Anatomical references for the transopercular approach to the insula: a 1.5 Tesla magnetic resonance study
摘要
This study aimed to establish the topographic relation of the limiting sulci of the insula with structures on the brain surface, in addition to determining a new anatomical point to objectively identify the Berger-Sanai quadrants.
Methods1.5 Tesla MRI was used to analyze 100 insulas and their relation to the brain surface. The projection of the anterior (ALS), superior (SLS), and inferior (ILS) limiting sulci of the insula onto the brain surface was determined, together with the relations between these sulci and the anterior Sylvian point (ASP), the inferior frontal sulcus (IFS), and the superior temporal sulcus (STS). The central point of the Berger-Sanai quadrants was identified based on the inferior Rolandic point (IRP). The projection of this central point onto the insula and the brain surface were also identified.
ResultsThe following measurements were calculated: the mean anteroposterior distance between the ASP and ALS, 3.2 mm ± 0.7 mm; the mean craniocaudal distance from the ASP to the SLS, 10.5 mm ± 1.8 mm; the mean craniocaudal distance between the IFS and SLS, 15.5 mm ± 2.5 mm; the mean craniocaudal distance from the end of the IFS to the SLS, 13.5 mm ± 2.9 mm; the mean craniocaudal distance between the STS and ILS, 4.0 mm ± 1.9 mm; the mean craniocaudal distance from the end of the STS to the ILS, 6.1 mm ± 2.4 mm; and the mean laterolateral distance from the STS to the ILS, 22.7 mm ± 3.5 mm. The central point of the Berger Sanai quadrants was determined to be over the Sylvian fissure, at a mean distance of 7.3 mm ± 1.2 mm anterior to the IRP. This point projected over the precentral gyrus in 79% of cases and the posterior short gyrus of the insula in 68%.
ConclusionsThe data obtained in this study demonstrate a close topographic relationship between easily identifiable structures on the brain surface (ASP, IFS and STS) and the limiting sulci of the insula. We propose a simple, novel way to find the central point of the Berger Sanai quadrants based on their relation with the IRP. The findings determined here can assist neurosurgeons in locating the insula, especially in transopercular approaches.