Microsurgerical anatomy of transcallosal-transchoroidal approach to the third ventricle

Abstract

Objective To supply microanatomic data for the application of the transcallosal-transchoroidal approach, and discuss its clinical value of this application. Methods Twelve adult cadaveric wet brains were carefully dissected under microscope with a magnification ranging for 4-10 times, and the anatomic features of the paracele, the choroids plexus, the choroidal fissure and the diatela were successively explored. Three adult cadaveric fresh heads were studied,simulating the procedures of the transcallosal-transchoroidal approach. Observation was performed on related anatomic structures, and measurement of relative parameter was taken, too. Results In the body of the lateral ventricle, the choroid plexus is located in the medial part of the floor. The choroidal fissure is a C-shaped natural cleft between the thalamus and the fomix, being white translucent membranes, and it could be identified by following the choroid plexus in the lateral ventricle. After carefully opening the taenia fornicis, the contents of the velum interpositum are exposed. The cavity of the third vertricle is reached through opening the roof of the third vertricle between the 2 internal cerebral veins. The distances between the coronal suture at the medial border of the brain and the callosal sulcus were （39.12±3.94） mm; the distances between the coronal suture at the medial border of the brain and the interventricular foramen were （61.53±4.02） mm; the distances between the posterior border of the interventricular foremen and the coalesced area of the fornix and the callosum were （28.65±2.23） mm; the AC-PC distances were （25.94±2.16） mm; the distances between the interventricular foremen and the corpus albicans were （19.62±1.79） mm. Conclusion As compared with other approaches to the third ventricle, the transcallosal-transchoroidal approach, which follows a natural route, is of advantages in few injury and wide exposure, we suggest, therefore, that the transcallosal-transchoroidal approach be extensively adopted in clinical neurosurgery. Key words: Choroid plexus; Choroid fissure; Third ventricle; Microsurgical anatomy