Morphometric measurements and variations of cerebral sulci in autopsy cases

Objective: Cerebral sulci are anatomical structures that limit the gyri and separate them from other gyri making them more apparent. Also, they are known as the main microanatomic delimiting landmarks and surgical corridors in neurosurgery. Functional asymmetry (dominancy) in cerebral structures which emerges during postnatal development is a known feature. It is a matter of curiosity that whether there is a convergence between the morphological asymmetry and the functional asymmetry, and also its significance in surgery. In our study, it was aimed to make morphometric measurements of several sulci on the lateral aspects of the cerebrum in regard to main sulci and related reference key points, to investigate the possible variations and to compare morphometric measurements of the hemispheres.Materials and Methods: Our study was carried out on forensic autopsy cadavers having no cerebral damage. A total of 100 cerebral hemispheres from 50 cadavers were examined. The lengths of several sulci on the superolateral aspect of the hemispheres and the distances between the sulci and nearby sulci and reference key points were measured. Digital compass and folding plastic ruler were used for measurements. Encountered variations were examined and photographed.Results: Morphometric measurements: It was observed that the lengths of the anterior, ascending and posterior branches of lateral sulcus (LS) were 22.98±7.436, 27.62±6.244, and 76.75±10.10 mm, respectively; whereas the length of external occipital fissure was 30.97±5.323 mm. The distances between superior and inferior Rolandic (IR) points of central sulcus (CS), CS and LS, and IR and anterior Sylvian (AS) points were found as 94.51±7.424, 5.170±3.995 and 29.59±5.093 mm, respectively. The distances between the posterior extremity of the superior frontal sulcus and precentral sulcus (preCS), CS and interhemispheric fissure (IHF) were 2.500±5.746, 16.46±8.812, and 24.44±5.686 mm, respectively. In addition, the distances between the posterior extremity of the inferior frontal sulcus and preCS, CS, LS and AS point were measured as 3.880±4.985, 17.13±6.405, 33.35±5.665 and 39.44±6.830 mm, respectively. While the measurements of the distances between the anterior extremity of intraparietal sulcus and postcentral sulcus, CS, and IHF were 4.400±7.339, 18.78±8.587 and 32.03±7.428 mm; the distance between posterior extremity of superior temporal sulcus and LS was observed 30.89±6.644 mm, as well. Evaluation of the variations: Superior frontal sulcus (SFS), inferior frontal sulcus (IFS), superior temporal sulcus (STS), precentral sulcus (preCS) and postcentral sulcus (postCS) were found to be discontinuous in 60%, 46%, 41%, 84% and 70% of the hemispheres, respectively. Evaluation of the asymmetry: Many differences in morphometric measurements were seen between left and right hemispheres. However, only four of them showed statistically significant results as follows: The distances between SFS posterior end and longitudinal fissure (right 26.52±6.085 mm, left 22.36±4.411 mm, p=0.000), STS posterior end and lateral sulcus posterior end (right 27.50±5.898mm, left 34.28±5.562mm, p=0.000), as well as lengths of external occipital fissure (right 27.94±4.206 mm, left 34.00±4.562 mm, p=0.000), and discontinuous course of STS (right 26%, left 56%).Conclusion: It is difficult to recognize cerebral sulci during surgery and variations are frequently encountered. Furthermore, there is usually a morphological partial asymmetry between the right and left hemispheres for any individual. Also, some of our measurements were found to be compatible with the ones in the literature, while others were incompatible. Therefore, we think that it may be important to consider variations and asymmetry as well as racial and country-specific variations in both neurosurgery and anatomy education.Keywords: cerebral hemisphere, sulcus, morphometric measurements, variation, asymmetry.