Morphological characteristics of the thalamoperforating arteries

Abstract

Objective: The aim of this study was to investigate the morphological characteristics of the thalamoperforating arteries that arise from the P1 segment of the posterior cerebral artery.

Methods: Thalamoperforating arteries located in the interpeduncular fossa were dissected in 26 formalin-fixed human cadaver brains. We investigated the origin site of thalamoperforating arteries from the P1 segment, number and diameter, and variations in their origin.

Results: Thalamoperforating arteries arose from the superior, posterior or posterosuperior surfaces of the P1 segment at the mean 1.93 mm (range, 0.41-4.71 mm) distance from the basilar apex and entered the brain through the posterior perforated substance. The average number was 3.6 (range 1-8) and mean diameter was 0.70 mm (range 0.24-1.18 mm). Thalamoperforating arteries could be classified into five different types according to their origin at the P1 segment : Type I (bilateral multiple), 38.5%; Type II (unilateral single, unilateral multiple), 26.9%; Type III (bilateral single), 19.2%; Type IV (unilateral single), 11.5%; Type V (unilateral multiple), 3.8%. In 15.4% of all specimens, thalamoperforating arteries arose from the only one side of P1 segment and were not noted in the other side. In such cases, the branches arising from the one side of P1 segment supplied the opposite side.

Conclusion: Variations in the origin of the thalamoperforating arteries should be keep in mind to perform the surgical clipping, endovascular treatment or operation involving the interpeduncular fossa. In particular, unilateral single branch seems to be very risky and significant for surgical technique or endovascular treatment.

Keywords: Cadaver; Morphology; Posterior cerebral artery; Thalamoperforating artery.

Fig. 1

Photographs showing the anatomical structures in the interpeduncular fossa. The measured vascular structures are visible on the anteroinferior view of the interpeducular fossa (A and B). On the midsagittal section of the brain stem (C), thalamoperforating arteries arise from the superior (white arrow), posterosuperior (red arrow) and posterior surfaces (black arrow) of the P1 segment and enter the midbrain through the posterior perforated substance (arrowheads). There are visible two perforating arteries (white arrows) arising from the ventral surface of BA on the anteroinferior view of the interpeduncular fossa (D). a, diameter of the P1 segment; b, diameter of the BA; c, distance of the P1 segment; d, distance between the bifurcation of BA and the 1st origin of the thalamoperforating artery (red arrows); e, diameter of the thalamoperforating artery. BA : basilar artery, ICA : internal carotid artery, Lt : left, MMB : mamillary body, OT : optic nerve, Pcom : posterior communicating artery, P1 : P1 segment of posterior cerebral artery, Rt : right, SCA : superior cerebellar artery.

Fig. 2

Photograph showing the bilateral multiple thalamoperforating arteries (black arrows). BA : basilar artery, Lt : left, P1 : P1 segment of posterior cerebral artery, Rt : right.

Fig. 3

Photograph showing the unilateral single and unilateral multiple type of thalamoperforating artery. Single thalamoperforating artery (white arrow) arising from the superior surface of the right P1 segment is visible. Multiple thalamoperforating arteries (arrow heads) arising from the posterior surface of the left P1 segment is also visible. BA : basilar artery, Lt : left, P1 : P1 segment of posterior cerebral artery, Rt : right.

Fig. 4

Photograph showing the bilateral single type of thalamoperforating arteries (black arrows). BA : basilar artery, ICA : internal carotid artery, Lt : left, Pcom : posterior communicating artery, P1 : P1 segment of posterior cerebral artery, Rt : right, SCA : superior cerebellar artery.

Fig. 5

Photograph showing the unilateral single thalamoperforating artery (white arrow). BA : basilar artery, Lt : left, P1 : P1 segment of posterior cerebral artery, Rt : right.

Fig. 6

Photograph showing the unilateral multiple thalamoperforating arteries (black arrows). Prominent posterior communicating artery is visible on right side. Thalamoperating artery arising from the left P1 segment is not visible. BA : basilar artery, Lt : left, Pcom : posterior communicating artery, P1 : P1 segment of posterior cerebral artery, Rt : right.