- Department of Endovascular Neurosurgery, Saitama Medical University International Medical Center, Hidaka, Japan
Correspondence Address:
Koki Onodera, Department of Endovascular Neurosurgery, Saitama Medical University International Medical Center, Hidaka, Japan.
DOI:10.25259/SNI_493_2024
Copyright: © 2024 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, transform, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.How to cite this article: Koki Onodera, Kuya Azekami, Noriyuki Yahagi, Ryutaro Kimura, Ryuta Kajimoto, Masataka Yoshimura, Shinya Kohyama. Spontaneous disappearance of a small unruptured cerebral aneurysm in the clinoid segment of the internal carotid artery: A case report and literature review. 23-Aug-2024;15:299
How to cite this URL: Koki Onodera, Kuya Azekami, Noriyuki Yahagi, Ryutaro Kimura, Ryuta Kajimoto, Masataka Yoshimura, Shinya Kohyama. Spontaneous disappearance of a small unruptured cerebral aneurysm in the clinoid segment of the internal carotid artery: A case report and literature review. 23-Aug-2024;15:299. Available from: https://surgicalneurologyint.com/?post_type=surgicalint_articles&p=13055
Abstract
Background: Various degrees of thrombosis have been reported in patients with giant aneurysms. However, small, unruptured aneurysms rarely resolve spontaneously. Herein, we report a case of a small unruptured aneurysm in the clinoid segment (C3) of the left internal carotid artery (ICA) that showed almost complete occlusion at the 1-year follow-up.
Case Description: A 66-year-old woman developed a subarachnoid hemorrhage on the left side of the perimesencephalic cistern. Cerebral angiography performed on admission revealed no evidence of hemorrhage. Subsequent cerebral angiography on day 12 revealed a dissecting aneurysm on a branch of the superior cerebellar artery (SCA), and the patient underwent parental artery occlusion with 25% n-butyl-2-cyanoacrylate. The postoperative course was uneventful, and the patient was discharged on day 22 with a modified Rankin Scale score of 1. The 1 year follow-up cerebral angiogram demonstrated that the dissecting aneurysm in the SCA branch remained occluded. Notably, a small 2-mm unruptured aneurysm in the clinoid segment (C3) of the left ICA, which was present at the onset of subarachnoid hemorrhage, was almost completely occluded without intervention. Magnetic resonance angiography 1 year after spontaneous resolution of the aneurysm showed no apparent recurrence.
Conclusion: This case highlights that even small, unruptured aneurysms can develop spontaneous occlusions.
Keywords: Small aneurysm, Spontaneous disappearance, Thrombosis, Unruptured cerebral aneurysm
INTRODUCTION
Intracranial aneurysms can partially or completely disappear on neuroimaging studies due to thrombosis.[
CASE REPORT
A 66-year-old woman without a notable medical history was brought to her primary physician with a sudden onset of occipital pain while swimming. She was referred to our hospital after a computed tomography (CT) scan showed a subarachnoid hemorrhage on the left side of the perimesencephalic cistern [
Figure 1:
(a) Computed tomography scan on admission showing subarachnoid haemorrhage on the left side of the perimesencephalic cistern. (b) Three-dimensional digital subtraction angiography (3D-DSA) performed on admission showing a saccular aneurysm measuring 1.9 mm at the neck and 2 mm in depth in the left internal carotid artery (ICA). (c and d) 3D-DSA on day 12 before and after parent artery occlusion with 25% n-butyl-2-cyanoacrylate performed for a dissecting aneurysm in the branch of the left superior cerebellar artery.
Figure 2:
(a) One year follow-up three-dimensional digital subtraction angiography showing spontaneous, almost complete occlusion of the Internal carotid artery (ICA) aneurysm with a slight bulge remaining at its neck. (b) Magnetic resonance angiography one year after disappearance of the aneurysm showing no apparent recurrence.
DISCUSSION
Spontaneous resolution of cerebral aneurysms is common in ruptured aneurysms,[
However, the spontaneous disappearance of small unruptured aneurysms is rare, and the underlying mechanism has not been clarified. Despite the lack of configuration features that predispose patients to thrombus formation, ischemic events have been reported in small unruptured saccular aneurysms, and distal clot embolization from the aneurysmal sac is the most common mechanism.[
The interval between the identification and disappearance of small aneurysms ranges from 1 to 15 years, and the degree of disappearance varies.[
Yamada et al. showed the spontaneous disappearance of small unruptured aneurysms in the clinoid segment of the ICA with intra-aneurysmal T2 high intensity, suggesting thrombosis.[
There is no consensus regarding the management of small thrombotic aneurysms. Vandenbulcke et al. reported that none of the 13 (0%) thrombotic aneurysms measuring <10 mm ruptured, although one of 6 (17%) measuring 10-20 mm and 2 (100%) larger than 20 mm thrombotic aneurysms ruptured, and that aneurysm size was the factor predicting rupture.[
In addition, Akimoto et al. reported a small unruptured aneurysm of the distal anterior cerebral artery that completely occluded spontaneously but recurred 2 years later,[
CONCLUSION
Here, we report the spontaneous disappearance of a small unruptured aneurysm in the clinoid segment of the ICA. The etiology of this phenomenon has not yet been elucidated. However, neuroimaging findings suggested that this may be related to thrombosis. Long-term follow-up is required due to the potential risk of recanalization and ischemic stroke, in addition to clarifying the etiology.
Ethical approval
The Institutional Review Board approval is not required.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Disclaimer
The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.
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