Association of cerebral arteriovenous malformation with cerebral arterial fenestration

Paediatric subarachnoid haemorrhage and severe vasospasm secondary to traumatic pseudoaneurysm of a fenestrated vertebral artery: a case report and review of the literature

Paediatric intracranial aneurysms are rare entities accounting for less than 5% of all age intracranial aneurysms. Traumatic aneurysms are more common in children and have an association with anatomical variations such as arterial fenestrations. Here, we present a case of a child initially presenting with traumatic subarachnoid haemorrhage who returned to baseline and was discharged home only to return within 2 weeks with diffuse subarachnoid and intraventricular re-haemorrhage. A dissecting aneurysm of a duplicated (fenestrated) V4 vertebral artery segment was identified as a rare cause of rebleeding. We describe a course complicated by severe vasospasm delaying aneurysm detection and treatment. Dissecting aneurysms in children should be considered in all cases of delayed post-traumatic cranial rebleeding, particularly where there is anomalous arterial anatomy.

Anatomical variations of human vertebral and basilar arteries: A current review of the literature

The vertebral artery originates from the subclavian artery and is divided into four segments (V1-V4). In its intracranial segment (V4), the two vertebral arteries join to form the basilar artery, an unpaired medium-sized artery. However, apart from this typical description, several anatomical variations may occur in the human body. Although in some cases such variations may be asymptomatic, they may be also associated with several pathological conditions, neurological complications, surgical complications, and increased risk of developing vascular diseases. Therefore, it is crucial to obtain sufficient information on the anatomy and variants of both arteries to prevent such complications and ensure the safe completion of surgical and radiological treatments. For this reason, we reviewed studies published up to January 2022 concerning the reported variations of the vertebral artery and basilar artery regarding their origin, course, length, and diameter. We believe that the thorough presentation of these variations would help surgeons worldwide during their daily clinical and surgical practice.

Unusual Finding of Vertebral Artery Fenestration in Spontaneous Deep Nuclear Hemorrhage

Vertebral artery fenestration is accidentally detected during angiography or autopsy. Spontaneous deep nuclear hemorrhage in association with vertebral artery fenestration is a very unusual finding in angiography. Such an unusual finding has not been reported in the English literature. Here, we report two cases of spontaneous deep nuclear hemorrhage that presented with features of raised intracranial pressure. Computed tomography revealed a deep nuclear acute bleed in both cases. Digital subtraction angiographic findings were normal other than the presence of a long segment vertebral artery fenestration. Both extracranial and intracranial variations were detected. Although the existence of vascular fenestration in the vertebrobasilar system produces less clinical importance, it may influence the management of cervical and intracranial pathologies to avoid iatrogenic injury. 

Vertebral Artery Fenestration

Fenestration of the vertebral artery is a rare vascular anomaly that has been observed at autopsy and on angiography. It is most commonly seen in the extracranial segments of the vertebral artery. This congenital anomaly can arise during multiple different stages of embryological development of the vertebral artery. The clinical significance is unclear, but multiple studies have reported association with other vascular anomalies. Awareness of vascular anomalies is crucial to avoid iatrogenic injuries during endovascular diagnostic and therapeutic interventions. Here, we present a case of a patient with an intracranial vertebral artery fenestration that was identified during work-up for a foramen magnum mass.

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.

Intracranial arterial fenestrations associated with arteriovenous malformations diagnosed by CT angiography

BACKGROUND

Fenestrations involving aneurysms have been well documented. Only sporadic papers have been reported on fenestrations associated with AVMs (arteriovenous malformations) with few cases. Our study is to determine the rate of co-occurrence of fenestrations and AVMs and to analyze the possible relationship between them by CTA.

METHODS

Between January 2006 and February 2012, the CTA data of 5,657 consecutive patients were retrospectively reviewed.

RESULTS

A total of 12 cases (.21%) of fenestrations associated with AVMs were found. Of these, single-fenestrations were identified in 9 cases, and multifenestrations were found in 3 cases. Among 349 fenestrations, there were 15 cases of multifenestrations. The frequency of multifenestrations among fenestrated patients without AVMs was 3.6%. There was no significant difference in the incidence of AVMs in cases with and without fenestrations (3.4% and 2.7%), and there was no significant difference in the incidence of fenestration in cases with and without AVMs (7.7% and 6.1%, χ(2) = .643, P = .423).

CONCLUSIONS

CTA may play a vital role in assessing the anomalies of co-occurring AVM and fenestration, with an incidence of .21%. The frequency of multifenestrations in fenestrated cases with AVMs was higher than those without AVMs, though there is no significant association between fenestrations and AVMs.

Fenestrated vertebral artery

Fenestrations of the vertebral arteries (VAs) are usually identified angiographically. A left fenestrated vertebral artery (fVA) is reported here, identified in an adult specimen by microdissection. The distal segment of this VA was fenestrated and it consisted of two arms, the caudal one being larger than the cranial one. The caudal end of the rostral arm and the left posterior inferior cerebellar artery (PICA) were inserted at the same point. The anterior spinal artery was leaving the caudal arm of the fVA. On that side the anterior inferior cerebellar artery (AICA) was rudimentary, its cerebellar hemispheric territory being supplied by the PICA. The rostral arm of the fVA and the AICA were united by an anastomosis coursing on the ventral side of the olive. The AICA-to-fVA anastomosis, as well as the PICA, were supplying perforator arteries of the retro-olivary sulcus. Anatomical details of various arterial morphologies are important during specific surgical and interventional procedures.

Basilar artery fenestration detected with CT angiography

OBJECTIVES

To analyse the characteristics of basilar artery (BA) fenestrations and their coexistence with aneurysms and other anomalies in a massive cases by computed tomographic angiography (CTA).

METHODS

A total of 5,657 sequential cerebral CTA images performed from January 2006 to February 2012 were reviewed. CTA images were obtained from the raw datasets by using volume rendering and maximal intensity projection reconstruction.

RESULTS

One hundred and thirty-two (2.33 %) BA fenestrations were detected with CTA, and most common at the proximal segment (n = 124). BA fenestration-associated aneurysms were found in 34 cases and 7 located at the posterior circulation, and the frequency of posterior circulation aneurysms was significantly different in patients with and without BA fenestrations (P = 0.025). Other associated anomalies included arteriovenous malformation (n = 7) and moyamoya disease (n = 6). BA fenestrations were classified into Type I (74 cases), Type II (15 cases), Type III (41 cases) and Type IV (2 cases). A significant difference was observed between Types II + III associated with convex-lens-like and slit-like fenestrations (P = 0.008).

CONCLUSIONS

BA fenestrations were found in 2.33 % with CTA. They were significantly more often associated with posterior circulation aneurysms than those without BA fenestration. The anterior inferior cerebral artery (AICA) tends to originate more often from convex-lens-like fenestration than slit-like.

KEY POINTS

• Basilar artery fenestrations were found in 2.33 % of patients undergoing CT angiography. • Fenestrations were seen more often in the lower third with slit-like configurations. • No obvious relationship exists between basilar artery fenestration and aneurysm formation. • Basilar artery fenestrations perhaps predispose a patient to posterior circulation aneurysm formation. • The AICA tends to originate more often from convex-lens-like than slit-like fenestrations.

Fenestration and duplication of the vertebral artery: the anatomical and clinical points of view

The vertebral artery (VA) acts as a foundation for the posterior circulation of the head and neck. It presents a number of anomalies that can be easily visualized thanks to modern imaging techniques, such as MR and CT angiography or color Doppler ulrasonography. Determining the appropriate terminology for those anomalies can be sometimes more challenging than their recognition. One particular challenge concerns the differentiation between VA fenestration and duplication. Because of the different clinical prognoses associated with those anomalies, confusion should be avoided. Knowledge of the morphological anomalies associated with the VA is important for both radiologists and head and neck surgeons, because any injury to the VA can result in a threat to the vascular supply of the brain stem, the cerebral or cerebellar hemispheres, the thalamus, cervical nerve roots and particularly the lateral medulla (Wallenberg's syndrome). This article analyses world literature concerning the issue of VA fenestration and duplication to facilitate a differential diagnosis.

A rare case of supraclinoid internal carotid artery (ICA) fenestration in combination with duplication of the middle cerebral artery (MCA) originating from the ICA fenestration and an associated aneurysm

Fenestrations and duplications of the cervical and intracranial arteries are rare anatomic variants, reported to be associated with aneurysms or other vascular anomalies. We here present a patient with a supraclinoid ICA fenestration in combination with a duplication of the MCA originating from the ICA fenestration and an associated aneurysm.

Fenestrations of the intracranial vertebrobasilar system diagnosed by MR angiography

INTRODUCTION

Fenestrations of cerebral arteries are most common in the vertebrobasilar (VB) system, and magnetic resonance (MR) angiographic studies of these variations are sparse.

METHODS

We retrospectively reviewed MR angiographic images of 3,327 patients; images were obtained using two 1.5-T imagers and picked up fenestrations of the intracranial vertebral artery (VA), VB junction, and basilar artery (BA) for evaluation.

RESULTS

In 92 patients, we found 93 fenestrations (2.80%), which included 18 of the intracranial VA (0.54% prevalence), 6 of the VB junction (0.18%), and 69 of the BA (2.07%). Most VA fenestrations were large, and the posterior inferior cerebellar artery arose from the fenestrated segment in 10 patients (56%). Fenestrations of the VB junction were small and triangular. Sixty-five (94%) of the 69 BA fenestrations were located at the proximal segment and had small slit-like configurations. The anterior inferior cerebellar artery arose from the fenestrated segment in 27 patients (37%). We found 18 cerebral aneurysms in 16 (17%) of the 92 patients with fenestration but detected only one aneurysm at the fenestration.

CONCLUSION

The overall prevalence of fenestrations of the intracranial VB system was 2.77%. We found associated cerebral aneurysms relatively frequently but rarely at the fenestration.

Cerebral aneurysm in the long fenestration at the middle portion of m1 segment

We report a unique case of bilateral mirror image M1 aneurysms, one of which was an unruptured aneurysm arising from the proximal end of right middle cerebral artery fenestration with long loop and the other ruptured aneurysm from the contralateral side. We clipped ruptured aneurysm first and unruptured one in three months after the first operation. The difficulties of identifying this unusual vascular anomaly and possible problems during the surgery of an aneurysm at the site of fenestration are discussed with a review of the literature.

Fenestrations of intracranial arteries detected with 3D rotational angiography

BACKGROUND AND PURPOSE

Fenestrations of intracranial arteries are variants resulting from incomplete fusion of primitive vessels. An association with aneurysms is suggested in many studies. On conventional angiography, fenestrations are rarely visible. 3D rotational angiography (3DRA) provides improved visualization of cerebral vessels from any desired angle. We used 3DRA to assess the frequency and location of fenestrations of intracranial arteries and a possible relationship with aneurysms.

MATERIALS AND METHODS

In 208 patients with suspected intracranial aneurysms, 3DRA of 1, 2, or 3 cerebral vessels (in 143, 16, and 49 patients) was reviewed for the presence and location of fenestrations and aneurysms. When fenestrations were present in combination with aneurysms, we noted the relationship of the locations.

RESULTS

In 59 of 208 patients, 61 fenestrations were detected (28%). Fenestrations were more frequent in the anterior than in the posterior circulation (23% versus 7%), and the most common location was the anterior communicating artery (AcomA) (43 of 61, 70%). The frequency of fenestrations in 185 patients with aneurysms was not different from the frequency in 23 patients without aneurysms. Of 220 aneurysms present in 208 patients, 10 aneurysms (4.5%) were located on a fenestration. Of 61 fenestrations, 51 (84%) were not associated with an aneurysm.

CONCLUSIONS

With 3DRA, fenestrations were found in 28% of patients. In our study, fenestrations occurred more often in the anterior than in the posterior circulation, and the most common location was the AcomA. A definite relationship between fenestrations and aneurysms cannot be concluded from our data.

CT angiographic depiction of a supraclinoid ICA fenestration mimicking aneurysm, confirmed with catheter angiography

Fenestrations (segmental duplications) of the intracranial arteries are rare anomalies that have been associated with aneurysms. Fenestrations of the supraclinoid ICA are extremely rare, with only a few reported cases. We present a supraclinoid ICA fenestration, which on axial CTA images initially mimicked an aneurysm, but was correctly delineated as a fenestration on multiplanar reformatted and 3D reconstructed images. Confirmation was made with conventional angiography. To our knowledge, this represents the first time that this rare variant has been identified with cross-sectional imaging. A review of the literature including proposed embryology is provided.

Fenestration of the Middle Cerebral Artery Detected by MR Angiography

Unlike fenestration of the posterior cerebral arterial circulation, fenestration of the anterior cerebral arterial circulation has not been well described. We investigated the location and configuration of fenestration of the middle cerebral artery (MCA) detected by magnetic resonance (MR) angiography. We found 6 fenestrations of the MCA among cranial MR angiography images obtained from about 2,000 patients during the past 9 years at our institution using either of two 1.5T imagers. All images were obtained by the three-dimensional time-of-flight technique. Maximum-intensity projection images in the horizontal rotation view were displayed stereoscopically. All 6 fenestrations had small slit-like configurations, five located at the proximal M1 segment, the other, at the middle M1 segment. No associated aneurysm was found. Although MCA fenestration is extremely rare and cerebral artery fenestration usually has no clinical significance, an aneurysm can arise at the proximal end of the fenestration. Thus, recognizing MCA fenestration is important when interpreting cranial MR angiograms.

Imaging the vertebral artery

Although conventional intraarterial digital subtraction angiography remains the gold standard method for imaging the vertebral artery, noninvasive modalities such as ultrasound, multislice computed tomographic angiography and magnetic resonance angiography are constantly improving and are playing an increasingly important role in diagnosing vertebral artery pathology in clinical practice. This paper reviews the current state of vertebral artery imaging from an evidence-based perspective. Normal anatomy, normal variants and a number of pathological entities such as vertebral atherosclerosis, arterial dissection, arteriovenous fistula, subclavian steal syndrome and vertebrobasilar dolichoectasia are discussed.

Reevaluation of the Morphological Parameters according to 11 Different Duplications of the Fetal Vertebral Artery at Prevertebral (V1) and Intracranial (V4) Parts

It is noted that the vertebral artery lies buried in a sea of generalities, prejudices, fear, and ignorance in the clinical literature. This fact is the reason why this observation is based on 11 cases, selected from 206 fetal cases, of various duplications of the vertebral artery. Aberrant or anastomotic vessels are illustrated and their definition is largely modified according to the recent anatomic terminology. Duplications of the vertebral artery indicate the 'segmental duplication' as a first form, and the presence of an abnormal 'fenestra' in the vessel's trunk as a second form of duplication. There are 9 (5 at prevertebral and 4 at intracranial parts) or 4.36% cases of 'segmental duplication' of the vertebral artery and 2 or 0.98% 'arteria vertebralis unifenestrata' at the intracranial part of all 206 cases. Successive morphological parameters of aberrant or anastomotic vessels are described and discussed according to personal cases and cases in the literature.