Daniel LeeAmerican University of Caribbean School of Medicine, Sint Maarten
Title: Topography of the sigmoid dural sinus subject to the shape of skull and its relevance in middle ear surgeries
Introduction: The individual variability of the sigmoid sinus is one of the limiting factors in posterior cranial fossa surgery. We hypothesized that the cranial phenotype influences the shape of the posterior cranial fossa and the position of the sigmoid sinus in relation to the internal and external acoustic meatuses.
Materials and Methods: The topography of the sigmoid sinus was studied on 26 magnetic resonance venograms and 35 embalmed cadavers by morphometric analysis, dissection, and photo modeling techniques. By the value of the cranial index, all specimens were subdivided into dolichocephalic, mesocephalic, and brachycephalic groups for comparison of variables.
Results: The data show that the transverse diameter of the posterior cranial fossa correlates positively with the laterolateral diameter of the skull. The distance between the external acoustic meatus and the transverse-sigmoid sinus junction correlates positively with the anteroposterior diameter of the skull and picks in patients with dolichocephalic skulls compared to the other cranial phenotypes. The majority of cases with low and extremely approximated to the external acoustic canal position of the sigmoid sinus were recorded in the brachycephalic group (82%); while the higher localization of the sigmoid sinus was typical for the dolichocephalic patients (63%). The diameter of the sigmoid groove prevailed in the mesocephalic group but revealed its smallest value in the brachycephalic specimens.
Conclusion: The shape of the skull reflects the morphology of the posterior cranial fossa and influences the topographic characteristics of the sigmoid sinus that must be considered in the selection of surgical approach to the inner ear and pontocerebellar angle.
Daniel Lee is a graduate from the University of Texas at Austin, and now he is currently attending American University of the Caribbean (Sint. Maarten) as an MD candidate.