Analysis of the Anatomical Variations in Sylvian Fissure Using MRI

Abstract Background  The most common surgical approach in neurosurgery to diagnose and treat tumors and aneurysms is the transylvian-pterional approach. The classification of Sylvian fissure (SF) was proposed based on pure anatomical observations by Yasargil. The SF is the most identifiable feature of the superolateral brain surface, which divides the parietal and frontal lobes from the temporal lobe which lies below. Aim  The aim was to identify the anatomical variations in SF (bilaterally) in the normal population and to identify its morphological asymmetry. Setting and Design  This was a retrospective, observational descriptive record-based study which was done to identify the anatomical variations and morphological asymmetry in SF (bilaterally) in the normal healthy population using a 1.5-T magnetic resonance imaging (MRI) system. Materials and Methods  The SF was classified into five types. The categorization of the SF was done by MRI, either using T1-weighted images in three planes. Statistical Analysis  Percentage and frequency using SPSS 23.0. Results  In this study, we found that type 4 was most common in the general population of 100 patients. We found type 1 was most common in age groups above 50 up to 60 years of age. Types 2 and 4 SF were found in all age groups. Bilateral presentation of the SF can be considered as symmetric in 85% of the general population and asymmetric in 15% of the population considered in this study. Conclusion  Classification of the SF types on MRI was shown to be reliable and practicable. Sound knowledge of SF anatomy before neurosurgery can help reduce procedure-related morbidity, ischemic lesions, or edema.