Forniks ve İlişkili Yapıların Mikrocerrahi ve Ak Madde Anatomisi

The fornix, which is the main efferent and afferent pathway of the hippocampus, is one of the important parts of the limbic system. Due to the functions it undertakes and its close proximity to other critical structures of the brain, the fornix has been on the agenda of neurosurgery practice as well as neuroscience studies. Mastering the microsurgical and white matter anatomy of the fornix and the neural system it is involved in is of critical importance in the surgical treatment of lesions located in the lateral and third ventricle. We aim our study to guide neurosurgeons in this regard. Human cadaver brain dissections, which formed the basis of our study, were performed in the neurosurgery laboratory affiliated to Yeditepe University School of Medicine. 12 human cadaver brain specimens fixed in 10% formalin for at least 1 month were frozen at -18 °C for not less than 2 weeks. Afterwards, it was dissolved under running tap water and made ready for dissection. Dissections was performed in stages from medial to lateral, superior to inferior, and inferior to superior; using appropriate microsurgical instruments and under the surgical microscope. Each stage of the dissections was photographed with a digital camera. MR tractography studies were completed using the "DSI Studio" software and the publicly available "Human Connectome Project" database. Histological images were obtained by staining 5 µm-thick microsections with "luxol fast blue" on mega slides, after the general section of the area to be studied was taken. Ground information about the fornix, its comparative anatomy, and the historical development of the fornix literature were reviewed. Anatomy of the fornix and related structures was depicted combining the white matter dissection technique, MR tractography and histological studies. It was emphasized that fornicotomy, which has lost its popularity today, may again come to the fore as an option in epilepsy surgery with the contribution of developing neuronavigation technology. Surgical interventions that can be preferred in the surgical treatment of lesions located in the lateral ventricle and third ventricle, with the focus of fornix damage, are discussed in comparison with the data obtained from the dissections. In order to minimize the risk of fornix damage, which increases especially in third ventricle surgery, the technical features of the usable surgical intervention, its alternatives and complications other than fornix damage were detailed. It was determined that in the posterior interhemispheric transcallosal approach, which can be preferred in lesions located posterior to the third ventricle and extending superiorly, callosotomy should be limited to ending 1 cm anterior from the posterior end of the splenium.