Proximal Posterior Cerebral Artery Research Articles

Thromboembolic Events in the Posterior Circulation After Flow Diversion—A Closer Look at Coverage of the Posterior Cerebral Artery

Flow diversion for bifurcation aneurysms requires excluding one of the branches from the parent artery, raising concern for ischemic events. We evaluated thromboembolic events and their relationship with covering the origin of the posterior cerebral artery (PCA). This retrospective analysis included patients with confirmed basilar and proximal PCA aneurysms treated with flow diversion between 2013 and 2023. Procedures were classified according to the coverage of the origin of the PCA. Thromboembolic events associated with the excluded PCA were evaluated. Of the total 28 aneurysms included, 7 were at the basilar tip, 16 in the basilar trunk, and 5 in the first segment of the PCA; 15 were treated by excluding one of the PCAs. Dual antiplatelet therapy included aspirin and ticagrelor (57.1%), aspirin and clopidogrel (35.7%), or aspirin and prasugrel (3.57%). Complete and near-complete aneurysm occlusion was achieved in 80.8% of the aneurysms treated at a median follow-up of 12.31 months. Thromboembolic complications occurred in 3 patients (2 with basilar perforator stroke and 1 with basilar in-stent thrombosis). However, the difference in these events was not statistically significant between patients with PCA coverage and those without (P= 0.46). Diminished flow and a lack of flow was seen in 8 and 7 of the covered vessels, respectively. A modified Rankin scale score of ≤2 was reported for 89.3% of patients at a median clinical follow-up of 5.5 months. The incidence of thromboembolic events is high in distal basilar and proximal PCA aneurysms; however, PCA coverage was not associated with their occurrence. There was no difference in postprocedural disability between patients whose aneurysms were treated by excluding one of the PCAs and those who were not.

Impact of Circle of Willis Anatomical Variations on Outcomes in Aneurysmal Subarachnoid Hemorrhage (P7-5.027)

<h3>Objective:</h3> We sought to determine the association between circle of Willis (CoW) anatomical variations and outcomes in aneurysmal subarachnoid hemorrhage (aSAH) patients. <h3>Background:</h3> The impact of CoW anatomical variations on vasospasm risk and functional outcome in patients with aSAH is poorly understood. <h3>Design/Methods:</h3> We performed a retrospective study on a single center cohort of patients with aSAH admitted to an academic center between 2015 and 2022. After reviewing imaging, we classified CoW variants into 4 categories: 1) incomplete anterior segments if either proximal anterior cerebral or anterior communicating arteries were absent or hypoplastic (with a 1mm diameter cutoff), 2) incomplete posterior segments if posterior communicating or proximal posterior cerebral arteries were absent or hypoplastic; 3) complete CoW; 4) others. Outcomes include vasospasm based on transcranial Doppler (TCD) criteria and poor functional outcome defined as modified Rankin Scale 4–6 at 3 months post discharge. Binary logistic regression analysis was used to test the association of each CoW variant with outcomes. <h3>Results:</h3> We included 178 patients with aSAH (mean age 55.9 years [SD 13.6], 56% female). Eighty percent of patients had incomplete CoW and they were older than those with complete CoW (mean age 57.4 [SD12.7] vs 49.9 [15.4]; p=0.003). Incomplete posterior segments were seen in 73% of patients. The presence of incomplete anterior segments was more common in females (11% vs 1%; p=0.01) and it was associated with vasospasm (OR 2.39, 95% CI 1.02–5.63; p=0.042), but not with poor functional outcome (p=0.89). There was no association between incomplete posterior segments and vasospasm risk (p=0.29) or poor functional outcome (p=0.93). <h3>Conclusions:</h3> Anatomical variations of the CoW may affect TCD findings but did not appear to be associated with poor outcomes. Larger prospective studies are needed to explore clinical significance of CoW variants in aSAH patients. <b>Disclosure:</b> Scott Moody has nothing to disclose. Mr. Pham has nothing to disclose. Mr. Ozcan has nothing to disclose. Miss Haripottawekul has nothing to disclose. Dr. Subramaniam has nothing to disclose. Dr. Reznik has received personal compensation in the range of $10,000-$49,999 for serving as an Expert Witness for Morrison Mahoney. The institution of Dr. Reznik has received research support from NIDUS. The institution of Dr. Furie has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Janssen/BMS. The institution of Dr. Furie has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for ACTICOR. Dr. Furie has received personal compensation in the range of $5,000-$9,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for BMJ/JNNP. The institution of Dr. Furie has received research support from NINDS. Dr. Yaghi has nothing to disclose. Dr. Mahta has nothing to disclose.

Combined open revascularization and endovascular treatment of complex intracranial aneurysms: case series.

The treatment of complex intracranial aneurysms can be challenging with stand-alone open or endovascular techniques, particularly after rupture. A combined open and endovascular strategy can potentially limit the risk of extensive dissections with open-only techniques, and allow for aggressive definitive endovascular treatments with minimized downstream ischemic risk. Retrospective, single-institution review of consecutive patients undergoing combined open revascularization and endovascular embolization/occlusion for complex intracranial aneurysms from 1/2016 to 6/2022. Ten patients (4 male [40%]; mean age 51.9 ± 8.7 years) underwent combined open revascularization and endovascular treatment of intracranial aneurysms. The majority of aneurysms, 9/10 (90%), were ruptured and 8/10 (80%) were fusiform in morphology. Aneurysms of the posterior circulation represented 8/10 (80%) of the cases (vertebral artery [VA] involving the posterior inferior cerebellar artery [PICA] origin, proximal PICA or anterior inferior cerebellar artery/PICA complex, or proximal posterior cerebral artery). Revascularization strategies included intracranial-to-intracranial (IC-IC; 7/10 [70%]) and extracranial-to-intracranial (EC-IC; 3/10 [30%]) constructs, with 100% postoperative patency. Initial endovascular procedures (consisting of aneurysm/vessel sacrifice in 9/10 patients) were performed early after surgery (0.7 ± 1.5 days). In one patient, secondary endovascular vessel sacrifice was performed after an initial sub-occlusive embolization. Treatment related strokes were diagnosed in 3/10 patients (30%), largely from involved or nearby perforators. All bypasses with follow-up were patent (median 14.0, range 4-72 months). Good outcomes (defined as a Glasgow Outcomes Scale ≥4 and modified Rankin Scale ≤2) occurred in 6/10 patients (60%). A variety of complex aneurysms not amenable to stand-alone open or endovascular techniques can be successfully treated with combined open and endovascular approaches. Recognition and preservation of perforators is critical to treatment success.

Abstract 89: Mechanical Thrombectomy Or Medical Management Alone For Isolated Posterior Cerebral Artery Occlusion. An International Multicentric Observational Study.

Introduction: Whether endovascular therapy (EVT) added on best medical management (BMM, including intravenous thrombolysis [IVT] if indicated), as compared to BMM alone, is beneficial in acute ischemic stroke (AIS) with isolated posterior cerebral artery occlusion is unknown. Methods: We conducted a multicenter international observational study of consecutive AIS patients admitted within 6hrs from last seen well in 26 stroke centers in France, Switzerland and USA with isolated proximal posterior cerebral artery strokes (P1 or P2 occlusions) and treated either with EVT+BMM or BMM alone. Propensity score with inverse probability of treatment weighting was used to account for baseline between-groups differences. The primary outcome was 3-month good functional outcome (modified Rankin score [mRS] 0-2). Secondary outcomes were excellent functional outcome (mRS 0-1) and symptomatic intracranial hemorrhage (sICH) at 24hrs. We searched for an interaction between treatment group and (1) occlusion site (P1 vs . P2), (2) NIHSS score (&lt;10 vs. ≥10), and (3) IVT use. Results: Overall, 810 AIS patients were included (180 and 630 in the EVT+BMM and BMM alone groups, respectively). Median age was 74yo (IQR 63-83), 352 (44%) were female, median NIHSS was 6 (IQR 4-10), 594 (73%) received IVT, and occlusion site was P1 in 205 (25%) and P2 in 605 (75%) patients. Baseline clinical and radiological data were similar between the 2 groups following propensity-score weighting. EVT was not associated with good (adjusted OR=0.86; 95%CI: 0.67-1.09; P =0.21) or excellent (adjusted OR=1.10; 95%CI: 0.87-1.39; P =0.42) functional outcome but was associated with higher risk of sICH (OR=2.71; 95%CI: 1.41-5.21; P =0.003). No interaction was found between EVT effect and (1) NIHSS score, (2) occlusion site, or (3) IVT use for either outcome. Conclusion: In our population of AIS patients with isolated P1 or P2 occlusion, EVT was not associated with higher rates of good or excellent functional outcome as compared to BMM alone. However, EVT was associated with higher rates of sICH. Randomized trials are warranted.

Bypass surgery for ruptured dissecting aneurysms of the proximal posterior cerebral artery: illustrative case.

BACKGROUNDPosterior cerebral artery (PCA) dissecting aneurysms commonly occur in the proximal PCA and are considered rare. The treatment of proximal PCA dissecting aneurysms is challenging because of the existence of perforators supplying the vital neural structures. Recently, endovascular intervention has been used; however, concerns for ischemic or hemorrhagic complications exist.OBSERVATIONSA 54-year-old woman presented with subarachnoid hemorrhage due to dissecting aneurysm rupture at the P1-P2 junction of the PCA. The thalamoperforating artery (TPA) and medial posterior choroidal artery (MPchA) originated from the proximal end and the distal end of the aneurysm, respectively. Additionally, the posterior communicating artery (PcomA) connected with the dissected segment. To preserve these perforators, we performed surgical trapping combined with superficial temporal artery (STA) PCA anastomosis. Clips were applied for trapping the proximal and distal end of the aneurysm, with preservation of the TPA and MPchA origin. PcomA was left open for blood flow preservation to the perforators directly arising from the aneurysm. The postoperative course was uneventful, and the patient was discharged.LESSONSSurgical trapping using STA-PCA bypass could be a treatment of choice for proximal PCA dissecting aneurysms, considering its potential for cure and prevention of ischemic complications.

Endovascular Treatment of Acute Ischemic Stroke Due to Isolated Proximal Posterior Artery Occlusion.

BackgroundAcute ischemic stroke (AIS) due to isolated proximal posterior cerebral artery (PPCA) occlusion is rare but associated with high morbidity and mortality rates. However, the optimal treatment strategy for patients with AIS caused by PPCA remains unclear. We discuss our single-center experience with endovascular treatment (EVT) in patients with PPCA.MethodsData from patients with AIS due to PPCA occlusion were retrospectively analyzed. We analyzed procedural details, the degree of reperfusion, functional outcomes, and complications. Functional outcomes were determined using the modified Rankin Scale (mRS) at 90 days, and good outcome was defined as mRS 0–2 at 90 days. Successful reperfusion was defined as modified treatment in cerebral ischemia (mTICI) 2b−3 after endovascular therapy. Safety variables included symptomatic hemorrhage (defined as an increase of four or more points in the National Institute of Health Stroke Scale score), vessel perforation or dissection, and new ischemic stroke in different territories.ResultsSeven patients were included in this study. The mean age of the patients was 64 ± 12.4 years. Successful reperfusion was achieved in all seven patients (100%). Good outcomes were achieved at 90 days in 2 patients (28.6%), and favorable outcomes were observed in five patients (71.4%). One patient underwent angioplasty as rescue therapy after three attempts. One patient died because of severe gastrointestinal bleeding 24 h after EVT, which was probably a complication of intravenous alteplase. One patient had an embolism in the basilar artery and achieved complete reperfusion after rescue thrombectomy. Another patient had a complication of vessel dissection in the PPCA and underwent stent implantation as rescue therapy. We observed no recurrence of ischemic stroke or any intracranial hemorrhage on non-contrast computed tomography 24 h after the procedure.ConclusionEVT may represent an alternative treatment strategy for patients with acute ischemic stroke caused by PPCA.

Diagnostic Impact of Monitoring Visual Evoked Potentials to Prevent Visual Complications During Endovascular Treatment for Intracranial Aneurysm.

IntroductionThe present study aimed to determine the incidence of intraprocedural visual-evoked potential (VEP) changes and to identify correlations with intraprocedural ischemic complications during endovascular treatment in patients with intracranial aneurysm related to visual function.MethodsThis study analyzed data from 104 consecutive patients who underwent endovascular coil embolization to treat intracranial aneurysms related to visual function under VEP and transcranial motor evoked potential (MEP) monitoring. We analyzed associations between significant changes in MEP and VEP, defined as a >50% decrease in amplitude, and both intraprocedural complications and postoperative neurological deficits. Factors associated with postoperative neurological deficits were also assessed.ResultsTreated aneurysms were predominantly located in the internal carotid artery (95%). Five (5%) were located in the posterior cerebral artery (PCA). Significant decreases in intraprocedural VEP occurred in four patients (4%), although one of those four patients did not show concomitant MEP decreases during procedures. Immediate salvage procedures avoided postoperative visual disturbances. All VEP decreases were transient and not associated with postoperative visual impairment. One of three cases who underwent intraoperative balloon occlusion test showed tolerance to balloon occlusion of the proximal PCA under VEP assessment; parent artery occlusion was performed without postoperative visual disturbance in that case.ConclusionAlthough significant VEP decreases occurred 4% during neuro-endovascular aneurysm treatment related to visual function, intraprocedural VEP monitoring identifies ischemic changes associated with visual pathways and facilitates prompt initiation of salvage procedures.

Mechanical Thrombectomy in Isolated Occlusion of the Proximal Posterior Cerebral Artery.

Introduction: Endovascular therapy (EVT) is established as first-line treatment for acute ischemic stroke (AIS) due to large vessel occlusion (LVO) in the anterior circulation. For basilar artery occlusion, recent randomized clinical trials demonstrated not only equipoise but also advantages for EVT under particular circumstances. It remains unclear whether EVT offers an advantage over best medical management (BMM) including thrombolysis (IVT) in isolated occlusion of the proximal posterior cerebral artery (PCAO).Methods: Patients with AIS due to PCAO proven by CT or MR angiography were retrospectively identified from local databases at four comprehensive stroke centers in Germany, USA, and Taiwan between 2012 and 2020. Demographic and clinical data were collected, and imaging characteristics including pretherapeutic, interventional, and follow-up imaging were reviewed locally at each center. Patients were grouped according to therapy, i.e., BMM including IVT alone vs. BMM and EVT. Efficacy endpoints were early neurological improvement (ENI) after 24 h or at discharge, good outcome (modified Rankin scale 0–2) after 3 months, as well as hemorrhagic complications and in-house deaths as safety endpoints.Results: We included 130 patients of whom 23 (17.7%) received EVT. EVT patients had more proximal occlusions (69.9 vs. 43%, p = 0.023) and had a better premorbid function [premorbid mRS, 0 (0–4) vs. 1 (0–3), p < 0.01] when compared to BMM patients. IVT showed a trend toward being less performed in the EVT group (21.7 vs. 41.1%, p = 0.1), while other baseline parameters were balanced. Successful reperfusion was achieved in 52% of EVT patients. ENI was more frequent in the EVT group (61 vs. 35.5%, p = 0.034). Good outcome at 90 days and safety endpoints did not differ. In a bivariate analysis, ENI was independently predicted by the use of EVT (OR, 2.76; CI, 1.055–7.04) and the baseline National Institutes of Health Stroke Scale (NIHSS) (OR, 1.082; CI, 1.027–1.141 per point increase).Discussion: EVT in isolated PCAO appears safe and feasible. Positive effects on clinical outcome are primarily on ENI but also depend on the initial stroke severity. Further prospective or randomized studies are needed to better describe the potential long-term clinical benefits of EVT for PCAO as compared with best medical management.

Reader response: Optimizing in-hospital triage for large vessel occlusion using a novel clinical scale (GAI2AA).

In their development of the GAI2AA scale,1 Ohta et al. identified a history of atrial fibrillation (AF) or AF on ECG as independent predictors of an anterior circulation large vessel occlusion (LVO) in patients presenting within 4.5 hours of symptom onset. Using a different case definition—all patients who had an occlusion of the common carotid, internal carotid, proximal middle cerebral, anterior or posterior cerebral arteries, or the vertebrobasilar system—and a different patient population—patients admitted to the University of Kentucky Medical Center vs 3 Japanese stroke centers—we also found that a history of AF was associated with an LVO (36.2% vs 18.5%, p < 0.001),2 although the frequency was less than reported by Ohta et al. (65% vs 24%, p < 0.001). In our cohort, the C-statistic for LVO based on a history of AF alone (0.579; 95% CI 0.540–0.617) reflected no more than moderate discriminative capacity and did not improve the accuracy of the Cincinnati Prehospital Stroke Severity scale, Los Angeles Motor Scale, Rapid Arterial Occlusion Evaluation score, or the Field Assessment Stroke Triage for Emergency Destination scale. Nonetheless, simply obtaining a history of AF can alert emergency responders that a patient with an acute focal neurologic deficit may have an LVO.

Circle of Willis abnormalities and their clinical importance in ageing brains: A cadaveric anatomical and pathological study

The circle of Willis (CW) located at the base of the brain forms an important collateral network to maintain adequate cerebral perfusion, especially in clinical situations requiring compensatory changes in blood flow. Morphopathological changes in the CW may relate to the severity of the symptoms of certain neurodegenerative and cerebrovascular disorders. The purpose of this study was to investigate the CW abnormalities and their clinical importance in ageing brains. The CW was examined macroscopically in 73 formalin-fixed samples to determine the degree of stenosis of each CW component, atherosclerosis of the CW, hypoplasia (threshold diameter < 1 mm), anatomical variations and aneurysms. Age-related neurodegenerative and cerebrovascular pathologies were screened using immunohistopathological techniques on specific neuroanatomical regions based on standard guidelines. The majority of the elderly brains −93 % (68/73) presented at least a single hypoplastic CW component at death. Anatomical variations were mostly identified in communicating arteries, followed by proximal posterior and anterior cerebral arteries. Arterial bifurcations were found to be the predominant sites for cerebral aneurysms. More than 90 % of the elderly brains presented CW atherosclerosis at death. CW abnormalities did not show any strong associations with neurodegenerative pathologies except for an “at risk” significant association observed between Braak’s neurofibrillary tangle (NFT) stages 1-VI and CW atherosclerosis grades ≥ mild (p = 0.05). However, a significant association was observed between microscopic infarcts in deep white matter and hypoplasia in communicating arteries with Fisher’s exact test (p < 0.05). Overall, CW abnormalities were predominant in the ageing brains, however their relationships to the occurrence and severity of the symptoms of neurodegenerative pathologies were found to be low.

Acute hemorrhagic cerebral artery dissection: Characteristics and endovascular treatment.

Acute hemorrhagic cerebral artery dissection may show a subtle stenosis and bulge on an angiogram, for which diagnosis and treatment are difficult. This report describes seven cases of acute hemorrhagic cerebral artery dissection treated by endovascular techniques. From January 2018 to April 2019, seven patients (22-76 years old) were diagnosed with subarachnoid hemorrhage caused by cerebral artery dissection. Six patients were treated by low-profile visualized intraluminal support stent-assisted coiling and there was a sacrifice of the posterior cerebral artery in one patient. Cerebral angiography results were obtained immediately after intervention and at follow-up. Clinical outcome was evaluated by a modified Rankin Scale score. Four dissections were angiographic changes of subtle stenosis and small bulges; three were apparent angiographic changes of stenosis or fusiform morphologies. All seven aneurysms were completely obliterated, a low-profile visualized intraluminal support stent was used in six patients and coil occlusion of the parent artery in one patient. Complications occurred in two cases of proximal posterior cerebral artery dissection. One bleeding complication was observed intra-procedure and one ischemic complication was observed after stent-assisted coiling. The angiographic and clinical follow-up was obtained at 3-8 months in five patients. Good recovery was achieved for six patients (modified Rankin Score 0); one patient who presented Weber syndrome caused by ischemic complication had a modified Rankin Score of two at 8 months follow-up. Hemorrhagic cerebral artery dissection may show subtle stenosis, small bulges or fusiform morphologies on angiograms. Treatment of proximal posterior cerebral artery dissection is challenging. Endovascular reconstruction with a low-profile visualized intraluminal support stent was effective depending on the angiographic morphology.

Collaborative Treatment Using Surgical and Radiological Approaches for a Ruptured Dissecting Aneurysm Involving Proximal PCA (P1-2) and Posterior Communicating Artery: A Case Report

We report a case of collaborative treatment using surgical and radiological approaches for a ruptured dissecting aneurysm around the proximal posterior cerebral artery (P1-P2) and the posterior communicating artery. A 37-year-old woman was admitted to our hospital with a severe headache for 3 days. On admission, a computed tomography scan revealed a subarachnoid hemorrhage and a cerebral angiogram showed a dissecting aneurysm involving the proximal posterior cerebral artery (P1-P2) and posterior communicating artery. Although parent artery occlusion was indispensable for complete treatment, it posed the risk of ischemic complications in the right posterior cerebral artery distribution. A preoperative assessment of her three-dimensional digital subtraction angiogram enabled the consideration of a more feasible approach of collaborative treatment using surgical and radiological techniques. A successful outcome was obtained at the right P1 occlusion using coils and by the placement of the superficial temporal artery-posterior temporal artery bypass, followed by proximal clipping of the right posterior communicating artery. She was discharged without any neurological complications after 38 days.

Large Vessel Occlusion in Acute Ischemic Stroke Patients: A Dual-Center Estimate Based on a Broad Definition of Occlusion Site

Background: Accurate assessment of the frequency of large vessel occlusion (LVO) is important to determine needs for neurointerventionists and thrombectomy-capable stroke facilities. Current estimates vary from 13% to 52%, depending on acute ischemic stroke (AIS) definition and methods for AIS and LVO determination. We sought to estimate LVO prevalence among confirmed and suspected AIS patients at 2 comprehensive US stroke centers using a broad occlusion site definition: internal carotid artery (ICA), first and second segments of the middle cerebral artery (MCA M1,M2), the anterior cerebral artery, vertebral artery, basilar artery, or the proximal posterior cerebral artery. Methods: We analyzed prospectively maintained stroke databases of patients presenting to the centers between January and December 2017. ICD-10 coding was used to determine the number of patients discharged with an AIS diagnosis. Computed tomography angiography (CTA) or magnetic resonance angiography (MRA) was reviewed to determine LVO presence and site. Percentages of patients with LVO among the confirmed AIS population were reported. Results: Among 2245 patients with an AIS discharge diagnosis, 418 (18.6%:95% confidence interval [CI] 17.3%-20.0%) had LVO documented on CTA or MRA. Most common occlusion site was M1 (n=139 [33.3%]), followed by M2 (n=114 [27.3%]), ICA (n=69[16.5%]), and tandem ICA-MCA lesions (n=44 [10.5%]). Presentation National Institutes of Health Stroke Scale scores were significantly different for different occlusion sites (P=.02). Conclusions: The LVO prevalence in our large series of consecutive AIS patients was 18.6% (95% CI 17.3%-20.0%). Despite the use of a broad definition, this estimate is less than that reported in most previous studies.

Tentorial Incision vs. Retraction of the Tentorial Edge during the Subtemporal Approach: Anatomical Comparison in Cadaveric Dissections and Retrospective Clinical Case Series.

Objective The aim of this study was to compare tentorial incision (group A) versus retraction and tack up suture (group B) of the tentorial edge during the subtemporal approach for surgery in the high basilar region. Design 24 cadaveric dissections and 4 clinical cases of aneurysms of the high basilar region are presented. Assessment included visibility and operability afforded by either tentorial incision creating a dural flap (group A) or retraction of the tentorial edge and tethering with a suture (group B). Four patients, two with superior cerebellar artery aneurysms and two with proximal posterior cerebral artery aneurysms were treated with each approach. Results In the quantitative evaluations, we found no significant difference in the exposure of the posterior cerebral, superior cerebellar, and perforant arteries as well as surgical working area provided by either approach. However, tentorial incision allowed a significantly greater exposure of the basilar artery and the fourth cranial nerve (both p < 0.001). Concerning operability, tentorial incision provided no objective advantage for direct clipping of the high basilar region (groups A vs. B, p > 0.05). Subjectively, clipping of the high basilar segment was feasible using tentorial tethering only. Conclusion Retraction of the free edge of the tentorium downward by tethering with a suture is simple and fast method for exposure of aneurysms in the high basilar region when the pathology does not require a proximal control. In our data the rather more invasive and time consuming tentorial incision provided an additional objectified advantage only for placement of a proximal temporary clip.

Revascularization of the upper posterior circulation with the anterior temporal artery: an anatomical feasibility study.

OBJECTIVE In various disease processes, including unclippable aneurysms, a bypass to the upper posterior circulation (UPC) including the superior cerebellar artery (SCA) and posterior cerebral artery (PCA) may be needed. Various revascularization options exist, but the role of intracranial (IC) donors has not been scrutinized. The objective of this study was to evaluate the anatomical feasibility of utilizing the anterior temporal artery (ATA) for revascularization of the UPC. METHODS ATA-SCA and ATA-PCA bypasses were performed on 14 cadaver specimens. After performing an orbitozygomatic craniotomy and opening the basal cisterns, the ATA was divided at the M3-M4 junction and mobilized to the crural cistern to complete an end-to-side bypass to the SCA and PCA. The length of the recipient artery between the anastomosis and origin was measured. RESULTS Seventeen ATAs were found. Successful anastomosis was performed in 14 (82%) of the ATAs. The anastomosis point on the PCA was 14.2 mm from its origin on the basilar artery. The SCA anastomosis point was 10.1 mm from its origin. Three ATAs did not reach the UPC region due to a common opercular origin with the middle temporal artery. The ATA-SCA bypass was also applied to the management of an incompletely coiled SCA aneurysm. CONCLUSIONS The ATA is a promising IC donor for UPC revascularization. The ATA is exposed en route to the proximal SCA and PCA through the pterional-orbitozygomatic approach. Also, the end-to-side anastomosis provides an efficient and straightforward bypass without the need to harvest a graft or perform multiple or difficult anastomoses.

PB 3 Abnormal height of basilar artery bifurcation in adults with Pompe disease

Introduction The evidence for an involvement of the cerebral arteries in adults with Pompe disease is increasing.Typical changes are dilation, elongation and distension of the vertebrobasilar arteries ( [Laforet et al., 2008] , [Sacconi et al., 2010] , [Hensel et al., 2014] , [Montagnese et al., 2016] ). Methods In 15 adults with Pompe disease (age 57 ± 13 years, 8 females) and 12 controls with comparable age and cardiovascular risk factors (age 53 ± 6 years, 4 females) the cerebral arteries were examined with a time of flight MR-angiography.The angle of departure of the superior cerebellar artery (SUCA) was measured from the basilar artery (BA) ( Figs.1 and 2 ).In addition, the level of the bifurcation of the BA was evaluated by a Smoker’s criteria based definition ( Smoker et al., 1986 ) (score at or below the dorsum sellae, score 1 within suprasellar cistern, score 2 at the level of third ventricle floor, score 3 indenting and elevating floor of third ventricle). Results In adults with Pompe disease the angle of SUCA departure was 59° (sum left and right 119°, controls: left 75° and right 83°, sum 159°).Compared with a preliminary MR-angiography five years before ( Hensel et al., 2014 ) the angle of departure decreased from 5 to 11° (n = 5 patients).In 11/15 Pompe patients, the bifurcation of the BA was abnormally high (Smoker score 0: 0 patients, score 1: 4 patients, score 2: 5 patients and score 3: 6 patients).In controls this was rarer and less pronounced (Smoker score 0: 6 patients, score 1: 5 patients, score 2: 0 and score 3: 1 patient).The Smoker score was lower among young Pompe patients than in older patients.In 7/15 (47%) of Pompe patients and in 1/12 (8%) of the controls the proximal posterior cerebral artery (PCA) indenting the hypothalamus (arrow in Fig.3 ).One patient developed a hemorrhage in the thalamus, which was supplied by the displaced superiorly PCA. Discussion The results indicate a upwards displacement of the distal basilar artery in adults with Pompe disease.Such upwards displacement in patients with dolichoectasia of other origin is associated with any stroke and subsequently increased dolichoectatic progress ( Passero and Rossi, 2008 ). In our patients the degree of displacement increases with patient age or duration of the disease. These could represent an accelerated destruction of vertebrobasilar arteries in adults with Pompe disease. The abnormal height of basilar bifurcation could represent an early and easy recognizable sign for cerebrovascular involvement as well.

Isolated intracranial fibromuscular dysplasia of the posterior cerebral artery

Fibromuscular dysplasia (FMD) is a nonatherosclerotic, noninflammatory arterial disease that most commonly affects the renal and internal carotid arteries, but intracranial FMD is very rare. We report a patient with FMD involving the posterior cerebral arteries (PCAs). A 24year old female was presented with a 4day history of right homonymous hemianopsia with throbbing headache in the left temporo-occipital area. The brain magnetic resonance imaging (MRI) revealed an acute ischemic stroke in the left PCA territory, while the Time of Flight (TOF) magnetic resonance angiogram (MRA) showed segmental luminal irregularities in the left proximal PCA. The conventional angiogram revealed the “string of beads” appearance, a characteristic that is pathognomonic for FMD. The patient’s inhospital clinical course was stable, while there was no recurrence of stroke. This is the second report of FMD of the PCA. Notwithstanding incredibly rare incidences of isolated intracranial FMD and nonspecific findings of MRA, such a pathophysiology should be considered as the cause for a stroke in young patients, especially those with no cardiovascular risk factor.

Technical Description of the Medial and Lateral Anterior Temporal Approach for the Treatment of Complex Proximal Posterior Cerebral Artery Aneurysms

Posterior cerebral artery (PCA) aneurysms are often fusiform and associated with multiple intracranial aneurysms. A bypass procedure in combination with proximal occlusion or aneurysm trapping is considered to be effective for the treatment of patients with complex PCA aneurysms. Because of the deep, narrowed surgical corridor and the surrounding sensitive neuroanatomic structures, microsurgical procedures applied to the PCA are technically demanding. The authors present a technical report of a complex aneurysm formation located at the postcommunicating segment of the PCA (PCA-P2) treated via an anterior temporal approach. A 68-year-old woman had an unruptured PCA-P2 aneurysm formation, which was discovered incidentally. The fusiform aneurysm shape of the distal aneurysm aggravated direct microsurgical and endovascular treatment. After an individual case discussion, the patient underwent a microsurgical clipping of the proximal P2 segment aneurysm and the distal PCA-P2 segment aneurysm was treated by trapping after the application of a superficial temporal artery (STA) to PCA-P2 bypass using an anterior temporal approach. Postoperative computed tomography angiography showed the exclusion of the proximal PCA-P2 aneurysm and an adequate flow from the STA to PCA-P2 bypass to the distal PCA segments. The patient showed a modified Rankin scale of 0 after follow-up at 1 and 3 months. The anterior temporal approach is feasible for the microsurgical management of complex postcommunicating PCA aneurysms and the application of bypass procedures.

Lateral Thalamic Infarction and the Vascular Geometry of the Posterior Cerebral Artery

Background: The geometric properties of the parental artery affect the development of local atherosclerosis and perforator infarction. In this study, we aimed at investigating the association between vascular geometry of the posterior cerebral artery (PCA) and the development of isolated lateral thalamic infarction (LTI), the most frequent type of thalamic infarction. Methods: The geometric properties of the corresponding PCA in LTI patients were assessed and they include the diameters of the distal basilar artery (BA) and proximal PCA, distal BA - PCA angle, first PCA angle (angle between P1 and P2), and the presence of the posterior communicating artery (Pcom). These parameters obtained from the ipsilesional PCA were compared with the contralesional PCA and the corresponding PCA in age- and sex-matched controls. Results: Forty-five LTI patients were enrolled. The ipsilesional PCA in LTI patients demonstrated a greater ipsilesional P1 - P2 angle (81.4 ± 22.6 vs. 71.3 ± 23.2°, respectively; p = 0.04) and a higher prevalence of Pcom (42.2 vs. 13.3%; p = 0.002) when compared to control subjects. In comparison with the contralesional PCA, ipsilesional PCA demonstrated a smaller diameter, larger angle between P1 and P2 segment, and a higher prevalence of Pcom. The presence of hyperlipidemia (OR 3.548 (1.283-9.811); p = 0.02) and Pcom (OR 3.507 (1.104-11.135); p = 0.03) was a factor that was independently associated with LTI. Conclusions: Local hemodynamics in the PCA may be influenced by the P1 - P2 angle and the presence of Pcom, which are associated with the development of LTI.

Sparing of the hippocampus indicates better collateral blood flow in acute posterior cerebral artery occlusion.

In acute posterior cerebral artery, occlusion involvement of the hippocampus is a common finding. Nevertheless, until today, infarction and ischemic lesion evolution in the hippocampus has not been studied systematically. Evaluation of hippocampal infarction patterns in posterior cerebral artery occlusion in the very early phase (≤six-hours) and ischemic lesion evolution on follow-up magnetic resonance imaging in relation to collateral blood flow assessed by a magnetic resonance imaging-based approach was conducted. In 28 patients [mean age 69·4 ± 13·8 years, 19 (67·9%) males, 10 (32·1%) females] with proximal posterior cerebral artery occlusion, magnetic resonance imaging findings were analyzed, with emphasis on hippocampal infarction patterns on diffusion-weighted images and collateralization on dynamic 4D angiograms derived from perfusion-weighted raw images. On initial diffusion-weighted images, we identified all known hippocampal infarction patterns: type 1 (complete) in 6/18 (33·3%) patients, type 2 (lateral) in 10/18 (55·6%) patients, and type 3 (dorsal) and type 4 (circumscribed) in 1/18 (5·6%) patient respectively. On dynamic 4D angiograms, the grade of collateralization was classified as 1 in 9 (32·1%), 2 in 1 (3·6%), 3 in 10 (35·7%), and 4 in 8 (28·6%) patients. On follow-up diffusion-weighted images, we found new ischemic lesions in three and infarction growth in the hippocampus in five patients. Patients with better collateralization (grades 3 and 4) less often had hippocampal infarctions on initial (P = 0·003)/follow-up diffusion-weighted images (P = 0·046) as well as type 1 on initial (P = 0·007)/follow-up diffusion-weighted images (P = 0·005). Involvement of the hippocampus in proximal posterior cerebral artery occlusion is frequently but not obligatorily observed and highly dependent on the extent of collateralization. The same holds true for hippocampal infarction patterns.