2025 Proffered Presentations
S115: EXOCRANIAL OSEOUS MAPPING AS KEYLANDMARKS TO ESTIMATE THE PROXIMITY OF THE STYLOMASTOID FORAMEN: A MORPHOMETRIC ANATOMICAL DESCRIPTION IN MEXICAN POPULATION
Erik Burgos-Sosa, MD1; Jose J. Julian-Mendoza, MD1; J. Stephan Sanchez-Torrijos, AF2; Lorena Valencia-Caballero, MD2; Mario A. Taylor-Martínez, MD1; Agustín Dorantes-Argandar, MD, FAANS1; 1Skull Base & Minimally Invasive Neurosurgery, Hospital Angeles Pedregal, Mexico City; 2Department of Anatomy, National Autonomous University of Mexico, Mexico City
Background: Estimating the exact position of the stylomastoid foramen is crucial for several procedures of skull base surgery, and it may imply the recognition of some external key landmarks. This could prevent some complications with knowing the relation and the exact osseous anatomy. Here, we described some nuances and compared some differences with the current literature. In dorsolateral approaches is important to recognize the location of the stylomastoid foramen. Here, we found in our analysis some external topographic projections as key landmarks to estimate the exact point of the stylomastoid foramen.
Methods: Specimens were obtained from the anthropology department of the Faculty of Medicine of the National Autonomous University of Mexico, and the Surgical Neuroanatomy Laboratory of the University La Salle, Mexican Faculty of Medicine. Craniums were used to analyze and measure the juxtaposition of the stylomastoid foramen from the groove point of the digastric groove, emissary mastoid foramen, posteroinferior tympano-mastoid suture, and the jugular process of the occipital bone. Measures from the groove point and the distal emissary mastoid foramen were obtained using a caliper for the longitudinal distance, and a metric cord for curvilinear distance.
Results: 19 dry skulls, corresponding to 37 sides were analyzed to visualize the proximity of the extracranial orifice of the stylomastoid foramen with some osseous key landmarks. The variants and the morphometric differences of the estimated distances were compared with the current descriptions, in addition to some technical nuances from the key landmarks were described.
Conclusions: The extracranial key osseous landmarks as de groove point and the inferior border of the tympanomastoid suture represent a viable reference for estimating the stylomastoid foramen exit point. The variability of emissary mastoid foramen could be discerned in relation to the anatomical pattern of exit. These key landmarks could be used at the moment of the drilling of the mastoid, or during the removal of the posterior belly of the digastric muscle during the rectosigmoid, or far lateral approach.