Axial sections through the overlying cortex were made with the hippocampus intact to verify the overlying relationships. Measurements between the outer temporal lobe cortical landmarks (sulci and gyri) and the underlying hippocampus (both its head and tail) were then made with digital calipers (Mitutoyo, Japan). The pia and arachnoid mater had been previously removed to better visualize the cortical surface. The specimens were then turned and pin exit sites were marked externally using smaller pins. Once the hippocampus was isolated from a mesial approach, 6-cm long straight needles were placed into its head, tail, and the midpoint between these structures, and passed laterally in the axial plane until they reached the cortical surface. Brains were next hemisected in the midline and the fornix identified and followed toward the left and right hippocampus. The specimens were derived from 6 male and 4 female cadavers aged 35 to 75 years (mean 65 years) at death. Ten formalin-fixed cadaveric brains (20 hemispheres) were removed from the craniums. Such landmarks can be used to refine or verify the accuracy of intraoperative image-guidance, and especially when such navigation is not used or is unavailable. Here, we have attempted to study more precise superficial anatomical landmarks to guide the surgeon to the deeper lying hippocampus. Aggressive resection of these medial temporal lobe structures has been associated with improved surgical outcomes. Traditionally attributed to the formation and storage of memory, manipulation of the dominant hippocampal formation may result in cognitive and memory dysfunction after surgery.Īnterior temporal lobectomy with amygdalohippocampectomy has proven efficacious for cessation of intractable seizures of medial temporal lobe origin. The hippocampus and surrounding formation are made up of the cornu ammonis (hippocampus proper), subiculum, dentate gyrus, supracallosal gyrus, alveus, fimbria, and fornix. Medial temporal lobe epilepsy is often caused by medial temporal lobe sclerosis or lesional epileptogenic foci within the amygdala and hippocampal formation. Keywords: Anatomy, epilepsy surgery, hippocampectomy, landmarks, neurosurgery, temporal lobeĮven with advancements in the pharmacological treatment of epilepsy, there is still a group of patients whose seizures have a higher tendency to be refractory to medical therapy. Such landmarks may be used in localizing the hippocampus during amygdalohippocampectomy and depth electrode implantation in verifying the accuracy of image-guided methods and as adjuvant methodologies when these latter technologies are not used or are unavailable. Based on this study, there are relatively constant anatomical landmarks between the hippocampus and overlying temporal cortex. The mean distance from the anterior temporal tip to the hippocampal head was identical in the cadavers and MRIs of patients with medial temporal lobe sclerosis.Ĭonclusions:Additional landmarks for localizing the underlying hippocampus may be helpful in temporal lobe surgery. The length of the hippocampus tended to be shorter in females, but this too failed to reach statistical significance. Although the hippocampus tended to be more superiorly located in female specimens and on the left side, this did not reach statistical significance. Results:In general, the length of the hippocampus was along the inferior temporal sulcus and inferior aspect of the middle temporal gyrus. The authors also validated their study using magnetic resonance imaging (MRI) scans of 10 patients suffering from medial temporal lobe sclerosis where the distance from the hippocampal head to the anterior temporal tip was measured. They then measured the distance between the hippocampus and superficial landmarks. Methods:The authors removed 10 human cadaveric brains from the cranium and observed the relationships between the lateral temporal neocortex and the underlying hippocampus. Background:Accessing the hippocampus for amygdalohippocampectomy and minimally invasive procedures, such as depth electrode placement, require an accurate knowledge regarding the location of the hippocampus.
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