Anatomy of the floor of the third ventricle in relation to endoscopic ventriculostomy

Abstract

Neuroanatomical structures that form the floor of the third ventricle (FTV) and neighboring tissues are important in the context of third ventriculostomy (TV) procedures. Thorough knowledge of the anatomical and histological organization of the region would be useful in understanding and preventing surgical complications. Taking the third ventricle region as a model, we aimed to simulate TV and make measurements of 23 cadaver brains, as well as perform histological examinations of the third ventricular floor on five cadaver brains. During the endoscopic TV, we examined the degree to which the structures surrounding the FTV were affected by surgical simulation. To make a clinical comparison, the distance between the center of the FTV and the basilar apex was measured on cranial magnetic resonance images (MRIs) of 15 subjects with normal ventricular systems and 15 subjects with moderately enlarged ventricles. Histological examination revealed that the ependymal cells and arachnoid membrane formed the inner and outer surfaces of the third ventricle floor, respectively, whereas the stroma was made up of glial cells exclusively. This region was gliotic and avascular. When cadaver brains with normal and hydrocephalic ventricles were compared, there were significant differences in the distance between the center of the floor and the basilar apex (P < 0.001). On the basis of our study, the optimal site for TV fenestration and balloon inflation is just anterior to the mamillary bodies to avoid injury to neighboring structures.

Endoscopic Third Ventriculostomy in Patients with Shunt Malfunction

“…In a previous study, MRI was performed after EVD insertion 22) , but this may distort the patient's original anatomy. As shown in a study by Aydin et al 1) , in most cases with ventriculomegaly the basilar artery gets closer to the third ventricle floor. This allows direct visualization of the pulsations of the basilar artery and its silhouette.…”

Adjustment of the endoscopic third ventriculostomy entry point based on the anatomical relationship between coronal and sagittal sutures

“…Too anterior an entry point places the column of the fornix at risk for injury, while too posterior an entry point places structures such as the thalamostriate vein, venous angle, anterior caudate vein, superior choroidal vein, or anterior thalamus at risk. [1][2][3]5,6,8,10,[16][17][18]22,24,25 Our measurements allow the placement of the bur hole to be adjusted in relation to the coronal suture.…”

“…4 Traditionally, the coronal suture is used as an empirical landmark for this trajectory, with the bur hole placed in relation to it. 1 The coronal suture, however, does not course perpendicular to the midline. Instead, it projects anteriorly as it proceeds laterally from the sagittal suture.…”

Histological analysis of the third ventricle floor in hydrocephalic and nonhydrocephalic brains: application to neuroendocrine complications following third ventriculostomy procedures

“…Aydin et al 2 found that the area between the infundibulum and mammillary bodies was composed of glial cells only, whereas the inner and outer surfaces of the third ventricle were covered with ependymal cells and arachnoidal cells, respectively. The stroma was composed of glial cells and was avascular.…”