Posterior Communicating Artery Research Articles

Failure of the Pipeline Embolization Device in Posterior Communicating Artery Aneurysms Associated with a Fetal Posterior Cerebral Artery.

The pipeline embolization device has emerged as an important endovascular option. This is in part due to safety, efficacy, and possibly the ability to shorten the operative time considerably. With this new technology, some limitations are emerging as experience accumulates. We report three cases of posterior communicating (PCOM) artery aneurysms associated with fetal posterior cerebral artery where pipeline embolization was unsuccessful in obliterating the aneurysms. PCOM artery aneurysms associated with a fetal PCA should be managed either by microsurgical clipping or coiling when feasible.

Hemodynamic and morphological characteristics of unruptured posterior communicating artery aneurysms with oculomotor nerve palsy.

OBJECT Unruptured posterior communicating artery (PCoA) aneurysms with oculomotor nerve palsy (ONP) have a very high risk of rupture. This study investigated the hemodynamic and morphological characteristics of intracranial aneurysms with high rupture risk by analyzing PCoA aneurysms with ONP. METHODS Fourteen unruptured PCoA aneurysms with ONP, 33 ruptured PCoA aneurysms, and 21 asymptomatic unruptured PCoA aneurysms were included in this study. The clinical, morphological, and hemodynamic characteristics were compared among the different groups. RESULTS The clinical characteristics did not differ among the 3 groups (p > 0.05), whereas the morphological and hemodynamic analyses showed that size, aspect ratio, size ratio, undulation index, nonsphericity index, ellipticity index, normalized wall shear stress (WSS), and percentage of low WSS area differed significantly (p < 0.05) among the 3 groups. Furthermore, multiple comparisons revealed that these parameters differed significantly between the ONP group and the asymptomatic unruptured group and between the ruptured group and the asymptomatic unruptured group, except for size, which differed significantly only between the ONP group and the asymptomatic unruptured group (p = 0.0005). No morphological or hemodynamic parameters differed between the ONP group and the ruptured group. CONCLUSIONS Unruptured PCoA aneurysms with ONP demonstrated a distinctive morphological-hemodynamic pattern that was significantly different compared with asymptomatic unruptured PCoA aneurysms and was similar to ruptured PCoA aneurysms. The larger size, more irregular shape, and lower WSS might be related to the high rupture risk of PCoA aneurysms.

Neurovascular stents in pediatric population

The purpose of the study is to analyze the results obtained using stents for the treatment of neurovascular diseases in pediatric patients. A retrospective study of 6-year period was undertaken evaluating clinical charts and imaging studies of patients treated with stents because of neurovascular diseases. Nine patients were managed with 10 stents. Seven children were females. The median age was 11years. There were four cases of broad neck cerebral aneurysms, a pseudoaneurysm of the cervical internal carotid artery, a vertebro-jugular fistula, two patients with internal carotid artery (ICA) stenosis affecting the cervical and supraclinoid segment, and a vertebral artery dissection. The only complication was a silent posterior communicating artery (PCoA) thrombosis in a PCoA aneurysm treated with two stents. Dual antiplatelet therapy was given after the procedure to avoid in stent thrombosis. Stents are safe and effective for treatment of neurovascular diseases in children, but studies are needed in order to protocolize the use of antiplatelet drugs in children.

The role of the circle of Willis in internal carotid artery stenosis and anatomical variations: a computational study based on a patient-specific three-dimensional model.

BackgroundThe aim of this study is to provide better insights into the cerebral perfusion patterns and collateral mechanism of the circle of Willis (CoW) under anatomical and pathological variations.MethodsIn the current study, a patient-specific three-dimensional computational model of the CoW was reconstructed based on the computed tomography (CT) images. The Carreau model was applied to simulate the non-Newtonian property of blood. Flow distributions in five common anatomical variations coexisting with different degrees of stenosis in the right internal carotid artery (RICA) were investigated to obtain detailed flow information.ResultsWith the development of stenosis in unilateral internal carotid artery (ICA), the cerebral blood supply decreased when the degree of stenosis increased. The blood supply of the ipsilateral middle cerebral artery (MCA) was most affected by the stenosis of ICA. The anterior communicating artery (ACoA) and ipsilateral posterior communicating artery (PCoA) functioned as the important collateral circulation channels when unilateral stenosis occurred. The blood flow of the anterior circulation and the total cerebral blood flow (CBF) reached to the minimum in the configuration of the contralateral proximal anterior cerebral artery (A1) absence coexisting with unilateral ICA stenosis.ConclusionsCommunicating arteries provided important collateral channels in the complete CoW when stenosis in unilateral ICA occurred. The cross-flow in the ACoA is a sensitive indicator of the morphological change of the ICA. The collateral function of the PCoA on the affected side will not be fully activated until a severe stenosis occurred in unilateral ICA. The absence of unilateral A1 coexisting with the stenosis in the contralateral ICA could be the most dangerous configuration in terms of the total cerebral blood supply. The findings of this study would enhance the understanding of the collateral mechanism of the CoW under different anatomical variations.

Impact of Aneurysm Projection on Intraoperative Complications During Surgical Clipping of Ruptured Posterior Communicating Artery Aneurysms.

Surgical clipping of ruptured posterior communicating artery (PCoA) aneurysms is a well-established procedure to date. However, preoperative factors associated with procedure-related risk require further elucidation. To investigate the impact of the direction of aneurysm projection on the incidence of procedure-related complications during surgical clipping of ruptured PCoA aneurysms. A total of 65 patients with ruptured PCoA aneurysms who underwent surgical clipping were retrospectively analyzed from a single-center, prospective, observational cohort database in this study. The aneurysms were categorized into lateral and posterior projection groups, depending on direction of the dome. Characteristics and operative findings of each projection group were identified. We also evaluated any correlation of aneurysm projection with the incidence of procedure-related complications. Patients with ruptured PCoA aneurysms with posterior projection more likely presented with good-admission-grade subarachnoid hemorrhage (P = .01, χ test) and were less to also have intracerebral hematoma (P = .01). These aneurysms were found to be associated with higher incidence of intraoperative rupture (P = .02), complex clipping with fenestrated clips (P = .02), and dense adherence to PCoA or its perforators (P = .04) by univariate analysis. Aneurysms with posterior projection were also correlated with procedure-related complications, including postoperative cerebral infarction or hematoma formation (odds ratio, 5.87; 95% confidence interval, 1.11-31.1; P = .04) by multivariable analysis. Ruptured PCoA aneurysms with posterior projection carried a higher risk of procedure-related complications of surgical clipping than those with lateral projection.

Anatomic Study of Posterior Communicating Artery in Computed Tomographic Image.

This study aims to provide an anatomic data of posterior communicating artery (PComA) and its anatomic relationship to the adjacent structures, so as to guide surgeons in the surgery of internal carotid artery-posterior communicating artery aneurysm clipping and sellar tumors resection without injuring the PComA. Computer topographic angiography images of 123 individuals were reviewed, and the measurements were done on coronal, sagittal, axial, and other user-defined planes after multiplanar reconstruction. Posterior communicating artery was classified in the reconstructed three-dimensional image, measured in proper planes, and located by the structures such as anterior clinoid process (ACP), posterior clinoid process (PCP), and sagittal midline. Six types of PComA were identified in this study based on its existence and origin. The initial part of PComA can be located by ACP, PCP, and sagittal midline based on some particular angles and distances. Posterior communicating artery varies in different individuals, and the radiologic study of it is an optimal way to analyze the variances. The anatomic relations between PComA and basic skull structures such as the ACP and PCP are especially important for neurosurgeons.

Clipping Versus Coiling in the Management of Posterior Communicating Artery Aneurysms with Third Nerve Palsy: A Systematic Review and Meta-Analysis

To compare surgical clipping with endovascular coiling in terms of recovery from oculomotor nerve palsy (ONP) in the management of posterior communicating artery (PCoA) aneurysms causing third nerve palsy. We conducted a systematic review of the literature and meta-analysis. The meta-analysis included 11 relevant studies involving 384 patients with third nerve palsy caused by PCoA aneurysms at baseline, of whom 257 (67.0%) were treated by clipping and 127 were treated by coiling (33.0%). Pooled odds ratios of the impact of clipping or coiling on complete ONP recovery, lack of ONP recovery, and procedure-related death were calculated. The overall complete ONP recovery rate was 42.5% in the coiling group compared with 83.6% in the clipping group. The increase in complete ONP recovery in the clipping group corresponds to an overall pooled Mantel-Haenszel odds ratio of 4.44 (95% confidence interval = 1.66-11.84). Subgroup analysis revealed a clear benefit of clipping over coiling in patients with ruptured aneurysms, but not in patients with unruptured aneurysms. No procedure-related deaths were reported by any of the 11 studies. Surgical clipping of PCoA aneurysms causing third nerve palsy achieves better ONP recovery than endovascular coiling; this could be particularly true in the case of ruptured aneurysms. In view of the purely observational data, statements about this effect should be made with great caution. A randomized trial would better address the therapeutic dilemma, but pending the results of such a trial, we recommend treating PCoA aneurysms causing ONP with surgery.

Resolution of Oculomotor Nerve Palsy Secondary to Posterior Communicating Artery Aneurysms: Comparison of Clipping and Coiling.

Previous studies have attempted to determine the best treatment for oculomotor nerve palsy (ONP) secondary to posterior communicating artery (PCoA) aneurysms, but have been limited by small sample sizes and limited treatment. To analyze the treatment of ONP secondary to PCoA with both coiling and clipping in ruptured and unruptured aneurysms. Data from 2 large academic centers was retrospectively collected over 22 years, yielding a total of 93 patients with ONP secondary to PCoA aneurysms. These patients were combined with 321 patients from the literature review for large data analyses. Onset symptoms, recovery, and time to resolution were evaluated with respect to treatment and aneurysm rupture status. For all patients presenting with ONP (n = 414) 56.6% of those treated with microsurgical clipping made a full recovery vs 41.5% of those treated with endovascular coil embolization (P = .02). Of patients with a complete ONP (n = 229), full recovery occurred in 47.3% of those treated with clipping but in only 20% of those undergoing coiling (P = .01). For patients presenting with ruptured aneurysms (n = 130), full recovery occurred in 70.9% compared with 49.3% coiled patients (P = .01). Additionally, although patients with full ONP recovery had a median time to treatment of 4 days, those without full ONP recovery had a median time to treatment of 7 days (P = .01). Patients with ONP secondary to PCoA aneurysms treated with clipping showed higher rates of full ONP resolution than patients treated with coil embolization. Larger prospective studies are needed to determine the true potential of recovery associated with each treatment. EUH, Emory University HospitalIQR, interquartile rangeJHU, Johns Hopkins UniversitymRS, modified Rankin ScaleONP, oculomotor nerve palsyPCoA, posterior communicating arterySAH, subarachnoid hemorrhage.

Clinical, morphological, and hemodynamic independent characteristic factors for rupture of posterior communicating artery aneurysms

ObjectiveTo identify clinical, morphological, and hemodynamic independent characteristic factors that discriminate posterior communicating artery (PCoA) aneurysm rupture status.Methods173 patients with single PCoA aneurysms (108 ruptured, 65 unruptured) between January 2012...

Analyses of risk factors for posterior communicating artery aneurysm rupture

Objective To analyze the risk factors for posterior communicating artery (PCoA) aneurysm rupture from the clinical and morphological aspects. Methods Consecutive patients with single PCoA aneurysm admitted to hospital from January 2011 to December 2013 were analyzed retrospectively. The clinical data and imaging characteristics were analyzed with univariate analysis and multivariate logistic regression analysis. Results Univariate analysis indicated that there were significant differences in the rupture rate of PCoA aneurysms in the history of hypertension (χ2=23.013, P=0.000) , aspect ratio (AR) ≥1.5 (χ2=8.492, P=0.004), directions of different aneurysm tops (χ2=15.057, P=0.002), and aneurysm blebs (χ2=18.952, P=0.000) between the two groups. The results of multivariate logistic regression analysis were the history of hypertension (OR, 13.240, P=0.000), presence of aneurysm blebs (OR, 12.933, P=0.001), age less than 60 years (OR, 3.766, P=0.010), AR ≥1.5 (OR=4.997, P=0.001), and posterior-inferior-lateral directions of aneurysm tops (OR, 7.584, P=0.038). Conclusion The history of hypertension, presence of aneurysm blebs, age less than 60 years, AR ≥1.5 and posterior-inferior-lateral directions of aneurysm tops were the risk factors for PCoA aneurysm rupture. Key words: Intracranial aneurysm; Risk factors; Posterior communicating artery

Association Between Vascular Anatomy and Posterior Communicating Artery Aneurysms

Hemodynamic stress, conditioned by the geometry and morphology of the vessel trees, plays an important role in the formation of intracranial aneurysms. The aim of this study was to identify image-based location-specific morphologic parameters that are associated with posterior communicating artery (PCoA) aneurysms. Morphologic parameters obtained from computed tomography angiography of 56 patients with PCoA aneurysms and 23 control patients were evaluated with 3D Slicer, an open-source image analysis software, to generate 3-dimensional models of the aneurysms and surrounding vasculature. Segment lengths, diameters, and vessel-to-vessel angles were examined. To control for genetic and clinical risk factors, the unaffected contralateral side of patients with unilateral PCoA aneurysms was used as a control group for internal carotid artery (ICA)-related parameters. A separate control group with visible PCoAs and aneurysms elsewhere was used as a control group for PCoA-related parameters. Internal carotid artery-related parameters were not statistically different between the PCoA aneurysm and control groups. Univariate and multivariate subgroup analysis for patients with visualized PCoAs demonstrated that a larger PCoA diameter was significantly associated with the presence of a PCoA aneurysm (odds ratio = 12.1, 95% confidence interval = 1.3-17.1, P = 0.04) after adjusting for other morphologic parameters. Larger PCoA diameters are associated with the presence of PCoA aneurysms. These parameters may provide objective metrics to assess aneurysm formation and growth risk stratification in high-risk patients.

Surgical management of recurrent intracranial aneurysms after embolization

Background Endovascular therapy is the first treatment choice for intracranial aneurysms currently, but it has a high recurrence rate. Some patients require surgical clipping because of the difficulty of re-embolization. This study retrospectively analyzed the clinical data of 11 cases who underwent clipping operation because of the recurrence after endovascular therapy. Combining with domestic and foreign related literatures, this paper discusses the principles and techniques of surgical treatment for recurrent aneurysms. Methods There were a total of 11 patients with 12 recurrent aneurysms after embolization, including 3 anterior communicating artery (ACoA) aneurysms, 3 middle cerebral artery (MCA) aneurysms, 2 posterior communicating artery (PCoA) aneurysms, one anterior cerebral artery (ACA) aneurysm, one vertebral artery (VA) aneurysm, one basilar tip aneurysm and one superior cerebellar artery (SCA) aneurysm. There were 7 small aneurysms and 4 large aneurysms. All patients underwent surgical clipping under microscope. After operation, 11 aneurysms were complete clipped, and one was proximally blocked. The coils were reserved in 7 aneurysms, and were removed or partially removed in 5 aneurysms. Results All patients were followed up for an average of 22 months after surgery. There were 9 cases (9/11) with the Glasgow Outcome Scale (GOS) score improved or remaining unchanged compared with preoperation. One of them presented left limb weakness after operation, with the muscle strength Grade 3, while recovered to Grade 4-5 on discharge. The other 2 patients died after surgery. One case had a critical condition before surgery, and the other was secondary to thrombosis and pneumonia. Both of them had a GOS score of 2 when discharged, and died after discharge. Conclusions There is high surgical difficulty in recurrent aneurysms, however, with adequate preoperative evaluation and surgical design, it can still promise safe and effective results. DOI: 10.3969/j.issn.1672-6731.2015.03.010

Symptomatic regrowth of a small intracranial aneurysm that had ruptured and completely thrombosed: a case report

Abstract We report a case of small internal carotid–posterior communication artery (IC–PC) aneurysm that was completely thrombosed after initial bleeding, but subsequently became symptomatic, causing a mass effect. A 54-year-old woman initially presented with grade-five subarachnoid hemorrhage from a small right IC–PC aneurysm. The aneurysm was treated conservatively and completely thrombosed within 35 days. The patient slowly recovered and remained well until 4 years later, when she developed right oculomotor nerve palsy. Imaging revealed relapse of the aneurysm, and repair led to symptom resolution. This case offers a reminder that totally thrombosed aneurysms carry a risk of regrowth if left untreated.

Anatomical Variations in the Posterior Circle of Willis and Vascular Pathologies in Isolated Unilateral Thalamic Infarction.

To characterize relations between configurations of the posterior part of the Circle of Willis (CoW) and the occurrence of unilateral thalamic infarction. From a magnetic resonance imaging report database, we identified and analyzed 111 patients with acute isolated unilateral thalamic infarction on diffusion-weighted imaging (DWI). Vascular pathologies were noted on magnetic resonance angiography (MRA) and the diameter of the posterior communicating artery (PComA) and the P1 and P2 segments of the posterior cerebral artery determined. Most infarctions were observed in the territory of the inferolateral arteries (70.2%), followed by the paramedian (16.3%), tuberothalamic (8.7%), and posterior choroidal arteries (4.8%). Relevant vascular pathologies included stenosis of the basilar artery (4.5%), P1 segment stenosis (4.5%)/occlusion (.9%), and P2 segment stenosis (14.4%)/occlusion (4.5%). Paramedian thalamic infarction was associated with ipsilateral P1 segment hypoplasia/absence (P < .001); tuberothalamic infarction with ipsilateral PComA hypoplasia/absence (P = .08). Furthermore, the diameter of the relevant CoW segment was smaller in patients with ipsilateral thalamic infarction. Assessment of CoW configuration on MRA may be helpful to understand the appearance of unilateral thalamic stroke independent from stroke etiology. A smaller diameter of the relevant CoW segment might be a risk factor for ipsilateral thalamic stroke in the corresponding thalamic vascular territory.

Abstract T P416: Bilateral Common Carotid Artery Stenosis in Normotensive Rats Impairs Short-Term Memory and Dilation in Penetrating Arterioles

Chronic cerebral hypoperfusion (CCH) is a risk factor for cognitive impairment. Reduced blood flow through the common carotid arteries induced by bilateral common carotid artery stenosis (BCAS) is a physiologically relevant model of CCH. We hypothesized that BCAS in Wistar Kyoto (WKY) rats would impair cognitive function, we further proposed that in an effort to compensate for the reduced blood flow BCAS would lead to increased dilation and outward remodeling in the penetrating arterioles (PAs). Data are shown as mean±SEM, SHAM vs BCAS. BCAS reduced pial artery perfusion in 20-week-old male WKY rats (469±8 vs 299±21 perfusion units p&lt;0.05). Short-term memory, evaluated by novel object recognition testing, was impaired (novel exploration quotient: 0.62±0.09 vs 0.46±0.14, p&lt;0.05). PA reactivity and structure were assessed by pressure myography. There was no difference in myogenic tone between the groups [SHAM (n=4) and BCAS (n=7), % average tone: 34.5±9.8]. Contrary to our hypothesis, BCAS impaired endothelial function of PAs from 28-29 weeks old WKY rats, as evidenced by reduced dilation to endothelium dependent dilator carbachol (% change in diameter from baseline at 10-5M: 7.0±4.1 vs -1.8±5.6, Student’s t-test p&lt;0.05). Inhibition of nitric oxide and prostacyclin production did not change the response to carbachol or the myogenic tone in either group. This suggests that endothelium derived hyperpolarizing factor (EDHF) plays a role in PA dilation in the SHAM rats; the role of EDHF in the PAs from the BCAS rats remains to be investigated but the lack of dilation to carbachol under any conditions suggests a general impairment in endothelial function. There was no difference in the PA passive structure between the groups. Work from our lab suggests that CCH leads to outward remodeling of the posterior communicating artery (PCA). Lumen diameter of the PCAs is important in regulating the severity of CCH. BCAS increased lumen diameter, wall-to-lumen ratio and distensibility of the PCAs (two-way ANOVA, p&lt;0.05). These data suggest that BCAS impairs short-term memory, and may contribute to impaired endothelium dependent dilation of the PAs. BCAS in normotensive WKY rats also leads to outward remodeling in the PCAs but it did not alter PA passive structure.

Quantitative study of the opticocarotid and carotid-oculomotor windows for the interpeduncular fossa, before and after internal carotid artery mobilization and posterior communicating division.

The management of basilar apex (BX) aneurysms remains problematic. We quantified the surgical exposure of the BX through the opticocarotid window (OCW) and the carotid-oculomotor window (COW), before and after mobilization of the internal carotid artery and division of the posterior communicating artery (PCoA). Eleven silicone-injected cadaveric heads were dissected bilaterally. The surgical dissection was divided into 4 major steps: (1) supraorbital modified orbitozygomatic craniotomy, (2) mobilization of the internal carotid artery after drilling out the anterior clinoid process intradurally and cutting the distal dural ring, (3) drilling out the posterior clinoid process and dorsum sellae, and (4) dividing the PCoA from the posterior third portion of the vessel. A frameless navigation system was used to quantify the surgical exposure area of the BX through the OCW and COW. The total surgical area increased significantly from steps 1 to 4 (P < .001) in both OCW and COW groups. Overall, there was a larger total surgical area obtained in the COW compared with the OCW (P = .010). ICA mobilization increased the surgical area for temporary (P < .001) and permanent (P < .003) clip application in both windows. The division of PCoA significantly increased the overall surgical area for permanent clip application (P < .003). Compared with the OCW, the COW had a significantly increased change in the area for permanent clip application in the low-lying group (P = .03). When approaching the BX via the pterion route, the appropriate surgical step and window should be selected according to characteristics of the PCoA and height of the BX.

Experimental study of hemodynamics in the Circle of Willis.

BackgroundThe Circle of Willis (CoW) is an important collateral pathway of the cerebral blood flow. An experimental study of the cerebral blood flow (CBF) distribution in different anatomical variations may help to a better understanding of the collateral mechanism of the CoW.MethodsAn in-vitro test rig was developed to simulate the physiological cerebral blood flow in the CoW. Ten anatomical variations were considered in this study, include a set of different degrees of stenosis in L-ICA and L-ICA occlusion coexist with common anatomical variations. Volume flow rates of efferent arteries and pressure signals at the end of communicating arteries of each case were recorded. Physiological pressure waveforms were applied as inlet boundary condition.ResultsIn the development of L-ICA stenosis, the total CBF decreases with the increase of stenosis degree. The blood supply of ipsilateral middle cerebral artery (MCA) was affected most by the stenosis of L-ICA. Anterior communicating artery (ACoA) and ipsilateral posterior communicating artery (PCoA) function as important collateral pathways of cerebral collateral circulation when unilateral stenosis occurred. The blood supply of anterior cerebral circulation was compensated by the posterior cerebral circulation through ipsilateral PCoA when L-ICA stenosis degree is greater than 40% and the affected side was compensated immediately by the unaffected side through ACoA. Blood flow of the anterior circulation and the total CBF reached the minimum among all cases studied when L-ICA occlusion coexist with the absence of PCoA.ConclusionThe results demonstrated the flow distribution patterns of the CoW under anatomical variations and clarified the collateral mechanism of the CoW. The flow ACoA is the most sensitive indexes to the morphology change of ipsilateral ICA. The relative independence of the circulation in anterior and posterior sections of the CoW is not broken and the function of ipsilateral PCoA is not activated until a severe stenosis of unilateral ICA occurs. PCoA is the most important collateral pathway of the collateral circulation and the missing of PCoA has the highest risk of stroke when the ipsilateral ICA has severe stenosis. These findings may provide the basis for future therapeutic and diagnosis applications.

Co-existence of Three Types of Fibromuscular Dysplasia associated with True Posterior Communicating Artery Aneurysm

Coexistence of three types of fibromuscular dysplasia (FMD) is extremely rare and it has never been reported associated with true posterior communicating artery (PCoA) aneurysm. Here we present a 54-year-old patient with bilateral carotid and left vertebral arteries FMD involvement and a ruptured “true” aneurysm of the left PCoA itself that was treated with guglielmi detachable coils (GDCs) that allowed exclusion of the aneurysm with parent vessel preservation. As our case shows, flow-related true PCoA aneurysm and the common angioarchitectural aspects of PCoA of the previously reported cases highlight the importance of hemodynamic stress, reflected in changed blood flow patterns, for the formation and/or rupture of this unusual subgroup of intracranial aneurysms.

Failure of Flow Diverter Treatment of Intracranial Aneurysms Related to the Fetal-type Posterior Communicating Artery.

PurposeThe pipeline embolization device (PED) is a flow diverter that has shown promise in the treatment of intracranial aneurysms. Close to one-fifth of aneurysms, however, fail to occlude after PED placement. This study aims to identify anatomical features and clinicopathologic factors that may predispose failed aneurysm occlusion with the PED.Materials and MethodsWe retrospectively reviewed all anterior circulation unruptured saccular aneurysms treated with the PED in a single-center. The primary outcome measure was angiographic occlusion. Anatomical features and potential predictors, including gender, aneurysm location, size, height, aspect ratio, neck width, prior treatment and the number of PED, were studied using binary logistic regression.Results29 anterior circulation unruptured saccular aneurysms with a mean size of 6.99 mm treated with the PED in a single center were retrospectively studied. The overall occlusion rate was 79.3% after a mean follow-up of 9.2 months. Four aneurysms were related to the fetal-type posterior communicating artery (PComA), and all were refractory to flow diverter treatment. Female gender was significantly associated with a higher occlusion rate. We present the anatomical features and propose possible pathophysiological mechanisms of these PComA aneurysms that failed flow diverter treatment.ConclusionA PComA aneurysm with persistent fetal-type circulation appears to be particularly refractory to flow diverter treatment, especially when the aneurysm incorporates a significant portion of the PComA. Our experience suggested that flow diverting stents alone may not be the ideal treatment for this subgroup of aneurysms, and alternative modalities should be considered. Female patients were found to have a significantly higher rate of treatment success.

Morphometric Study of the Anterior Thalamoperforating Arteries.

ObjectiveTo evaluate the morphometry of the anterior thalamoperforating arteries (ATPA).MethodsA microanatomical study was performed in 79 specimens from 42 formalin-fixed adult cadaver brains. The origins of the ATPAs were divided into anterior, middle, and posterior segments according to the crowding pattern. The morphometry of the ATPAs, including the premammillary artery (PMA), were examined under a surgical microscope.ResultsThe anterior and middle segments of the ATPAs arose at mean intervals of 1.75±1.62 mm and 5.86±2.05 mm from the internal carotid artery (ICA), and the interval between these segments was a mean of 3.17±1.64 mm. The posterior segment arose at a mean interval of 2.43±1.46 mm from the posterior cerebral artery (PCA), and the interval between the middle and posterior segments was a mean of 3.45±1.39 mm. The mean numbers of perforators were 2.66±1.19, 3.03±1.84, and 1.67±0.98 in the anterior, middle, and posterior segments, respectively. The PMA originated from the middle segment in 66% of cases. A perforator-free zone was located >2 mm from the ICA in 30.4% and >2 mm from the PCA in 67.1% of cases.ConclusionMost perforators arose from the anterior and middle segments, within the anterior two-thirds of the posterior communicating artery (PCoA). The safest perforator-free zone was located closest to the PCA. These anatomical findings may be helpful to verify safety when treating lesions around the PCoA and in the interpeduncular fossa.