Angiographic infundibular dilation: Is it worth exploring?

Introduction: Infundibular dilations are generally considered normal anatomical variants devoid of pathogenic significance. However, some of them change in time and show certain characteristics similar to saccular aneurysms. Case Report: A 40-year-old male patient was hospitalized due to subarachnoid hemorrhage, resulting from the rupture of an aneurysm at the level of the anterior communicating artery. Additionally, an infundibular dilation of 6 mm in diameter was detected at the level of the right posterior communicating artery. The patient underwent an open surgery, using the pterional craniotomy approach to the right. The aneurysm of the anterior communicating artery was clipped with some difficulty because previous Pedro Nogarotto Cembraneli1, Italo Nogarotto Cembraneli2, Renata Brasileiro de Faria Cavalcante3, Volmer Fernandes Valente Junior3, José Edison da Silva Cavalcante4, Rherold Santana5, Julia Brasileiro de Faria Cavalcante1 Affiliations: 1MD, Santa Mônica Hospital, Aparecida de Goiânia, GO, Brazil; 2Medical Sciences Course, Health Sciences School, Faculdade Ceres (FACERES), São José do Rio Preto, SP, Brazil; 3MD, Neurosurgeon, Member of the Brazilian Society of Neurosurgery (SBN), Santa Monica Hospital, Aparecida de Goiânia – GO, Brazil; 4MD, PhD in Neurosurgery, Neurosurgeon, Member of the Brazilian Society of Neurosurgery (SBN), Head of the Neurosurgery Medical Residency Service, Santa Monica Hospital, Aparecida de Goiânia – GO, Brazil; 5MD, Resident in Neurosurgery at Santa Mônica Hospital, Aparecida de Goiânia, GO, Brazil. Corresponding Author: Pedro Nogarotto Cembraneli, Santa Mônica Hospital, Chácara Aurora, BR-153, km 8,5 Vila Sul, Aparecida de Goiânia, GO, Brazil; Email: pedrocembranelli@hotmail.com Received: 11 August 2020 Accepted: 27 October 2020 Published: 18 December 2020 hemorrhage and hematoma were covering the aneurysmal neck. A mini clip was used to laterally decrease the infundibular dilation. Upon releasing the clip, we evidenced not an infundibulum, but a typical aneurysm, with the posterior communicating artery well attached to its wall, which was released and exposed at the time of clipping. Conclusion: Infundibular dilation is a potential source of bleeding, but it rarely ruptures and is little valued by radiologists and neurosurgeons. The care inherent in the discovery of an infundibular aneurysm, even if it is insidious, must be the same as that applied to classical types of aneurysm. Moreover, the therapeutic approach should be chosen when the infundibular aneurysm is equal to or greater than 4 mm in diameter.


INTRODUCTION
The posterior communicating arteries originate from the cerebral part of the internal carotid arteries on both sides, mainly due to the posterolateral or posterior aspect, and after a course of approximately 12 mm it Int J Case Rep Images 2020;11:101182Z01PC2020. www.ijcasereportsandimages.com Cembraneli et al. 2 joins the posterior cerebral artery in the interpeduncular cistern [1][2][3]. The posterior communicating arteries may present conical, triangular, or funnel-shaped infundibular dilations, which are considered normal anatomical variants devoid of pathogenic significance. Nonetheless, some of them change in time and show certain characteristics that are similar to saccular aneurysms [3,4].
Although they rarely rupture, infundibular dilations are a potential source of bleeding, and therefore are little valued by radiologists and neurosurgeons. Radiological control is usually disregarded even by the patients. Consequently, they are often only diagnosed in the presence of subarachnoid hemorrhage, when they rupture [5][6][7].

CASE REPORT
A 40-year-old male patient, with no previous diseases, was hospitalized due to subarachnoid hemorrhage, resulting from the rupture of an aneurysm at the level of the anterior communicating artery, diagnosed through conventional cerebral angiography, by catheterization ( Figure 1). In addition to this aneurysm, an infundibular dilation of 6 mm in diameter was detected at the level of the right posterior communicating artery (Figures 2 and 3). The radiologist suggested that it was a simple infundibular dilation, and the main focus of the radiological interpretation was to assess the characteristics of the anterior communicating artery aneurysm that had caused the subarachnoid hemorrhage.
Our team decided for an open surgery, using the pterional craniotomy approach to the right. The aneurysm of the anterior communicating artery was clipped with some difficulty, since previous hemorrhage and hematoma were covering the aneurysmal neck.   Immediately after, we explored the referred infundibular dilation. At first, the image observed in the microscope was really very typical of a dilation in the emergence of the posterior communicating artery, triangle-shaped and with an enlarged base, as it can be seen in the angiography ( Figure 4).
We chose to use a mini clip to laterally decrease the infundibular dilation. Upon releasing the clip, we evidenced not an infundibulum, but a typical aneurysm, with the posterior communicating artery well attached to its wall, which was released and exposed at the time of this clipping ( Figure 5). Int J Case Rep Images 2020;11:101182Z01PC2020. www.ijcasereportsandimages.com Cembraneli et al. 3

DISCUSSION
The reported incidence of infundibular dilation of the posterior communicating artery detected by angiography varies from 6% to 17% and increases with age. The dilation is approximately triangle-shaped and its diameter does not exceed 3 mm [8,9].
The exact and natural history of infundibular dilation is still controversial [6, 10]. Radiological images not always clarify the real shape of this dilation, or reveal hidden or adherent vessels on its surface, hence the difficulty of indicating surgery without a precise diagnosis [8, 11, 12].
The differential diagnosis between an infundibular dilation and a small aneurysm is not always easy, even with conventional service techniques. Given that dilations are considered benign, the most sophisticated radiological techniques are not used. Sometimes, the structure of the service does not allow the purchase of more sophisticated devices [6, 7, 12].

CONCLUSION
The care inherent in the discovery of an infundibular aneurysm, even if it is insidious, must be the same as that applied to classical types of aneurysm. Systematic follow-ups with imaging exams (angiography, magnetic resonance imaging, tomography) should be performed. Moreover, the therapeutic approach should be chosen when the infundibular aneurysm is equal to or greater than 4 mm in diameter. M, Takaku

Guarantor of Submission
The corresponding author is the guarantor of submission.

Source of Support
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Consent Statement
Written informed consent was obtained from the patient for publication of this article.