Brain abscess as a rare complication of endovascular coiling for cerebral aneurysm: A case report and literature review

Abstract

Background:

Brain abscess following coil embolization of aneurysms is rare, with only few cases described in the literature. Herein, we report this specific case and review the existing literature on this rare infectious complication associated with the endovascular treatment of cerebral aneurysms.

Case Description:

A 51-year-old patient developed a brain abscess 3 months after endovascular embolization of a giant internal carotid artery aneurysm. The patient experienced rapid clinical deterioration, requiring emergency surgical intervention for abscess drainage and decompressive craniectomy. Cultures of the abscess revealed the presence of Staphylococcus epidermidis and Staphylococcus hominis, both coagulase-negative staphylococci. Besides the intensive care, the patients died of sepsis.

Conclusion:

Perianeurysmal brain abscess in patients undergoing aneurysm coil embolization is a rare but potentially life-threatening. Treatment generally follows the protocol applied to cerebral abscesses in other conditions, involving surgical drainage and intravenous antibiotic therapy. However, before proceeding with drainage, it is crucial to confirm the absence of residual aneurysm or recanalization of a previously treated aneurysm to avoid hemorrhage risks.

INTRODUCTION

Aneurysms are present in up to 5% of the population and are an important cause of hemorrhagic stroke. In recent decades, endovascular coiling embolization has established itself as the primary treatment modality for cerebral aneurysms, standing out for its low complication rates.[23] The main complications arising from coiling embolization are intraprocedural aneurysm rupture, while infectious complications are rare events.[10] The occurrence of brain abscesses as a result of endovascular coiling embolization is rarely reported, with few cases described in the literature.[17] In this article, we report a rare case of brain abscess following endovascular embolization of an aneurysm of the right internal carotid artery (ICA).

CASE DESCRIPTION

A 51-year-old female patient was admitted to the emergency room with a complaint of 3-month chronic headache associated with visual loss for 2 days. Physical examination revealed bilateral blindness without light perception in both eyes and the absence of pupillary light reflexes. Head computed tomography (CT) revealed a rounded, well-defined hyperdense lesion, located close to the sellar region [Figure 1a]. Magnetic resonance angiography [Figure 1b] and then the digital subtraction angiography (DSA) revealed a giant partially thrombosed right ICA aneurysm [Figure 1c]. It was decided for endovascular treatment and coil embolization was performed with occlusion of the aneurysm and the parental vessel after an appropriate occlusion test. The patient was discharged without new deficits.

Figure 1:

(a) Noncontrast head computed tomography showing a rounded, well-defined hyperdense lesion on the sellar region; (b) Time-of-flight magnetic resonance angiography showing a rounded, well-defined lesion on the sellar region, suggestive of internal carotid artery (ICA) aneurysm; (c) digital subtraction angiography depicting a giant, partially thrombosed, right ICA aneurysm.

Three months later, the patient was readmitted with complaints of headache and speech impairment. On physical examination, anisocoric pupils (right > left) and impaired level of consciousness were observed. Blood tests revealed leukocytosis (15,670/mm³), elevated C-reactive protein (145.86 mg/L), and lactate levels (10.4 mmol/L). Head CT showed a left periventricular cystic lesion with perilesional edema [Figure 2a]. Magnetic resonance imaging showed a deep frontal cystic lesion on the left, around the region of the embolization material of the previous aneurysm, with restricted diffusion, suggesting a periembolization abscess [Figure 2b]. DSA was performed, showing no aneurysm recanalization [Figure 2c].

Figure 2:

(a) Noncontrast head computed tomography showing a left periventricular cystic lesion; (b) TWI magnetic resonance imaging showing a deep frontal cystic lesion around the region of the previous aneurysm with restricted diffusion, suggesting a periembolization abscess; (c) digital subtraction angiography showing no aneurysm recanalization.

The patient experienced rapid clinical deterioration, a presenting fever of 39°C, without changes in the cervical region, and progressed to a coma. Empirical antibiotic therapy with meropenem and vancomycin was initiated, and emergency surgical treatment with abscess drainage and decompressive craniectomy was performed. Culture of the abscess developed Staphylococcus epidermidis and Staphylococcus hominis. Despite surgical intervention, the patient remained in a coma and on mechanical ventilation. One month after surgery, she died as a result of sepsis.

DISCUSSION

We identified only 11 cases described in the literature, including the case in this article, of patients with cerebral abscess associated with aneurysm embolization, and their characteristics are described in Table 1. In almost all cases, except for one, the abscess developed within 3 months after the procedure. Some factors are thought to lead to the formation of brain abscesses following aneurysm embolization, including issues with the blood–brain barrier due to periprocedural ischemia or the release of inflammatory mediators.[6,21] The formation of this infectious process is due to pyogenic organisms carried into the tissue environment or by secondary infection from necrotic foci. Abscesses have a central region of necrotic cells, surrounded by a layer of preserved neutrophils and encircled by dilated vessels and proliferating fibroblasts, indicating the onset of repair.[16] The risk of bacteremia following an endovascular procedure increases with the duration of the procedure and can reach up to 32% in procedures lasting more than 2 h. Improper handling and hospital contamination of medical devices are hypothetical risks for secondary infections related to endovascular procedures. The most frequently associated agents are Staphylococcus aureus and Pseudomonas aeruginosa, microorganisms related to skin and hospital colonization, respectively. Hematogenous spread and percutaneous colonization of systemic infection are the proposed forms of bacterial dissemination in late cerebral abscesses related to endovascular procedures.[14,20] The aneurysms described in the literature whose treatment was complicated by brain abscess were large in size, with most classified as giant (≥25 mm).[19] After the embolization of an aneurysm with coils, there is the release of inflammatory mediators by the platelets recruited after a few days.[11,12,20] These substances from inflammation are released in greater quantities by large aneurysms. Furthermore, the weaknesses in the vessel wall, which are near or embedded in the neural parenchyma, easily develop vascular channels originating from the pial surface.[3,21] In excessively large aneurysms, the excessive development of vasa vasorum and the destabilization of the blood–brain barrier can lead to the transmission of infectious agents to the adjacent neural parenchyma during bacteremia.[4,5,24] The most common aneurysmal topography was the ICA, corresponding to four cases of the total. The ICA is the most common site of occurrence of giant aneurysms, which may explain this finding.[18] In addition, aneurysms of the paraclinoid carotid artery are located near the sphenoid sinus. Larger lesions can even erode the sphenoid bone, as seen in the presented case. This finding also allows speculation about a possible dissemination of bacteria that typically colonize this paranasal sinus by contiguity. Most patients required surgical treatment, with drainage being the most commonly performed procedure. In fact, surgical drainage in conjunction with intravenous antibiotic therapy is the most commonly indicated treatment for brain abscesses. Adequate pus drainage usually provides immediate clinical improvement, reducing the mass effect, intracranial pressure, and favoring a better response to antibiotic treatment, including proportioning the identification of the causative agent. This method was not applied in Al-Okaili and Patel’s study, as the authors indicated that the brain abscess could not be drained due to high risks related to its depth and the potential for causing hemorrhage.[1] Furthermore, Kirollos et al. noted that there was no significant mass effect in the brain, and only antibiotic therapy was needed.[13] In the case reported here, a decompressive craniectomy was performed in addition to abscess drainage due to significant associated cerebral edema and clinical signs of brain herniation. Surgical antibiotic prophylaxis was not used in the cases of endovascular embolization mentioned, including the case of the current report, as it only prevents periprocedural bacteremia and not subsequent infections.[22] The patient’s abscess culture report revealed the presence of the bacterial species S. hominis and S. epidermidis, both of which are coagulase-negative staphylococci. These species are part of the human skin microbiota and may harbor strains that form biofilms, allowing adhesion to medical devices.[2] DiazRomero et al.[7] also reported bacteria from this same group, making the current case the second among those reported to present this characteristic. In addition to the current case, Staphylococcus sp. was identified in four of the eleven cases, becoming the most common bacterial group among the cases in which microorganisms were detected [Table 1].[7,8,11,15] Regarding the treatment outcome, among the reported cases, only two cases had a fatal outcome, including the case reported here. In the report by Chen et al., the patient died due to aneurysm rupture after abscess drainage.[4] This is a major concern in the care of these patients. Abscess drainage may affect a possible residual aneurysm or cause a sudden decompression near the aneurysm, with the risk of bleeding. Therefore, it seems important to confirm the absence of a residual aneurysm or recanalization of a previously treated aneurysm before performing abscess drainage. However, angiographic imaging should be obtained promptly so as not to delay the surgical treatment of the abscess. In the case reported here, the patient’s clinical condition worsened after all necessary tests, requiring surgical intervention under more critical conditions.

Table 1:

Literature review of brain abscess cases following endovascular treatment of an aneurysm.

CONCLUSION

Perianeurysmal brain abscess is a rare but potentially serious complication in patients undergoing aneurysm coil embolization, especially in giant ICA aneurysms. Similar to other brain abscess situations, surgical drainage and intravenous antibiotic therapy are the main treatment measures. However, ruling out a residual aneurysm in the vicinity of the abscess is a reasonable approach before proceeding with the drainage procedure.

Ethical approval:

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.