed presence of foramen of Vesalius bilaterally, 25% unilaterally and one particular skull showed doubled opening on the left side with the presence of a bony septum. This is a rare variation which was less documented in the literature. Conclusion: The knowledge of variations in foramen of Vesalius may help the surgeons for safer planning and execution of the trigeminal rhizotomy technique.

Foramen Vesalius - constant or variable foramen

Introduction/Objective. The foramen of Vesalius (FV) is a variable foramen located at the base of the skull, anteromedial to the foramen ovale, and lateral to the foramen rotundum. Through this foramen, passes one of the emissary veins, which establishes communication between the cavernous sinus and the pterygoid plexus. The aim of the study was to determine the incidence of this foramen in adults depending on gender, along with the number of foramina, distributions relative to the side of the skull and diameter of the foramen. Methods. A material used in the study were digital CT scans of adult paranasal cavities from the archives of the Radiology Center, archived in the PACS software system. We analyzed axial CT sections of 1 mm thickness. The research included 500 subjects (250 males and 250 females). Results. The foramen of Vesalius was present in 67.6% of respondents. In 50.9% cases, the foramen was bilateral and in 49.1% it was unilateral. The average oblique diameter of the foramen in men was 1.75 ? 0.59 mm and in women 1.56 ? 0.48 mm. In 22 subjects (6.51%) the foramina were doubled, and 2 (0.60%) were tripled. Conclusion. There was no statistically significant difference in the incidence of the foramen of Vesalius concerning gender. The mean diameter of the foramen was statistically higher in males. The presence of this foramen is important for neurosurgeons because, during the percutaneous trigeminal rhizotomy, the needle can pass through this foramen, injure the surrounding blood vessels, and lead to intracranial hemorrhage.

Occurrence of the Foramen of Vesalius and Its Morphometry Relevant to Clinical Consideration

All 377 dry skulls were examined for the occurrence and morphometry of the foramen of Vesalius (FV) both in the middle cranial fossa and at the extracranial view of the skull base. There were 25.9% and 10.9% of FV found at the extracranial view of the skull base and in the middle cranial fossa, respectively. Total patent FV were 16.1% (11.9% unilaterally and 4.2% bilaterally). Most FV were found in male and on the left side. Comparatively, FV at the extracranial view of the skull base had a larger maximum diameter. The distance between FV and the foramen ovale (FO) was as short as2.05±1.09 mm measured at the extracranial view of the skull base. In conclusion, although the existence of FV is inconstant, its occurrence could not be negligible. The proximity of FV to FO should remind neurosurgeons to be cautious when performing the surgical approach through FO.