O limite anterolateral do lobo occipital: estudo anatômico e em neuroimagem

Abstract

Introduction: The precise localization of brain lesions is easily done on the frontal lobe, anterior part of the temporal and parietal lobes, insula and posterior part of the occipital lobe (OL). At the posterior portions of the temporal and parietal lobes as well as the anterior portion of the OL the precise localization of lesions is difficult due to the imprecise delimitation of these lobes on the superolateral surface of the cerebral cortex. To find more precise anatomical landmarks, the anterolateral limit of the OL (At-OL) was studied in anatomical specimens and with neuroimaging.Methods: Ten formalin fixed human cadaveric heads injected on their vascular tree were used. A bilateral temporo-parieto-occipital craniotomy was performed. The following distances were measured: (1) pre-occipital tentorial plica (PTPO) to the junction between the lambdoid suture and the superior border of the sulcus of the transverse sinus (PTPO-SL); (2) PTPO to sinodural angle (PTPOPP); (3) lambda to the parieto-occipital sulcus (L-SPO) and (4) pre-occipital notch (IPO) to the termination of the Labbés vein on the inferior margin of the temporal lobe. 355 normal CT scans and 204 normal MRI images of the head were studied. The axial images of the exams were used to define the IPO as well as its bony attachment (PO). The relationship between Labbés vein (VL)and the At-OL of was also observed in imaging. Results: A dural fold over the transverse sinus (PTPO) was found on the tentorium of all anatomical specimens. This PTPO had a direct relationship with the IPO in all specimens and was attached to a bony eminence at the lateralcranial wall. The averages of the distances were: (1) PTPO-SL 6.5mm (±6.4mm SD); (2) PTPO-PP 18,1mm (±7.8mm SD); (3) L-SPO 10.8mm (±5mm SD) and (4) 8.8mm (±10.1mm SD). The PO and/or the IPO were identified in 60.3% of the CT scans and 90.5% of the MRIs. The VL was found in 77.7% of MRI in the proximity of the IPO. Conclusions: The osseous (asterion, lambda and PO), dural (PTPO) and vascular (VL) references can be used to define the At-OL in neuroimage and surgical approaches.