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

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.

Vascular Complications in Autosomal Dominant Polycystic Kidney Disease: Perspectives, Paradigms, and Current State of Play

Autosomal dominant polycystic kidney disease (ADPKD) is the leading cause of inherited kidney disease with significant contributions to CKD and end-stage kidney disease. The underlying polycystin proteins (PC1 and PC2) have widespread tissue expression and complex functional roles making ADPKD a systemic disease. Vascular complications, particularly intracranial aneurysms (ICA) are the most feared due to their potential for devastating neurological complications and sudden death. Intracranial aneurysms occur in 8-12% of all patients with ADPKD, but the risk is intensified 4-5-fold in those with a positive family history. The basis for this genetic risk is not well understood and could conceivably be due to features of the germline mutation with a significant contribution of other genetic modifiers and/or environmental factors. Here we review what is known about the natural history and genetics of unruptured ICA in ADPKD including the prevalence and risk factors for aneurysm formation and subarachnoid hemorrhage. We discuss two alternative screening strategies and recommend a practical algorithm that targets those at highest risk for ICA with a positive family history for screening.

Infundibular dilatation perforating vessel of anterior communicating artery

Background:

Infundibular dilatation at cerebral arteries is primary located at the posterior communicating artery. This report describes a rare case of infundibular dilatation perforating the branch of an anterior communication artery (AcomA) which mimicked an AcomA aneurysm.

Case Description:

The 54-year-old female presented with acute headache in the left temporal area with the right hemianesthesia. The magnetic resonance imaging and magnetic resonance angiography of the brain revealed a small outpouching lesion arising from the medial wall of the proximal A2 of the left ACA presenting as a suspected AcomA aneurysm. The cerebral angiogram showed a funnel-shaped dilatation of the anterior communicating artery with a single perforating branch arising from a dome size 1.4 × 1.1 mm, compatible with an infundibular dilatation perforating a branch of the AcomA.

Conclusion:

The infundibular dilatation perforating vessel of AcomA is a rare condition and can mimic an AcomA aneurysm. Three-dimensional angiography helps to evaluate differentiation of the characteristics enabling accurate diagnosis.

Locations, associations and temporal evolution of intracranial arterial infundibular dilatations in children

BACKGROUND

There are few data in the literature on the characteristics and natural history of intracranial arterial infundibular dilatations in children.

METHODS

An institutional review board-approved retrospective review was performed of infundibula reported on MR angiography in patients <18 years of age at our tertiary pediatric institute from 1998 to 2016. Clinical data (age, sex, diagnosis, other vascular variants/pathologies) were recorded and images assessed for vessel of origin, infundibulum size and exact location. Ratios of infundibulum:parent artery were assessed at diagnosis and last follow-up. Temporal evolution to aneurysm was evaluated.

RESULTS

We found 60 intracranial infundibula in 60 children (male:female=27:33; mean age 9.7±5.2 years, range 2-18 years,). Family history of aneurysms was present in 2/60 (3.3%). Syndromic association was found in 14/60 (23.3%), most frequently sickle cell disease (4/14=28.6%). Mean infundibulum size was 2.2±0.5 mm, with mean ratio to parent artery of 0.54±0.17. The most common location was on the P1-posterior cerebral artery (34/63=56.7%), whereas posterior communicating infundibula were seen in only 4/60 (6.7%) cases. Other cerebrovascular variants were seen in 12/60 (20%) patients. On follow-up imaging (in 32/60 patients over 86 patient-years, mean 32.3±35.7 months), no significant change in infundibulum:parent artery ratio was noted. None of the infundibular dilatations showed interval evolution to aneurysm.

CONCLUSION

We present the largest reported cohort of pediatric intracranial arterial infundibula, which we found to be distinct from their adult counterparts with regard to location, etiology and temporal evolution. Growth over time and/or aneurysmal formation are rare, not necessitating frequent short-term imaging surveillance during childhood.

De novo Aneurysm Formation on Internal Carotid Artery at Origin of Thick Posterior Communicating Artery: 7 Years after Transient Occlusion of Contralateral Internal Carotid Artery

The incidence of de novo intracranial aneurysm formation has been reported to be 0.84% per year. It is rare for de novo aneurysm formation to be observed on serial radiological examinations. A 64-year-old male with a history of right internal carotid artery (ICA) occlusion 7 years ago had subarachnoid hemorrhage (SAH) due to a ruptured left ICA aneurysm at the bifurcation of the posterior communicating artery (PComA). At the time of ICA occlusion, the left PComA was thick, about 3.0 mm in diameter, and no aneurysm was detected on radiological examinations. Thirty-eight months later, a small aneurysm was detected on the left ICA on magnetic resonance angiography (MRA). At the onset of SAH, the aneurysm was larger than that observed on the previous MRA. Left frontotemporal craniotomy was performed, and the aneurysm was clipped. A thick PComA might contribute to the development of an aneurysm at its origin due to hemodynamic stress. Persistent hemodynamic stress may cause enlargement of an aneurysm in 4 years and its subsequent rupture. In patient with a thick PComA, close observation is necessary to screen for de novo formation of a cerebral aneurysm.