Vuk Djulejić

Microsurgical anatomy of the perforating branches of the vertebral artery.

BACKGROUND There is limited data in the literature related to the microanatomic features of the perforating branches of the vertebral artery. METHODS The 44 vertebral arteries and their branches were injected with india ink or a radiopaque substance and examined under the stereoscopic microscope. RESULTS The perforating arteries were noted to range in number from 1 to 11 (mean, 6.5) and in diameter between 100 microm and 520 microm (average, 243 microm). They arose from the vertebral artery (VA) (54.54%), 8 from the right, the left or both VAs. The anterior spinal artery (ASA), which was singular (81.82%), duplicated (13.64%), or plexiform (4.55%), always gave rise to the perforators. The vascular roots of the ASA were the source of the perforators in 95.45% of the brains. The latter vessels arose from the anterolateral arteries in 50% of the cases. The anastomoses involving the perforators, which were present in 40.91% of the brains, varied in diameter between 100 microm and 350 microm (mean, 169 microm). The perforating vessels gave rise to the side branches in 95.45% of the brains that varied in diameter from 100 microm to 300 microm (average, 161 microm). The perforators usually entered the foramen cecum and the anterior median sulcus, and then continued close and parallel to the raphe of the medulla. The perforators can be compressed by a VA aneurysm, which was found in one among the 71 examined patients with cerebral aneurysms. CONCLUSIONS The obtained data give additional information about the vascular anatomy of the pontomedullary region.

Microanatomy of the Intrachoroidal Vasculature of the Lateral Ventricle

OBJECTIVE: Intraventricular surgery requires a detailed knowledge of the microanatomy of the choroid plexus vasculature. METHODS: Twenty choroid plexuses were microdissected, and two additional plexuses were prepared for microscopic examination. RESULTS: The choroid plexus was perfused primarily by the anterior choroidal artery (AChA) and the lateral posterior choroidal artery (LPChA). The AChA, which averaged 650 &mgr;m in diameter, most often (in 75% of cases) divided into the medial and lateral trunks, which averaged 450 &mgr;m in diameter. The medial trunk gave off the bush-like intrachoroidal branches, whereas the lateral trunk divided into the parallel arteries. The inferior LPChA was present in 50% of the hemispheres, both the inferior and superior LPChAs in 40%, and their common trunk in 10%. In 40%, the LPChA, which averaged 670 &mgr;m in diameter, divided into the terminal trunks, with a mean diameter of 490 &mgr;m. The anastomoses involving the trunks of the LPChA and other choroidal arteries averaged 310 &mgr;m in diameter. All primary intrachoroidal branches of the AChA and LPChA were divided into three groups. The parallel branches, which averaged from 220 to 230 &mgr;m in diameter, coursed along the lateral part of the choroid plexus. The tortuous glomus vessels, which averaged 310 &mgr;m in size, originated from the AChA (45%), the LPChA (15%), or both (40%). The bush-like vessels, with a mean diameter between 155 and 190 &mgr;m, ramified into smaller twigs, up to the intrachoroidal capillaries. CONCLUSION: The data obtained on the microanatomy of the intrachoroidal vasculature may have certain neurosurgical implications.

Clinical significance of blood supply to the internal capsule and basal ganglia

Although the general vascular supply of the basal ganglia and internal capsule is well known, precise data are lacking regarding the variations of the vascular territories in the two regions. Twelve hemispheres were studied following an injection of coloured ink into the main cerebral arteries, namely the anterior cerebral (ACA), middle cerebral (MCA), anterior choroidal (AChA) and posterior cerebral artery (PCA). Serial sections of the injected hemispheres were taken in the axial or coronal plane. In 75% of the hemispheres, ACA perforators were seen to supply the inferomedial part of the head of the caudate nucleus and the anterior limb of the internal capsule, as well as the anterior and inferior portions of the putamen and globus pallidus. The MCA vessels perfused the superolateral part of the head and body of the caudate nucleus, the superior part of the entire internal capsule, most of the putamen and part of the globus pallidus. The AChA perforators perfused the medial segment of the globus pallidus, the inferior part of the posterior limb, the retrolenticular and sublenticular portions of the internal capsule, and occasionally its genu. The same segment of the globus pallidus and the inferior part of the genu of the internal capsule were most likely supplied by the perforators of the internal carotid artery. A predominance of ACA territory was noticed in one specimen (8.33%) and a predominance of MCA territory in two specimens (16.67%). The obtained anatomical data may help radiologic determination of perforators involved in ischemic events, as well as a better understanding of the neurological deficits in the same events.

Common features of the cerebral perforating arteries and their clinical significance

Dear Editor, I would like to thank Matthieu Delion and his colleagues for their compliments regarding our article [1]. At the same time, I am sorry for having not cited their valuable paper [2] on the insular branches of the middle cerebral artery. In general, there are some discrepancies in the terminology and definition of the insular and perforating branches. As we mentioned in our article, there are three main types of the branches of the cerebral arteries: the leptomeningeal, perforating and choroidal [3]. The superficial leptomeningeal vessels give rise to the penetrating branches, i.e. the cortical, subcortical and medullary twigs; the latter of which supply most of the white matter of the cerebral hemispheres, i.e. the centrum semiovale and the corona radiata [4]. On the other hand, the deep perforating vessels mainly originate from the basal cerebral arteries and supply the central hemispheric region, including the basal ganglia and the internal capsule. Accordingly, the mentioned long insular arteries, which arise from the M2 and M3 segments of the MCA, have nothing to do with the perforating vessels of the MCA from both the morphological aspect and the region of supply. These long insular vessels simply belong to the penetrating (medullary) twigs, which were not the subject of our article. As regards the short and medium-sized insular vessels, some of them can be classified as the Batypical^ perforators. However, we presented only the typical perforating arteries, i.e. those with certain common features, as was clearly described in our paper. For that reason, we did not mention the atypical perforators, such as those to the claustrum, the cerebellar roof nuclei and the hypothalamus. In any case, I am grateful to Delion and co-workers for their comment on our article, and for presenting the findings of their research.

Morphometric analysis, region of supply and microanatomy of the lenticulostriate arteries and their clinical significance.

The lenticulostriate arteries (LSA) and their microanatomy, region of supply and atherosclerosis were examined in 24 microdissected brains, arterial casts, and histological specimens. The LSA ranged from 2 to 12 in number and from 0.10 mm to 1.28 mm in diameter. They always arose from the initial segment of the middle cerebral artery (MCA), often from the MCA leptomeningeal branches (38.24%), and rarely from the insular segment (2.94%). They always originated as individual branches, often (61.76%) with their own common stems. In two hemispheres we found that the LSA supplied either a larger or a smaller portion of the basal ganglia and internal capsule than usual. The number of twigs to the innominate substance (substantia innominata) (3-11), and their diameters (0.07-0.30 mm), has been described for the first time, to our knowledge. Microatheromas were found in two LSA. Data about the LSA microanatomy and territory could form the basis of safer neurosurgery, more accurate neuroimaging evaluation, and precise neurological diagnosis in patients with focal ischemic lesions in the basal ganglia and internal capsule.

Glucocorticoid levels after exposure to predator odor and chronic psychosocial stress with dexamethasone application in rats.

This study was conducted to explore the effects of specific psychosocial paradigm on predator animal posttraumatic stress model and to test the hypothesis that psychosocially stressed rats would exibit abnormal levels of cortisol and a larger suppression of cortisol levels after the application of dexamethasone. Animals were divided in two groups: experimental and control groups. The experimental group was exposed to two types of stressors: acute immobilization stress, and combined predator stress and daily social stress with application of dexamethasone. Blood sampling was performed at three different times. We found statistically significant results after analyzing the differences between cortisol levels in different times of blood sampling in the group of animals exposed to stress with dexamethasone application. Statistical significance was found when we compared the experimental group with the control group in terms of elevated cortisol levels during blood sampling after stress paradigm exposition. Many significant disruptions in the functioning of the hypothalamic–pituitary–adrenal axis were observed, such as decrease in basal cortisol levels and enhanced dexamethasone‐induced inhibition of cortisol levels. These findings are important because their impact can translate to human individuals with posttraumatic stress disorder, which is the most important role of every animal model in research.

Effects of Chronic Psychosocial Stress on Reduction of Basal Glucocorticoid Levels and Suppression of Glucocorticoid Levels Following Dexamethasone Administration in Animal Model of PTSD

Aim: To further examine the neurobiological mechanisms and their outcomes responsible for the PTSD sequelae induced by laboratory animal model and to explore the effects of chronic psychosocial paradigm. We tested the hypothesis that our animal model of PTSD would display abnormalities in glucocorticoid levels that are manifest in people with PTSD and that psychosocially stressed rats exhibit a significantly greater suppression of corticosterone levels than control rats following the administration of dexamethasone.