Microsurgical anatomy of the lateral posterior choroidal artery: implications for intraventricular surgery involving the choroid plexus.

Abstract

The lateral posterior choroidal artery (LPChA) should be a major surgical consideration in the microsurgical management of lateral ventricular tumors. Here the authors aim to delineate the microsurgical anatomy of the LPChA by using anatomical microdissections. They describe the trajectory, segments, and variations of the LPChA and discuss the surgical implications when approaching the choroid plexus using different routes. Twelve colored silicone-injected, lightly fixed, postmortem human head specimens were prepared for dissection. The origin, diameter, trunk, course, segment, length, spatial relationships, and anastomosis of the LPChA were investigated. The surgical landmarks of 4 different approaches to the LPChA were also examined thoroughly. The LPChA was present in 23 hemispheres (96%), and in 14 (61%) it originated from the posterior segment of the P2 (i.e., P2P); most commonly (61%) the LPChA had 2 trunks, and in 17 hemispheres (74%) it had a C-shaped trajectory. According to its course, the authors divided the LPChA into 3 segments: 1) cisternal, from PCA to choroidal fissure (length 10.6 ± 2.5 mm); 2) forniceal, starting at the choroidal fissure, 8.2 ± 5.7 mm posterior to the inferior choroidal point, and terminating at the posterior level of the choroidal fissure (length 28.7 ± 6.8 mm); and 3) pulvinar, starting at the posterior choroidal fissure and terminating in the pulvinar (length 5.9 ± 2.2 mm). The LPChA was divided into 3 patterns according to its entrance into the choroidal fissure: A (anterior) 78%; B (posterior) 13%; and C (mixed) 9%. The transsylvian trans-limen insulae approach provided the best exposure for cisternal and proximal forniceal segments; the lateral transtemporal approach facilitated a more direct approach to the forniceal segment, including cases with posterior entrance; the transparietal transcortical and contralateral posterior interhemispheric transfalcine transprecuneus approaches provided direct access to the pulvinar segment of the LPChA and to the posterior forniceal segment, including cases with posterior choroidal entrance. The LPChA typically runs in the medial border of the choroid plexus, which may facilitate its recognition during surgery. The distance between the AChA at the inferior choroidal point and the LPChA is a valuable reference during surgery, but there are cases of posterior choroidal entrance. Most frequently, there are 2 or more LPChA trunks, which makes possible the sacrifice of one trunk feeding the tumor while preserving the other that provides supply to relevant structures. The intraventricular approaches can be selected based on the tumor location and the LPChA anatomy.