Igor Lima Maldonado1,2,3, Christophe Destrieux1,2, Eduardo Carvalhal Ribas4, Bruna Siqueira de Abreu Brito Guimarães5, Patrícia Pontes Cruz6, Hugues Duffau7,8. 1. 1UMR 1253, iBrain, Université de Tours, Inserm, Tours, France. 2. 2CHRU de Tours, France. 3. 3Le Studium Loire Valley Institute for Advanced Studies, Orléans, France. 4. 4Department of Neurology, Discipline of Neurosurgery, University of São Paulo Medical School (FMUSP), São Paulo, Brazil. 5. 5Faculdade de Medicina da Bahia, Universidade Federal da Bahia, Salvador, Brazil. 6. 6Departamento de Ciências da Vida, Universidade do Estado da Bahia, Salvador, Brazil. 7. 7Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, Montpellier, France; and. 8. 8INSERM-1051, Team 4, Saint-Eloi Hospital, Institute for Neurosciences of Montpellier, France.
Abstract
OBJECTIVE: The sagittal stratum is divided into two layers. In classic descriptions, the stratum sagittale internum corresponds to optic radiations (RADs), whereas the stratum sagittale externum corresponds to fibers of the inferior longitudinal fasciculus. Although advanced for the time it was proposed, this schematic organization seems simplistic considering the recent progress on the understanding of cerebral connectivity and needs to be updated. Therefore, the authors sought to investigate the composition of the sagittal stratum and to detail the anatomical relationships among the macroscopic fasciculi. METHODS: The authors performed a layer-by-layer fiber dissection from the superolateral aspect to the ventricular cavity in 20 cadaveric human hemispheres. RESULTS: Diverse bundles of white matter were observed to contribute to the sagittal stratum and their spatial arrangement was highly consistent from one individual to another. This was the case of the middle longitudinal fasciculus, the inferior fronto-occipital fasciculus, the RADs, and other posterior thalamic radiations directed to nonvisual areas of the cerebral cortex. In addition, small contributions to the sagittal stratum came from the anterior commissure anteriorly and the inferior longitudinal fasciculus inferiorly. CONCLUSIONS: A general model of sagittal stratum organization in layers is possible, but the composition of the external layer is much more complex than is mentioned in classic descriptions. A small contribution of the inferior longitudinal fasciculus is the main difference between the present results and the classic descriptions in which this bundle was considered to entirely correspond to the stratum sagittale externum. This subject has important implications both for fundamental research and neurosurgery, as well as for the development of surgical approaches for the cerebral parenchyma and ventricular system.
OBJECTIVE: The sagittal stratum is divided into two layers. In classic descriptions, the stratum sagittale internum corresponds to optic radiations (RADs), whereas the stratum sagittale externum corresponds to fibers of the inferior longitudinal fasciculus. Although advanced for the time it was proposed, this schematic organization seems simplistic considering the recent progress on the understanding of cerebral connectivity and needs to be updated. Therefore, the authors sought to investigate the composition of the sagittal stratum and to detail the anatomical relationships among the macroscopic fasciculi. METHODS: The authors performed a layer-by-layer fiber dissection from the superolateral aspect to the ventricular cavity in 20 cadaveric human hemispheres. RESULTS: Diverse bundles of white matter were observed to contribute to the sagittal stratum and their spatial arrangement was highly consistent from one individual to another. This was the case of the middle longitudinal fasciculus, the inferior fronto-occipital fasciculus, the RADs, and other posterior thalamic radiations directed to nonvisual areas of the cerebral cortex. In addition, small contributions to the sagittal stratum came from the anterior commissure anteriorly and the inferior longitudinal fasciculus inferiorly. CONCLUSIONS: A general model of sagittal stratum organization in layers is possible, but the composition of the external layer is much more complex than is mentioned in classic descriptions. A small contribution of the inferior longitudinal fasciculus is the main difference between the present results and the classic descriptions in which this bundle was considered to entirely correspond to the stratum sagittale externum. This subject has important implications both for fundamental research and neurosurgery, as well as for the development of surgical approaches for the cerebral parenchyma and ventricular system.
Authors: Pablo González-López; Giulia Cossu; Cynthia M Thomas; Jeffery S Marston; Cristina Gómez; Etienne Pralong; Mahmoud Messerer; Roy T Daniel Journal: Front Neurol Date: 2022-02-15 Impact factor: 4.003