Letter to Editor – Reply to “Morphometry of Rolandic Fissure and Bridge of Wagner”

Résumé fourni par la source

It was worthreading the article titled “Morphometry of Rolandic Fissure and Bridge of Wagner” by the authors Shinde and Patel. The study was very well performed, and their findings are very well articulated and compared with previous such studies.[1] The article was a descriptive study of 50 human cerebral hemispheres from 25 formalin-embalmed cadavers which is an impressive number, but the duration and nature of the study (prospective or retrospective) are not specified. If one considers the ethics committee permission that was granted in 2023, the study period was probably less than a year and to dissect/analyze, so many cerebral hemispheres in such a short time must have been a herculean task and it deserves appreciation. The authors report their findings of morphometry of Sylvian fissure and Wagner’s bridge. In the result section, they have mentioned – ”A proper bridge of Wagner joining precentral and postcentral sulcus was not seen but communications formed in adjacent gyrus was found on either side of pre- and postcentral sulcus.” However, in the conclusion section, they have termed these bridges as Wagner’s bridges, which appears incorrect, and this inaccuracy may lead to confusion and misinterpretation by the potential readers. To further clarify on this terminology, a question was framed – ”What should be considered as “Wagner’s bridge” – a gyral bridge connecting the pre- and postcentral gyrus bridging the central sulcus or any gyral bridge that bridges any sulcus? Moreover, the relevant literature was reviewed. This question is very important, as the gyral bridge connecting across the central sulcus is exceptionally rare and only few cases are reported till now.[2] Central sulcus is a very prominent, uninterrupted sulcus on the cerebral convexity that extends from the interhemispheric fissure craniomedially to the subcentral gyrus caudolaterally that separates it from the Sylvian fissure. However, interrupted precentral and postcentral sulci due to gyral bridges across the precentral sulcus and postcentral sulcus, respectively, are usually seen and should not be considered a variation.[2] Wagner was the first to describe in the preserved brain of CH Fuchs, a famous German physician, an unusual gyral bridge in both the cerebral hemispheres, connecting the precentral gyrus and the postcentral gyrus thus dividing the central sulcus on both the sides.[3] Schweizer re-evaluated that brain specimen with an magnetic resonance imaging (MRI) and reinspected the gross brain specimen. It revealed that the actual unusual bridge across the central sulcus was present only on the left side. On the right side, the gyral bridge connected postcentral gyrus to one of the gyrus posterior to the postcentral gyrus as evident on the gross specimen photo in Figure 1 of the article by Shinde and Patel, which is not a very unusual finding and was reported in 40% cases in one series as compared to 22% by the authors.[1,2] Interestingly, the MRI revealed a transverse connection between the precentral and postcentral gyrus present across the central sulcus in its depth in the right hemisphere and it terminated just below the brain surface and was not visible on gross inspection.[2] This connection should be considered as pli de passage fronto-parietal Moyen as termed by Broca in 1888 and initially described by Heschl in 1877.[4,5] The presence of such nonsurfacing gyral bridges was described by White et al. as a very consistent finding.[6] Hence, one can realize that, in CH Fuchs’ brain, Wagner’s bridge was present in the left hemisphere and pli de passage fronto-parietal Moyen was present in the right hemisphere. To conclude, Wagner probably intended to report the rare anatomical variation of interrupted central sulcus by a gyral bridge evident on the brain surface. So as an anatomist, one should use the term “Wagner’s bridge” selectively and restrict it only to a gyral bridge which qualifies the two criteria of – (1) interrupting the central sulcus and (2) appearing on the brain surface, to differentiate it from – (1) other gyral bridges across other sulci which are relatively common and (2) pli de passage of front-parietal Moyen of Broca, which are not evident on brain surface but are a consistent finding in the human brain. Considering all these details, it is evident that the authors have reported gyral bridges which are not actually Wagner’s bridges. At the end, it is imperative to highlight an error on the part of authors, where they mention – ”Thickness of motor cortex in postcentral gyrus was 1.5 times that of sensory cortex in precentral gyrus. We found that average thickness of precentral gyrus was 1.47 cm and postcentral gyrus was 2.16 cm.” This statement is obviously incorrect as primary motor cortex lies in the precentral gyrus (Brodmann area 4), is thicker and primary sensory cortex lies in postcentral gyrus (Brodmann area 3), is thinner as compared to the motor cortex.[7] Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.