The Thalamogeniculate Perforators of the Posterior Cerebral Artery: The Microsurgical Anatomy

Abstract

Abstract The thalamogeniculate (TG); arteries of 30 forebrain hemispheres were examined. These vessels varied from 2 to 12 in number (mean, 5.7);, and from 70 to 580 μm in caliber (mean, 345.8 μm);. The average caliber of all the TG vessels per posterior cerebral artery ranged from 700 to 3400 μm (mean, 1972 μm);. The TG arteries most often originated as individual vessels; however, in 26.67% of the hemispheres examined they shared a common site of origin, and 33.33% of the hemispheres they arose from common stems. The common stems ranged from 320 to 800 μm in diameter (mean, 583 μm);. The TG branches arose from the crural or ambient (P2); segment of the posterior cerebral artery in 80% of the hemispheres, from the P2 and the quadrigeminal (P3); segment in 20%, from both the distal segment of the posterior cerebral artery and the common temporal artery (13.33%);, or from the distal segment and either the calcarine (3.33%); or parieto-occipital artery (3.33%);. The TG arteries usually penetrated the medial geniculate body (100%);, pulvinar thalami (80%);, brachium of the superior colliculus (53.33%);, or lateral geniculate body (13.33%);. The collateral branches of the TG arteries were noted to reach the medial geniculate body (76.67%);, pulvinar (70%);, brachium of the superior colliculus (40%);, crus cerebri (40%);, and lateral geniculate body (6.67%);. The anastomoses were present in 66.67%, usually between the TG vessels and the medial posterior choroidal artery (33.33%);, or the mesencephalothalamic artery (26.67%);. They ranged in number from 1 to 3 (mean, 1.2);, and in caliber from 90 to 400 μm (mean, 197 μm);. In spite of the anastomoses, the TG arteries must be spared during surgery within the ambient cistern.