Morphometric Study of the Anterior Thalamoperforating Arteries

Objective : To evaluate the morphometry of the anterior thalamoperforating arteries (ATPA). Methods : A microanatomical study was performed in 79 specimens from 42 formalin-fixed adult cadaver brains. The origins of the ATPAs were divided into anterior, middle, and posterior segments according to the crowding pattern. The morphometry of the ATPAs, including the premammillary artery (PMA), were examined under a surgical microscope. Results : The anterior and middle segments of the ATPAs arose at mean intervals of $1.75{\pm}1.62$ mm and $5.86{\pm}2.05$ mm from the internal carotid artery (ICA), and the interval between these segments was a mean of $3.17{\pm}1.64$ mm. The posterior segment arose at a mean interval of $2.43{\pm}1.46$ mm from the posterior cerebral artery (PCA), and the interval between the middle and posterior segments was a mean of $3.45{\pm}1.39$ mm. The mean numbers of perforators were $2.66{\pm}1.19$, $3.03{\pm}1.84$, and $1.67{\pm}0.98$ in the anterior, middle, and posterior segments, respectively. The PMA originated from the middle segment in 66% of cases. A perforator-free zone was located >2 mm from the ICA in 30.4% and >2 mm from the PCA in 67.1% of cases. Conclusion : Most perforators arose from the anterior and middle segments, within the anterior two-thirds of the posterior communicating artery (PCoA). The safest perforator-free zone was located closest to the PCA. These anatomical findings may be helpful to verify safety when treating lesions around the PCoA and in the interpeduncular fossa.