Segmental unfused basilar artery with kissing aneurysms: report of three cases and literature review

Treatment of an intracranial aneurysm in the setting of fenestration of cranial division of the internal carotid artery: Technical considerations and a literature review

Although rare, cerebral arterial fenestration may present challenges in diagnosis and treatment. Here we present a case of a supraclinoid internal carotid artery (ICA) fenestration adjacent to an ICA aneurysm, successfully treated with balloon-assisted coil embolization. A female in her 50's presented with an acute subarachnoid hemorrhage from a ruptured left ICA-ophthalmic artery (OA) aneurysm. Digital subtraction angiography revealed a focal ICA fenestration distal to the posterior communicating artery (Pcom). The patient underwent successful coil embolization of the aneurysm using the balloon-assisted technique. No immediate hemorrhagic, thromboembolic, or neurological complications were observed. The patient was discharged in good condition after 2 weeks of hospitalization. A comprehensive literature review of 33 cases was subsequently performed to understand the characteristics of this condition. Cases involving the cranial division of the ICA forming the fenestration exhibited caliber differences significantly more frequently (p = 0.02). Embryological insights revealed distinctions between the cranial divisions of the ICA, influencing fenestration morphology and associated aneurysm formation. Endovascular treatment poses the risk of vascular injury, necessitating the identification of this variation and procedural planning.

Vascular supply of the hindbrain: Basic longitudinal and axial angioarchitecture

The basic pattern of arterial vascularization is highly conserved across vertebrates and develops under neuromeric rules. The hindbrain has an angioarchitecture that is homologous to that of the spinal cord, and the hindbrain vascular system can be analyzed at the longitudinal and axial structures. During development, there are two main longitudinal arteries: the longitudinal neural artery and primitive lateral basilovertebral anastomosis. This review discusses the basic pattern of the blood supply of the hindbrain, the development of vascularization, and the anatomical variations, with a special reference to the embryological point of view of two main longitudinal anastomoses (longitudinal neural artery and primitive lateral basilovertebral anastomosis). The formation of commonly observed variations, such as fenestration and duplication of the vertebrobasilar artery, or primitive trigeminal artery variant, can be explained by the partial persistence of the primitive lateral basilovertebral anastomosis. Understanding the pattern and the development of the blood supply of the hindbrain provides useful information of the various anomalies of the vertebrobasilar junction and cerebellar arteries.

Duplication of the internal maxillary artery: Anatomical and clinical considerations

Duplication of the internal maxillary artery (IMAX) results from a failed regression of either the embryological superficial or deep ring and is reported to be exceedingly rare. We present a patient with this rare anatomical variant who was treated by endovascular technique in the clinical context of an acute oropharyngeal hemorrhage.

Cerebral neurovascular embryology, anatomic variations, and congenital brain arteriovenous lesions

Cerebral neurovascular development is a complex and coordinated process driven by the changing spatial and temporal metabolic demands of the developing brain. Familiarity with the process is helpful in understanding neurovascular anatomic variants and congenital arteriovenous shunting lesions encountered in endovascular neuroradiological practice. Herein, the processes of vasculogenesis and angiogenesis are reviewed, followed by examination of the morphogenesis of the cerebral arterial and venous systems. Common arterial anatomic variants are reviewed with an emphasis on their development. Finally, endothelial genetic mutations affecting angiogenesis are examined to consider their probable role in the development of three types of congenital brain arteriovenous fistulas: vein of Galen malformations, pial arteriovenous fistulas, and dural sinus malformations.

Complex basilar artery fenestration aneurysm successfully treated with single flow diverter using novel "crossing flow diverter technique" - A rare case report and review of literature

Basilar artery fenestration aneurysms are very rare and endovascular management of large and complex aneurysms is extremely challenging. Most of these type of cases are managed with stent assisted coiling, dual flow diverters (FD) and single FD with additional coiling of aneurysm and occlusion of one of the vertebral artery. Here, we report a case of large complex basilar artery fenestration aneurysm successfully treated with single FD using novel technique called "crossing flow diverter technique" without any additional coiling of aneurysm or occlusion of vertebral artery. Using this technique cost of procedure and procedural complexity inherent with other above mentioned techniques can be significantly reduced.

Association of tetralogy of Fallot with multiple variations of the cerebral arteries diagnosed by magnetic resonance angiography

Tetralogy of Fallot very rarely manifests with variations of the cerebral arteries, but we detected an extremely rare combination comprising 3 such variants –bilateral carotid–anterior cerebral arteries anastomoses, the vertebral–anterior inferior cerebellar arteries anastomosis (proximal basilar artery duplication) and a nonbifurcating cervical carotid artery– in a 19-year-old man during magnetic resonance angiography to evaluate syncope. Recognition and correct diagnosis of these variations are crucial prior to surgical or radiological cerebrovascular intervention. Both partial maximum-intensity-projection images and source images are useful in identifying these vessels on MR angiography.

Kissing aneurysms of the distal anterior cerebral artery: A case report and literature review

Intracranial 'kissing' aneurysms are rare types of multiple aneurysms referring to two adjacent aneurysms arising from identical or different arteries with separate origins and partially adherent walls. The present study reported a 54-year-old female patient, who was identified with a 'kissing' aneurysm in the A3 segment of the bilateral anterior cerebral arteries, as demonstrated by head computed tomography and emergency cerebral digital subtraction angiography analysis. In total, 12 days following the clipping of the aneurysms, the patient was discharged with a Modified Rankin Scale=0 and recovered well with no neurological deficits. Based on previous literature, it was indicated that the majority of patients with 'kissing' aneurysm have a good prognosis and the cure rate is as high as 96.8%. However, the recovery rate may not be that high as the sample size is not large enough to thoroughly demonstrate the complete prognosis of 'kissing' aneurysms.

Anomalies and Normal Variants of the Cerebral Arterial Supply: A Comprehensive Pictorial Review with a Proposed Workflow for Classification and Significance

Cerebral arteries may exhibit a wide range of variation from normal anatomy, which can be incidentally discovered during imaging. Knowledge of such variants is crucial to differentiate them from pathologies, to understand the etiology of certain pathologies directly related to a vascular variant, and to depict the changes in collateral circulation in patients with certain variants. Detection of particular variants may lead to the discovery of other nonvascular or vascular anomalies, especially aneurysms, and may also affect planning of endovascular or neurosurgical interventions. In this review, we summarize the variants and anomalies of cerebral arteries seen on cross-sectional imaging classified by a morphological approach and categorize their significance from a clinical perspective. This structured review is intended to serve as a guide for daily use in clinical practice.

Kissing Aneurysms at Fenestrated Proximal Basilar Artery: Double-barrel Stent-assisted Coiling Using Dual Closed-cell Stents

Kissing aneurysms associated with a proximal basilar artery fenestration are an exceedingly rare and unique therapeutic challenge due to anatomical complexity. This report describes double-barrel stent-assisted technique with dual closed-cell stents for the successful endovascular coiling of kissing aneurysms from a proximal basilar artery fenestration.

Treatment of fenestrated vertebrobasilar junction-related aneurysms with endovascular techniques

Fenestrated vertebrobasilar junction-related aneurysms (fVBJ-AN) are uncommon and endovascular management strategies have become the first options for the treatment of these lesions. This clinical study aimed to report our experience in the endovascular management of these lesions and to review the literature. We retrospectively reviewed 10 consecutive patients harboring 12 fVBJ-AN between January 2007 and December 2014. The demographic, angiographic and clinical data were reviewed. Additionally, a literature review was performed. Endovascular management strategies were successfully applied in all 10 patients. Post-procedural angiograms indicated total occlusion in eight (66.7%) aneurysms, a residual neck in one (8.3%) aneurysm, and three residual aneurysms (25%). No procedure-related complications were observed. Follow-up angiograms were obtained in eight patients and revealed nine occluded aneurysms and one improved aneurysm; two patients were lost to angiographic follow-up. Clinical follow-ups were obtained in all patients (until July 2015), and the modified Rankin Scale scores at 69.5months (range 17-101months) of follow-up were 0 in eight patients and 1 in two patients. Endovascular management strategies provided a high occlusion rate and an acceptable complication rate and are thus efficacious in the treatment of fVBJ-AN. Further studies are necessary to validate the utility of these treatments due to the low incidence of fVBJ-AN.

Dual flow diversion stents for aneurysm treatment in a partial unfused basilar artery

Unfused basilar arteries, frequently but erroneously referred to as 'fenestrations', are not uncommonly associated with aneurysms. The difficulty in treating these aneurysms lie in the fact that they are often wide necked and frequently incorporate both channels of the unfused segment, with varying calibres of the channels, necessitating technically challenging treatment strategies. It is important to preserve both channels because of the potential presence of perforating arteries originating from these segments. There are numerous case reports of such aneurysms being treated by coils alone, coiling with balloon assistance and stent-assisted coiling in configurations such as 'X', 'double barrel' or waffle cone. We present an exemplary case, in which an aneurysm on a partial unfused basilar segment was treated with parallel flow diverters with an excellent result on follow-up imaging.

Embolization of Ruptured Aneurysm Arising From Basilar Artery Fenestration Using Hydrocoils

Aneurysms arising from the basilar artery fenestration are considered among the rare cerebrovascular diseases. Here, we report on a 44-year-old gentleman who presented with the sudden onset of severe headache complicated by several episodes of vomiting and an altered level of consciousness. A subarachnoid hemorrhage in the interpeduncle and ambient cisterns was detected by computed tomography of the head. During left vertebral arteriography, a basilar fenestration with a ruptured aneurysm just above the proximal end of vertebrobasilar junction was identified. The aneurysm was successfully occluded by means of endovascular treatment using Hydrosoft coils. In the 15-month follow-up angiography, 100% occlusion without recurrence and recanalization was observed. Bilateral anterior inferior cerebellar arteries and both channels of the basilar artery fenestration were entirely filled in follow-up angiograms.

Cerebral arterial fenestrations

Arterial fenestrations are an anatomic variant with indeterminate significance. Given the controversy surrounding fenestrations we sought their prevalence within our practice along with their association with other cerebrovascular anomalies. We retrospectively reviewed 10,927 patients undergoing digital subtraction angiography between 1992 and 2011. Dictated reports were searched for the terms "fenestration" or "fenestrated" with images reviewed for relevance, yielding 228 unique cases. A Medline database search from February 1964 to January 2013 generated 304 citations, 127 cases of which were selected for analysis. Cerebral arterial fenestrations were identified in 228 patients (2.1%). At least one aneurysm was noted in 60.5% of patients, with an aneurysm arising from the fenestration in 19.6% of patients. Aneurysmal subarachnoid hemorrhage or non-aneurysmal subarachnoid hemorrhage were present in 60.1% and 15.8%, respectively. For the subset of patients with an aneurysm arising directly from a fenestration relative to those patients with an aneurysm not immediately associated with a fenestration, the prevalence of aneurysmal subarachnoid hemorrhage was 66.7% vs. 58.6% (p = 0.58). Fenestrations were more often within the posterior circulation (73.2%) than the anterior circulation (24.6%), though there was no difference in the prevalence of aneurysms within these groups (61.1% vs. 60.7%, p = 1.0). Cerebral arterial fenestrations are an anatomic variant more often manifesting at the anterior communicating arterial complex and basilar artery and with no definite pathological relationship with aneurysms.

Fenestrations of the basilar artery demonstrated on magnetic resonance angiograms: an analysis of 212 cases

Fenestration of the basilar artery (BA) is a rare variant of the intracranial artery, well demonstrated in autopsy and angiographic studies. Some angiographic series show a high incidence of associated aneurysms at the basilar fenestration site. The purpose of this study is to report the incidence of BA fenestration, its configurations, associated aneurysms, and arterial anomalies in a large series of intracranial MR angiograms (MRAs). A total of 16,416 MRAs were retrospectively reviewed to identify the location, size and associated intracranial arterial anomalies of BA fenestrations. All images were obtained with the time-of-flight (TOF) technique. Of the 16,416 MRAs, 215 fenestrations were found in 212 cases (1.29%). Most fenestrations were located in the proximal BA. The average length of the fenestration was 4.6 mm; the largest was 15.6 mm. No aneurysm was found at the site of the fenestration. Thirteen aneurysms were found in nine cases at locations other than the BA: seven in the middle cerebral artery (MCA), one in the anterior cerebral artery (ACA), one in the anterior communicating artery (Acom), one in the vertebral artery (VA), one at the carotid siphon, and two at the internal carotid-posterior communicating artery (IC-PC). Arterial anomalies in other locations were found in 26 cases. BA fenestrations were found in 1.29% of the 16,416 cases studied. There were no aneurysms at the BA fenestration site. Aneurysms at the BA fenestration site may be an exceedingly rare phenomenon.

Normal and abnormal embryology and development of the intracranial vascular system

The brain vascular system develops in such a way that it continuously adapts the supply of oxygen and other nutrients to the needs of the parenchyma. To accompany the developing brain vesicles, it evolves in several steps: superficial meningeal network first; intraventricular choroid plexuses which determine the arterial pattern; penetrating capillaries from the surface to the ventricular germinal matrix forming simple transcerebral arteriovenous loops; cortical capillaries last, mainly in the last trimester. The venous return becomes connected to both the surface and to the choroidal veins, so forming distinct meningeal and subependymal venous drainage systems, while the arteries are on the surface only. While the arterial system was determined early (week 8), the venous system is continuously remodeled by the morphological changes of the base of the skull and the expansion of the brain vesicles. Until late in gestation, the vascular system is made of simple endothelial channels in which the arterial or venous fate is determined primarily by the direction of flow.

Vertebrobasilar junction fenestration with dumbbell-shaped aneurysms formation: computational fluid dynamics analysis

BACKGROUND

We report 8 rare cases of paired ANs involving fenestrated vertebrobasilar junction and demonstrate the flow patterns of the paired ANs by qualitative CFD analysis in 5 cases.

METHODS

Two-dimensional and 3-dimensional angiographic features of 8 cases were reviewed. Nine patient-specific geometries of CFD models in 5 cases were created for flow analysis.

RESULTS

All 8 cases had 2 ANs, one large and the other small, projecting to the opposite sides at the proximal end of fenestrated vertebrobasilar junction. The different angiographic findings between right VA and left VA suggested the different hemodynamic characteristics of the respective VAs. Computational fluid dynamics analysis also demonstrated that the inflows of these paired ANs were different between right VA and left VA. Flow simulations by CFD were consistent with angiographic findings.

CONCLUSION

Intrinsic wall defects at fenestrated vertebrobasilar junction and specific hemodynamic stresses from 2 inflows may contribute to the formation of a pair of dumbbell-shaped ANs.

Endovascular treatment of basilar artery aneurysms associated with distal fenestration. A case report

SUMMARY

Segmental non-fusion of the basilar artery results from failed fusion of the neural arteries and from regression of the bridging arteries that connect the longitudinal arteries. This condition is associated with aneurysm formation in 7% of cases. Distally unfused arteries with associated aneurysms are very rare. We report on a case of successful endovascular treatment of an aneurysm of the distally unfused basilar trunk.

Giant fusiform aneurysm arising from fenestrated posterior cerebral artery and basilar tip variation: case report

OBJECTIVE

A giant fusiform aneurysm in the posterior cerebral artery (PCA) is rare, as is fenestration of the PCA and basilar apex variation. We describe the angiographic and surgical findings of a giant fusiform aneurysm in the P1-P2 PCA segment associated with PCA bilateral fenestration and superior cerebellar artery double origin.

CLINICAL PRESENTATION

A 26-year-old woman presented with a 2-month history of visual blurring. Digital subtraction angiography showed a giant (2.5 cm) fusiform PCA aneurysm in the right P1-P2 segment. The 3-dimensional view showed a caudal fusion pattern from the upper portion of the basilar artery associated with a bilateral long fenestration of the P1 and P2 segments and superior cerebellar artery double origin.

INTERVENTION

Surgical trapping of the right P1-P2 segment, including the posterior communicating artery, was performed by a pretemporal approach. Angiograms performed 3 and 13 months after surgery showed complete aneurysm exclusion, and the PCA was permeated and filled the PCA territory. Clinical follow-up at 14 months showed the patient with no deficits and a return to normal life.

CONCLUSION

To our knowledge, this is the first report of a giant fusiform aneurysm of the PCA associated with P1-P2 segment fenestration and other variations of the basilar apex (bilateral superior cerebellar artery duplication and caudal fusion). Comprehension of the embryology and anatomy of the PCA and its related vessels and branches is fundamental to the decision-making process for a PCA aneurysm, especially when parent vessel occlusion is planned.

Fenestrated anterior cerebral artery with associated arterial anomalies. Case reports and literature review

SUMMARY

Fenestration of the A2 segment is extremely rare. Cerebrovascular fenestration may be associated with an increased incidence of cerebral aneurysm and other vascular anomalies. Two case reports are presented which identify a fenestration of the A2 segment and other normal variations of the intra-cerebral circulation. A review of the literature has been undertaken to determine the prevalence and embryology of anterior cerebral artery fenestrations, their clinical significance and the association with aneurysm formation and other intracranial vascular anomalies.

Endovascular treatment of "kissing aneurysms" at the anterior communicating artery

Kissing aneurysms are the rare type of multiple aneurysms. They are adjacent aneurysms of different origin arteries in the same region, which require great care in diagnosis and treatment. We report a case of kissing aneurysms at the anterior communicating artery (AcomA) which were treated by endovascular coil embolization.

Endovascular management of multiple cerebral aneurysms in acute subarachnoid hemorrhage associated with fenestrated basilar artery. A case report and literature review

Aneurysms arising from the fenestration of the basilar artery are rare. We describe a patient with two aneurysms originating from the fenestration of the basilar artery and the middle cerebral artery. Endovascular treatment with detachable platinum coils was performed, and two aneurysms were cured at the same time. Endovascular treatment of aneurysms associated with fenestrated basilar artery appears to offer advantages over traditional open surgical techniques.