Infected giant pseudoaneurysm of the extracranial internal carotid artery with vascular tortuosity: a case report

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J Korean Soc Geriatr Neurosurg. 2025;21(2):77-80

Publication date (electronic) : 2025 September 26

doi : https://doi.org/10.51638/jksgn.2025.00038

Dahoon Hong, Tae Wan Kim, Inho Oh

Department of Neurosurgery, VHS Medical Center, Seoul, Korea

Corresponding Author: Tae Wan Kim, -- Department of Neurosurgery, VHS Medical Center, 53 Jinhwangdo-ro 61-gil, Gangdong-gu, Seoul 05368, Korea E-mail: euro3399@naver.com

Received 2025 April 16; Revised 2025 June 5; Accepted 2025 June 13.

Abstract

Introduction

Extracranial carotid artery pseudoaneurysms (ECAPs) are rare and sometimes difficult to diagnose. The optimal treatment for carotid artery pseudoaneurysms remains controversial, as endovascular and surgical treatments have their own advantages and disadvantages. Surgical treatment provides direct visualization of the pseudoaneurysm, removal of inflammatory tissues around the pseudoaneurysm, and definite reconstruction of the artery [1,2]. Meanwhile, endovascular treatments are less invasive and can relatively lower the risk of damage to surrounding structures, such as nerves, immediate stroke, and rupture of pseudoaneurysms [3,4]. The disadvantages of endovascular treatment include stent infection, bacterial embolization, and risk of cerebral abscess formation [5]. Relatively high complication rates are observed during surgical procedures [6]. A combined approach, involving initial stent insertion followed by definite surgery, is also recommended [7]. In this case report, we highlight the different treatment options for an infected ECAP, emphasizing that surgical treatment should be recommended when endovascular treatment fails.

Case Report

A 76-year-old man was admitted to our hospital’s emergency department with a chief complaint of high-grade fever exceeding 39 °C. His medical history included a coronavirus disease 2019 infection a month earlier. He underwent an initial enhanced neck computed tomography (CT), which revealed no notable abnormalities. As such, the patient was admitted with fever of unknown origin. Further imaging with Torso positron emission tomography-CT revealed increased fluorodeoxyglucose uptake in the left carotid space. Upon re-evaluation of the initial enhanced neck CT, a pseudoaneurysm with an enhancing wall in the left carotid space was identified. This finding raised the suspicion of a deep neck infection in conjunction with acute epiglottitis.

Carotid magnetic resonance angiography (MRA) revealed a left proximal cervical internal carotid artery (ICA) blowout with pseudoaneurysm formation and large pseudoaneurysm originating from the left proximal ICA (Fig. 1). The patient was transferred to our department and underwent cerebral angiography. A large pseudoaneurysm of the left ICA measuring 2.5 cm in diameter was confirmed. No collateral flow across the circle of Willis was noted, even with left ICA compression. Additionally, no ICA filling through the posterior communicating artery channel was observed (Fig. 2). Therefore, sacrificing the ICA was impossible, and we attempted to maintain ICA flow using a covered stent through the affected ICA segment. Endovascular treatment by using a covered stent (COVERA-PLUS 6×40; BD Biosciences) was planned. During the procedure, the microwire and microcatheter were successfully advanced beyond the petrous ICA segment. However, owing to the vascular tortuosity, the stent could not be navigated beyond the lesion (Fig. 3).

Fig. 1.

(A) Enhanced computed tomography of the neck shows heterogeneous inflammatory swelling with peripheral ring enhancement in the left parapharyngeal and retropharyngeal space. (B) Magnetic resonance angiography (carotid) shows a large pseudoaneurysm originating from the left proximal internal carotid artery.

Fig. 2.

(A) Cerebral angiography reveals a 2.5-cm large pseudoaneurysm from the left internal carotid artery. (B) The posterior circulation shows no specific abnormal finding on cerebral angiography.

Fig. 3.

(A) A microwire and microcatheter are successfully advanced beyond the petrous segment of the internal carotid artery. (B) The stent cannot be navigated beyond the lesion.

After the procedure, the patient was treated conservatively with antibiotics. We attempted a second endovascular treatment using a flow diverter (DELIVO 6×50, Acandis), which was more flexible than a sole stent. During angiography, an increase in the pseudoaneurysm size (2.5 cm in diameter to 5.0 cm) was noted, with severe narrowing of the cervical ICA proximal to the pseudoaneurysm. Catheterization of the aneurysmal outflow failed due to outlet narrowing (Fig. 4).

Fig. 4.

(A) Second angiogram shows an increase in pseudoaneurysm size (diameter, 2.5 cm to 5.0 cm) and severe narrowing of the cervical internal carotid artery proximal to the pseudoaneurysm. (B) The catheterization to aneurysmal outflow fails due to outlet narrowing.

Therefore, surgical intervention was planned. Following clamping of the common carotid artery (CCA) and external carotid artery (ECA), a shunt catheter was connected. Subsequently, an aneurysmectomy was performed. A bypass was performed between the distal ICA bulb and orifice using a 6 mm synthetic graft hemashield (12×6 mm, Hemagard Knitted Bifurcation; Maquet). Postoperative carotid CT revealed removal of the pseudoaneurysm and improvement in CCA flow, with patent flow in the left proximal ICA (Fig. 5).

Fig. 5.

After surgical treatment, (A) a patent flow of the left proximal internal carotid artery (ICA) is confirmed and (B) bypass graft state at the left proximal ICA is also observed on carotid 3-dimensional computed tomography angiography.

After surgical treatment, C-reactive protein level decreased, and the patient was transferred to a convalescent hospital.

Discussion

Etiologies of pseudoaneurysms include trauma, iatrogenic vascular injury, arterial wall degeneration, and infection [1]. Unlike aneurysms, the wall of a pseudoaneurysm consists of adventitia, periarterial fibrous tissue, and hematoma. Progressive pseudoaneurysm enlargement results in pulsatile hematoma. This leads to clot propagation, embolism, and hemorrhage [8]. Infected pseudoaneurysms are triggered by vascular weakening and dilatation caused by inflammation.

Infected pseudoaneurysms account for approximately 5% of all pseudoaneurysms [9]. Infected extracranial pseudoaneurysms are caused by direct invasion of the adjacent abscess through the vascular wall and the hematogenous spread of infected foci. Staphylococcus spp. is the most common pathogen. The most common causes of infected carotid artery pseudoaneurysms are postoperative infection and bacterial endocarditis. On the other hand, cervical lymphadenitis is the most common cause in children [10]. Neck swelling and fever are the most common symptoms [6]. Infected carotid artery aneurysms are associated with high morbidity and mortality due to complications such as rupture, stroke, cranial nerve palsy, hematogenous spread of the infected material, and airway compression. Digital subtraction angiography is the gold standard diagnostic tool owing to its high sensitivity and specificity [11]. Enhanced CT angiography and positron emission tomography are supplementary diagnostic tool [12]. Ultrasonography and carotid MRA are also useful [2].

Recently, the incidence of infected pseudoaneurysms has decreased due to advances in antibiotics [8,13]. The use of broad-spectrum antibiotics in all patients with infected pseudoaneurysms is recommended before endovascular and/or surgical treatment [6,14], and continuous use after treatment for at least 6 weeks [12]. Blood culture is an important diagnostic tool; however, almost half of the patients show negative findings. Culture of the pseudoaneurysmal wall shows a positive finding in >90% of cases [14]. The differential diagnosis between a pseudoaneurysm and an abscess/mass is crucial. However, unnecessary biopsy and debridement could lead to serious complications like hemorrhages [15].

Endovascular treatment includes covered stent grafting, coil embolization, and detachable balloon embolization [11]. Endovascular treatment is more commonly used for pseudoaneurysms than for true large aneurysms [16]. It is also typically used more often than surgical treatment in post-traumatic and postoperative pseudoaneurysm cases [3]. Coil embolization is a restrictive method used when a pseudoaneurysm has a wide neck and fusiform shape due to the risk of recanalization and migration of the embolus [13]. Endovascular treatment demonstrates a relatively low early complication rate [6,16], less damage to adjacent structures and cranial nerves, and a lower risk of bleeding during the procedure compared to direct surgical treatment [4]. The risk of an unstable thrombus with manipulating a pseudoaneurysm is a relative contraindication for endovascular treatment, and the distal artery should be protected during the procedure.

Notably, ligation the carotid artery is restricted; ligation of the ICA can be used only when contralateral ICA flow and an intact circle of Willis are confirmed [2]. Open surgical treatment is associated with fewer complications due to postoperative ischemic changes and ensures better long-term outcomes. Direct visualization of the pseudoaneurysm can also enable wide debridement of the infected lesion [1]. Surgical treatment, including restoration of vascular continuity, may be necessary. Vascular reconstruction methods include primary closure, patch angioplasty, and resection with anastomosis. The most common method is resection with an autogenous interposition bypass [10]. When using a bypass graft, autologous material from the saphenous and internal jugular veins may lower the risk of infection compared to heterologous or prosthetic grafts [17]. When the vessel is elongated and tortuous, end-to-end anastomosis is preferred over graft [18]. Endovascular treatment should be chosen carefully for infected pseudoaneurysms and considered as a last option [3].

More recently, staged treatments have recently been considered. Endovascular stent insertion is preferentially carried out and followed by surgical treatment and debridement [5,7]. The prosthetic material used for the infected lesion is limited, and long-term follow-up of safety is not satisfactory.

Conclusion

The gold standard treatment for infected pseudoaneurysms remains unclear, and endovascular treatment and open surgery have their own advantages and disadvantages. Thus, appropriate treatment methods must be selected depending on the circumstances. Our case of an infected pseudoaneurysm of the ICA shows that surgical treatment should be recommended when endovascular treatment fails.

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