P1 Segment Of Posterior Cerebral Artery Research Articles

The effects of P2 segment of posterior cerebral artery to thalamus blood supply pattern on gait in cerebral small vessel disease: A 7 T MRI based study

Gait disturbance is a manifestation of cerebral small vessel disease (CSVD). The posterolateral thalamus (PL), whose blood is mainly supplied by the P2 segment of posterior cerebral artery (P2-PCA), plays pivotal roles in gait regulation. We investigated the influence of the distance between P2-PCA and PL on gait with varying CSVD burden. 71 participants were divided into low and high CSVD burden groups. The distance from P2-PCA to PL was measured using 7 T TOF-MRA and categorized into an immediate or distant PCA-to-thalamus pattern. Functional connectivity (FC) and voxel-based morphometry were assessed to evaluate functional and structural alterations. In the low CSVD burden group, immediate PCA-to-thalamus supply strongly correlates with longer step length and higher wave phase time percent, and exhibited enhanced FCs in left supplementary motor area, right precentral cortex (PreCG.R). While in the high CSVD burden group, no association between PCA-to-thalamus pattern and gait was found, and we observed reduced FC in PreCG.R with immediate PCA-to-thalamus pattern. Higher CSVD burden was associated with decreased gray matter density in bilateral thalamus. However, no significant structural thalamic change was observed between the two types of PCA-to-thalamus patterns in all patients. Our study demonstrated patients with immediate PCA-to-thalamus supply exhibited better gait performance in low CSVD burden populations, which also correlated with enhanced FCs in motor-related cortex, indicating the beneficial effects of the immediate PCA-to-thalamus supply pattern. In the higher burden CSVD populations, the effects of PCA-to-thalamus pattern on gait are void, attributable to the CSVD-related thalamic destruction and impairment of thalamus-related FC.

The incidence of medium vessel occlusions: a population-based study.

The incidence of medium vessel occlusion (MeVO) is not well known. The objective of our study is to perform a population-based assessment to estimate the incidence of MeVOs. Consecutive patients from Olmsted County, Minnesota who presented for acute ischemic stroke seen at Mayo Clinic Hospital from 1/1/2018 to 12/31/2020 who were found to have a MeVO were included in this study. MeVO was defined as occlusion at or beyond the level of the middle cerebral artery M2 segment, anterior cerebral artery A2 segment, posterior cerebral artery P1 segment, and cerebellar arteries. Census data for Olmsted County was obtained from the United States Census Bureau from the year 2020. A total of 1,718 patients were screened for the study, 77 patients fulfilled inclusion criteria to be included in the study. Presenting NIHSS was 9 (± 7). The population of Olmsted County was estimated to be 162,847. The incidence rate for MeVO was 16 cases (95% CI 12-19) per 100,000 people per year. Based on estimates of the US population in 2020 of 331,449,281 people, we estimate there are 52,236 (95% CI 40,635-64,002) new cases of MeVOs per year. As the only stroke center in Olmsted County, we have been able to estimate the incidence of ischemic stroke due to MeVO. While the incidence of MeVOs is less than both large and small vessel occlusions, they still represent a significant proportion of strokes with significant morbidity and mortality that would benefit from further studies in both acute intervention and prevention.

Extremely long posterior cerebral artery P1 segment.

Excluding aplasia and hypoplasia of the P1 segment of the posterior cerebral artery (PCA), anatomical variations in the PCA are rare. To our best knowledge, there are few reports of an extremely long P1 segment of the PCA. Herein, we report a rare case of an extremely long P1 segment of the PCA, which was diagnosed by 1.5-T magnetic resonance angiography (MRA). A 96-year-old woman was transferred by ambulance to our hospital with impaired consciousness. Her symptom improved, and magnetic resonance imaging showed no significant findings. MRA revealed an extremely long P1 segment of the left PCA. The length of the P1 segment of the left PCA was 27.3mm. The left posterior communicating artery (PCoA) was 20.9mm, which is not considered long. The left anterior choroidal artery branched from the internal carotid artery distal to the PCoA branching position. Basilar artery fenestration was also incidentally identified. Careful imaging assessment was important for identifying the extremely long P1 segment of the PCA in the present case. This rare anatomical variation can also be confirmed by 1.5-T MRA.

Abstract Number: LBA7 Outcomes of Endovascular Thrombectomy Versus Medical Treatment in Ischemic Strokes Secondary to Medium Vessel Occlusion

Introduction Acute ischemic stroke (AIS) from arterial occlusions are treated with emergent endovascular thrombectomy (EVT) when clinically appropriate. Clinical outcomes of EVT in medium vessel occlusion (MVO) compared to large vessel occlusion (LVO) have neither been well established nor compared to alternate medical management. Our aim was to evaluate outcomes of patients with AIS secondary to MVO undergoing EVT. Methods We conducted a retrospective chart review of patients presenting to our comprehensive stroke center with MVO‐associated AIS undergoing EVT or aggressive intra‐arterial thrombolytic treatment with concurrent administration of IV eptifibatide. We assessed occlusion site, NIHSS (presentation, 7 day or discharge, 3 months), modified Rankin Scale (baseline, 90‐day), and intracranial hemorrhage (ICH) rate. MVO was defined as occlusion of pure M2 middle cerebral artery without M1 segment involvement, anterior cerebral artery A1 segment or more distal, and posterior cerebral artery P1 segment or more distal. Mann‐Whitney U test, Fisher exact test statistic, and T‐test statistic were used for analysis. Social science statistics software was used for data analysis. Results From August 2020 to December 2021, out of 175 patients who underwent EVT, 50 had MVO (n = 33 M2 occlusion, n = 12 M3 occlusion, n = 1 for P1, P2, A1, A2, A3 each). Twelve subjects with MVO received aggressive medical management with concurrent IV eptifibatide. Subjects between arms were similar at baseline (median NIHSS 11 [95% CI 10.75, 14.32]; mean age 71.5 [95% CI 69.24, 73.77]; male 48.39% [n = 30]). The difference between initial NIHSS and discharge NIHSS was statistically significant in the EVT arm (Z‐Score = 4.03; p‐value < .00001) but not in the medical arm (Z‐score = 1.96; p‐value 0.05). Hemorrhagic transformation occurred in 28% (n = 14) of EVT arm and 16.67% (n = 2) of medical arm. This was not statistically significant (Fisher value: 0.71). Median 90 day mRS was 1 (95% CI [0.89, 2.11]). The difference between 90 day mRS was not significantly different (Z‐score = ‐1.20; p‐value 0.23). Conclusions In our patient cohort, endovascular therapy was safe in medium vessel occlusion and may have more favorable clinical outcomes as illustrated by higher delta NIHSS in the endovascular thrombectomy group. Larger, prospective studies are needed to validate our results.

Abstract TMP86: Clinical Outcomes Of Endovascular Thrombectomy Versus Acute Medical Treatment In Acute Ischemic Strokes Secondary To Medium Vessel Occlusion

Introduction: Acute ischemic stroke (AIS) from arterial occlusions are treated with emergent endovascular thrombectomy (EVT) when clinically appropriate. Clinical outcomes of EVT in medium vessel occlusion (MVO) compared to large vessel occlusion (LVO) have neither been well established nor compared to alternate medical management. Our aim was to evaluate outcomes of patients with AIS secondary to MVO undergoing EVT. Methods: We conducted a retrospective chart review of patients presenting to with MVO-associated AIS undergoing EVT or aggressive intra-arterial thrombolytic treatment with concurrent administration of IV eptifibatide. We assessed occlusion site, NIHSS (presentation, 7 day or discharge, 3 months), mRS (baseline, 90-day), and intracranial hemorrhage (ICH) rate. MVO was defined as occlusion of pure M2 middle cerebral artery without M1 segment involvement, anterior cerebral artery A1 segment or more distal, and posterior cerebral artery P1 segment or more distal. Mann-Whitney U test, Fisher exact test statistic, and T-test statistic were used for analysis. Results: From August 2020 to December 2021, out of 175 patients who underwent EVT, 50 had MVO (n=33 M2 occlusion, n=12 M3 occlusion, n=1 for P1, P2, A1, A2, A3 each). Twelve subjects with MVO received aggressive medical management with concurrent IV eptifibatide. Subjects between arms were similar at baseline (median NIHSS 11 [95% CI 10.75, 14.32]; mean age 71.5 [95% CI 69.24, 73.77]; male 48.39% [n=30]). The difference between initial NIHSS and discharge NIHSS was statistically significant in the EVT arm (Z-Score=4.03; p-value < .00001) but not in the medical arm (Z-score=1.96; p-value 0.05). Hemorrhagic transformation occurred in 28% (n=14) of EVT arm and 16.67% (n=2) of medical arm. This was not statistically significant (Fisher value: 0.71). Median 90 day mRS was 1 (95% CI [0.89, 2.11]). The difference between 90 day mRS was not significantly different (Z-score=-1.20; p-value 0.23). Conclusion: In our patient cohort, endovascular therapy was safe in medium vessel occlusion and may have more favorable clinical outcomes as illustrated by higher delta NIHSS in the endovascular thrombectomy group. Larger, prospective studies are needed to validate our results.

Morphometric analysis of normal and variant anatomy of posterior cerebral artery and the incidence of fetal posterior cerebral artery in Uttar Pradesh region: A computed tomography angiographic study

Introduction: The aim is to study morphometric analysis of normal and variant anatomy of posterior cerebral artery (PCA) and incidence of fetal PCA (FPCA) in Uttar Pradesh region. The PCA and its cortical branches supply blood to the occipital lobe, inferomedial temporal lobe, and portions of posterior inferior parietal lobe. Fetal-type PCA is a common anatomic variation of PCA that is closely associated with intracranial aneurysm. The present study provides the description of PCA regarding its normal morphology, morphometry, and variations in Uttar Pradesh region. Material and Methods: The study evaluated 100 computed tomography angiograms. Results: Among arteries that displayed normal anatomy, mean diameter of PCA was observed to be 4.29 ± 0.74 mm on the right side and 2.47 ± 0.74 mm on the left side. Mean diameter in males and in females was found to be 2.48 ± 0.73 mm and 2.47 ± 0.74 mm, respectively. In 56.5% of cases, the diameters of P1 segment of PCAs ranged from 2.1 to 3 mm whereas >3 mm diameter was observed in 18.5% cases. Nineteen percent cases showed 1.1–2 mm. In 6% cases, hypoplasia (≤1 mm) of PCA was observed. FPCA was observed in 26% cases. Unilateral observed in 17% cases and bilateral in 9% cases and the difference was statistically significant (P < 0.000). Discussion and Conclusion: Anomalies of PCA may assume considerable significance in surgeries of head and neck, which require ligation of internal carotid and common carotid artery. Awareness of these anatomical variations described shall prove to be useful for any cerebrovascular procedures.

Abstract 1122‐000184: Cerebral Arterial Variations in Patients with Ischemic Stroke Undergoing Mechanical Thrombectomy

Introduction : This study aimed to determine what anatomical variants of the Circle of Willis (CoW) and the middle cerebral artery(MCA) are observed in patients with acute M1 occlusion and whether their prevalence differs from that described as “normal” in anatomy textbooks. Methods : We have performed a retrospective assessment of radiological examinations of patients with stroke due to middle cerebral artery M1 segment occlusion. All patients underwent mechanical thrombectomy from January 2015 until March 2021. The anatomy of the CoW was assessed on initial CT‐angiography and DSA. Branches of the MCA were observed on control DSA after recanalization. Results : A total of 100 patients were included in the analysis (58 females and 42 males, mean age: 71.6 +/‐ 13.9). Fully complete CoW was observed in 19% of patients. A total of 10% of patients had an incomplete anterior portion of CoW. In the incomplete anterior portion subgroup, the most common variation was the absence of anterior communicating artery (6% of total hemispheres), followed by the absence of one A1 (3% of total hemispheres). An incomplete posterior portion of CoW was identified in 79% of the patients. The absence of posterior communicating artery (PCoA) was observed in 59 patients. Sixteen patients had adult‐type PCoA, 3 patients had transitional‐type PCoA and 21 patients had fetal‐type posterior cerebral artery (PCA). In the subgroup of patients with fetal‐type posterior circle, 5 patients had no P1 segment of PCA. Anterior temporal branch of MCA was observed in 45% of the patients. Middle cerebral artery bifurcation was found in 80% of hemispheres, and trifurcation in 20%. In the bifurcation subgroup, 26% of MCAs had a dominating upper branch and 18% had a dominating lower branch. A duplicate MCA was observed in one hemisphere. Conclusions : In comparison to normal anatomy described in anatomy textbooks, the population of patients suffering from ischemic stroke due to M1 occlusion had a lower proportion of complete and closed CoW. A foetal type PCoA was observed to be prevalent (21%) in patients suffering from acute M1 occlusion. Detailed anatomical knowledge of anatomical variants of CoW in patients undergoing mechanical thrombectomy is essential for clinicians performing intravascular interventions and may aid procedure planning.

Remodeling of the Posterior Cerebral Artery P1-Segment after Pipeline Flow Diverter Treatment of Posterior Communicating Artery Aneurysms.

Introduction: Flow diverters such as the pipeline embolization device (PED) cause hemodynamic changes of the treated vessel segment. In posterior communicating artery (PcomA), aneurysms’ unique anatomic consideration have to be taken in account due to the connection between the anterior and posterior circulation. We hypothesize that in conjunction with PcomA remodeling, there will also be remodeling of the ipsilateral P1 segment of the posterior cerebral artery (PCA) after PED treatment for PcomA aneurysms. Methods: We retrospectively collected radiological as well as clinical data of PcomA aneurysm patients treated with PED including PcomA and P1 vessel diameters before and after treatment as well as patient and aneurysm characteristics. Results: Overall, 14 PcomA aneurysm patients were included for analysis and PED treatment was performed without complications in all patients. In 10 out of 14 patients (71%), a decrease in PcomA diameter was observed and there was a significant mean decrease of 0.78 mm in PcomA diameter on angiographic last follow-up (LFU) (p = 0.003). In the same patient population (10 out of 14 patients), there was meanwhile a significant mean increase of 0.43 mm in the ipsilateral P1 segment diameter observed (p = 0.015). These vessel remodeling effects were in direct correlation with aneurysm occlusion since all of these patients showed aneurysm occlusion at LFU while 29% showed only partial occlusion without vessel remodeling effects. A decrease in PcomA diameter was directly associated with aneurysm occlusion (p = 0.042). There were no neurologic complications on LFU. Conclusion: In the treatment of PcomA aneurysms with PED, the P1 segment of the PCA increases in diameter while the PcomA diameter decreases. Our results suggest that this remodeling effect is associated with aneurysm occlusion and decrease of PcomA is hemodynamically compensated for by an increase in the ipsilateral P1 diameter.

Abstract TMP101: Relationship Between RNF213 p.R4810K (c.14429G&gt;A) Variant and Anatomical Variations of the Circle of Willis

Background and purpose: RING finger protein 213 ( RNF213 ) gene is strongly associated with intracranial arterial stenosis as well as Moyamoya disease and its dysregulation is known to impair cerebral perfusion in rodents. We thus investigated the relationship between RNF213 p.R4810K (c.14429G&gt;A) variant and the anatomical variations of the circle of Willis in cerebrovascular disease. Methods: We consecutively enrolled non-cardioembolic stroke or transient ischemic attack patients with (n = 20) or without (n = 80) RNF213 p.R4810K (c.14429G&gt;A) variation from those who participated in the biobank of our Institute over the past 2 years. Moyamoya disease cases were excluded. We evaluated anatomical variations of the vessels constituting the circle of the Willis, namely, intracranial internal carotid artery, anterior communicating artery (AcomA), anterior cerebral artery A1 segment, posterior communicating artery (PcomA), posterior cerebral artery P1 segment, and middle cerebral artery M1 segment, using maximum intensity projection of a time-of-flight magnetic resonance angiography collected at 3 Tesla. Results: The RNF213 p.R4810K (c.14429G&gt;A) variant carrier had higher frequency of focal narrowing of the M1 segment compared to the non-carrier (50% vs 10%, p&lt;0.01) and an absence of AcomA (15% vs 3.7%, p=0.09). By contrast, unexpectedly, unilateral or bilateral absence of PcomA was significantly less frequent (25% vs 61%, p&lt;0.01). Multivariate analysis adjusted for age and sex showed that the variant carrier state was independently associated with unilateral or bilateral presence of PcomA (odds ratio (OR) 4.44, 95% confidence interval (CI) 1.01 - 20.6, p&lt;0.05) and focal M1 narrowing (OR 3.30, 95% CI 0.82 - 12.6, p=0.09). Conclusions: The RNF 213 p.R4810K (c.14429G&gt;A) variant carrier showed higher frequency of arteriopathy in the anterior circulation accompanied by higher patency rate of PcomA. In the variant carrier, dysplasia of the anterior circulation arteries may lead to compensatory collateral flow from posterior to anterior circulation through PcomA.

Variations of the Circle of Willis at the End of the Human Embryonic Period.

Variations of the circle of Willis (CW) influence blood supply to the brain and adjacent structures in adults. We examined the formation of the CW in 20 human embryo samples at the end of the embryonic period using 3-D reconstructions of serial histological sections. The CW was closed in all samples, and did not form in a single plane, but was composed of multiple stair-like planes. The artery acutely curved at the caudal part of the CW, namely, at the inlet of the basilar artery and bifurcation of the P1 segment of the posterior cerebral artery (PCA), reflecting flexure of the mesencephalon and diencephalon at this stage. Variations were observed in 17 of 20 samples-only anterior parts (anterior communicating artery [Acom] and anterior cerebral artery [ACA]) in 10 samples, only posterior parts (posterior communicating artery [Pcom]) in one sample, and both anterior and posterior parts in six samples. Variations included the Acom formed as partially duplicated in three samples, duplicated in four, plexiform in three, and no channel as a result of a single azygos ACA in one. The ACA formed as duplicated in two, median ACA in two, and right hypoplasia in one. The Pcom formed in hypoplasia of either side in six samples. Variations observed in this study are similar to those observed in fetuses, neonates, and adults. The P1 segment of PCA was very large in all samples. The present observations indicate that variations in the CW are present from the initiation of CW formation. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.

Morphometric analysis of the arteries of Willis Polygon

Abstract Objective: Willis polygon forms the basis of the arterial circulation of the cerebrum. Willis polygon is a vascular structure whom variations are not rare. Knowledge of the anatomy and preservation of its integrity is crucial for performing neurovascular surgery and intracranial tumour surgery. Because of the important vascular and neurological structures, approaches to this region are considered extremely risky. One of the main variations in-person basis is the diameter differences of the arteries, which forms Willis polygon, between the left and right hemispheres. About structure and variations, studies of Rhoton and Yasargil had formed the touchstone. Our aim is to contribute to the literature and clinical studies, to be done in the future, by comparing our results with previous studies about variations and morphometric features of Willis polygon. Methods: Arteries of 30 fresh cadaver brains were examined during autopsies in T.C. Ministry of Justice Istanbul Forensic Science Institute. Bilaterally anterior cerebral artery A1 segment lengths, distance between anterior communicating artery-callosomarginal artery outputs, posterior cerebral artery P1 segment lengths were measured using a digital calliper. After dissections and measures, photos of the region were taken and vascular anatomy and variations noted. From every single cerebrum samples were obtained from bilaterally A1, A2, callosomarginal artery, middle cerebral artery, posterior communicant artery, P1 and basilar artery. Samples were fixed by using 10% buffered-formalin. Taken samples were transported to Marmara University Faculty of Medicine, Department of Anatomy Laboratory. Samples were examined and interior diameters were measured under the microscope. Results: Our results with artery diameters and lengths were similar with literature. Different from literature, in anterior cerebral artery A1 segment, posterior cerebral artery P1 segment and posterior communicant artery no aplasia were noted. In 50% of the samples, callosomarginal artery were originate from A2 segment. In one case, we observed left and right pericallosal arteries were joined together at the end of the A2 segment and continued as a single pericallosal artery. We could not find any information about this variation in the literature. Conclusion: Before surgical operations, detailed knowledge of Willis polygon and evaluation of the pre-op cerebral angiography considering possible variations, reduce mortality and morbidity ratios. In addition, because of the role of flow gradients of Willis polygon in aneurysm formation, and in terms of better understanding the collateral circulation which is important in vascular occlusive diseases and vascular surgery, we believe, more anatomic studies about this region needed.

Association between patency of the circle of Willis and diabetes mellitus in patients with cerebral ischaemic stroke.

ObjectiveTo examine patency of the cerebral anterior and posterior communicating arteries in patients with ischaemic stroke with or without diabetes mellitus.MethodsThis retrospective study included patients with acute ischaemic stroke treated between July 2011 and May 2016. Cerebral infarction was evaluated by magnetic resonance imaging. Anterior and posterior communicating-artery patency was determined using magnetic resonance angiography. Vessels were defined as patent or occluded.ResultsOut of 1 406 patients, incidence of vertebral basilar artery brain infarction and posterior cerebral artery brain infarction were significantly higher in patients with diabetes versus those without diabetes (35.5% versus 22.3% and 11.7% versus 6.8%, respectively). Among patients with posterior cerebral artery brain infarction, anterior and posterior communicating-artery patency rates were higher in patients with diabetes versus those without diabetes (66.7 versus 23.5% and 33.3% versus 5.9% [bilateral], respectively). Among patients with vertebral basilar artery infarction and posterior cerebral artery P1 segment infarction, patency rate of the anterior communicating artery was higher in patients with diabetes versus those without diabetes (55.7% versus 45.9%).ConclusionAmong patients with ischaemic stroke, patency rate of the circle of Willis may be higher in patients with diabetes than those without diabetes.

Clinical features and endovascular therapy of posterior cerebral artery aneurysms: a report of 17 cases

Objective To investigate the clinical features, endovascular embolization therapy, and treatment outcome of posterior cerebral artery aneurysms. Methods The clinical features, treatment and prognosis of 17 patients with posterior cerebral artery aneurysms embolized endovascularly at the Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology from January 2009 to March 2015 were analyzed retrospectively. A total of 18 aneurysms were in 17 cases, 11 (61%) of them were saccular aneurysms, 7 (39%) were fusiform or dissecting aneurysms. Four aneurysms were located in the posterior cerebral artery P1 segment, 1 in P1 and P2 junction zone, 9 in P2 segment, and 4 in P3 segment and beyond. Eight aneurysms were treated with intracapsular coil embolization only, retaining the parent arteries, 6 aneurysms were treated with coil embolization and the parent arteries were occluded at the same time, 1 aneurysm was implanted stents, 1 aneurysm was treated with ballon-assisted embolization, and 2 were not treated.The modified Rankin scale(mRS) was used to evaluate the prognosis. The follow up time ranged from 1 to 5 years. Results In the 18 aneurysms, immediate angiography after aneurysm surgery showed that the treated 15 aneurysms were totally embolized. No cerebral ischemia occurred in 6 patients treated with parent artery embolization. One patient with cerebral arteriovenous malformation occurred rebleeding after procedure and left neurological dysfunction after symptomatic treatment, other patients did not have intervention-related complications and the symptom of neurological deficit. In 17 patients with posterior cerebral artery aneurysms, 16 patients completed follow-up and 1 patient lost to follow up.No recurrence in the 14 treated aneurysms have been demonstrated in the DSA reviews during the follow-up period.The mRS 0 was in 12 cases, 1 in 2 cases, 2 in 3 cases. Conclusions The posterior cerebral artery aneurysms are often located in P2 segments. Dissecting or fusiform aneurysms are more common than other types. According to the characteristics of aneurysms, the appropriate endovascular embolization scheme can be selected. The treatment process is safe and reliable, and the satisfactory efficacy can be obtained. Key words: Intracranial aneurysm; Posterior cerebral artery; Endovascular procedures; Treatment outcome

Posterior cerebral artery P1 segment at the stoma during endoscopic third ventriculostomy in adults

ObjectivesA serious catastrophic complication of endoscopic third ventriculostomy (ETV) is basilar artery (BA) damage. Although the BA has been discussed as the cause of haemorrhage and even pseudoaneurysm, variations of...

Perforating arteries originating from the posterior communicating artery: a 7.0-Tesla MRI study

The aim of this study was to investigate the ability of time-of-flight (TOF) magnetic resonance (MR) angiography at 7.0 Tesla to show the perforating branches of the posterior communicating artery (PCoA), and to investigate the presence of such visible perforating branches in relation to the size of the feeding PCoA. The secondary aim was to visualise and describe the anterior choroidal artery and the perforating branches of the P1-segment of posterior cerebral artery (P1). Forty-six healthy volunteers underwent TOF MR angiography at 7.0 Tesla. With 7.0-Tesla imaging, we visualised for the first time perforating arteries originating from the PCoA in vivo without the use of contrast agents. A perforating artery from the PCoA was found in a large proportion of the PCoAs (64%). The presence was associated with a larger diameter of the underlying PCoA (1.23 versus 1.06 mm, P = 0.03). The anterior choroidal artery was visible bilaterally in all participants. In 83% of all P1s, one or two perforating branches were visible. Non-invasive assessment of the perforating arteries of the PCoA together with the anterior choroidal artery and the perforating arteries of the P1 may increase our understanding of infarcts in the deep brain structures supplied by these arteries.

Coil Embolization of Two Flow-Related Aneurysms in P1 Segment of the Posterior Cerebral Artery in a Patient with Occlusion of the Ipsilateral Internal Carotid Artery

Aneurysms of the posterior cerebral artery (PCA) are uncommon (about 1% of all intracranial aneurysms) and their neurosurgical treatment is associated with high operative risk. We report on two saccular aneurysms of the P1 segment of the right PCA, combined with occlusion of the C1 segment of the internal carotid artery (ICA) detected during routine diagnostic studies in a 58-year-old patient with slight sensory loss in the left extremities. The aneurysms were embolized during two consecutive sessions, without subsequent complications. Endovascular intervention is an efficient method in the treatment of multiple aneurysms in the P1 segment of the PCA.

Endovascular Occlusion of the Posterior Cerebral Artery in the Treatment of P2 Ruptured Aneurysms

Four cases of posterior cerebral artery (PCA) aneurysms are described. The aneurysms were located at the P2 segment of PCA. All cases presented with a subarachnoid hemorrhage (SAH). Endovascular treatment was performed, with occlusion of the aneurysm and parent vessel, using platinum coils. Two patients developed a homonymus lateral hemianopia after treatment.

Utilization of self-expanding stents in the treatment of intracranial atherosclerotic disease in the distal small cerebral vessels

Previously, endovascular treatment of stenosis related to intracranial atherosclerosis (ICAD) involving arteries measuring less than 2 mm in diameter was limited. To our knowledge, there are no reports in the literature addressing stent placement for treatment of stenosis in arteries of this size. Four patients aged 33 to 80 years (mean 57.5 years) with medically refractory ICAD underwent angioplasty and stenting of small (<2 mm) distal intracerebral arteries. Vessel location and length of follow-up were anterior cerebral artery (ACA) A1 segment (5 months), ACA A2 segment (18 months), middle cerebral artery M1 segment (18 months), and posterior cerebral artery P1 segment (8 months) with vessel calibers ranging from 1.2 to 1.8 mm. Clinical and imaging follow-up ranged from 5 to 18 months. All procedures were successfully performed without complications. Follow-up out to 18 months demonstrated one vessel that went on to occlusion while the other stented vessel segments remained patent. One patient died 8 months after stenting, but the death was not related to neurological disease. The remaining patients experienced resolution of the presenting symptomatology and remained asymptomatic throughout follow-up. In this small series, stenoses of distal (<2 mm) cerebral arteries were amenable to treatment using new self-expanding stents. We safely and successfully treated four arteries smaller than 2 mm in diameter with newer self-expanding stents. All patients remained clinically asymptomatic. One stent occluded at 5 months and the others remained patent during follow-up. Longer term clinical follow-up is required to determine the durability and viability of this therapy.