Angiographic pitfall: duplicated tapered A1 segment of the anterior cerebral artery mimicking an anterior communicating artery aneurysm

A Systematic Review and Case Illustrations of Misdiagnosing Intracranial Aneurysms

Modern neuroimaging methods do not completely rule out false diagnoses of intracranial aneurysms which can lead to an unwarranted operation associated with risks of complications. However, surgical interventions for falsely diagnosed aneurysms are quite rare. The purpose of this study is to demonstrate two clinical cases of false-positive aneurysms and a systematic review of the literature dedicated to the incidence and etiology of false-positive aneurysms, identifying risk factors associated with false-positive aneurysms. A literature search in two databases (PubMed and Web of Science) using keywords "mimicking an intracranial aneurysm", "presenting as an intracranial aneurysm", "false positive intracranial aneurysms", and "neurosurgery" was conducted. A total of 243 papers were found in the initial search in two databases. Sixteen papers (including 20 patients) were included in the final analysis. There were 10 women and 10 men. The most common location of false-positive aneurysms was the bifurcation of the middle cerebral artery (MCA). In the posterior circulation, false-positive aneurysms were identified either on the basilar artery, or at the vertebro-basilar junction. The main causes of false intracranial aneurysm diagnosis included artery occlusion with vascular stump formation, infundibular widening, fenestration, arterial dissection, contrast extravasation, and venous varix. In conclusion, summarizing the results of our analysis, we can say that surgical interventions for false-positive aneurysms are an underestimated problem in vascular neurosurgery. Despite extremely rare published clinical observations, the actual frequency of erroneous surgical interventions for false-positive aneurysms is unknown.

False positive angiographic aneurysm of the anterior segment of the M1 bifurcation of the middle cerebral artery: a case report

Occlusion of an intracranial arterial branch, resulting in a false positive aneurysm on vascular imaging, is extremely rare, with only a few reports in the literature and mostly in the posterior circulation artery or the middle cerebral artery (MCA) bifurcation. We report a case of a 69 years-old woman with a subacute infarct lesion in the left frontal lobe, for whom both computed tomographic angiography (CTA) and digital subtraction angiography (DSA) of the cerebral vessels showed aneurysms in the anterior segment of the M1 bifurcation of the middle cerebral artery (MCA) and in the bifurcation of the MCA. The aneurysm in the MCA bifurcation was found during craniotomy, whereas the anterior segment of the M1 bifurcation had intact branch vessels with severe atherosclerosis and no aneurysm was present. The branch vessel of M1 was presumed to be atherosclerotic occlusion resulting in the distal vessels without contrast filling on CTA and DSA, and only the occluded stump at the beginning of the vessel was filled with contrast, showing an aneurysm-like morphology, which was very confusing. This case highlights to neurologists that the diagnosis of aneurysm by cerebrovascular CTA or DSA must be carefully differentiated to avoid misdiagnosis, especially if the unruptured aneurysm is in an uncommon location in combination with ischemic cerebrovascular disease.

Fenestrated Anterior Communicating Artery Complex Mimicking an Unruptured Aneurysm: Diagnostic Pitfall

Anatomical variations often occur in the anterior communicating artery (AComA) complex, and a careful preoperative evaluation is required before repair of this lesion. We report a case of a fenestrated AComA complex mimicking an unruptured cerebral aneurysm. A 49-year-old woman was referred to our hospital under suspicion of unruptured aneurysms of the AComA and the left middle cerebral artery on magnetic resonance angiography (MRA). Additional three-dimensional computed tomographic angiography (CTA) showed the lesion arising from the AComA complex with a maximum diameter of 4.2 mm. Intraoperative findings showed that the putative aneurysm was actually a fenestrated AComA complex as the blood vessels that formed the AComA complex were dilated and meandering. After the operation, MRA and CTA three-dimensional images were reviewed again but we could still not diagnose the lesion as a fenestrated AComA complex rather than an aneurysm. However, in the MRA source image, a secant line in the lesion was the only finding suggestive of a fenestration. The AComA complex is often associated with various vascular malformations, and it is essential to consider this association in the preoperative evaluation. The interpretation of source images may be helpful for accurate diagnosis and surgical planning.

Endovascular treatment of an aneurysm associated with fenestration of the supraclinoid internal carotid artery: Case report and review of the literature

Background

Fenestrations or divisions of the vascular lumen into separate channels appear to be common anatomical variations in patients with intracranial aneurysms. The most frequent sites of occurrence are the anterior communicating artery (ACom), followed by vertebrobasilar and middle cerebral artery (MCA) locations.

Case presentation

A 61-year-old female was brought to the emergency department after experiencing severe headache with abrupt onset, nausea, and vomiting. Clinical examination on arrival showed a drowsy patient (GCS 14), with neck stiffness, but no cranial nerve palsies or other neurological deficits (Hunt-Hess 2). Non-contrast head CT and CT angiography revealed subarachnoid and intraventricular hemorrhage (modified Fisher 4) and two saccular aneurysms, one located on the right supraclinoid ICA with peripheral calcifications, measuring 20 × 12 mm, the second on the left MCA bifurcation, 6 × 4 mm. 3D rotational angiography revealed a right ICA fenestration located between the ophthalmic (OA) and posterior communicating artery (PCom). The proximal part of the fenestration harbored a large saccular aneurysm projecting superiorly with the neck engulfing the origin of the fenestration; due to the favorable neck and geometry of the aneurysm, endovascular coil occlusion was chosen as a treatment option without balloon or stent assistance. The decision was taken to clip the MCA aneurysm.

Conclusion

Supraclinoid ICA fenestrations are rare anatomical variations. Endovascular treatment of supraclinoid ICA fenestration-related aneurysms is feasible and safe, with the notable concern of perforators originating from the limbs.

Magnetic resonance angiography determined variations in the circle of Willis: Analysis of a large series from a single center

OBJECTIVE

The purpose of this study is to evaluate and describe the prevalence and patterns of arterial variants in the circle of Willis (CW) seen in noncontrast three-dimensional time-of-flight magnetic resonance angiography in a series of patients with cerebral vascular accidents (CVAs).

MATERIALS AND METHODS

A descriptive study was undertaken in 200 patients who presented for screening for CVA in the Department of Radiodiagnosis and Imaging, St. John's Medical College Hospital, Bengaluru, from September 2014 to September 2016.

RESULTS

The most common types of CW in a single subject were anterior variant Type A and posterior variant Type E. Type A in the anterior circulation is the normal adult pattern. There is a single anterior communicating artery. The internal carotid artery bifurcates into the precommunicating segment of the anterior cerebral artery and middle cerebral artery. Type E in the posterior circulation is hypoplasia or absence of both posterior communicating arteries and isolation of the anterior and posterior parts of the circle at this level. Overall, CW variants were slightly more common in women than in men.

CONCLUSION

Our findings show that the configuration of the CW may vary greatly in the general population. The wide range in the morphology of CW warrants further research on various races and larger populations to confirm the influence of genetic, regional, environmental, and hemodynamic factors or their combination.

Anatomical variations of the anterior communicating artery complex: gender relationship

Purpose

The anatomy of the anterior communicating artery complex plays a critical role in surgical treatment of anterior cerebral circulation aneurysms. A thorough description of vascular variations of the anterior communicating artery complex seems to be lacking. The aim of this study was to describe the anatomical variations of the anterior communicating artery complex.

Methods

The study group consisted of 411 subjects (52.31 % women), without any intracranial pathologies, that had undergone head computed tomography angiography. We used maximum intensity projections, volume rendering and multi planar reconstructions to study and classify the anatomical variations of the anterior communicating and anterior cerebral arteries.

Results

Male subjects had a significantly higher prevalence of the typical anterior communicating artery complex (59.69 vs. 46.05 %; p < 0.01). The aplastic anterior communicating artery (23.26 vs. 15.88 %; p = 0.04) and triple A2 segment of the anterior cerebral artery (1.86 vs. 0.00 %; p = 0.05) were more common in women than in men.

Conclusion

Female subjects have a higher incidence of variations in the anterior communicating artery complex. There is a higher incidence of anterior communicating artery aplasia among women.

Relationship between the morphology of A-1 segment of anterior cerebral artery and anterior communicating artery aneurysms

BACKGROUND

The anterior communicating artery (ACoA) is one of the most frequent sites for cerebral aneurysm. The peculiar directions of projection of aneurysms offer great challenges to clinical treatment.

OBJETIVES

To establish the relationship between morphology of A-1 segment of anterior cerebral artery (ACA) and aneurismal projection.

METHODS

Randomly selected digital subtraction angiography data of 264 anterior communicating artery aneurysms (ACoAA) cases and 296 cases of other cerebral vascular diseases in the same period were retrospectively analyzed.

RESULTS

Among 264 ACoAA patients, the morphology of A-1 segment showed type 1a in 158 sides, type 1b in 11, type 2a in 35, type 1 2b in 87, type 3 in 171 and absence in 66. The morphology of A-1 segment in 296 patients with other cerebral vascular diseases displayed type 1a in 195 sides, type 1b in 20, type 2a in 47, type 2b in 74, type 3 in 217 and absence in 39. The non-visualization of A-1 segment in the group of ACoAA occurred more than in the control group (χ(2)=11.482, p=0.001). The classifications of ACoAAs in 264 patients were confirmed as anterior-superior type in 121 cases, anterior-inferior type in 105, complicated type in 16, posterior-inferior type in 12 and posterior-superior type in 10. The correlation between morphology of A-1 segment of ACA and classifications of ACoAA was significant (p=0.000; C=0.619, p=0.000). The direction of ACoAA was downward when the A-1 segment of ACA was Type 1a or Type 2a, and was upward when it was Type 1a or Type 2a and was upward or downward or complicated when it was Type 3.

CONCLUSION

The relationship between morphology of A-1 segment of ACA and classification of ACoAA is clarified in the present study, which is helpful to surgical treatment.