Medullary Arteries Research Articles

Vascular patterns in the normal and pathological human adrenal cortex.

The vasculature of the adrenal gland has been studied by microinjection techniques in a variety of species. While there is general agreement about the overall patterns, some uncertainty still exists over the structure of medullary arteries and the connections between the sinusoids of the cortex and medulla. We have taken a new approach to these problems by applying immunohistochemical techniques to the human adrenal gland, identifying overall vascular patterns by endothelial expression of CD34 and muscular channels by smooth muscle actin. We have also examined adrenal nodules, adenomas and carcinomas to see whether these can be differentiated on the basis of their vascular patterns. The general pattern in the normal gland was similar to that found in injection studies, but there appeared to be more connections between sinusoids of the zona fasciculata than previously reported. There was direct continuity between cortical and medullary sinusoids. Medullary arteries were demonstrated as thin-walled vessels. Immunopositivity for smooth muscle actin was present in sinusoids, apparently in endothelial cells, suggesting that they may express this protein and thus have a contractile function. Macronodules and adenomas could not be reliably distinguished, both showing a rich network of sinusoidal vessels. Carcinomas showed marked disorganization, with large-calibre vessels interspersed with irregular networks of vessels of very small calibre.

Adrenal Microvascularization in the Common Tree Shrew (Tupaia glis) as Revealed by Scanning Electron Microscopy of Vascular Corrosion Casts

The blood supply of the adrenal gland in the common tree shrew (Tupaia glis) was studied by use of transmission electron microscopy and vascular corrosion cast/scanning electron microscopy techniques. It was found that the gland receives its blood supply from branches of the inferior phrenic, aorta and renal arteries. Upon reaching the gland, these arteries divide into cortical and medullary arteries. The cortical arteries give rise to the subcapsular capillary plexuses which partially enclose the clusters of cells in the zona glomerulosa (ZG) and appear as lobular-like microvascular networks before running among the cellular cords in the zona fasciculata (ZF) and zona reticularis (ZR). It was noted that the capillaries in ZG and ZR are with more anastomoses than those in the ZF. Capillaries from the ZR become the sinusoidal capillaries in the adrenal medulla before proceeding to the peripheral radicles of the central vein. The medullary arteries penetrate the adrenal cortex and occasionally give off small branches to supply the inner cortex, especially the ZR. Their main branches break up into small or conventional capillaries in the adrenal medulla. These capillaries drain the blood into the peripheral radicles of the central vein and medullary collecting veins which proceed further into a very large central vein. The present findings illustrate that the adrenal medulla receives two blood supplies that yield somewhat different influences upon the adrenal medulla. The portal blood vessel could not be illustrated in the tree shrew adrenal gland.

Subcortical hypoperfusion associated with asymptomatic white matter lesions on magnetic resonance imaging.

We examined whether hemodynamic and metabolic abnormalities in the cerebral white matter, basal ganglia, and thalamus are associated with asymptomatic white matter lesions (WML) depicted on MR images. A positron emission tomographic study with H2(15)O, C15O, and 15O2 was performed in eight normal control subjects without any WML (mean +/- 1 SD age, 68.5 +/- 10.2 years) and in 15 asymptomatic subjects with WML (71.3 +/- 8.5 years) to measure regional cerebral blood flow (CBF), cerebral blood volume, oxygen extraction fraction (OEF), and oxygen metabolic rate. In the cerebral white matter in the asymptomatic subjects with WML, significantly lower CBF (20.3 +/- 3.9 mL/100 mL per minute; P < .05) and significantly higher OEF (0.43 +/- 0.08; P < .05) were found compared with those for control subjects (23.5 +/- 2.6 mL/100 mL per minute and 0.37 +/- 0.06, respectively). The severity of WML was not related to the magnitude of hypoperfusion. In the basal ganglia, significantly lower CBF (44.9 +/- 6.9 mL/100 mL per minute; P < .01) and significantly higher OEF (0.54 +/- 0.08; P < .01) were found in the WML group than in control subjects (70.1 +/- 12.0 mL/100 mL/min and 0.39 +/- 0.03, respectively). In the thalamus, there was no significant difference in CBF and OEF between the control and WML groups. Hypoperfusion of the cerebral white matter and basal ganglia in asymptomatic WML subjects may be induced by the arteriosclerosis of long penetrating medullary arteries and lenticulostriate arteries but may not be directly related to the production of WML. The role of hypoperfusion in the production of WML and acceleration of its development remains to be elucidated.

O-26-389 - Selection of treatment for spinal arteriovenous malformations

BACKGROUNDPerimedullary arteriovenous fistulas (AVFs) are abnormal vascular connections between medullary arteries and veins without an intervening nidus. It is thought to be difficult to treat Type II AVFs which have multiple feeding branches. We performed intraoperative transvenous embolization to treat Type II AVFs.CASE REPORTA 30-year-old man with Type II perimedullary arteriovenous fistulas (AVFs), present at the level of the L-1 vertebral body, underwent surgical and endovascular treatment. The patient displayed slight motor weakness (45) and slight hypesthesia in the right lower extremity. Angiograms demonstrated that an anterior spinal artery and posterior spinal arteries were feeding arteries for the perimedullary AVFs. The patient underwent surgical occlusion of the fistulas three times. Fistulas present on the dorsal surface of the spinal cord were occluded with hemoclips, while those located on the ventral and ventolateral aspect of the spinal cord were occluded transvenously with isobuthyl-2-cyanoacrylate (IBCA) during surgery. Total occlusion of the perimedullary AVFs was achieved with these procedures, and no change was noted postsurgically in the patient's symptoms.CONCLUSIONSIn summary, Type II perimedullary AVFs are sometimes difficult to treat using either embolization or open surgery. In such cases, both open surgery and intraoperative transvenous embolization should be performed in order to obtain occlusion of multiple fistulas.

The blood supply of the hypoglossal nerve: The microsurgical anatomy of its cisternal segment

While the characteristics of the vasculature of the second (intracanalicular) segment of the hypoglossal nerve are well known, the vascularization of the first (cisternal) segment of this nerve has not been examined so far. Many pathologic processes and malformations can be located in the premedullary cistern, which may affect the vasculature of the cisternal segment. Consequently, we decided to examine the blood supply of the cisternal segment. The anatomic features of the cisternal segment and its vasculature were examined in 15 hypoglossal nerves after injection of india ink and gelatin into the vertebrobasilar arterial system. The cisternal segment was noted to consist of 3-15 long roots, which usually formed two trunks of the hypoglossal nerve. The roots of each nerve received blood from the anterolateral and the lateral medullary arteries, which ranged from 3 to 5 in number and between 100 microns and 500 microns in caliber. These arteries may arise from the perforating branches or the pontomedullary branch of the basilar artery; the vertebral artery or its perforators; the anterior spinal artery or its vascular roots; the posterior spinal artery; and the posterior inferior cerebellar artery. The main hypoglossal arteries, which ranged in diameter from 20 microns to 80 microns, always coursed along the dorsal surface of the roots of the hypoglossal nerve. The cisternal segment of the hypoglossal nerve was always vascularized by several vessels, which mainly originated from the vertebral artery and its branches. This observation was discussed from the neurosurgical point of view.

A source of haemorrhage in adult patients with moyamoya disease: the significance of tributaries from the choroidal artery.

This study concerns 19 patients over 16 years of age with Moyamoya disease. Ten cases of intracranial haemorrhage, as the initial haemorrhagic event in patients aged from 21 to 55 (haemorrhagic group) and 9 cases of ischaemic events in 18- to 53-year-old patients (ischaemic group) were included. All haemorrhages were associated with intraventricular haemorrhages (IVH); and all but one case of thalamic haemorrhage were thought to be primary IVH (2 cases of small paraventricular haemorrhage; 2 of small haemorrhages in the splenium; 5 with no intracerebral haematoma). In the 9 patients of the ischaemic group, there were 2 cases of transient ischaemic attacks and 7 of cerebral infarction. Angiographic evaluations demonstrated that the abnormal basal vessel formation and the collateral supplies from the external carotid arteries were poorly developed in both groups. In contrast, the collateral circulation via the choroidal and posterior pericallosal arteries was well demonstrated. Furthermore, marked enlargement of the choroidal arteries and the medullary arteries derived from them was seen more frequently in the haemorrhagic group. These findings suggested that the haemodynamic load in the vessels supplying the walls of the posterior parts of the ventricles and the periventricular region was increased, especially in the haemorrhagic group. Those vessels were considered to be important sites of IVH in adult patients with Moyamoya disease.

Vulnerability of great medullary artery.

The present study describes anatomic observations on great medullary artery and intercostal arteries pertinent to thoracolumbar spinal surgery. This study reveals the vulnerable course of the great medullary artery and its relationship to the lateral or posterolateral approach to thoracic spine. There are no previous anatomic data on the length of the great medullary artery, its intradural course, its relationship with the anterior spinal artery, and the distance between two adjacent intercostal arteries. The location of the intercostal arteries was defined, and the distance between two adjacent arteries was measured at a point on the lateral surface of the vertebra midway between its anteroposterior diameter. The intradural length of the great medullary artery and the angle it formed with the anterior spinal artery at the point of anastomosis were also measured. The mean intradural length of the great medullary artery was 3.6 cm (range, 1.7-8.1 cm), and it passed over 1-3 disc spaces before joining the anterior spinal artery at a mean angle of 20.1 degrees (range, 12-28 degrees). The average distance between two adjacent intercostal arteries from T6 to L2 was 3.6 cm (range, 2.8-4.0 cm), which provides a safe window through which a herniated thoracic disc may be approached if surgery is indicated. The acute angle between the great medullary artery and anterior spinal artery indicates that these two arteries are in close proximity for considerable length and are liable to be compressed together with the intervening vascular collaterals by a space-occupying lesion, such as disc herniation or a fractured fragment. The longer the intradural course of the great medullary artery, the more vulnerable it is to compression by disc herniation or fracture. The intercostal and lumbar arteries are located at the midportion of the lateral aspect of the vertebral bodies rather than at the level of intervertebral discs. Discectomy or decompression of the anterior thoracic canal may be accomplished through a lateral or posterolateral extracavitary approach between two intercostal or lumbar arteries.

Postnatal development of the blood vasculature in the rat adrenal gland: a scanning electron microscope study of microcorrosion casts.

Postnatal development of the blood vasculature in the rat adrenal gland was examined with scanning electron microscopy (SEM), using a microcorrosion casting method. The cortical vascular bed on postnatal day 1 (P1) was incipient, consisting of an outer capillary layer and an inner sinusoidal vascular layer of the juxtamedullary zone. The vascular bed grew continuously with clearer zonal differentiation as the maturation proceeded. By P7 the outer capillary layer had differentiated into the vasculature of the glomerular and fascicular zone, while the juxtamedullary sinusoidal vascular layer had reduced its thickness to differentiate into the vasculature of the reticular zone. The neonatal adrenal vasculature consisted only of the cortico-medullary system. The medullary arteries and the medullary capillary bed were first observed on P14. The adrenomedulla thus came to receive a twofold blood supply by this time. Before the establishment of the medullary arterial system, the medulla appeared to receive its blood supply partly from the cortical capillaries and partly from the radial sinusoidal vessels passing through the cortical vascular bed. The radial sinusoidal vessels were suggested to differentiate into the cortical capillaries. The medullary arteries may originate from the vessels associated with chromaffin bodies incorporated into the adrenal gland or differentiate from the radial sinusoidal vessels. Histological changes, including cortical cell involution and hemorrhage occurring during the neonatal period, would seem to have crucial relevance to the remodeling of the adrenal vasculature.

Paraplegia, epidural analgesia, and thoracic aneurysmectomy.

Paraplegia, epidural analgesia, and thoracic aneurysmectomy.

Local transfer of hormones between blood vessels within the adrenal gland may explain the functional interaction between the adrenal cortex and medulla

The adrenal cortex has a local stimulatory action on synthesis and secretion of adrenaline by the adrenal medulla. This interaction may be based on nervous transmission and/or on glucocorticoids secreted trom the cortex either exerting paracrine effects or reaching the medulla through the local vascular system. The existence of a dual capillary network, a portal system, now seems unlikely. However, a new concept is postulated: the high demand for glucocorticoids in the medulla may be met by local transfer to blood vessels within the adrenal gland, particularly the medullary arteries.

Treatment of Type II perimedullary arteriovenous fistulas by intraoperative transvenous embolization: Case report

BACKGROUND Perimedullary arteriovenous fistulas (AVFs) are abnormal vascular connections between medullary arteries and veins without an intervening nidus. It is thought to be difficult to treat Type II AVFs which have multiple feeding branches. We performed intraoperative transvenous embolization to treat Type II AVFs. CASE REPORT A 30-year-old man with Type II perimedullary arteriovenous fistulas (AVFs), present at the level of the L-1 vertebral body, underwent surgical and endovascular treatment. The patient displayed slight motor weakness ( 4 5 ) and slight hypesthesia in the right lower extremity. Angiograms demonstrated that an anterior spinal artery and posterior spinal arteries were feeding arteries for the perimedullary AVFs. The patient underwent surgical occlusion of the fistulas three times. Fistulas present on the dorsal surface of the spinal cord were occluded with hemoclips, while those located on the ventral and ventolateral aspect of the spinal cord were occluded transvenously with isobuthyl-2-cyanoacrylate (IBCA) during surgery. Total occlusion of the perimedullary AVFs was achieved with these procedures, and no change was noted postsurgically in the patient's symptoms. CONCLUSIONS In summary, Type II perimedullary AVFs are sometimes difficult to treat using either embolization or open surgery. In such cases, both open surgery and intraoperative transvenous embolization should be performed in order to obtain occlusion of multiple fistulas.

The effect of radicular arteries ligation on the spinal cord blood supply in cats.

In order to study the contribution of the radicular arteries to the blood supply of the spinal cord, we performed experimental occlusion of these arteries in cats. In 43 cats, under thiopental anaesthesia, unilateral, bilateral, single or multiple ligations of dorsal radicular arteries were carried out. The animals were killed at the 1st, 2nd and 7th postoperative day. The spinal cords were removed and preserved in formalin solution for 1 month and then examined, using light microscopy. We conclude that bilateral or multiple ligations are capable of producing ischaemic lesions in the spinal cord, more profound by the seventh postoperative day, while single ligations do not produce such lesions, unless a medullary artery is involved. The ischaemic lesions which were observed were associated with clinical neurological deficits.

脳血管攣縮に対する診断と治療

In the present study, we report on the hemodynamic mechanism of appearance of hemiparesis after aneurysmal subarachnoid hemorrhage (SAH), usefulness of intracisternally located echography to detect narrowing of the first segment (M1 segment) of the middle cerebral artery, clinical introduction of dynamic digital subtraction angiography (dynamic DSA) to measure local transit time in the territory of spastic intracranial vessels, and finally the clinical results of endovascular treatment using percutaneous transluminal angioplasty and/or papaverine hydrochloride. Appearance of hemiparesis due to delayed vasospasm was thought to be caused by decrease in blood flow in the corona radiata fed by lenticulostriate arteries and medullary arteries of the middle cerebral artery. Intracisternally located echography detected a decrease in inner diameter of M1 segment. When the mean transit time lasted over 5.52 sec just after endovascular treatment for delayed vasospasm, cerebral infarction occurred, resulting in motor and/or cortical deficits. Thirteen (56.5%) of 23 patients endovascularlly treated for delayed vasospasm, resulted in good recovery more than three months after onset of SAH.

Morphometry of structural preservation of tunica media in aged and hypertensive human intracerebral arteries.

Medial smooth muscle cell necrosis has been reported as a lesion that may precede angionecrosis, which is a major cause of not only hypertensive brain hemorrhage but also lacunar infarct. We morphometrically studied a loss of smooth muscle cells in the media of cerebral arteries in relation to clinical risk factors. The lateral striate, ie, perforating arteries and the medullary arteries in the subcortical white matter of the temporal lobe (100 to 400 microns in diameter) were histologically investigated in 121 autopsied brains. Medial area was measured quantitatively, and the number of nuclei of smooth muscle cells in the area was calculated in 1210 cross-sectional arteries of histological sections. The influence on the structural (ie, smooth muscle cell) preservation of the tunica media (ratio of number of smooth muscle cell nuclei to medial area [N-MA ratio]) of age, blood pressure, serum lipids, and presence of absence of extracerebral severe atherosclerosis was investigated. The N-MA ratio decreased slightly with age in both arteries. A reverse correlation between N-MA ratio and age was seen in groups both with and without hypertension. The mean N-MA ratio in the hypertensive group was significantly lower than that of the nonhypertensive group (P < .001) in all decades of life. The mean N-MA ratio of the perforating arteries was slightly lower than that of the medullary arteries in both groups. Severe atherosclerosis of the internal carotid arteries, even with hypertension, mitigated a decrease of the N-MA ratio, which was as slight as that in the nonhypertensive group. Serum cholesterol in this group was higher than in both the conventional hypertensive group (P < .005) and the nonhypertensive group (P < .001). Although both hypertension and age were significant risk factors for medial smooth muscle cell necrosis, hypertension was relatively more significant. Medial smooth muscle cells of the perforating arteries in the basal ganglia were more vulnerable than those of the medullary arteries. Cerebral small arteries in subjects with severe atherosclerosis of the carotid and major cerebral arteries (hypertension in eight of nine subjects) may have been protected from extensive loss of medial smooth muscles presumably because of both high serum cholesterol and decreased wall tensile stress associated with reduced blood perfusion due to severe atherosclerotic stenosis.

The Pial Ligaments of the Anterior Spinal Artery and Their Stretch Receptors

The pial sheath of the anterior spinal artery displays a system of ligaments that course along the ventral surfaces of the anterior spinal artery and its medullary feeder arteries on the lower half of the spinal cord. Frequently, discrete ligamentous straps extend from these anterior spinal artery ligaments to the sheath of an anterior spinal nerve root to reinforce the general cauda equina pial connections to this system. Microscopy of ligament sections revealed that numerous Golgi-type neurofascicular receptors were oriented longitudinally among the ligament fascicles and associated with well-myelinated nerves. As this type of mechanoreceptor has been known only in association with stretch reflex mediation in the musculoskeletal system, it appeared likely that these anterior spinal artery ligaments and their homologous type of receptors may be implicated in sensing distraction of the thoracolumbar spinal cord and protectively modifying the actions of the involved spinal musculature.

The Pial Ligaments of the Anterior Spinal Artery and Their Stretch Receptors

The pial sheath of the anterior spinal artery displays a system of ligaments that course along the ventral surfaces of the anterior spinal artery and its medullary feeder arteries on the lower half of the spinal cord. Frequently, discrete ligamentous straps extend from these anterior spinal artery ligaments to the sheath of an anterior spinal nerve root to reinforce the general cauda equina pial connections to this system. Microscopy of ligament sections revealed that numerous Golgi-type neurofascicular receptors were oriented longitudinally among the ligament fascicles and associated with well-myelinated nerves. As this type of mechanoreceptor has been known only in association with stretch reflex mediation in the musculoskeletal system, it appeared likely that these anterior spinal artery ligaments and their homologous type of receptors may be implicated in sensing distraction of the thoracolumbar spinal cord and protectively modifying the actions of the involved spinal musculature.

Morphological changes in spiral artery of the mammalian ovary with age.

Morphological changes which take place in ovarian arteries at different ages in human and monkey, were investigated by light microscopy, transmission electron microscopy and scanning electron microscopy. The ovarian arteries in both species were characterized by a spiral configuration throughout their course. The hilar and medullar arteries were especially convoluted. In the pubertal monkey, the hilar and medullary arteries exhibited some intimal thickenings in which smooth muscle cells of a synthetic phenotype were longitudinally arranged. These arteries in adult monkeys had considerable intimal thickening. In a 30-year-old woman, arteries with intimal thickenings were detected in the hilus and medulla. Around 40 years of age, the intima of the arteries were considerably thickened with a diameter usually equal to half of the wall. In women after menopause, the tunica intima of these arteries was approximately two-thirds or more of the total artery wall thickness. Spiral arteries of the ovary were also thickened with advancing age.

Leukoaraiosis and dementia in hypertensive patients.

Although our previous study demonstrated that dementia of the Binswanger type may be a disconnection dementia caused by leukoaraiosis, some hypertensive patients with marked leukoaraiosis do not develop dementia. The goal of the present study is to elucidate the pathophysiology of nondemented hypertensive patients with leukoaraiosis. We performed clinical and neuroradiological studies, including positron emission tomography, in eight hypertensive patients with leukoaraiosis. Four patients were demented, and two among the other four who were not demented at the first examination developed dementia during the follow-up period. Digital subtraction angiography of the cervical and intracranial arteries demonstrated stenotic lesions in only one patient. Cerebral blood flow and oxygen metabolism in patients with dementia were markedly reduced in the white matter (59-67% of control values). In contrast, cerebral blood flow in the white matter of patients without dementia was reduced less markedly (74% of control), oxygen extraction fraction in the white matter was significantly increased (130% of control), and oxygen metabolism remained at almost-normal levels not only in the white matter but also in the cortical area. Hypertension-caused arteriosclerotic changes of the long penetrating medullary arteries may cause misery perfusion and later ischemic damage in the periventricular white matter. Preserved oxygen metabolism in hypertensive patients with leukoaraiosis may represent the early stage of vascular dementia of the Binswanger type.

Ischemic myelopathy: a review of spinal vasculature and related clinical syndromes.

This article provides a comprehensive review of spinal vascular anatomy (arterial and venous) and clinical syndromes that result from the disruption of blood flow to or from the spinal cord. Blood is supplied to the spinal cord through three longitudinal channels: one anterior and two posterior spinal arteries. These vessels, which originate as branches of the vertebral arteries and run caudally along the spinal cord, are augmented by a variable number of medullary arteries. A vascular ring, or vasa coronae, surrounds the cord and connects these longitudinal channels. Central arteries from the anterior spinal artery and penetrating vessels from the vasa coronae provide blood directly to the cord. Venous flow from the spinal cord is also accomplished through a system of anterior and posterior spinal vessels draining through a variable number of medullary veins and an extensive valveless vertebral venous plexus. The disruption of blood flow to or from the spinal cord can result in infarction, with permanent neurologic loss and physical impairment. The clinical presentation in cases of ischemic myelopathy can be variable. Discrete syndromes based on the occlusion of specific vessels are reported and include venous infarction, anterior and posterior spinal artery syndrome, and central infarction.

Anatomy of the anterior spinal artery in pigs

AbstractThe anatomy of the anterior spinal artery in pigs was studied to determine whether or not the artery was continuous, as it is humans, or discontinuous. Six porcine carcasses were embalmed, and 24 hr later injected with pigmented latex through the thoracic aorta. The spinal column was removed, and the spinal cord was dissected with analysis of the anterior spinal artery. In all cases, the artery was continuous, and perfused by 18 ± 3 medullary arteries. The pig would thus be suitable as a model for the study of human diseases in which the anatomy of the anterior spinal artery is a factor. © 1992 Wiley‐Liss, Inc.