Branches Of Posterior Cerebral Artery Research Articles

Parent Artery Occlusion for Posterior Cerebral Artery Aneurysms

We review four cases of posterior cerebral artery (PCA) aneurysm, of which three showed intolerance of parent artery occlusion. In two, balloon test occlusion (BTO) indicated poor opacification of the PCA branches from the anastomoses, and therefore, permanent occlusion was not attempted.

破裂細菌性脳動脈りゅうの治療

Ruptured intracranial infective aneurysms are well-known but relatively uncommon. During the past 7 years, we treated 7 cases of angiographically verified, ruptured infective aneurysms. They comprised 1.8% of all the ruptured intracranial aneurysms treated at our institution during the same period. The incidence of ruptured mycotic aneurysm among patients with active infective endocarditis was 13.0% (7 out of 54). Five patients presented with intracerebral hemorrhage, and 2 with pure acute subdural hematoma. Five aneurysms (71.4%) were located on the distal branch of the middle cerebral artery, and 2 (28.6%) on the distal branch of posterior cerebral artery. Four of the 7 aneurysms (57.1%) were located in the “watershed” area between middle and posterior cerebral arteries. Two patients who presented with acute subdural hematoma were in a life-threatening condition and required emergency surgery; 1 patient showed rapid clinical deterioration due to repeated rebleeding from the aneurysm. Among the 5 patients who presented with intracerebral hemorrhage, 1 underwent evacuation of hematoma and excision of the aneurysms, 2 underwent conservative treatment with antibiotics, and the other 2 were too critically ill to be treated. The infective organism could be identified in 4 of the treated 5 cases; penicillin G was given in 4 patients and cefcapene in one. All 5 treated patients returned to normal life. Ruptured intracranial infective aneurysm should be excised as soon as possible because rebleeding from the aneurysm can cause rapid clinical deterioration.

Imaging of Vestibular Aqueduct, Endolymphatic Duct and Sac and Adenocarcinoma of Probably Endolymphatic Sac Origin

We review four cases of posterior cerebral artery (PCA) aneurysm, of which three showed intolerance of parent artery occlusion. In two, balloon test occlusion (BTO) indicated poor opaci- fication of the PCA branches from the anastomoses, and therefore, permanent occlusion was not attempted.

Parasplenial AVMに対するparieto-occipital interhemispheric approach

We present the cases of 2 surgically treated patients with parasplenial arteriovenous malformations (AVMs). The AVMs fed through the pericallosal artery and posterior cerebral artery (PCA) and drained toward the vein of Galen. We adopted parieto-occipital interhemispheric approach to these AVMs with the patients in a lateral-semiprone position.Preoperative embolization of the feeding PCA branches was performed in 1 patient, and a contralateral interhemispheric approach to the AVM side was performed in the other patient because of the difficulty in the preservation of the bridging veins of the AVM side. Complete excision was accomplished in these patients without postoperative neurological deficits except transient memory disturbance in one case.The results of this experience indicate that parasplenial AVMs can be effectively treated by surgical resection via a parieto-occipital interhemispheric approach with, if necessary, preoperative embolization of the feeding PCA branches.

Mechanics of large and small cerebral arteries in chronic hypertension.

The goal of this study was to investigate factors that contribute to reductions in internal diameter of large and small cerebral arteries during chronic hypertension. We measured diameter of second- and third-order branches of the posterior cerebral artery in vitro during maximal dilation with EDTA in 6-mo-old stroke-prone spontaneously hypertensive rats (SHRSP, n = 7) and Wistar-Kyoto rats (WKY, n = 7). Cross-sectional area of the vessel wall, measured histologically, was not significantly different at 70 mmHg in SHRSP and WKY in large or small branches of posterior cerebral artery. In large branches of posterior cerebral artery, external and internal diameters were significantly less at 70 mmHg in SHRSP than in WKY, whereas external and internal diameters converged at 0 mmHg in the two groups of rats. In small branches, on the other hand, external and internal diameters were significantly less at all levels of intravascular pressure in SHRSP than in WKY. The stress-strain relation in posterior cerebral artery of SHRSP was shifted to the left in large branches and to the right in small branches, which indicates that distensibility was reduced in large cerebral arteries of SHRSP and increased in small cerebral arteries. These findings suggest that different mechanisms are responsible for impairment of maximal dilator capacity in large and small cerebral arteries of SHRSP: reduced distensibility in large arteries and remodeling with reduced external diameter in small arteries. Furthermore the findings provide additional support for the concept that hypertrophy may not be a primary factor in impaired maximal dilation.

Abnormal Photoreactivity in Ictal Migraine: Reversal by Sumatriptan

The reactivity of posterior cerebral artery (PCA) to light stimulation was studied with transcranial Doppler in 9 migraine patients (5 with aura, 4 without aura) within six hours of the onset of headache (mean 115 +/- 78 minutes). The PCA mean flow velocity was recorded while the patient was in the dark and with the eyes closed and, subsequently, while the light was on and with the eyes open. Both symptomatic and asymptomatic sides were recorded. The same test was repeated thirty minutes after injection of sumatriptan 6 mg subcutaneously and again on the third day after cessation of the attack. Photoreactivity was calculated, for each side and for each situation, as percent relative increase of the corresponding averaged mean flow velocity recorded in darkness. The results showed that, although absolute flow velocities were not statistically different between sides and situations, photoreactivity was significantly increased on the symptomatic side during attacks (+28% vs 15% respectively). After sumatriptan, photoreactivity became symmetrical and (nonsignificantly) inferior to the values recorded in the interictal period. These findings suggest that, during headache, peripheral resistance branches of PCA on the symptomatic side are hypersensitive to vasodilatory stimuli. This could represent the counterpart of the clinical scotomata and photophobia commonly experienced by migraine patients during attacks.

Selective endovascular techniques in the treatment of cerebral mycotic aneurysms

The aim of this study was to evaluate the role of endovascular treatment for intracranial mycotic aneurysms. The clinical and angiographic features of three patients with endocarditic vegetation (two with Streptococcus viridans and one with Staphylococcus) were reviewed retrospectively. Patients were selected for this treatment according to the clinical setting and aneurysm location. In two cases, selective catheterization of a distal middle cerebral and posterior cerebral artery branch with a microcatheter followed by superselective amobarbital testing of the parent vessel was preliminary to the occlusion of that vessel with autologous clot or glue. The third patient was treated by selective occlusion of the aneurysm by intra-aneurysmal placement of platinum minicoils. Two patients presented with intracranial hemorrhage and in one the lesion was found on computerized tomography. All three aneurysms had been excluded from the circulation at the 6-month follow-up review. The only complication from the procedure, despite the septic nature and distal localization, was balloon deflation in one patient, who was successfully retreated with coils. Endovascular embolization is indicated in patients who are at risk of hemorrhage and cannot undergo the standard procedure. The superselective amobarbital test allows selection of patients who will tolerate distal vessel occlusion. This endovascular procedure represents a safe and effective treatment for these lesions.

Single calcium channels in resistance-sized cerebral arteries from rats.

Unitary currents through single calcium channels were measured from cell-attached patches on smooth muscle cells isolated from resistance-sized branches of posterior cerebral arteries from Wistar-Kyoto normotensive rats. Barium (80 and 10 mM) was used as the charge carrier, with and without the dihydropyridine calcium channel agonist BAY R 5417. Unitary currents decreased on membrane depolarization, with a slope conductance of 19.4 pS (80 mM barium). Channel open-state probability (Po) was steeply voltage dependent. Peak Po during test pulses from -70 mV increased e-fold per 4.5-mV depolarization. Mean peak Po at potentials positive to +10 mV was 0.44. Po at steady membrane potentials was also steeply voltage dependent, changing e-fold per 4.5 mV in the absence of inactivation. Steady-state Po at positive potentials was substantially lower than peak Po elicited by test pulses, suggesting that steady-state inactivation can reduce Po by as much as 10-fold. Membrane depolarization decreased the longest mean closed time but had little effect on the mean open time of single calcium channels measured during steady-state recordings. Lowering the external barium concentration from 80 to 10 mM reduced the single channel conductance to 12.4 pS and shifted the relationship between steady-state Po and membrane potential by about -30 mV. BAY R 5417 also shifted this relationship by about -15 mV.

Embolism from vertebral artery origin occlusive disease.

We report 10 patients with severe occlusive disease of the vertebral artery (VA) origin in the neck with intra-arterial embolism to the posterior circulation. The VA lesions in seven patients were complete occlusions, and three patients had severe atherostenosis. All patients had strokes in the vertebrobasilar territory. The most frequent recipient sites of intra-arterial embolism were the intracranial VA-posterior inferior cerebellar artery region (8), and the distal basilar artery (BA) and its superior cerebellar and posterior cerebral artery branches (7). Two patients had pontine infarction due to BA embolism. The most common clinical signs were due to cerebellar infarction. Atherosclerotic disease of the VA origin has features in common with disease of the internal carotid artery origin. Both have similar risk factors and demography, and each can cause strokes by intracranial intra-arterial embolism.

Radical surgery of a galenic aneurysm with regional cerebral blood flow analysis: A case report

Successful surgical treatment of a case of aneurysm of the vein of Galen is presented. An 11-month-old boy was admitted with episodes of convulsive attacks. Neurora-diological examination revealed an aneurysm of the vein of Galen filled by branches of posterior cerebral arteries and left thalamoperforating artery. Regional cerebral blood flow, which was measured by a method of xenon-enhanced computed tomography, showed a low flow area in the frontal and occipital regions. The aneurysm was approached through the bilateral parietooccipital interhemisphere, freed from the feeders, and ligated. During the operation, cortical blood flow was monitored for prevention of normal perfusion pressure breakthrough. After the feeders were successfully clipped, the blood flow increased and became normalized in the related cortex. There was no postoperative neurological deterioration.

Stroke in patients with fusiform vertebrobasilar aneurysms.

We studied seven patients with brainstem infarction and large fusiform vertebrobasilar (VB) aneurysms to clarify the clinical, radiologic, and pathologic features. All presented with pontine infarcts; one also had a cerebellar infarct. VB TIAs preceded brainstem infarction in four patients. Angiography and CT documented VB fusiform aneurysmal dilatation. Four had intraluminal thrombi and one had severe basilar artery stenosis. Two distinct clinical pictures emerged: unilateral pontine infarcts with favorable outcome, presumably related to obstruction of a pontine penetrating artery at its origin from the posterior wall of the aneurysmal basilar artery, and major fatal bilateral pontine infarcts from basilar artery occlusion. Two patients came to autopsy. One had thrombus in the dilated basilar artery and a posterior cerebral artery branch embolus with hemorrhagic occipital infarction; the other had basilar artery thrombus with aneurysmal rupture and subarachnoid hemorrhage. Fusiform VB aneurysms caused brainstem stroke by intraluminal thrombus, local embolism, atherostenosis, and obstruction of paramedian penetrating arteries. Subarachnoid hemorrhage is an uncommon complication.

Spontaneous vasomotion in pressurized cerebral arteries from genetically hypertensive rats.

Resistance-sized branches of posterior cerebral arteries from Wistar-Kyoto (WKY), spontaneously hypertensive (SHR), spontaneously hypertensive stroke-prone (SHRSP), and antihypertensive-treated SHRSP (SHRSP-TRT) rats were studied in vitro. After the rats were killed, arterial segments were excised, mounted on microcannulas, and pressurized. After equilibration, intravascular pressure was increased in a stepwise fashion from 30 to 150-200 mmHg. All vessels developed a myogenic tone, which resulted in diameter reductions of 31-37% at 100 mmHg when compared with fully relaxed diameters [approximately 200 micron in 1 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid]. Differences in the extent of tone were not significant between animal groups (P greater than 0.05). Rhythmic vasomotion was present in 94% SHRSP and 100% SHRSP-TRT, 83% SHR, and only 6% of the WKY arteries. At higher pressures, the amplitude of the diameter oscillations decreased and frequency increased. Vasomotion was unaltered by tetrodotoxin or indomethacin, but could be abolished by cooling to 34 degrees C, ouabain (a depolarizing solution containing 125 mM K+), potassium-free physiological saline solution, or by calcium entry blockade with diltiazem or MnCl2. In normally quiescent WKY arteries, vasomotion, which was qualitatively similar to that observed in the hypertensive strains, could be induced by the addition of 5 mM tetraethylammonium chloride. Thus intrinsic oscillations in membrane calcium and potassium conductance may underlie the rhythmic contractile activity of rat cerebral arteries. This property appears to have a major genetic component, the expression of which is relatively independent of blood pressure history and is not related to the myogenic properties of the preparation.

Influence of transmural pressure of myogenic responses of isolated cerebral arteries of the rat.

We examined the diameter responses of isolated and pressurized posterior cerebral artery branches to various static and dynamic pressure alterations. These vessels, dissected from an anatomically identifiable location in the rat brain, developed tone when placed in a normal calcium physiological salt solution (1.6 mM Ca-PSS). Following a series of transmural pressure steps (delta p) of 25 or 50 mm Hg completed in 1-2 s and made every 5 min, they attained additional tone resulting in a mean luminal diameter of 139 micron at 100 mm Hg which was 35% less than their relaxed size measured in 1 mM EGTA-PSS. Continuous measurements of wall thickness and lumen diameter were obtained using a video electronic system in 1-2 mm long arterial segments, and autoregulatory gain factors calculated. Myogenic responses were obtained from each of 6 vessels taken from 6 WKY rats. Diameters following the step pressure changes were usually stable within 2-4 min. The data defined a myogenic regulatory pressure range from 49-145 mm Hg. Gain values averaged about 17% of that necessary for these arteries to maintain perfect flow autoregulation. Our results for myogenicity are comparable with the pressure range for blood flow autoregulation reported by others for the rat. We conclude that myogenic mechanisms, at least in this size artery, are partly responsible for flow autoregulation, and that they are supplemented by metabolic mechanisms operative in the intact rat brain.