Microanatomy of the thalamic branches of the medial posterior choroidal artery and their clinical significance

Abstract Bacground There is a small amount of data regarding the microanatomy of the medial posterior choroidal artery (MPChA) and its thalamic branches, which supply the important regions of the diencephalon. This is why we examined the latter branches in detail. Methods Arteries of the 22 halves of the midbrain and diencephalon were injected with a 10% mixture of India ink and gelatin, and then microdissected under the stereoscopic microscope. The additional 4 specimens were injected with methylmetacrylate to obtain the vascular casts. Finally, computerized tomographic (CT) scans of 58 patients with thalamic ischemia were examined. Results The MPChA, which was singular (92.3%) and rarely double (7.8%), arose from the P1 (11.6%), P2 (69.2%) or P3 segment (11.6%) of the posterior cerebral artery (PCA), or from its terminal branches (7.8%). The MPChA, after encircling the midbrain, coursed along the roof of the third ventricle. It gave off 3.69 pulvinar twigs on average, measuring 0.25 mm in diameter, and 4.87 thalamic branches averaging 0.29 mm in caliber. The former twigs nourished the caudomedial part of the pulvinar. The thalamic branches mainly supplied the mediodorsal nucleus of the thalamus. Anastomoses were 2.71 in number and 0.18 mm in diameter. One CT scan showed a small lacunar infarction in the MPChA region. Conclusions We provided detailed microanatomic data regarding the pulvinar and thalamic branches, which supply very important thalamic nuclei. There is a great anatomic, neurosurgical, neurologic, and neuroradiologic significance of these branches. Key points Thalamic branches most often originate from the ambient and quadrigeminal segment of the medial posterior choroidal artery Thalamic twigs average 4.87 in number, and 0.29 mm in diameter These branches most often supply the pulvinar and the mediodorsal thalamic nucleus One CT scan showed a small lacunar infarction in the MPChA thalamic region