Enlargement to a saccular aneurysm and subsequent rupture of infundibular widening of posterior communicating artery

Stability of infundibular dilatations: a single center follow-up study and systematic review of the literature

PURPOSE

Although infundibular dilatations (IDs) have been thought to be benign anatomical variants, case reports suggest that they can grow and rupture. The aim of this study was to determine whether IDs have a tendency to grow or rupture.

METHODS

The study population was collected from the Tampere University Hospital (TAUH) Aneurysm Database. The presence of IDs was screened from the medical records and imaging studies of 356 intracranial aneurysm patients left to follow-up from 2005 to 2020. The imaging studies were reviewed to confirm the IDs, and their clinical course. Finally, we performed a systematic review of published cases of ID leading to aneurysmatic rupture from PubMed.

RESULTS

We found 97 typical IDs in 83 patients and 9 preaneurysmal lesions resembling ID in 9 patients. Out of the typical cone-shaped IDs, none grew or ruptured in a total follow-up of 409 patient-years. One preaneurysmal lesion ruptured during a follow-up: this lesion had components of both infundibular dilatation and aneurysm at the beginning of follow-up. In the systematic literature search, we found 20 cases of aneurysmatic SAHs originating from an ID. Of those, only 7 had imaging available prerupture. All 7 IDs were typically cone-shaped, but a branching vessel originating from the apex of ID was only seen in 4/7.

CONCLUSION

Typical infundibular dilatations seem to be benign anatomical variants that are stable and, thus, do not need prophylactic treatment or imaging follow-up. Likely, the SAHs reported from IDs were actually caused by misdiagnosed preaneurysmal lesions.

Flow Diversion for the Management of Ruptured Intracranial Arterial Infudibular Dilatation: Proof of Principle and Therapeutic Protocol

Thought to be benign anatomical variants, cerebral infundibular dilatations (ID) are most commonly encountered at the junction of the internal carotid artery (ICA) and the posterior communicating artery (PcomA). The true nature of this entity remains controversial, as some literature reports suggest they should be considered preaneurysmal lesions and a potential source of devastating subarachnoid hemorrhage. This report describes cases of presumably ruptured IDs and their therapeutic endovascular management. We retrospectively reviewed and analyzed patients with isolated subarachnoid hemorrhage (SAH) where the only potential cause was ruptured cerebral IDs, treated or not, between January 2012 and June 2021. Morphological and radiological features, treatment and procedural considerations, clinical and angiographic outcomes were also reviewed. Natural history of the ID is poorly understood, and its relation to SAH remains controversial. Ruptured cerebral IDs can be the suspected cause of bleeding if no other vascular lesion is present during multimodal examinations. Endovascular flow diversion stenting is safe and effective for the proper treatment of ruptured IDs. Pending further validations with longitudinal data are needed to legitimate the natural course of these mysterious lesions.

Ruptured Infundibular dilatation of the posterior communicating artery

OBJECTIVE

An infundibulum of the posterior communicating artery (PcomA) or infundibular dilatation (ID) is considered to be a benign anatomical variant. However, some evidence suggests that ID is a pre-aneurysmal state. This case series presents cases of ruptured IDs and aneurysms originating from the IDs.

METHODS

Between April 2002 and June 2020, 1337 patients were treated for aneurysmal subarachnoid hemorrhage (SAH). Among them, 7 patients with ruptured PcomA IDs were identified. Rupture IDs of the PcomA were categorized into 1) direct rupture of IDs, and 2) rupture of aneurysms originating from IDs. The clinical and radiographic factors were retrospectively reviewed.

RESULTS

Two patients experienced direct rupture of IDs, while the other 5 patients presented with ruptured aneurysms originating from IDs. The 2 patients with direct rupture of IDs at presentation were relatively younger (< 50 years), while the other 5 patients with ruptured aneurysms originating from IDs were over 70 and had a history of aneurysmal SAH due to other intracranial aneurysms. Ruptured IDs were treated with microsurgery or endovascular treatment. There were no complications related to the procedure for securing ruptured IDs. Five (71.4%) patients showed favorable outcomes. One patient with initial Hunt and Hess grade 4 died due to initial brain damage with cerebral vasospasm and medical complications.

CONCLUSIONS

ID of the PcomA rarely causes SAH with or without aneurysm formation. Thus, patients with IDs of the PcomA should be carefully followed up for a long period, especially those with a history of aneurysmal SAH.

Infundibular Dilations and Subarachnoid Hemorrhage: to Treat or Not to Treat?

BACKGROUND

Infundibular dilations are funnel-shaped widenings at the origin of a cerebral artery, most commonly the posterior communicating artery. Controversy exists as to whether an infundibulum represents a normal anatomic variant or a lesion with the potential for rupture and subarachnoid hemorrhage (SAH).

METHODS

We reviewed all reported cases of infundibular dilations and SAH in the world literature and present an illustrative case.

RESULTS

Most infundibula in the context of SAH were associated with an aneurysm either on or near an infundibulum. However, there have been 7 reports in which the infundibulum could have been the primary site of rupture and no associated aneurysm was identified. Close review reveals significant limitations of those 7 reports.

CONCLUSIONS

The literature, and our own experience, do not support the treatment of infundibula, even in SAH patients. Treatment should be directed toward an associated aneurysm, not the infundibulum.

A tiny bleb at Junctional Dilatation of the Posterior Communicating Artery as a Predisposing Factor for Development of a De Novo Aneurysm

Formation of de novo aneurysm from a junctional dilatation at the origin site of the posterior communicating artery (PcomA) has been rarely reported. In this case report, three females in sixth decades of age developed a de novo aneurysm from the junctional dilatation of the PComA with a tiny bleb-like lesion over 5 years after initial presentation.

Infundibular dilations of the posterior communicating arteries: pathogenesis, anatomical variants, aneurysm formation, and subarachnoid hemorrhage

Background

Cerebrovascular infundibular dilations (IDs) are triangular-shaped widenings less than 3 mm in diameter, which are most commonly found at the posterior communicating artery (PCoA). The aims of this systematic review are to elucidate the natural histories of IDs, determine their risk of progression to significant pathology, and discuss potential management options.

Methods

A comprehensive literature search of PubMed was used to find all case reports and series relating to cerebral IDs. IDs were classified into three types: type I IDs do not exhibit morphological change over a long follow-up period, type II IDs evolve into saccular aneurysms, while type III IDs are those that result in subarachnoid hemorrhage without prior aneurysmal progression. Data were extracted from studies that demonstrated type II or III IDs.

Results

We reviewed 16 cases of type II and seven cases of type III IDs. For type II IDs, 81.3% of patients were female with a median age at diagnosis of 38. All type II IDs were located at the PCoA without a clear predilection for sidedness. Median time to aneurysm progression was 7.5 years. For type III IDs there was no clear gender preponderance and the median age at diagnosis was 51. The PCoA was involved in 85.7% of cases, with 57.1% of IDs occurring on the left. Most patients were treated with clipping. Risk factors for aneurysm formation appear to be female gender, young age, left-sided localization, coexisting aneurysms, and hypertension.

Conclusions

IDs can rarely progress to aneurysms or rupture. Young patients with type II or III IDs with coexisting aneurysms or hypertension may benefit from long-term imaging surveillance.

Are infundibular dilatations at risk of further transformation? Ten-year progression of a prior documented infundibulum into a saccular aneurysm and rupture: Case report and a review of the literature

Infundibular dilatations (IFDs) are conical, triangular, or funnel-shaped enlargements at the origin of cerebral arteries, and they are primarily located (7-25%) on the posterior communicating artery (PComA). Progression over time into a saccular aneurysm with a risk of rupture of a previously demonstrated IFD has rarely been reported. We report the case of a 60-year-old female who presented 10 years earlier with a subarachnoid hemorrhage caused by a left internal carotid artery aneurysm rupture. At that time, the carotid angiography showed the left internal carotid artery aneurysm and a right posterior communicating artery infundibular dilatation. Neck clipping for the left internal carotid artery aneurysm was performed and the patient was discharged with no neurological deficit. Ten years later, the patient suffered a second fatal subarachnoid hemorrhage; carotid angiography revealed a right posterior communicating artery aneurysm developed from the previously documented infundibular dilatation with a de novo right anterior choroidal artery aneurysm. This case is another proof of the small but growing number of examples of infundibular transformation over time, as well as their risk of progression into saccular aneurysms and subsequent rupture.

First demonstration of resolution of an infundibulum by direct treatment of the arterial wall with Pipeline flow-diverting stent

INTRODUCTION

Infundibula are symmetrical funnel-shaped widening, measuring more than 3 mm at its base with the branch artery arising from its apex. The pathological significance of this entity remains controversial. Although a relatively common appearance in otherwise normal angiograms, they have occasionally been described to progress into saccular aneurysms or directly rupture.

METHODS/RESULTS

We describe the first case of a disappearing infundibulum after a flow diverting stent was deployed across the infundibulum during the treatment of an adjacent aneurysm.

CONCLUSIONS

We concur in the view that infundibula are at least pre-pathological lesions that may in certain circumstances require consideration for treatment. Our case for the first time offers a potential treatment option for such situations.

The Clinic of Neurosurgery at the Clinical Center of Serbia in Belgrade--building on the past

Neurosurgery as an independent discipline in Serbia has a distinguished history, beginning in 1938 when Dr. Milivoje Kostic, Professor and Chairman of Surgery, opened the Department of Neurosurgery within the Clinic of Surgery in Belgrade. Since then, thanks to the founding fathers' efforts and their successors' work, the Clinic for Neurosurgery in Belgrade has become a highly specialized health, scientific, and educational institution that is part of the University of Belgrade and is a referral center for all neurosurgical clinics in Serbia. Currently, the Clinic for Neurosurgery, with 160 patient beds, is one of the largest European institutions of its kind. Neurosurgery at the Clinical Center of Serbia (CCS) involves a wide range of patients and resources, with an average daily inpatient census of 15 to 20 patients. Each year, there are more than 3000 admissions at the neurosurgical service. Approximately 3500 operations per year are performed in the main campus neurosurgical operating rooms of CCS, while approximately 15,000 patients alone are evaluated in emergency room or inpatient consultations. Despite economic restraints, the department continues to grow in strength, and we remain optimistic of exciting times ahead for neurosurgery at the CCS.

Evolution from an infundibulum of the posterior communicating artery to a saccular aneurysm

INTRODUCTION

An infrequent case of a de novo aneurysm formation originating from an infundibulum at the origin of the posterior communicating artery (PcomA) is presented. The aneurysm developed within 7 years in a patient who initially presented with subarachnoid hemorrhage (SAH) from a saccular aneurysm of the vertebral artery.

CASE SUMMARY

A 43-year-old female patient was admitted to our hospital on 16th June 2000 after an acute onset of massive occipital headache. A computed tomography (CT) scan showed a subarachnoid hemorrhage (SAH) around the brainstem and 4-vessel angiography revealed an aneurysm originating from the V4 segment of the right vertebral artery (VA) as the cause of the SAH. A small aneurysm at the basilar artery (BA)/superior cerebellar artery (SCA) bifurcation was also found. Injection of the left internal carotid artery (ICA) showed a diffuse enlargement at the origin of the left PcomA, which at this time was considered to be a so-called infundibulum. The VA aneurysm was treated by coil occlusion. Follow-up digital subtraction angiography (DSA) in 2005 showed a de novo aneurysm formation at the VA junction, again treated by coil occlusion. The PcomA infundibulum at the left ICA was not examined. Follow-up angiography performed in 2007 revealed a saccular de novo aneurysm of the left ICA arising from the origin of the left PcomA with a maximum diameter of 12 mm. Coil occlusion of the PcomA aneurysm was subsequently carried out.

CONCLUSION

Infundibular widening of cerebral arteries can develop into true aneurysms. Mid-term and long-term follow-up MRI (e.g., in yearly intervals) is advised for infundibula with a diameter of 3 mm or more. In patients with other aneurysm(s), with a documented de novo aneurysm formation or with a familial occurrence of aneurysms, the risk of evolution of an infundibulum to a saccular aneurysm may be increased and follow-up should be even more stringent.