Cerebral mycotic aneurysm with internal carotid artery occlusion: a case description

Introduction

Infectious aneurysms involving the internal carotid artery are relatively uncommon, accounting for only 2–5% of all carotid aneurysms (1). Although most infectious aneurysms are caused by bacterial pathogens in the context of endocarditis, emerging evidence has indicated an increased incidence of fungal-derived internal carotid aneurysms (2). Infectious aneurysms often comorbid with severe subarachnoid hemorrhage or encephalitis as complications, but their comorbidities with thrombotic occlusion are scarcely documented. Currently, the diagnosis and management of fungal internal carotid aneurysms continue to pose significant challenges due to their rarity, unpredictable nature, and frequent occurrence without specific or alarming symptoms.

In this study, we present a case analysis of a 76-year-old male patient complicated by an occlusion of the ipsilateral cavernous segment of the internal carotid artery. This case not only enhances our understanding of cerebral mycotic aneurysm, but provides valuable insights into the diagnosis and treatment of such rare clinical conditions.

Case presentation

A 76-year-old emaciated man was admitted to our department with a 2-month history of headache. He had a medical history of hypertension and underwent partial duodenectomy with segmental intestinal resection for perforated duodenum complicated by periduodenal abscess formation, with no reported use of corticosteroids or immunosuppressants. Head computed tomography angiography (CTA) showed an intact internal carotid-cavernous sinus aneurysm measuring 1.2 cm × 0.9 cm (Figure 1A,1B, yellow arrows; Figure S1), which was enveloped by a space-occupying lesion in the right sphenoid sinus and posterior roof of the nasopharynx (Figure 1A, red arrow). Upon hospital admission, the patient’s hyponatremia was promptly corrected and blood pressure was carefully controlled to mitigate the risk of aneurysm rupture, while comprehensive diagnostic evaluation and therapeutic strategies were concurrently deliberated.

Figure 1 Radiological and pathological features. (A,B) Head CTA showing an intact internal carotid-cavernous sinus aneurysm (yellow arrows) and a sinus space-occupying lesion (red arrow). Head CTA (C,D) and digital subtraction angiography (E,F) confirming the right internal carotid artery occlusion (purple arrows) and the flow recanalization after thrombectomy (green arrows), respectively. (G) Brain magnetic resonance imaging suggesting the infarction (white arrows) and the infectious sinus lesion (red arrows). (H) Histopathological testing of the sinus lesion (black arrows; hematoxylin and eosin staining, ×100). CTA, computed tomography angiography.

On the third night after admission, the patient experienced a sudden loss of consciousness and speech. Neurological examinations showed unequal pupil diameter, absence of light reflex in the right pupil, deviated gaze towards the right side, shallow nasolabial sulcus on the left side, decreased muscle tone in the left limbs, grade one muscle strength in both the left upper and lower limbs, diminished deep tendon reflexes in all four limbs, and presence of Babinski’s sign and Hoffman’s sign on the left side. Both head CTA and digital subtraction angiography confirmed occlusion of the right internal carotid artery (Figure 1C,1D, purple arrows). After thorough communication with the patient’s family and acquisition of signed informed consent, emergency endovascular intervention was initiated approximately 4 hours after symptom onset. The procedure involved thrombectomy for the right internal carotid artery occlusion, followed by planned coil embolization of the cerebral aneurysm (main devices used: Rebar-18 microcatheter, Synchro guidewire, Solitaire 6 mm × 30 mm stent, and Echelon-10 microcatheter). However, due to unexpected technical difficulties encountered during super-selective catheterization, coil deployment was unsuccessful, necessitating termination of the procedure. Postoperative angiography demonstrated satisfactory patency restoration within previously occluded artery (Figure 1E,1F, green arrows). The patient demonstrated notable improvement in mental status following the surgical procedure, whereas all other neurological examination findings remained unchanged.

Ten days after thrombectomy, brain magnetic resonance imaging revealed an infarction focus in the right frontal-parietal-temporal lobes (Figure 1G, white arrows; Figure S1) and suggested invasive fungal rhinosinusitis as the most likely cause of the sinus lesion (Figure 1H, black arrows; Figure S1). The serum fungal 1-3-β-D-glucan test was positive (82.3 pg/mL; reference range, 0–60 pg/mL), while galactomannan, Aspergillus fumigatus immunoglobulin E, cryptococcus capsule polysaccharide, tuberculosis immunoassay, and multi-tumor biomarkers were negative. Blood levels of C-reactive protein (75.5 mg/L; reference range, 0–6 mg/L) and procalcitonin (0.2 ng/mL; reference range, 0–0.09 ng/mL) were significantly elevated. Therefore, a diagnosis of sinus-originated fungal internal carotid aneurysm was suspected.

Subsequently, the patient provided consent for endoscopic resection of the sinus lesion. Intraoperative pus culture subsequently identified Aspergillus fumigatus and Corynebacterium striatum as the causative pathogens. Histopathological examinations from the sinus and right sphenoid sinus have identified fibrous tissue hyperplasia with hemosiderin deposition, infiltration of lymphocytes, plasma cells and neutrophils, and mucosal adhesion (Figure 1H).

The patient was ultimately diagnosed with cerebral mycotic aneurysm complicated by an occlusion of the ipsilateral internal carotid artery. He received long-term antiplatelet therapy with aspirin and anti-infective treatment comprising fluconazole/voriconazole (loading dose of 200 mg every 12 hours on day 1; a maintenance regimen of 100 mg twice daily) and Vancomycin (1 g intravenously every 12 hours) based on the drug sensitivity testing results. Despite intensive nutrition and regular medication, the patient exhibited a progressive decline in consciousness and died of cardiorespiratory failure 1 month after discharge to home. The patient demonstrated subtle improvements in consciousness transitioning from stupor to drowsiness during combined therapeutic management, including antiplatelet therapy, blood pressure regulation, antimicrobial therapy (both antibacterial and antifungal), hyperbaric oxygen treatment, and intensive nutritional support, while other clinical parameters remained essentially stable. Then, his family formally declined further interventional treatment of the aneurysm and requested discharge against medical advice. Following discharge to home care, the patient ultimately succumbed to pulmonary infection 1 month post-discharge.

All procedures performed in this study were in accordance with the ethical standards of the Ethics Committee of the First Affiliated Hospital, Fujian Medical University (MTCA, ECFAH of FMU [2015] 084-2), and with the Helsinki Declaration and its subsequent amendments. Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

Invasive fungal rhinosinusitis, a life-threatening condition commonly caused by the Zygomycetes class (e.g., Rhizopus, Mucorale, and Rhizomucor species) and Aspergillus species, has been reported to result in various devastating extra- and intra-cranial complications, including invasion of cerebral arteries, formation of mycotic aneurysms, and cavernous sinus thrombosis (1). Cerebral mycotic aneurysms can occur in either the internal carotid artery system or the vertebrobasilar artery system (3,4). Patients with cerebral mycotic aneurysms often present with severe subarachnoid hemorrhage or encephalitis as complications (1,4,5), but reports on their associations with acute ischemic stroke due to an ipsilateral vascular occlusion are scarce.

The study presents a rare case of sinus Aspergillus-induced mycotic internal carotid aneurysm in an elderly man who subsequently experienced an ipsilateral internal carotid artery occlusion. Such diagnosis was made based on the clinical manifestations, typical imaging findings, as well as pathogenic and pathological evidence. Mechanistically, given the well-documented angioinvasive propensity of Aspergillus species and the patient’s immunocompromised status post-duodenectomy, the sinus-derived Aspergillus infection likely facilitated the development of destructive, space-occupying lesions with subsequent invasion into the adjacent cavernous segment of the internal carotid artery. Fungal infiltration of the arterial adventitia may induce inflammatory necrosis, culminating in mural thinning and structural compromise, thereby predisposing to cerebral aneurysm formation. Furthermore, intraluminal hyphal propagation could precipitate localized mycotic embolization accompanied by vascular occlusion (2). In the present case, our intraoperative observations support the hypothesis that direct fungal invasion of the vascular wall precipitated intimal disruption, ultimately giving rise to a dissecting aneurysm. These pathological alterations disrupt normal hemodynamics, fostering thrombus formation and subsequent ischemic infarction.

It is noteworthy to mention that cerebral mycotic aneurysm often results in unfavorable outcomes, with reported mortality rates ranging from 20% to 80% (1). There remains controversy regarding the optimal treatment strategies for unruptured cerebral mycotic aneurysms (2,6). In terms of surgical approaches, both embolization techniques (e.g., liquid and coil) and parent artery occlusion (PAO) with or without bypass are considered viable options for treating myotic aneurysms (7). Given the current lack of studies comparing their safety and efficacy for such a rare condition, it is essential to incorporate the perspectives of the patient and their families when selecting an appropriate surgical strategy, particularly in light of the conditions presented in this case.

Based on this case, it can be concluded that early angiographic imaging facilitates the identification of cerebral mycotic aneurysm. Caution should be exercised regarding the risk of an ipsilateral internal carotid artery occlusion when considering a diagnosis of mycotic internal aneurysm. This case expands our understanding of sinus-originated cerebral mycotic aneurysm and provides valuable insights for further investigations.

Acknowledgments

None.

Footnote

Funding: This work was granted by the National Natural Science Foundation of China (No. 82301707), the Fujian Provincial Health Technology Project (No. 2022GGA027), and the First Affiliated Hospital of Fujian Medical University (Nos. YJRC3975 and PT-82301707).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-21/coif). All authors report funding from the National Natural Science Foundation of China (No. 82301707), the Fujian Provincial Health Technology Project (No. 2022GGA027), and the First Affiliated Hospital of Fujian Medical University (Nos. YJRC3975 and PT-82301707). The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the Ethics Committee of the First Affiliated Hospital, Fujian Medical University (MTCA, ECFAH of FMU [2015] 084-2), and with the Helsinki Declaration and its subsequent amendments. Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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