Posterior cerebral artery (PCA)-accessory PCA (hyperplastic anterior choroidal artery) anastomosis detected on magnetic resonance angiography.

PURPOSE: To describe a case of posterior cerebral artery (PCA)-accessory PCA (hyperplastic anterior choroidal artery) anastomosis detected on magnetic resonance angiography. METHODS: A 76-year-old man with a history of cerebral infarction underwent cranial magnetic resonance (MR) imaging and MR angiography of the intracranial region for the evaluation of brain and vascular lesions. The MR machine was a 3-Tesla scanner. MR angiography was performed using a standard three-dimensional time-of-flight technique. RESULTS: There were two right PCAs. The parieto-occipital and calcarine arteries of the right PCA arose from the right ICA, indicative of accessory PCA, and there were three stenotic lesions at the proximal segment of this artery. The temporal artery of the right PCA originated from the basilar artery. A small anastomotic channel between these two arteries was identified on partial maximum intensity projection (MIP) images. Computed tomography angiography was additionally performed and the findings were confirmed. CONCLUSION: We speculated that the pressure gradient between the PCA and the accessory PCA enlarged the anastomotic channel. Partial MIP images are useful for diagnosing small arterial variations using MR angiography.

Replaced posterior cerebral artery.

PURPOSE: Replaced posterior cerebral artery (PCA), defined as a hyperplastic anterior choroidal artery (AChA) supplying all branches of the PCA, is an extremely rare anatomical variation. To the best of our knowledge, there are only a few reports of replaced PCA. METHODS: Herein, we report a case of replaced PCA diagnosed by digital subtraction angiography. RESULTS: A 76-year-old woman visited a neurosurgical clinic because of headache and vertigo. Magnetic resonance imaging and magnetic resonance angiography incidentally revealed a left internal carotid artery aneurysm. She was referred to our hospital for further examination and treatment of the unruptured intracranial aneurysm. Left internal carotid angiography revealed a paraclinoid aneurysm. We also incidentally found an anomalous hyperplastic AChA distal to the aneurysm. This hyperplastic AChA supplied not only the AChA territory but also the entire PCA territory. No vessels that could be a normal AChA or posterior communicating artery were identified along the left internal carotid artery. Vertebral angiography demonstrated that the left PCA was not visualized. With these findings, we diagnosed anomalous hyperplastic AChoA in this case as replaced PCA. CONCLUSION: Careful imaging assessment is important to identify replaced PCA. Both direct findings of a hyperplastic AChA course and perfusion territory and indirect findings of the absence of the original PCA are useful in the diagnosis of replaced PCA.

Extremely long posterior cerebral artery P1 segment.

PURPOSE: 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. METHODS: 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). RESULTS: 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 27.3 mm. The left posterior communicating artery (PCoA) was 20.9 mm, 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. CONCLUSION: 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.

Complete duplication of the posterior cerebral artery.

PURPOSE: Variations of the posterior cerebral artery (PCA) are rare, excluding aplasia or hypoplasia of the P1 segment. To the best of our knowledge, there are few reports of complete duplication of the PCA. METHODS: Herein, we report a case of complete duplication of the PCA diagnosed by 1.5 T magnetic resonance angiography. RESULTS: A 55-year-old woman visited our hospital for cerebrovascular disease screening. Magnetic resonance angiography revealed two right PCAs with similar diameters. One PCA originated as the P1 segment of the PCA branching from the basilar artery, and the other was the fetal-type posterior communicating artery (PCoA) branching from the internal carotid artery (ICA). Neither PCA supplied the right anterior choroidal artery (AChA) territory. Bilateral PCoAs branched from the same position as each ICA, respectively. The right AChA branched from the ICA distal to the PCoA branching position. CONCLUSION: Careful imaging assessment is important for identifying complete duplication of the PCA. In addition to the direct findings of AChA identification, the indirect findings of the PCoA branching position and that the PCAs did not supply the AChA territory were also useful for diagnosis in this case.

Posterior Communicating Artery Hypoplasia: A Risk Factor for Vertebral Artery Dissection Causing Subarachnoid Hemorrhage.

OBJECTIVE: Subarachnoid hemorrhage due to vertebral artery dissection is often fatal; however, its anatomical predictors remain unclear. We conducted a retrospective hospital-based case-control study to evaluate whether variations in the posterior communicating artery are associated with the risk of vertebral artery dissection with subarachnoid hemorrhage. MATERIALS AND METHODS: We obtained data from patients who underwent computed tomography angiography at our hospital between April 2010 and March 2020. Based on the connection between the anterior and posterior circulation of the arterial circle of Willis, the patients were categorized into a separated group (posterior communicating artery hypoplasia) and a connected group (all others). We evaluated the association between the development of posterior communicating artery and subarachnoid hemorrhage due to vertebral artery dissection using multivariate logistic regression analysis. RESULTS: Thirty-eight patients had subarachnoid hemorrhage due to vertebral artery dissection and 76 were identified as age- and sex-matched controls. In conditional multivariate logistic regression analysis, the separated group showed a significant association with subarachnoid hemorrhage due to vertebral artery dissection, with an adjusted odds ratio of 2.8 (95% confidence interval, 1.2-6.5; P = 0.021). CONCLUSIONS: The present study demonstrates that posterior communicating artery hypoplasia may be associated with subarachnoid hemorrhage due to vertebral artery dissection. Our results highlight the importance of anatomical variations in the cerebral artery and provide evidence to help develop preventive measures against strokes.

Fetal-type variant of the posterior cerebral artery and concurrent bilateral cerebral infarctions in a Korean male cadaver / Variante de tipo fetal de la arteria cerebral posterior e infartos cerebrales bilaterales concurrentes en un cadáver masculino coreano

SUMMARY: 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.

RESUMEN: La variante de tipo fetal de la arteria cerebral posterior es una variante relativamente común del círculo arterial cerebral (polígono de Willis) de arterial cerebral, pero las patologías cerebrales concurrentes no han sido bien informadas. Describimos un caso de variante de tipo fetal de la arteria cerebral posterior e infartos cerebrales bilaterales concurrentes en los territorios de la arteria cerebral media en un cadáver masculino coreano de 78 años. La variante de tipo fetal de la arteria cerebral posterior se encontró en la parte de derecha del círculo arterial cerebral, surgido de la arteria carótida interna con mayor diámetro que el segmento precomunicante de la arteria basilar. El examen histopatológico reveló que el giro supramarginal izquierdo y el lóbulo infraparietal derecho mostraban infartos cerebrales característicos con cambios cronológicos, respectivamente. El conocimiento sobre la variación en la arteria cerebral posterior combinado con las características clínicas, incluido el infarto cerebral es fundamental para los anatomistas y los médicos.

Risk Factors for the Recurrence of Posterior Communicating Artery Aneurysm: The Significance of Fetal-Type Posterior Cerebral artery.

OBJECTIVES: The purpose of this study was to investigate the risk factors associated with recurrence of posterior communicating artery aneurysms after treatment and to evaluate the significance of fetal-type posterior cerebral artery as an independent risk factor for recurrence of posterior communicating artery aneurysms. MATERIALS AND METHODS: The clinical and radiological findings of 220 posterior communicating artery aneurysms treated between January 2009 and December 2016 in a single tertiary institute were retrospectively reviewed. Univariate and multivariate analyses were performed to evaluate the association between clinical and radiological variables and recurrence. RESULTS: Of 220 posterior communicating artery aneurysms, 148 aneurysms were unruptured and 82 aneurysms were treated with surgery. Forty-six out of 220 aneurysms (20.9%) were associated with fetal-type posterior cerebral artery. Overall recurrence rate was 19% (42 out of 220 aneurysms) during mean 54.6 ± 29.8 months follow-up. Multivariate logistic regression analysis showed that size (OR=1.238; 95% CI, 1.087-1.409, p = 0.001), ruptured status (OR=2.699; 95% CI, 1.179-6.117, p = 0.019), endovascular treatment (OR=3.803; 95% CI, 1.330-10.875, p = 0.013), incomplete occlusion (OR=4.699; 95% CI, 1.999-11.048, p = <0.001) and fetal-type posterior cerebral artery (OR=3.533; 95% CI, 1.373-9.089, p = 0.009) were significantly associated with recurrence after treatment. CONCLUSIONS: The results demonstrated that fetal-type posterior cerebral artery may be an independent risk factor for the recurrence of posterior communicating artery aneurysms. Therefore, fetal-type posterior cerebral artery can be considered as an important risk factor for the recurrence of posterior communicating artery aneurysms, along with other known risk factors such as size, ruptured status, endovascular treatment, and incomplete occlusion.

Medial type persistent trigeminal artery associated with a saccular aneurysm at its trunk.

There are four types of fetal anastomosis between the carotid and vertebrobasilar arteries at 5 weeks gestation; from caudal to cranial position, these involve the proatlantal intersegmental, hypoglossal, otic, and trigeminal arteries. Excluding otic artery, these arteries may persist rarely. Persistent trigeminal artery (PTA) is the most common carotid-vertebrobasilar anastomosis, and the medial type (intrasellar) PTA is quite rare, accounting for approximately 10% of all PTA cases. An aneurysm is occasionally found at the origin of the PTA. Rarely, an aneurysm arises at the trunk of the PTA. Using magnetic resonance angiography, we identified a case of medial type PTA with an unruptured saccular aneurysm at its trunk.

Ascending pharyngeal artery-posterior inferior cerebellar artery anastomosis via the jugular foramen: a case report and literature review.

The posterior inferior cerebellar artery (PICA) rarely arises from the cavernous segment of the internal carotid artery (ICA) and is called persistent trigeminal artery variant. The PICA also can arise from the cervical segment of the ICA, and it enters the posterior fossa via the hypoglossal canal, where it is called persistent hypoglossal artery variant. Using magnetic resonance angiography (MRA), we diagnosed a 79-year-old man with a PICA arising from the ascending pharyngeal artery and passing through the medial side of the jugular foremen pars vascularis. Only six cases of this variation have been reported previously in the English language literature. To identify this variation on MRA, the careful observation of source images is useful. Recognizing this variation is important in order to avoid ischemic cerebellar complications during neck surgery and endovascular therapy.

Asymmetry of P1 and vertebral arteries is not related to basilar tip aneurysm development or rupture.

OBJECTIVE: Lately, morphological parameters of the surrounding vasculature aside from aneurysm size, specific for the aneurysm location, e.g., posterior cerebral artery angle for basilar artery tip aneurysms, could be identified to correlate with the risk of rupture. We examined further image-based morphological parameters of the aneurysm surrounding vasculature that could correlate with the growth or the risk of rupture of basilar artery tip aneurysms. METHODS: Data from 83 patients with basilar tip aneurysms (27 not ruptured; 56 ruptured) and 100 control patients were assessed (50 without aneurysms and 50 with aneurysms of the anterior circle of Willis). Anatomical parameters of the aneurysms were assessed and analyzed, as well as of the surrounding vasculature, namely the asymmetry of P1 and the vertebral arteries. RESULTS: Patients with basilar tip aneurysm showed no significant increase in P1 or vertebral artery asymmetry compared with the control patients or patients with aneurysms of the anterior circulation, neither was there a significant difference in asymmetry between cases with ruptured and unruptured aneurysms. Furthermore, we observed no significant correlations between P1 asymmetry and the aneurysm size or number of lobuli in the aneurysms. CONCLUSION: We observed no significant difference in aneurysm size, rupture, or lobulation associated with P1 or vertebral artery (surrounding vasculature) asymmetry. Therefore, the asymmetry of the surrounding vessels does not seem to be a promising morphological parameter for the evaluation of probability of rupture and growth in basilar tip aneurysms in future studies.

Fetal posterior cerebral artery duplication, true fetal posterior cerebral artery variation and trifurcation anterior cerebral artery association.

We would like to present a case with fetal posterior cerebral artery duplication and anterior cerebral artery trifurcation, which we detected using magnetic resonance angiography. We believe this is the first case defined in the literature. Embryological explanation of posterior cerebral artery variations is discussed in light of the literature.

Rare neurovascular conflict between oculomotor nerve and posterior communicating artery.

Paroxysmal diplopia could be the expression of a multitude of clinical or anatomical conditions. Both ophthalmological and neurological pathologies could be responsible of this symptom. Rarely, a neurovascular conflict involving the oculomotor nerve is the etiology. We present the case of a 75-year-old man who presented for a 20-year history of transient vertical diplopia. The radiological exams demonstrated the presence of a neurovascular conflict between the right oculomotor nerve and a fetal-type posterior communicating artery. This fetal posterior communicating artery had an aberrant downward course that compressed the third cranial nerve. Few cases of neurovascular conflict interesting the third cranial nerve were described in the literature whom the responsible artery was generally the superior cerebellar artery. No case of oculomotor nerve compression by the posterior communicating artery was published. Authors have reviewed the literature and discuss the embryology of the posterior communicating artery, pathophysiology, radiological findings, and therapeutic possibility.

Fetal origin of posterior cerebral artery related to poor collaterals in patients with acute ischemic stroke.

The anatomic variation of Circle of Willis (CW) has been shown to have a great impact on its compensatory capacity during acute ischemic stroke. The purpose of the study was to evaluate the effect of variations in CW on collateral circulation in patients with acute ischemic stroke who had major artery occlusion. Patients with acute ischemic stroke within 4.5 h of stroke onset who had at least moderate severity of stroke (NIHSS ≥ 6), caused by major artery occlusion were included. Multiphase computed tomography angiography (CTA) was performed. Variations in CW on each patient were recorded and compared between those with poor collateral and intermediate-good collateral circulation. There were 66 patients. Mean NIHSS was 15. Forty patients had poor collateral circulation and 26 patients had intermediate-good collateral circulation. There were variations in CW: no visualized posterior communicating artery (PCOM) (31/66, 47%), fetal origin of posterior cerebral artery (25/66, 38%), one anterior cerebral artery, segment A1 (A1) hypoplasia or atresia (16/66, 24%), one PCOM (8/66, 12%), and complete CW (3/66, 5%). Fetal origin of posterior cerebral artery (PCA) was associated with poor collateral circulation (48% vs 23%, p-value = 0.046). This pilot study showed that the presence of fetal origin of PCA was associated with poor collateral circulation in patients with acute ischemic stroke caused by major artery occlusion.

Distal superior cerebellar artery aneurysm located at the newly formed anastomotic site with the long circumferential artery of the posterior cerebral artery: A case report.

We describe a case of a distal superior cerebellar artery (SCA) aneurysm that arose from a unique collateral pathway between the SCA and long circumferential artery (LCA) of the posterior cerebral artery (PCA). The patient was a 69-year-old male who was admitted to our facility for an asymptomatic and incidentally identified cerebellar aneurysm. Magnetic resonance imaging showed a saccular aneurysm arising from the right SCA in the quadrigeminal cistern. Digital subtraction angiography revealed an unusually dilated branch from the aneurysmal sac. Furthermore, this branch had retrograde flow from the quadrigeminal segment to the anterior pontomesencephalic segment, was connected to the PCA at the P1 segment, and exited from the P2 segment. We attributed this unusual angioarchitecture to collateral circulation secondary to severe P1 stenosis. Thus, the dilated unusual branch is an LCA of the PCA for supplying the distal PCA with blood flow. As a result, the aneurysm is probably formed at the junction between the SCA and LCA. Endovascular coiling for the aneurysm was successfully performed with preserved collateral system.

Replaced posterior cerebral artery (PCA): origin of all branches of the PCA from the anterior choroidal artery diagnosed by MR angiography.

We present a rare variant of the right posterior cerebral artery (PCA), recently named "replaced PCA," that demonstrates the origin of all its branches from the right anterior choroidal artery (AChA) on magnetic resonance (MR) angiography. In this variation, the right posterior communicating artery (PCoA) is hypoplastic and resembles the transposition of the AChA and PCoA. Detection of such rare arterial variations on MR angiographic images requires careful review of images, including source images, and partial maximum-intensity-projection images aid their identification.

Hypoplasia of the internal carotid artery with associated fenestration and extremely long P1 segment of the ipsilateral posterior cerebral artery diagnosed by MR angiography.

We present what we believe is the first report of a patient with unilateral hypoplasia of the internal carotid artery with associated ipsilateral anomalous posterior cerebral artery, extremely long and fenestrated P1 segment that was diagnosed on magnetic resonance (MR) angiography. Careful review of MR angiographic images is important to detect rare arterial variations, and partial maximum-intensity-projection images aid their identification on MR angiography.

Percheron Infarction: Is It Just a Rare Cerebrovascular Variant or a Forewarning of Severe Multiple Posterior Circulation Infarcts.

Percheron infarction, arising from occlusion of the Artery of Percheron, is few, which can result in bilateral thalamic and mesencephalic infarctions. We herein showcase a confirmed case of the Percheron infarction at the admission day, in which the patient advanced into severe multiple posterior circulation infarcts, along with petechial hemorrhage within the infarcts, even given the right therapy without delay. It reminds us that whether we could or should take this special infarction as a forewarning of more harmful infarcts getting in the way, or at least a precaution of poor vessel condition.

Variation and Anomalies of the Posterior Cerebral Artery: Review and Pilot Study.

Variations and anomalies of the posterior cerebral artery (PCA) have several clinical implications, including assisting in understanding the clinical signs of a stroke. Anomalies have been described previously; however, few reports mention the origins, absence, duplication and triplication of the cortical branches. Furthermore, the PCA branching pattern has not been adequately described. The aim of this study was to describe the anatomy and anomalies of the PCA. Results of a pilot study were additionally included. The quantity, origin, diameter and length of the PCA cortical branches were described in this review, as well as the branching pattern and the anomalies. Accordingly, the pilot study reported on these aspects. In the pilot study it was evident that the description of the branching pattern is not the "normal" pattern, since it was only observed in one case. This pattern was re-evaluated and three groups were described; monofurcation, bifurcation and trifurcation. Furthermore, one case of a fenestration was observed. Aneurysms tend to form at branching points, thus knowledge of the branching pattern can aid in detection of ruptured and unruptured aneurysms in this region. This review outlined several gaps in the literature, and a pilot study was included to fill some of these gaps. Future research should especially focus on the branching pattern of the PCA. Possible sex, age and population differences may also exist.