Arterial Fenestrations Research Articles

Normal Cerebral Arterial Development and Variations

The cerebral vascular architecture is both unique and heterogeneous in its structure, organization, and function. For many years, it was believed that brain vasculature was dominated by nonanastomosing terminal or "end-arteries." This was primarily based upon the observation of discrete distribution of brain infarcts after embolic occlusion of particular vessels. It was not until the detailed anatomy work of Pfeiffer in 1928 that the new concept of an almost-uninterrupted vascular network of brain vasculature was proposed. Since then, the cerebral vascular anatomy and embryology has been studied in great detail. Its full description is beyond the scope of this article, and our aim is to provide a brief overview of the development of cranial arterial anatomy, with special emphasis on commonly encountered anatomical variations that may have clinical implications. The failure to recognize these can lead to misdiagnosis as well as otherwise-preventable iatrogenic injuries and complications. We describe the proposed underlying embryologic processes, pathology and clinical implications of these variations, including aberrant internal carotid arteries, carotid agenesis and hypoplasia, azygous anterior cerebral arteries, arterial fenestrations, and persistent embryonic vessels.

Fenestrated Internal Jugular Vein: Case Report

vein (IJV) are a rare congenital anomaly in the neck. Although many arterial fenestrations have been reported in the vertebral artery, basilar artery, middle cerebral artery, anterior cerebral artery, posterior inferior cerebellar artery, posterior cerebral artery, posterior communicating artery, and internal carotid artery, fenestration of the IJV is very rare (1). To our knowledge, there have been nine case reports of fenestrated IJVs (1-9). Prades et al. (2) reported that the incidence of fenestrated IJVs is 0.4%. We report an incidentally detected fenestrated IJV.

The frequency of intracranial arterial fenestrations: A study with 64-detector CT-angiography

Fenestration is a vascular variation that begins with a common origin, then splits into two parallel luminal channels and rejoins distally. Potential association between anomalies of cerebral circulation and increased occurrence of aneurysm makes intracranial arterial fenestrations important. The planning of intracranial arterial interventions may be complicated if a fenestration occurs proximal to the site of intended treatment. This study is planned to determine the frequency of fenestrations on CT angiography and to search whether there is relationship between aneurysms and fenestrations. CT angiographies of 395 consecutive patients, performed by 64-detector CT, were retrospectively reviewed for aneurysms and fenestrations. Overall fenestration frequency, fenestration frequency in patients with and without aneurysm, and aneurysm frequency in patients with and without fenestration were searched. Demographic characteristics of patients were also compared. Overall fenestration frequency was 12.9%. Vertebrobasilar system (5.56%) and anterior communicating region (5.32%) were the two most frequent sites of fenestration. The rate of fenestrations was not significantly different between patients who had and did not have aneurysms. Mean age was significantly higher, and females were predominant in patients with aneurysms. However our results did not show significant difference in age and sex of patients with fenestrations. The frequency of fenestrations in this study is higher than in previously published radiological studies, suggesting that fenestrations are relatively common. There is no significant relationship between the frequency of aneurysms and fenestrations.

Fenestration of the middle cerebral artery with an associated ruptured aneurysm

Intracranial arterial fenestrations are uncommon developmental anomalies that may alter local hemodynamic stress patterns and may be associated with intracranial aneurysms. A 75-year-old woman presented with a mild subarachnoid hemorrhage. Cerebral angiography demonstrated a 5 mm aneurysm arising from the middle cerebral artery (MCA) associated with a dramatic fenestration of the proximal M1 segment of the MCA. The patient underwent craniotomy with microsurgical aneurysm clipping. The aneurysm arose immediately distal to the fenestration. Several fine perforating arteries were dissected away from the neck of the aneurysm to allow for safe clip placement. Postoperatively, the patient awoke without deficit and was discharged to home on the fifth postoperative day in good condition. Anomalies of the intracranial vasculature are common and we describe a rare proximal MCA fenestration with an associated ruptured aneurysm at the site of the fenestration. Neurosurgeons should be thoroughly familiar with such potential “normal variants” to avoid operative complications that may result from the anomalous circulation in such cases.

Intracranial arterial fenestrations: frequency on CT angiography and association with other vascular lesions

Fenestrations (segmental duplications) of the intracranial arteries are rare anomalies, felt to result from incomplete fusion of primitive embryologic vessels. They have been associated with aneurysms and other vascular lesions. The rate of fenestrations based on published angiographic series has been much lower than that at cadaveric series. The purpose of this study is to determine the frequency of fenestrations and associated vascular lesions at CTA. A total of 504 sequential CTA studies from 2005 to 2006 were retrospectively reviewed for the presence of fenestrations, aneurysms and other vascular lesions. Fenestrations were present in 53 patients (11%). Their frequency was not significantly different in patients referred for aneurysm indications, when compared to those referred for non-aneurysm indications. As expected, there was a much higher frequency of aneurysms in the former group. Associated vascular lesions were relatively uncommon. Aneurysms were present at the fenestration site in three patients, and remote from the fenestration site in eight. One fenestration patient with an associated aneurysm at the fenestration site also had an AVM remote from the fenestration. The frequency of fenestrations in this study was higher than in previously published radiologic studies, suggesting that fenestrations are relatively common, and may be more frequently visualized using cross-sectional imaging. Association with aneurysms and other vascular lesions was relatively uncommon. Our results do not support the theory that fenestrations predispose a patient to aneurysms or vascular malformations remote from the site of the fenestration. Although the association of aneurysms at the site of fenestrations is well documented, our results do not show an overall higher rate of aneurysm formation in patients with fenestrations compared to those without.

“Duplicated” or “Multiple” Cervical Internal Carotid and Vertebral Arteries from Fenestration, Duplication and Vasa Vasorum to Segmental Rete

The appearance of multiple cervical arteries may be due to a variety of anatomic situations. Arterial fenestrations and duplications have different anatomic origins, with distinct appearances on angiography. They are associated with incomplete segmental development. The vasa vasorum of the internal carotid artery are rarely seen unless enlarged in pathological situations. They represent a peculiar segmental, in-situ, collateral circulation. Retes, on the other hand, correspond to a more complex reconstitution of an early segmental regression. Careful analysis of each of these features is required to choose the best appropriate terminology. The purpose of this paper is to report illustrative cases to enhance the distinctive features of each disposition.

Traumatic occlusion of one limb of an intracranial arterial fenestration

Three weeks after an automobile accident, a 35-year-old man experienced left throat and neck pain, numbness of the left face and tongue, dysphagia, left arm pain and weakness, and left miosis. At age 27, he had suffered an aneurysmal subarachnoid hemorrhage. Angiography at that time had also demonstrated a fenestration of the left intracranial vertebral artery. At the time of the second presentation, angiography showed that one of the limbs of the fenestration had become occluded. Although the vast majority of intracranial arterial fenestrations are asymptomatic, occlusion of one of the limbs of a fenestration may be the cause of stroke.

The layered fabric of cerebral artery fenestrations.

Intravascular bridges, resulting from developmental anomalies of brain arteries, are now better known as arterial fenestrations. Their tendency to develop aneurysms, similar to arterial bifurcations, makes their anatomy and microstructure important for study. Six segments of artery, each including a fenestration (five from the vertebrobasilar junction and one from the middle cerebral artery), were pressure distended, fixed, and sectioned. We made three-dimensional orientation measurements of smooth muscle and collagen, stained to enhance their birefringence, using the polarized light microscope. The general contour of the fenestrations is streamlined with a thickened layered subendothelium at the trailing or distal edge, structurally similar to the region of convergence of major brain arteries. Defects of the medial layer were found at both proximal and distal edges of all the fenestrations. Results included regional mean orientations of individual layers, with circular SDs. The medial layer was found to be coherently aligned perpendicular to the direction of blood flow, with a mean circular SD of 12 degrees. The adventitia was less coherent (mean circular SD, 16 degrees) with the same average orientation, and the multilayered subendothelium had layers of obliquely oriented fibers with a wide range of coherence for individual fiber groups. Layers of the side regions were analogous to those in segments of brain artery and differed significantly from the proximal and distal edges of the fenestration structure. The plasticity of form of the fenestrations at both the proximal and distal edges is in response to hemodynamic forces and is analogous to branching regions of brain arteries. Medial defects, a common feature in both brain arteries and fenestrations, may predispose the arterial fenestration to aneurysm formation.

Cerebral Arterial Fenestrations Associated with Intracranial Saccular Aneurysms

Cerebral Arterial Fenestrations Associated with Intracranial Saccular Aneurysms

Multiple arterial fenestrations, multiple aneurysms, and an arteriovenous malformation in a patient with subarachnoid hemorrhage

We report the case of a 49-year-old, right-handed man with multiple vascular pathologies, including a fenestrated anterior communicating artery and middle cerebral artery, an aneurysm of the anterior communicating artery, multiple aneurysms of the middle cerebral artery, and an arteriovenous malformation. Diagnoses were made through computed tomography, cerebral angiography, magnetic resonance imaging, and intraoperative dissection. The lesions were managed surgically in stages with satisfactory results. Congenital and hemodynamic factors may have combined to manifest in the anomalies present in this unique case. We believe that no similar combination of vascular pathology has been reported previously.