Microanatomy and possible clinical significance of anastomoses among hypothalamic arteries.

Abstract

We examined anastomoses among the hypothalamic arteries in 14 human brains using an injection technique, microdissection, and a stereoscopic microscope. Five to 22 anastomoses (mean 10.1) were found in all 14 brains on each side, varying from 20 to 280 (mean 71) /*m in diameter and from 0.1 to 5.3 (mean 1.52) mm long. A single hypothalamic artery may be connected to other vessels by one to 10 anastomoses. The anastomoses were channel-like or plexiform; both types may be ipsilateral or right-left. They connected the hypothalamic arteries "end-to-end," "end-to-side," and "side-to-side." The interconnected arteries ranged from 30 to 1,900 (mean 148) /xm in diameter. Anastomoses were most frequent among the commissural arteries and in the distribution of the superior hypophyseal arteries and the tuberoinfundibular branches of the posterior communicating artery. The largest anastomoses were found among the tuberoinfundibular branches of the posterior communicating and internal carotid arteries, as well as among the premamillary arteries and the mamillary branches. We discuss the neurologic, neuroendocrinologic, and neurosurgical significance of the described anastomoses. {Stroke 1989;20:1341-1352) M ost previous studies dealing with the anatomic examination of the hypothalamic arteries 1 -8 have only mentioned the presence of a "circuminfundibular plexus" without giving any information about the frequency, number, or size of the anastomoses within the plexus. Others 9 -12 drew special attention only to capillary connections and not to arterial anastomoses in the hypothalamopituitary region. Hence, there is an obvious lack of data concerning anastomoses among the hypothalamic arteries. These anastomoses could be of great neurologic, neuroendocrinologic, and neurosurgical significance for several reasons. Neurologists need information about the vascular pattern in the hypothalamic region to predict the risk of ischemic damage in that region following thromboembolic events and other pathologic processes that may compromise local blood flow; neurosurgeons, who perform delicate operations in the perichiasmatic, tuberal, and interpeduncular regions, must have detailed information on the hypothalamic microvasculature; and, finally, ongoing presence of Received October 17, 1988; accepted May 17, 1989. these anastomoses could be a way of locally regulating neurosecretory activity.Subjects and Methods We examined 28 sets of hypothalamic arteries in 14 brains of individuals aged 28-67 years. Each brain was carefully removed from the skull after cutting the internal carotid arteries (ICAs), optic nerves, and pituitary stalk as low as possible. Plastic catheters were placed in the basilar artery and in both ICAs. In most instances, the main stems of the middle cerebral and anterior choroidal arteries were ligated, as were the distal segments of the anterior cerebral arteries (ACAs) and the posterior cerebral arteries (PCAs). Thereafter, the components of the circle of Willis were irrigated with isotonic saline and injected wit...

The Human Brain

“…Intravascular resin injection (Mercox) and scanning electron microscopy (bar: 50 11m). For more information about the vasculature of the tuberal region, see [225,226,251,260]. I-VI cortical cell layers SC subcortical white matter Ai-A5 intracortical arteries, with respect to their extension into the cortex Vi-V5 intracortical veins, with respect to their extension into the cortex 1 arterial group (A6) crossing straight through the cortex and vascularizing the subcortical white matter 2 V5 veins, principal intracortical veins with respect to their size and large cortical territory 3 arterial ramifications stem from the main arterial trunk by an acute angle 4 venous ramifications reach the parent vessel at a right angle 1 typical aspect of an intra cortical artery 2 recurrent branch, note its ramifications towards the superficial cortical layers (arrows) 3 usual constriction of diameter at the point of origin of recurrent artery Cellular layers of the cortex I molecular layer II external granular layer III pyramidal layer IV internal granular layer V ganglionic layer VI multiform layer SC subcortical white matter 1-4 vascular layers of the cortex Note the difference in density between vascular layers.…”

Variations in the origin of the thalamoperforating arteries

“…These arteries supply the posterior part of the thalamus, the hypothalamus, subthalamus, substantia nigra, red nucleus, oculomotor nucleus, trochlear nucleus, reticular formation of the midbrain, pretectum, rhomboid fossa and posterior part of the internal capsule. [10][11][12]14,[17][18][19] The aim of the present study was to investigate variations in the thalamoperforating arteries that arise from the P 1 segment of the posterior cerebral artery.…”

Transient shivering during Wada test provides insight into human thermoregulation

“…The remainder of the hypothalamus receives blood from both the intermediate (arising from PCom) and posterior arterial groups (arising from PCA, PCom, and basilar artery) (Haymaker, 1969). The posterior hypothalamus is supplied by the branches of the posterior group (Haymaker, 1969; Marinkovic et al., 1989).…”