Precommunicating Segment Research Articles

Endovascular Treatment in Precommunicating Segment Aneurysms of Posterior Cerebral Artery

Pre-communicating (P1) segment aneurysms of the posterior cerebral artery (PCA) are rare, with few studies reported to date. Herein, we address the clinical and radiologic outcomes of their endovascular treatment. For this study, we retrieved prospectively collected data on 35 consecutive patients with 37 P1 aneurysms, analyzing the clinical ramifications and morphologic outcomes of treatment. All subjects received endovascular interventions between January 2001 and October 2021. There were 16 aneurysms (43.2%) of P1 segment sidewalls and 21 (56.8%) at P1/posterior communicating artery (PCoA) junctions. Five (13.5%) were fusiform, and 14 (37.8%) were ruptured. In 14 patients (40%), 16 aneurysms (43%) were associated with intracranial arterial occlusive disease of the anterior circulation. Selective coiling was undertaken in 34 aneurysms (91.9%), using single (n=24) or double (n=4) microcatheters, microcatheter protection (n=2), or stents (n=4); and trapping was done in 3 (8.1%). No procedure-related morbidity or mortality resulted. Excluding the trapped lesions, angiographic follow-up of 29 aneurysms obtained >6 months after embolization (mean, 12.4 month) revealed stable occlusion in 21 (72.4%), with some recanalization in the other 8 (minor: 3/29, 10.4%; major: 5/29, 17.2%). Aneurysms of P1 segment (vs other locations) are strongly associated with intracranial arterial occlusive disease of the anterior circulation and thus are likely flow related. Endovascular treatment of such lesions seems safe and efficacious, despite the array of technical strategies that their distinctive anatomic configurations impose.

Unilateral Oculomotor Nerve Palsy as a Rare Manifestation of Isolated Pre-Communicating Segment of Posterior Cerebral Artery Thrombosis.

Ipsilateral mydriasis (IM) is usually not acute. However, the acute occurrence of unilateral dilated pupil may result in acute ischemic stroke. Herein, we present 3 patients with IM, lateral eye deviation, ptosis, and contralateral hemiparesis due to isolated occlusion of the pre-communicating segment of the posterior cerebral artery with preservation of the posterior communicating artery, which was successfully treated by emergent mechanical thrombectomy. In a 3-month follow-up, all patients were independent without any neurological deficits.

Relationship between diameter asymmetry and blood flow in the pre-communicating (A1) segment of the anterior cerebral arteries

BackgroundAsymmetry in diameter between pre-communicating (A1) segments of the anterior cerebral arteries is related to anterior communicating artery aneurysm formation. Diameter asymmetry definitions vary and have not been related to blood flow measurements using the same imaging modality. We aimed to evaluate the relationship between A1-diameter asymmetry and blood flow asymmetry and to define a hemodynamically significant cut-off value for A1-diameter asymmetry. We assessed sex differences between different groups of A1-asymmetry. Materials and methods3-Tesla time-of-flight MRA and 4D-phase-contrast MRI were performed in 122 healthy participants. Diameter and blood flow measurements were performed halfway in both A1-segments. Participants were subdivided based on A1-diameter asymmetry: ≤10% (symmetric); 11–20%; 21–30%; 31–40%; and >40% (increasing asymmetry) groups. We studied the relationship between A1-diameter asymmetry and corresponding flow asymmetry (scatterplot and correlation). A hemodynamic-based cutoff value for A1-asymmetry was determined by comparing dominant A1 blood flow in the asymmetry groups to the mean blood flow of the symmetric A1-group (linear mixed-effects model). Sex-related differences in A1-diameter, blood flow and asymmetry were assessed with t-tests. ResultsA1-diameter asymmetry was linearly related to blood flow asymmetry between dominant and non-dominant sides. A1-diameter asymmetry >30% yielded statistically significant increased blood flow in the dominant A1 compared to symmetric A1s. Men had statistically significant larger A1-diameters, higher blood flow and a similar degree of A1-diameter asymmetry compared to women. ConclusionA1-diameter asymmetry is linearly related to blood flow asymmetry. A >30% A1-asymmetry can be used as hemodynamically significant cut-off value. There were no sex-related differences in A1-diameter asymmetry.

Endoscopic endonasal surgical anatomy through the prechiasmatic sulcus: the key window to suprachiasmatic and infrachiasmatic corridors

Classically, the transtuberculum and transplanum approaches have been utilized to reach the suprachiasmatic and infrachiasmatic corridors. The aim of this study was to provide a better understanding of the key endoscopic endonasal anatomy of the suprachiasmatic and infrachiasmatic corridors provided through selective removal of the prechiasmatic sulcus (SRPS). A SRPS was performed in 16 sides of 8 alcohol-fixed head specimens. Twenty anatomical measurements were collected on the suprachiasmatic and infrachiasmatic corridors. The transplanum and transtuberculum approaches were also performed. In the suprachiasmatic corridor, the SRPS exposed the anterior communicating artery (AComm) and the post-communicating segment of the anterior cerebral arteries in all the cases, while the pre-communicating segment of the anterior cerebral arteries, recurrent arteries of Heubner, and fronto-orbital arteries were visualized in 75% (12/16), 31% (5/16), and 69% (11/16) of cases, respectively. In the infrachiasmatic corridor, the ophthalmic segment of the internal carotid artery and superior hypophyseal arteries were always visible through the SRPS. The mean width and height of the prechiasmatic sulcus were 13.2mm and 9.6mm, respectively. The mean distances from the midpoint of the AComm to the anterior margin of the optic chiasm (OCh) was 5.3mm. The mean width of the infrachiasmatic corridor was 12.3mm at the level of the proximal margin of the ophthalmic segment of the internal carotid artery. The mean distances from the posterior superior limit of the pituitary stalk to the basilar tip and oculomotor nerve were 9.7mm and 12.3mm, respectively. The SRPS provides access to the main neurovascular and cisternal surgical landmarks of the suprachiasmatic and infrachiasmatic corridors. This anatomical area constitutes the key part of the approach to the suprasellar area. To afford adequate surgical maneuverability, the transplanum or transtuberculum approaches are usually a necessary extension.

Fetal-Type Variant of the Posterior Cerebral Artery and Concurrent Bilateral Cerebral Infarctions in a Korean Male Cadaver

Fetal-type variant of the posterior cerebral artery is a relatively common variant of the cerebral arterial circle (circle of Willis), but concurrent cerebral pathologies have not been well reported. We describe a case of fetal-type variant of the posterior cerebral artery and concurrent bilateral cerebral infarctions in the territories of the middle cerebral artery in a 78-year-old Korean male cadaver. Fetal-type variant of the posterior cerebral artery was found the right cerebral arterial circle, arose from the internal carotid artery with larger diameter than the pre-communicating segment from the basilar artery. Histopathological examination revealed that left supramarginal gyrus and right infraparietal lobule showed characteristic cerebral infarctions with chronological changes, respectively. Knowledge on the variation in the posterior cerebral artery combined with clinical features including cerebral infarction plays a pivotal role to anatomists and clinicians.

Morphological evaluation of the distal medial striate artery. A study with cadaveric material.

Objective: To evaluate the morphology of the distal medial striated artery, taking into account biometric variables useful for clinical and surgical management. Methods: A descriptive transversal study was performed with a sample of brains, who underwent autopsy at the Institute of Legal Medicine and Forensic Sciences of Bucaramanga-Colombia, which were evaluated using the perfusion technique of vascular structures with polyester resin.Results: The distal medial striated artery was presented in 1.4% and 4.2% duplicated in the right and left hemispheres respectively. Agenesis was presented in 2.8% in the left hemisphere. Its origin was 44.6% of the anterior cerebral artery junction site with the anterior communicating artery and was observed in 6 cases (4.2%) presented with a common trunk with the orbitofrontal artery. The main qualitative finding was the sinuous trajectory that was observed in 57.7% on the right side and 45.1% in the left hemisphere. Also, an important alteration found at the biometric analysis was hypoplasia that could be related to the decreased blood supply to the basal nuclei. The diameter was 0.5 ± 0.2 mm and its total length was 20.3 ± 4.1 mm.Conclusions: The topographical knowledge of this structure determines the vulnerability of its morphology because it can complicate surgical procedures performed in the anterior segment of the arterial circle of the brain. Besides, the observed collateral circulation contributes to the blood supply and the perfect functionality of the subcortical nervous structures.

The vascular patterns of the posterior part of the circulus arteriosus cerebri (Willisi).

Various authors defined three patterns of the posterior part of the circulus arteriosus cerebri Willisi (CW) according to the diameter of the posterior communicating artery (PCoA) and the precommunicating segment of the posterior cerebral artery (P1). In the adult pattern, the P1 has a diameter larger than the non-hypoplastic PCoA. In the transitional pattern, the diameter of the PCoA is equal to that of the P1. In the fetal pattern, the diameter of the P1 is smaller than the diameter of the PCoA. The study was aimed to evaluate the configurations and calibers of the posterior part of the CW. The work was conducted on 185 adult post-mortem brains. The CW and its branches were photographed by a digital camera. We used the software Image J to evaluate and process the gained images. The fetal pattern was found unilaterally in 8.37 %, and bilaterally in 4.86 %. The transitional pattern was observed unilaterally in 6.47 %, and bilaterally in 1 %. The prevalence of the unilateral and bilateral adult patterns was equal (21.62 % for each configuration). The hypoplastic PCoA was found unilaterally in 17.57 %, and bilaterally in 16.76 %. Various factors including genetic and environmental may affect the development of the cerebral vessels and their dimensions. The distinguishing of the vascular dimensions in vivo can help in the expectation and may be the avoidance of possible cerebrovascular disturbances in the future. Correlation and interdisciplinary cooperation of the studies dealing with morphology, radiology, and hemodynamics of the cerebral vessels are becoming an urgent need. The assumed results of this cooperation can be used in tabulating the calibers of the cerebral vessels and determining the threshold dimensions under which failure of hemodynamics and collateral function may appear (Tab. 2, Fig. 5, Ref. 28).

Study of Variant Posterior Cerebral Circulation and its Clinical Relevance

The cerebral blood flow is divided into an anterior circulation and a posterior circulation connected to each other in the form of a circle called Circle of Willis (CW). It is formed by the unification of the internal carotid (ICA) and vertebrobasilar systems Posteriorly, the basilar artery, formed by the left and right vertebral arteries, branches into a left and right posterior cerebral artery (PCA), forming the posterior circulation. The internal carotid system lies anteriorly and is joined to the posterior circulation by posterior communicating (PCoA) arteries. The internal carotid artery divides into anterior and middle cerebral artery. The two anterior cerebral arteries are joined to each other by an anterior communicating artery. The posterior cerebral artery before it joins the posterior communicating artery that means its proximal part is named as the pre communicating part (P1) and the distal part as the post communicating part (P2). In the adult P1 has a diameter larger than the PCoA so that the occipital lobe gets its blood supply mainly via the vertebrobasilar system whereas in the fetus the diameter of the ipsilateral precommunicating (P1) segment of PCA is less than the diameter of PCoA, so that the blood supply to [1] the occipital lobe is mainly via the internal carotid arteries. In some persons, there is a transitional configuration in which the PCoA is equal in diameter to the P1 segment of the PCA. These variations can cause complications if thrombotic material present in atherosclerotic plaques of ICA gets dislodged into PCA through a PCoA which has a larger diameter. In the present study, the configuration of posterior cerebral circulation and its clinical relevance was studied in 40 human brains in the department of anatomy at KJSMC. Adult Type PCA was found in 60% of the specimens studied, Fetal Type PCA was found in 12.5% of the specimens, Transitional Type PCA was found in 25% of the specimens and a combination of Adult and Transitional Type was found in 2.5% of the specimens.

Morphological characteristics of the anterior cerebral artery

Cerebral circulation, especially arterial, in recent decades has attracted the interest of anatomists and clinicians. The anterior cerebral artery (ACA) arises from the termination of the ipsilateral internal carotid artery, and supplies blood to the medial regions of the frontal and parietal cortex, corpus callosum and falx cerebri. The ACA is usually divided into 5 segments. The aim of this study was to determine the morphological and topographic characteristics of the A1 or precommunicating segment of the ACA. The investigations of anatomical characteristics of the A1 segment of ACA was made on 133 human brains without cerebrovascular pathology, from both sexes at age from 23 to 68. Brains were fixed in a 10% solution of formaldehyde, and the obtained material was analyzed using a stereoscopic light microscope. The length of the A1 segment of ACA was in range from 6.8 to 20.8 mm, with mean value of 13.9 mm on the left side and from 7.4 to 21.8 mm, with mean value of 14.6 mm on the right side. The diameter of A1 segment of ACA on the left side was in range from 1.1 to 3 mm, with a mean value of 2.2 mm. The diameter of A1 segment of ACA on the right side was in range from 0.6 to 3.1 mm, with a mean value of 2.0 mm. Hypoplastic caliber of A1 segment of the ACA was noticed in 8% and in 0.5% duplication of the A1 segment of the ACA was registered. Detailed anatomical knowledge of the A1 segment of ACA is important when considering vascular surgery in the area of the anterior portion of the circle of Willis, since is the most common site of intracranial aneurysm formation.

Coil embolization in precommunicating (A1) segment aneurysms of anterior cerebral artery

Precommunicating (A1) segment aneurysms of the anterior cerebral artery are rare and often pose technical challenges for coil embolization due to their distinctive configurations. Clinical and radiologic outcomes of treating such aneurysms through endovascular coil embolization are presented herein. Data accruing prospectively from May 2002 to August 2013 yielded 48 patients harboring 50 A1 segment aneurysms, each classified as proximal, middle, or distal by location. Clinical outcome of the patients and morphological outcome of the aneurysms were assessed, with emphasis on technical aspects of treatment. The aneurysms studied occupied either proximal (n = 39), middle (n = 6), or distal (n = 5). Proximal aneurysms were largely directed posteriorly (80 %), and most (97 %) were devoid of branches. Middle and distal aneurysms were associated with the medial lenticulostriate artery, cortical branches, or fenestrations. The preshaped "S" and steam-shaped "S" microcatheters facilitated aneurysm selection in 60 % of lesions. Single-microcatheter technique was most commonly applied for coil embolization (62 %), followed by balloon protection (16 %). Successful aneurysmal occlusion could be achieved in 76 % of the patients, with no procedure-related morbidity and mortality. At final follow-up (mean interval, 29.9 months), stable aneurysmal occlusion was sustained in 93 % of the patients (40/43). A1 segment aneurysms are amenable to safe and efficacious endovascular coil embolization by adjusting procedural strategy to accommodate distinctive anatomic configurations.

True posterior communicating artery aneurysms: are they more prone to rupture? A biomorphometric analysis

Posterior communicating artery (PCoA) aneurysms can occur at the junction with the internal carotid artery, posterior cerebral artery (PCA), or the proximal PCoA itself. Hemodynamic stressors contribute to aneurysm formation and may be associated with parent vessel size and aneurysm location. This study evaluates the correlation of various biomorphometric characteristics in 2 of the aforementioned types of PCoA aneurysms. Patients with PCoA aneurysms were analyzed using CT angiography. Source images and reconstructions were used to determine which aneurysms originated purely from the PCoA and those that originated from the internal carotid artery/PCoA junction. Morphometric analysis was performed on the aneurysm, the precommunicating segment of the PCA (P(1)), the ambient segment of the PCA (P(2)), and both PCoA arteries and were correlated to clinical presentation. Parametric and nonparametric analyses were performed to test for significance. A total of 77 PCoA aneurysms were analyzed, and 10 were found to be true PCoA aneurysms (13.0%). The ipsilateral PCoA/P(1) ratio (1.77 +/- 0.44 vs 0.82 +/- 0.46, p = 0.0001) and ipsilateral P(2)/P(1) ratio (1.73 +/- 0.40 vs 1.22 +/- 0.41, p = 0.0003) were significantly larger in true PCoA aneurysms. Interestingly, aneurysm size was statistically larger in the junctional aneurysms (0.14 +/- 0.1 vs 0.072 +/- 0.04 cm(3), p = 0.03). The prevalence of ruptured aneurysms was similar in both groups (approximately 80%, p value not significant). These data suggest that true PCoA aneurysms have a larger PCoA relative to the ipsilateral P(1) segment. To the authors' knowledge, this represents the first such biomorphometric comparison of these different types of PCoA aneurysms. Although statistically smaller in size, true PCoA aneurysms also have a similar prevalence of presenting as a ruptured aneurysm, suggesting that they might be more prone to rupture than a junctional aneurysms of similar size. Further analysis will be required to determine the biophysical factors affecting rupture rates.

Características morfológicas de aneurimas cerebrales del polígono de Willis: estudio anatómico directo

To determine the prevalence and morphologic characteristics of unruptured aneurysms of Willis' circle in a sample of mestizo Colombian population. A mixture of resin and mineral red was injected into cerebral arteries by dissection and canalization of common carotids and vertebral arteries of the encephalons of 125 mestizo male cadavers of 16 to 65 years old. The procedure was carried out during the autopsy course at the Legal Medicine Institute, Bucaramanga - Colombia. Then the encephalons were extracted and fixed. After that, the Willis' circles were identified and the presence of aneurysms at this level was determined with magnifying glass. A total of nine aneurysms were observed in six brains (4.8%). The most frequent location was the supraclinoid segment of the intern carotid artery, with 4 cases (44.4%), three of which were localized in the origin of the anterior choroidal artery. Additionally, three aneurysms were found in the anterior communicating artery (33.3%). From the remaining cases, one (11.1%) was localized in the pre-communicating segment of the anterior cerebral artery, and the other in the bifurcation of the basilar artery. The average size of the aneurysms was 2.49 mm SD 0.37. The affected encephalons presented concomitant variations of the Willis' circle configuration, being predominant the presence of hypoplasic posterior communicanting arteries. The aneurysm prevalence in the evaluated sample was similar to the reported in other populations. In this work, the presence of aneurysms on the origin of the anterior chorioid artery, an unusually reported localization, was prominent.

Power Doppler: An advance over colour Doppler for transcranial imaging?

The aim of this study is to compare the ability of mean frequency-based colour Doppler (CD) and power Doppler (PD) to identify the basal cerebral arteries in normal subjects. Fifty volunteers were recruited into the study. The temporal acoustic window was used to image the basal cerebral arteries bilaterally. The number of positively identified vessels was recorded, first using CD and then with PD. Our results show that both modalities were equally effective at demonstrating the anterior cerebral artery (ACA), the middle cerebral artery mainstream (MCA M1) and the precommunicating segment of the posterior cerebral artery (PCA P1; ACA: 82% and 83%; MCA M1: 84% and 89%; PCA P1: 81% and 83%; CD and PD, respectively). However, the M2 portion of the MCA (CD: 25%, PD: 54%; difference 29% [95% CI 20–38%]), the P2 portion of the PCA (CD: 67%, PD: 75%; difference 8% [95% CI 3–13%]) and the posterior communicating artery (CD: 15%, PD 32%; difference 17% [95% CI 10–24%]) were all identified in a significantly greater proportion of subjects using PD. Although its clinical value remains undetermined, PD offers significant advantages over colour-coded sonography in imaging small-calibre and low-flow arteries and those which run at unfavourable angles to the ultrasound beam.

A dosage study of the effect of the 21-aminosteroid U74006F on chronic cerebral vasospasm in a primate model

The efficacy of the 21-aminosteroid U74006F was investigated using different dosages in a restricted, randomized, placebo-controlled trial. Forty cynomolgous monkeys were divided into five groups of eight. There were two groups given treatment with placebos, one being saline and the other the vehicle in which U74006F was delivered. There were three U74006F treatment dosage groups: 0.3, 1.0, and 3.0 mg/kg. Each monkey underwent baseline cerebral angiography followed by right-sided craniectomy and subarachnoid placement of a clot around the middle cerebral artery (MCA). Treatment was administered intravenously every 8 hours for 6 days. Seven days after experimental subarachnoid hemorrhage, angiography was repeated, and the animals were killed. In both saline or vehicle placebo treatment groups, significant vasospasm (VSP) occurred on the clot side in the extradural internal carotid artery (C3), the intradural internal carotid artery, the precommunicating segment of the anterior cerebral artery (A1,) and the MCA (P less than 0.01). After U74006F treatment, significantly less VSP developed in the A1 on the clot side (0.3 mg/kg U74006F treatment group) and the MCA (all U74006F treatment groups, P less than 0.05). When the percentages of change from the baseline for the vessel diameters on the clot side were compared, VSP was attenuated in the A1 (P less than 0.05) and MCA (P less than 0.001) of all U74006F treatment groups as compared with the placebo treatment groups. Only 0.3 mg/kg of U74006F significantly prevented VSP in C3 (P less than 0.01). Although the 0.3 mg/kg dosage appeared to have the most favorable effect, no significant differences were observed among the three dosage groups. Electron microscopy of the MCA on the clot side in the animals treated with U74006F still showed luminal convolutions and morphological changes in the endothelial cells. These changes appeared less prominent in those MCAs with milder VSP. If these results in primates are applicable to humans, U74006F would be useful in reducing VSP after aneurysmal subarachnoid hemorrhage.

Ocular motor disturbances occurring as false localizing signs in ruptured intracranial aneurysms.

The clinical aspect and mechansims of production of ocular motor disturbances appearing as false localizing signs are discussed in four patients who were observed in a series of 102 consecutive admissions of patients with ruptured intracranial aneurysms. The aneurysms were located on the anterior communicating artery and the precommunicating segment of the right anterior cerebral artery.

Distribution of contrast media in cerebral angiography. I. Carotid angiography with filling of the basilar trunk

A propósito da passagem de contraste, nas angiografias por via carotídea, para vasos não pertencentes ao território de distribuição da artéria na qual o contraste foi injetado, foi feita uma revisão de 700 angiografias. O segmento pós-comunicante da artéria cerebral posterior ipsilateral foi encontrado em 42,5% dos casos; o segmento pós-comunicante da artéria cerebral anterior contralateral apareceu em 49,4%; maior ou menor extensão do segmento pré-comunicante da artéria cerebral anterior do lado oposto foi encontrada em 9,85%; a artéria cerebral média bem como o segmento pré-comunicante da cerebral anterior do lado oposto foram encontrados em 4,85% dos casos. A freqüência da visibilização de outras artérias não pertencentes ao território do vaso no qual o contraste foi injetado pode ser fàcilmente verificada no quadro 1. O motivo principal desta publicação foi dado por um grupo de 22 angiografias, nas quais o contraste, injetado por via carotídea, penetrou também no sistema vértebro-basilar. O fato verificado nestas 22 angiografias cerebrais tem sido relatado raramente. Da discussão do mecanismo pelo qual o contraste penetra no tronco basilar, chegando mesmo, por vêzes, até às artérias vertebrais, resultou uma hipótese segundo a qual o fenômeno seria condicionado por hipotensão arterial, acentuada, mas passageira, produzida por um reflexo hiperativo do seio carotídeo provocado pela própria injeção do contraste. Se fôr comprovada esta hipótese, a demonstração angiográfica de todo o sistema arterial encefálico com uma só injeção de contraste por via carotídea poderá ser viável, deliberadamente, empregando hipotensão induzida e controlada.