Segment Of Anterior Cerebral Artery Research Articles

Proximal Clipping and Distal High-Flow Bypass in the Treatment of Giant/Complex Intracranial Aneurysm: An Opportunity or a Risk from a Fluid-Structural Interaction Analysis.

Conventional clipping and endovascular treatment are difficult to apply for some giant intracranial aneurysms (GIAs), and sometimes extracranial-to-intracranial (EC-IC) bypass becomes the optional choice. However, not all GIA patients can benefit from it. This study aims to recognize the underlying problems. We included eligible patients in our care. Then, we researched from three levels: a retrospective review of clinical data, fluid-structural analysis from two representative patient-specific models, and fluid-structural interaction analysis for idealized models to investigate the hemodynamic and biomechanical mechanisms. In this article, we report nine patients with GIA who underwent EC-IC surgery. Of them, three experienced dangerous postoperative hemorrhage, and one patient died. Among these three patients, two lacked the A1 segment of the anterior cerebral artery (ACA). The numerical simulation showed that after surgery, for the patient with an unruptured aneurysm and existence of ACA, the wall deformation, wall stress, pressure, and area of the oscillatory shear index (OSI) > 0.2 were decreased by 43%, 39%, 33%, and 13%, while the patient without A1 segment having postoperative hemorrhage showed 36%, 45%, 13%, and 55% increased, respectively. Thus, we postulated a dangerous "stump phenomenon" in such conditions and further demonstrated it from idealized models with different sizes of ACA. Finally, we found a larger anastomosis angle and smaller diameter of the graft can alleviate this effect. Neurosurgeon should cautiously evaluate the opportunity and risk for such patients who have aplasia of the A1 segment of ACA when making clinical decisions.

Left anterior cerebral artery arising from a right internal carotid artery: a rare case of carotid-anterior cerebral artery anastomosis

Carotid-anterior cerebral artery anastomosis (carotid-ACA anastomosis) is described as infrequent vascular connections between the pre-ophthalmic segment of the internal carotid artery (ICA) and the A1 segment of the anterior cerebral artery (ACA). The embryological origin of these variant is still unclear and they are often associated to other vascular anomalies of the circle of Willis, as well as to the presence of aneurysms. Carotid-ACA anastomosis is often right-sided although left and bilateral cases have also been described. We report a rare case by MR angiography of a carotid-ACA anastomosis in which the abnormal vessel arises from the right ICA and takes an infraoptic course to join the A2 segment of the contralateral ACA, making this vascular anomaly function as a ‘left ACA with an origin at the right ICA’. The A1 segment of the left ACA is absent and both A2 segments of the ACAs present fenestration. To our knowledge, no similar cases have been reported in English literature so far.

Bihemispheric Right Anterior Cerebral Artery, Fenestrated Origin of the Left Pericallosal Artery, Fenestrated Basilar Artery, Double Right Posterior Cerebral Artery.

Anatomical variations of the cerebral vasculature are frequently encountered. The archived magnetic resonance angiogram of a 62-year-old male patient was studied anatomically on planar slices and 3-dimensional volume renderings. Numerous anatomical variants were found in that single case. In the vertebrobasilar system were found: the proximal basilar artery fenestration, with a unilateral origin from that fenestration of an anterior inferior cerebellar artery, and the unilateral origin of the superior cerebellar artery from the P1 segment of the main posterior cerebral artery (PCA). There were also unilateral variants of the right internal carotid artery (ICA): a subvariant of an accessory PCA leaving the ICA as a hyperplastic anterior choroidal artery and united to the main PCA by a short communicating branch, distinctive of the posterior communicating artery in that side (unilateral double PCA); a right bihemispheric anterior cerebral artery (ACA) but with complete agenesis of the contralateral A1 ACA segment; from the right ACA continued an anatomically normal ipsilateral A2 segment and a short transverse contralateral A2 that, in turn, sent off long pericallosal and callosomarginal arteries; and fenestrated origin of the left pericallosal artery. Therefore, an arterial variant in one of the main cerebral circulations could not exclude anatomical variants in the other cerebral circulatory beds.

Delayed Rupture of an Anterior Communicating Artery Pseudoaneurysm Caused by Distal Occlusion Thrombectomy Using a Stent Retriever: A Case Report and Mechanism of Injury

We report a case of delayed rupture of an anterior communicating artery (Acom) pseudoaneurysm following mechanical thrombectomy (MT) of a distal artery occlusion using a stent retriever. An elderly patient with right hemiparesis showed left proximal internal cerebral artery and middle cerebral artery occlusions. During MT, a fragmented thrombus moved to the anterior cerebral artery (ACA). A stent retriever was deployed to the occluded ACA, and the Acom and proximal ACA segment were significantly straightened. Additionally, we attempted a blind exchange mini-pinning (BEMP) technique, but a subarachnoid hemorrhage (SAH) occurred. Bleeding was almost entirely absorbed 9 days after the procedure, but the SAH recurred at 20 days, and computed tomography angiography revealed a new pseudoaneurysm formation in the Acom. We suggest that the proposed mechanism of pseudoaneurysm formation was likely due to the dislocation and avulsion of the Acom perforators when the ipsilateral ACA was pushed and pulled during MT.

The effect of hydrogen sulfide on the contractility of cerebral arterioles. A pilot study.

Endogenous gaseous substances, such as NO and CO have been found to be effective vasodilators earlier. H2S has been identified as an additional one, however, for that substance both vasodilatory and vasoconstrictor responses have been described in different vascular territories. Our aim was to examine the effect of hydrogen sulfide on the tone of cerebral arterioles and some aspects of its mechanism. The work was performed on excised rat anterior cerebral artery segments in vitro (diameter range 150-250 µm), using a pressure myograph system. We used NaHS as exogenous H2S donor, propargylglycine (PAG) to abolish the endogenous synthesis of hydrogen sulfide and 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) to examine the potential role of Cl-/HCO3 - exchanger in the effects of H2S. The time course of the events after application of exogenous H2S was also evaluated. Our findings revealed that in these pathologically important vessels (1) endogenously produced H2S is not a vasodilator, but a moderate vasoconstrictor; (2) H2S has a biphasic effect: low concentrations are moderate vasoconstrictors, while at higher concentrations the initial contraction is followed by dilatation; (3) that vasodilation is prevented by DIDS (4,4'-Diisothiocyanatostilbene-2,2'-disulfonic acid disodium, an inhibitor of the Cl-/HCO3 - exchanger). These studies confirm that H2S should be taken into consideration as a modulator of cerebral arteriolar tone in mammals.

Greater hemodynamic stresses initiated the anterior communicating artery aneurysm on the vascular bifurcation apex

ObjectiveTo investigate hemodynamic stresses associated with the anterior communicating artery (Acom) aneurysm formation using computational fluid dynamics (CFD) analysis. MethodsThree-dimensional geometries of the anterior cerebral artery (ACA) bifurcations in 20 patients with Acom aneurysms and 20 control subjects were used for CFD analysis to investigate hemodynamic stresses including the total and dynamic pressure, wall shear stress (WSS), vorticity and strain rate. ResultsAt the direct flow impinging center on the bifurcation apex, the total pressure was the maximal but decreased quickly from the impinging center to both daughter branches. The WSS, dynamic pressure, vorticity and strain rate were the minimal at the direct impinging center but increased rapidly and reached the peaks at both daughter branches. The ACA bifurcation angle was significantly (P < 0.001) greater in patients with than without Acom aneurysms (144.2° ± 4.1° vs. 105.1° ± 3.2°). Most aneurysms (70% and 85%, respectively) were deviated to the smaller daughter branch or to the daughter branch forming a smaller angle with the A1 segment of ACA, where the hemodynamic stresses were significantly (P < 0.05) greater than those on the contralateral daughter branch. After aneurysm formation, the hemodynamic stresses on the aneurysm dome were all significantly decreased compared with at the aneurysm initiation site with aneurysm virtual removal (P < 0.001). ConclusionFormation of the Acom aneurysm is closely associated with and is to decrease the locally abnormally enhanced hemodynamic stresses.

Type 4 persistent primitive olfactory artery associated with contralateral accessory middle cerebral artery arising from the fenestrated segment of the distal anterior cerebral artery

Persistent primitive olfactory artery (PPOA) is a rare variation of the proximal anterior cerebral artery (ACA) that generally follows an extreme anteroinferior course and takes a hairpin turn before continuing to the A2 segment of the ACA (type 1). There are four other types of extremely rare variations. The type 4 variation continues to the accessory middle cerebral artery (MCA) instead of the ACA. Only a few cases have been reported. We herein report a case of type 4 PPOA in which the contralateral side of the accessory MCA arose from the fenestrated segment of the distal ACA. No similar cases were found in the relevant English-language literature. For the identification of these variations on MR angiography, volume-rendering images were superior to maximum-intensity-projection images.

Prenatal imaging findings of unilateral hypoplasia of A1 segment of anterior cerebral artery

Prenatal imaging findings of unilateral hypoplasia of A1 segment of anterior cerebral artery

Assessment of Arterial Configurations of the Suprachiasmatic Region from the Endoscopic Endonasal Perspective: A Cadaveric Anatomical Study

Endoscopic endonasal surgery has proved to offer a practical route to treat suprasellar lesions, including tumors and vascular pathologies. Understanding the different configurations of the anterior cerebral communicating artery (ACoA) complex (ACoA-C) is crucial to properly navigate the suprachiasmatic space and decrease any vascular injury while approaching this region through an endonasal approach. An endoscopic endonasal transplanum-transtubercular approach was performed on 36 cadaveric heads (72 sides). The variations of the ACoA-C and feasibility of reaching its different components were analyzed. The surgical area exposure of the lamina terminalis was also quantified before and after mobilization of the ACoA-C. The typical ACoA-C configuration was found in 41.6% of specimens. The following 2 main variations were identified: accessory anterior cerebral artery segment 2 (5, 13.9%) and common trunk of anterior cerebral artery with absence of ACoA (5, 13.9%). Of 101 recurrent arteries of Heubner, 96 (95.0%) were identified within 4 mm proximal or distal to the ACoA. The mean lamina terminalis exposure area was 33.1 ± 16.7 mm2, which increased to 59.9 ± 11.9 mm2 after elevating the ACoA. A considerable amount of variation of the ACoA-C can be found through an endoscopic endonasal transplanum-transtubercular approach. These configurations determine the feasibility of lamina terminalis exposure and the complexity of reaching the ACoA. Assessment of ACoA morphology and its adjacent structures is crucial while approaching the suprachiasmatic through a transnasal corridor.

An MRI study of typical anatomical variants of the anterior communicating artery complex.

This magnetic resonance imaging study examined the most frequent anatomical variants of the anterior communicating artery (ACoA) complex of the cerebral arterial circle, and aimed to determine whether they were associated with ACoA complex aneurysm. The study enrolled 669 patients. Using three-dimensional time-of-flight magnetic resonance angiography, 617 patients were classified into the following groups based on the anatomical variation in the ACoA complex: no ACoA complex anomaly; ACoA complex aneurysm; and vascular anomaly distant from the cerebral arterial circle. Of the 617 classified subjects, the classical anatomical description applied to 48.73% in the no ACoA complex anomaly group and 37.5% in the ACoA complex aneurysm group. One variant (left anterior cerebral artery segment A1 hypoplasia) was significantly more frequent in the ACoA complex aneurysm group. There was no sex difference in the prevalence of any variant. Anatomical variants of the ACoA complex of the cerebral arterial circle were found in almost half of the subjects. One variant seemed to be associated with a higher likelihood of an aneurysm, but causality could not be inferred.

Safety and Outcomes of Thrombectomy in Ischemic Stroke With vs Without IV Thrombolysis.

To test the hypothesis that IV thrombolysis (IVT) treatment before endovascular thrombectomy (EVT) is associated with better outcomes in patients with anterior circulation large artery occlusion (LAO) stroke, we examined a large real-world database, the Safe Implementation of Treatment in Stroke-International Stroke Thrombectomy Register (SITS-ISTR). We identified centers recording ≥10 consecutive patients in the SITS-ISTR, with at least 70% available modified Rankin Scale (mRS) scores at 3 months during 2014 to 2019. We defined LAO as intracranial internal carotid artery, first and second segment of middle cerebral artery, and first segment of anterior cerebral artery. Main outcomes were functional independence (mRS score 0-2) and death at 3 months and symptomatic intracranial hemorrhage (SICH) per modified SITS-Monitoring Study. We performed propensity score-matched (PSM) and multivariable logistic regression analyses. Of 6,350 patients from 42 centers, 3,944 (62.1%) received IVT. IVT + EVT-treated patients had less frequent atrial fibrillation, ongoing anticoagulation, previous stroke, heart failure, and prestroke disability. PSM analysis showed that IVT + EVT-treated patients had a higher rate of functional independence than patients treated with EVT alone (46.4% vs 40.3%, p < 0.001) and a lower rate of death at 3 months (20.3% vs 23.3%, p = 0.035). SICH rates (3.5% vs 3.0%, p = 0.42) were similar in both groups. Multivariate adjustment yielded results consistent with PSM. Pretreatment with IVT was associated with favorable outcomes in EVT-treated LAO stroke in the SITS-ISTR. These findings, while indicative of international routine clinical practice, are limited by observational design, unmeasured confounding, and possible residual confounding by indication. This study provides Class II evidence that IVT before EVT increases the probability of functional independence at 3 months compared to EVT alone.

Safety and outcomes of routine endovascular thrombectomy in large artery occlusion recorded in the SITS Register: An observational study.

We aimed to evaluate the safety and outcomes of thrombectomy in anterior circulation acute ischaemic stroke recorded in the SITS-International Stroke Thrombectomy Register (SITS-ISTR) and compare them with pooled randomized controlled trials (RCTs) and two national registry studies. We identified centres recording ≥10 consecutive patients in the SITS-ISTR with at least 70% of available modified Rankin Scale (mRS) at 3months during 2014-2019. We defined large artery occlusion as intracranial internal carotid artery, first and second segment of middle cerebral artery and first segment of anterior cerebral artery. Outcome measures were functional independence (mRS score 0-2) and death at 3months and symptomatic intracranial haemorrhage (SICH) per modified SITS-MOST. Results are presented in the following order: SITS-ISTR, RCTs, MR CLEAN Registry and German Stroke Registry (GSR). Median age was 73, 68, 71 and 75years; baseline NIHSS score was 16, 17, 16 and 15; prior intravenous thrombolysis was 62%, 83%, 78% and 56%; onset to reperfusion time was 289, 285, 267 and 249min; successful recanalization (mTICI score 2b or 3) was 86%, 71%, 59% and 83%; functional independence at 3months was 45.5% (95% CI: 44-47), 46.0% (42-50), 38% (35-41) and 37% (35-41), respectively; death was 19.2% (19-21), 15.3% (12.7-18.4), 29.2% (27-32) and 28.6% (27-31); and SICH was 3.6% (3-4), 4.4% (3.0-6.4), 5.8% (4.7-7.1) and not available. Thrombectomy in routine clinical use registered in the SITS-ISTR showed safety and outcomes comparable to RCTs, and better functional outcomes and lower mortality than previous national registry studies.

Reference values for pulsatility index of fetal anterior and posterior cerebral arteries in prolonged pregnancy

To establish consistent normal reference values for fetal anterior cerebral artery (ACA) and posterior cerebral artery (PCA) pulsatility index (PI) in prolonged pregnancy. This prospective cross-sectional observational study included singleton normal prolonged pregnancies into two study groups according to the gestational age: from 40 + 0 to 40 + 6 and from 41 + 0 to 41 + 6 weeks. The PI was assessed in both anatomical segments of ACA (ACA-S1 and ACA-S2) and of PCA (PCA-S1 and PCA-S2) with color Doppler imaging and pulsed Doppler examination, and reference centiles charts were generated. PI values from the two investigated segments of each vessel were also compared. Data were obtained in 771 patients: n = 448 in the 40 + 0 and 40 + 6 weeks group, and n = 323 in the 41 + 0 and 41 + 6 weeks group. A moderate decrease in PI was observed as pregnancy progressed. No differences in PI values were found between the two anatomical segments of ACA and PCA. This study provides Doppler reference values for the fetal ACA and PCA PI. It also shows that Doppler examination could be performed indifferently in one of the two anatomical segments of these arteries.

Quantifying asymmetry of anterior cerebral arteries as a predictor of anterior communicating artery complex aneurysm

ObjectivesThe aim of this study was to establish an anatomical index for early prediction of the risk of development of aneurysms in anterior communicating arterial complex (AcomAC). The asymmetric diameter...

Endovascular deep brain stimulation: Investigating the relationship between vascular structures and deep brain stimulation targets

BackgroundEndovascular delivery of current using ‘stentrodes’ – electrode bearing stents – constitutes a potential alternative to conventional deep brain stimulation (DBS). The precise neuroanatomical relationships between DBS targets and the vascular system, however, are poorly characterized to date. ObjectiveTo establish the relationships between cerebrovascular system and DBS targets and investigate the feasibility of endovascular stimulation as an alternative to DBS. MethodsNeuroanatomical targets as employed during deep brain stimulation (anterior limb of the internal capsule, dentatorubrothalamic tract, fornix, globus pallidus pars interna, medial forebrain bundle, nucleus accumbens, pedunculopontine nucleus, subcallosal cingulate cortex, subthalamic nucleus, and ventral intermediate nucleus) were superimposed onto probabilistic vascular atlases obtained from 42 healthy individuals. Euclidian distances between targets and associated vessels were measured. To determine the electrical currents necessary to encapsulate the predefined neurosurgical targets and identify potentially side-effect inducing substrates, a preliminary volume of tissue activated (VTA) analysis was performed. ResultsSix out of ten DBS targets were deemed suitable for endovascular stimulation: medial forebrain bundle (vascular site: P1 segment of posterior cerebral artery), nucleus accumbens (vascular site: A1 segment of anterior cerebral artery), dentatorubrothalamic tract (vascular site: s2 segment of superior cerebellar artery), fornix (vascular site: internal cerebral vein), pedunculopontine nucleus (vascular site: lateral mesencephalic vein), and subcallosal cingulate cortex (vascular site: A2 segment of anterior cerebral artery). While VTAs effectively encapsulated mfb and NA at current thresholds of 3.5 V and 4.5 V respectively, incremental amplitude increases were required to effectively cover fornix, PPN and SCC target (mean voltage: 8.2 ± 4.8 V, range: 3.0–17.0 V). The side-effect profile associated with endovascular stimulation seems to be comparable to conventional lead implantation. Tailoring of targets towards vascular sites, however, may allow to reduce adverse effects, while maintaining the efficacy of neural entrainment within the target tissue. ConclusionsWhile several challenges remain at present, endovascular stimulation of select DBS targets seems feasible offering novel and exciting opportunities in the neuromodulation armamentarium.

Fenestrated A1 in Ruptured Anterior Communicating Artery Aneurysm: A Case Report

There is a lot of variation around the anterior communicating artery (Acom) and various classification systems have been quoted many times in literatures. Here we have reported a rare case of a 52-year-old woman who had ruptured Acomartery aneurysm. The angiography also showed a fenestration of the A1 segment of anterior cerebral artery.

Pericallosal Artery Aneurysm: systematic review

Background: Pericallosal artery aneurysms, from A2 to A5 segments of anterior cerebral artery, are uncommon (literature states 2.3-9.2% of brain aneurysms). They have a high mortality rate and tend to rupture easily during exposure. This study was done with the intention of pointing out the described presentations of pericallosal artery aneurysms. Materials and Methods: A systematic review related to pericallosal artery aneurysm was performed in the PubMed, MedLine (Ebsco), LILACS and Scielo databases, using as keywords: “pericallosal artery”, “distal anterior cerebral artery” and “aneurysm”. Results: Pericallosal artery aneurysms are present mainly in patients over 50 years of age (2.1:1 female to male). In younger patients (less than 20 years old) the seizure is the most frequent symptom, while in adults (20-59 years old) it is the thunderclap headache. They commonly present with Hunt &amp; Hess Grade (HH) II. However, 69% presented subarachnoid hemorrhage (SAH), presenting mainly with Fisher 4, which increases the chance of vasospasms. Conclusion: Thus, although the distal anterior cerebral artery (pericallosal) aneurysms display common symptoms, they usually have severe bleeding. Nonetheless, more studies are needed to analyze the epidemiological, demographic and clinical aspects of the pericallosal artery aneurysms

Infraoptic Course of Anterior Cerebral Artery Coexistence with Double Fenestration of Proximal A2 Segment of Anterior Cerebral Artery with Associated Dysplastic Anterior Communicating Artery Aneurysm Treated with Stent-Assisted Coiling.

Infraoptic Course of Anterior Cerebral Artery Coexistence with Double Fenestration of Proximal A2 Segment of Anterior Cerebral Artery with Associated Dysplastic Anterior Communicating Artery Aneurysm Treated with Stent-Assisted Coiling.

Anterior Communicating Artery Complex Aneurysms Are Caused by the Asymmetric Anterior Cerebral Arteries

Background: Rupture of anterior communicating artery complex (AcomAC) aneurysms is a common cause of haemorrhagic brain strokes. Ability to predict development of aneurysms in advance would allow stroke prevention. Asymmetry of the components of cerebral basal arterial network (CBAN) could alter hemodynamics and may contribute to formation of aneurysms. The asymmetric diameter ratio of first segments of anterior cerebral arteries (A1s), correlates with the occurrence of the AcomAC aneurysms. Materials and Methods: Cerebral Computed Tomography Angiography (CTA) scans of 166 adult patients of both sexes were studied. The internal diameters of the right and left A1 segments of anterior cerebral arteries, perpendicular to the long axis of the vessels were measured. Positions and presence or absence of aneurysms in AcomAC were recorded in each individual case. The ratio of the larger to the smaller A1 diameters was determined as a measure of the asymmetry of A1 segments of anterior cerebral arteries (ACAs). Findings: The risk of development of aneurysms in AcomAC was much greater (risk 80%, odds ratio = 47·3) when one A1 segment's radius was at least 50% larger (i.e. 2·25 times greater cross-sectional area) than the other. The risk of development of aneurysms was just 7·8%, if the A1 asymmetric ratio was less than 1·5 (odds ratio = 0·02). Conclusion: The asymmetry ratio of the A1 segments of anterior cerebral arteries is a good predictor for the development of aneurysms in the AcomAC region. Funding Statement: The authors stated: None. Declaration of Interests: The authors declare that there is no conflict of interests. Ethics Approval Statement: The use of images and accompanying information was approved for research purposes by the University of Adelaide Human Research Ethics Board (approval number: H2014-176). Patients’ personal details, have not been copied, documented, or included in this research.

Unruptured distal anterior cerebral artery mirror aneurysms associated with ruptured middle cerebral artery aneurysm: Case report

Introduction. Distal anterior cerebral artery (DACA) aneurysms, also known as pericallosal aneurysms are rare, while aneurysms in mirror position are extremely rare. These aneurysms have high tendency for rupture (PHASES score is always &gt; 4). In more than a half of the patients with the DACA aneurysm rupture, imaging reveals intracerebral hematoma which is a predictor of poor outcome. Case report. A 49- year-old female patient was treated endovascularly in other institution, due to middle cerebral artery aneurysm (MCA) rupture, when the two small bilateral aneurysms at the distal segments of anterior cerebral artery (ACA) were revealed, left one measuring 4.5 mm and the right one measuring 6 mm in size, with the aneurysmal neck width of 3 mm and 4 mm, respectively. The decision was made by the interventional neuroradiologist only to treat the bleeding MCA aneurysm immediately. The patient was referred to our department six months later, and it was decided to perform microsurgical occlusion of the remaining DACA aneurysms. Unilateral interhemispheric approach was chosen to reach the distal ACAs and aneurysms at pericallosal-callosomarginal junction were clipped and completely excluded from the circulation. Conclusion. Management of DACA aneurysms is a surgical chellenge, even for experienced neurosurgeons. It is controversial whether these should be surgically clipped or coiled endovascularly, especially in cases like this one when a same-stage, endovascular coiling might look like a perfect approach. Surgical treatment should be prompt due to their tendency to early rupture. Careful evaluation for multiplicity is mandatory.