Anterior Sylvian point, morphometric classification, and surgical utility

Background: The anterior Sylvian point (ASP) is defined as the most anterior portion of the Sylvian fissure (SF) and is three-dimensionally located between the pars triangularis of the frontal lobe and the pars opercularis of the temporal lobe. Despite the importance given to the ASP in numerous anatomical studies, little has been devoted to objectively describe and generate a correlation between this measurement and its microsurgical approach. Methods: This study was carried out at the laboratory of microsurgical neuroanatomy, second chair of anatomy of the University of Buenos Aires, and entails the morphometric analysis of 40 cerebral hemispheres, their digital registration and subsequent measurement of the ASP utilizing the international system of units, expressed in millimeters (mm). Our results were classified into three types (A, B, and C), defining type A as hemispheres with an ASP < 5 mm, type B as those between 5.1 mm and 10 mm, and type C as those with distances >10 mm. Results: ASP type B was the most frequent type in our sample, representing 45% of the right and 40% of the left hemispheres. This was followed by type A with 35% and 40%, respectively, and type C was found in a lower percentage. Conclusion: A considerable morphometric variation of the ASP was identified and classified into three types according to its distance (A, B, and C). Validation of this measurement is warranted for its subsequent microsurgical application regarding SF openings, suggesting that ASP type B and C could require less time and technical difficulty than type A.