Flow Diverter Implantation for Intracranial Aneurysm with Concomitant Cerebral Infarction in the Chronic Phase: A 3-Year Complete Obliteration Case

Introduction

Intracranial aneurysm (IA) is a localized pathological dilation of the arterial wall within the intracranial circulation, with an estimated incidence of approximately 3.2% in the general population [1]. Cerebral infarction (CI), a severe ischemic stroke condition [2], represents a major global health concern due to its high mortality and disability rates. Stroke is the second leading cause of disability and death globally, imposing a substantial burden on individuals and healthcare systems [3]. In 2010, there were 11.6 million cases of ischemic stroke and 5.3 million cases of hemorrhagic stroke worldwide; 63% of ischemic strokes and 80% of hemorrhagic strokes occurred in low- and middle-income countries [4]. By 2016, the number of new stroke cases had increased to 13.7 million, with 5.5 million stroke-related deaths, of which ischemic and hemorrhagic strokes constituted 2.7 million and 2.8 million, respectively [3]. The growing burden of ischemic stroke continues to pose a serious threat to global health and healthcare systems [5]. Effective management requires prompt initiation of standardized pharmacologic therapy [6].

IAs and ischemic CI are 2 critical but distinct cerebrovascular diseases [7]. Epidemiologically, the coexistence of unruptured IAs and chronic-phase CI is underrecognized but not uncommon. Studies have shown that 3% to 5% of patients with CI harbor unruptured IAs, whereas 1% to 2% of patients with IAs develop acute infarction due to thromboembolism or hypoperfusion [8]. The coexistence of chronic-phase infarction (≥21 days post-onset) and small unruptured IAs (<3 mm) remains a clinical “gray zone.” Current guidelines provide no clear recommendations regarding antiplatelet management, device selection, or timing of intervention, making these cases particularly complex [9]. In October 2021, our neurosurgery department employed a flow diverter (FD) to treat a patient with an IA and ipsilateral CI. By presenting this clinical case, we aim to contribute to the limited body of literature addressing this rare association and provide practical guidance for clinicians managing similar dual-pathology conditions.

Case Report

A 56-year-old man with a 5-year history of uncontrolled hypertension (systolic blood pressure ranging from 140 to 160 mmHg) and 3-year history of hyperlipidemia (total cholesterol: 6.2 mmol/L) presented to a local hospital on Day 1 with an acute onset of slurred speech and right-sided weakness at 7: 00 a.m., which had worsened over 2 h. Initial assessment at the local hospital (Day 1, 10: 00 a.m.) included cranial diffusion-weighted imaging and apparent diffusion coefficient scans, confirming a subacute CI in the left basal ganglia (Figure 1A, 1B). Concurrent computed tomography angiography revealed a small unruptured aneurysm in the ophthalmic segment of the left internal carotid artery (Figure 2A), but no further characterization was performed at that time. The patient’s treatment was modified to dual antiplatelet therapy (DAPT: aspirin 100 mg/day and clopidogrel 75 mg/day) based on a presumed cardioembolic infarction, with gradual improvement in limb strength from Medical Research Council grade 4- to 5- over the following 10 days. Due to the coexistence of an unruptured aneurysm and the need for specialized neurointerventional evaluation, he was transferred to our hospital on Day 15. On admission (Day 15, 9: 00 a.m.), neurological examination revealed mild residual slurred speech (National Institutes of Health Stroke Scale [NIHSS] score: 2) and right limb strength of Medical Research Council grade 5, without functional disability. Repeat magnetic resonance angiography (Figure 2B) on Day 16 confirmed the aneurysm’s location, and digital subtraction angiography (DSA) on Day 18 further characterized it as a 2.50×1.74×1.54 mm “bubble” aneurysm with a wide neck in the ophthalmic segment of the left internal carotid artery (Figure 2C). The aneurysm was asymptomatic; the patient reported no headache, cranial nerve palsy, or symptoms related to mass effect, consistent with an incidental finding during the infarction workup.

Given the coexistence of chronic-phase CI (≥21 days post-onset, with stable neurological status) and an unruptured small aneurysm, our multidisciplinary team – comprising neurosurgeons, neurointerventionalists, and stroke specialists – discussed 3 potential treatment strategies: 1. Deferred intervention but continued DAPT. This approach carried risks of aneurysm rupture (annual risk ~1% for small unruptured aneurysms, potentially increased by long-term antiplatelet therapy) and diagnostic challenges in distinguishing new neurological deficits caused by infarction recurrence from deficits due to aneurysm-related events. 2. Guglielmi detachable coil embolization. Although minimally invasive, this option was limited by the aneurysm’s small size and wide neck, increasing the risk of coil protrusion into the parent artery and incomplete occlusion. Reported 1-year obliteration rates are approximately 60% for small aneurysms in the ophthalmic segment. 3. FD implantation. This device, characterized by a dense mesh structure, redirects blood flow to promote aneurysm thrombosis and endothelialization. Its advantages include high long-term obliteration rates (> 80% at 3 years for small unruptured aneurysms) and compatibility with continued DAPT, which is essential for infarction management. Risks include perioperative thromboembolism (1%–3%, mitigated by pre-procedural DAPT loading) and delayed aneurysm rupture (<1%, reduced in chronic-phase infarction due to stabilization of the blood–brain barrier). The team selected FD implantation for this patient based on the following considerations: (1) the importance of sustained DAPT to prevent infarction recurrence, making conservative management unsuitable; (2) the aneurysm’s morphology (small size and wide neck), favoring FD over coil embolization; and (3) the minimally invasive nature of FD implantation, which lowered procedural risks in a patient recovering from recent infarction.

Continued DAPT and atorvastatin 20 mg/day were administered from Day 15 to Day 24 (in-hospital period). Daily neurological examinations showed progressive improvement in speech and limb strength, with an NIHSS score of 1 by Day 20. The patient underwent FD implantation (Pipeline™ Flex, 4.25×16 mm; Medtronic, USA) via right femoral artery access on Day 25. Intraoperative DSA confirmed proper device deployment with contrast stagnation within the aneurysm (Video 1). No intraoperative complications, such as vessel injury or thrombus formation, were observed. Postoperatively, the patient continued DAPT and atorvastatin. Neurological examinations (Days 1 to 7 postoperatively) revealed no new deficits (NIHSS score: 0). This regimen was maintained for 6 months to achieve 2 critical objectives: reducing the risk of in-stent FD thrombosis and preventing CI recurrence. After 6 months, based on aneurysm stability and the resolution of acute thromboembolic risk associated with the FD, antiplatelet therapy was de-escalated to single-agent aspirin (100 mg/day) to provide ongoing protection against CI recurrence while minimizing bleeding risks linked to prolonged DAPT. Follow-up assessments at 12 months (Video 2) and 36 months (Video 3) demonstrated complete aneurysm obliteration (Modified Raymond-Roy Class I) on DSA. The patient achieved a Glasgow Outcome Scale score of 5, modified Rankin Scale score of 0, NIHSS score of 0, and O’Kelly-Marotta Scale grade D; he remained asymptomatic with normal daily function and without ischemic or hemorrhagic events. Informed consent for report publication (all images and clinical data) was obtained from the patient, and all identifying information was anonymized. This case report was approved by our hospital’s ethics committee.

Discussion

IAs are pathological dilations of the intracranial arterial wall. Although relatively uncommon, rupture of an IA can result in diffuse subarachnoid hemorrhage, a life-threatening event and a major cause of cerebral hemorrhage [10]. CI, characterized by high mortality and disability rates, represents a severe form of ischemic stroke [3]. The coexistence of CI and IA presents a particularly complex clinical situation. If a patient with CI experiences aneurysm rupture and bleeding, the condition becomes critical, complicating treatment and potentially leading to poor outcomes [7]. The period between 6 and 21 days after CI onset is generally defined as the subacute phase; transition to the chronic phase begins after 21 days. During the subacute phase, endovascular treatment is generally avoided due to the risk of reperfusion injury, in which excessive capillary dilation may cause hemorrhage [11]. The use of antiplatelet therapy during this period also carries considerable risk. According to current stroke management standards, the subacute phase extends from 6 to 21 days after stroke onset, whereas the chronic phase begins after 21 days [12]. In the present case, the patient reached the chronic phase 25 days after CI onset (≥21 days post-onset), at which time surgery was performed. Clinical symptoms had gradually improved with medical therapy. Given the stability of the patient’s neurological condition and therapeutic response, along with the demonstrated safety and efficacy of flow diversion therapy, treatment at this stage was considered appropriate and safe.

To our knowledge, no previous reports have described the use of an FD to treat unruptured IAs in patients with chronic-phase CI. IAs and CI are distinct clinical entities; however, their overlapping pathophysiological mechanisms and shared risk factors – such as hypertension, atherosclerosis, and hemodynamic disturbances – create complex management challenges. Hypertension, for instance, accelerates both vascular wall degeneration (predisposing to IA formation) and atherosclerotic plaque progression (increasing CI risk) [10]. Moreover, IAs may exacerbate CI by altering distal cerebral perfusion, whereas CI-related inflammation and endothelial dysfunction may weaken aneurysm walls [13–17]. Stehouwer et al. demonstrated that aneurysmal subarachnoid hemorrhage complicated by parenchymal infarction is associated with poor prognosis [13]. Tajiri et al. also noted that vascular rupture or aneurysm formation in the cerebrum can exacerbate stroke, underscoring the dynamic interaction between aneurysmal pathology and ischemic brain injury [14]. Furthermore, Qureshi et al. reported that unruptured IAs may serve as foci for thrombosis and subsequent embolic stroke [15]. Kisilevsky et al. described a case of subacute bacterial endocarditis with a mycotic cerebral aneurysm (a fusiform aneurysm in the distal left middle cerebral artery) that was successfully treated with coil embolization [16]. Similarly, Poltrum et al. described a left middle cerebral artery aneurysm complicated by CI that was managed with surgical clipping [17]. In contrast, FD implantation in our case provided distinct advantages. Beyond reducing the recurrence risk associated with coil embolization alone, FDs are compatible with DAPT, which is essential to manage chronic-phase infarction. Morga et al. identified elevated whole blood viscosity as a risk factor for recurrence in coil-embolized IAs [18]; given their fine mesh and flow-redirecting structure, FDs facilitate intra-aneurysmal thrombosis [19] and promote complete obliteration. Although based on a single case, these findings suggest that small, incidentally detected aneurysms in patients with chronic-phase infarction can achieve favorable outcomes with FD treatment. Further studies are needed to validate these observations.

Recent advances in endovascular therapy have established it as a reliable approach for managing IAs. For unruptured aneurysms, the general annual rupture rate is approximately 1% [5], although this risk may be elevated in patients with chronic-phase CI. CI-associated vascular inflammation, endothelial dysfunction, and prolonged antiplatelet therapy – essential for infarction management – may theoretically weaken aneurysm walls or increase bleeding risks not fully reflected in general population data [7,12]. Conversely, once ruptured, aneurysms in patients with CI carry higher mortality (potentially exceeding the general 35% rate [5]) due to reduced cerebral perfusion reserve and the difficulty of balancing hemostasis with anticoagulation necessary for infarction management [13]. FDs, characterized by a fine and dense mesh design, enable direct repair of aneurysms [20]. Although craniotomy clipping remains an established and effective treatment, it is invasive and requires highly specialized neurosurgical expertise [17]. Guglielmi detachable coil embolization, a minimally invasive method, may not achieve complete aneurysm exclusion and can exacerbate symptoms by compressing nearby tissues [16]. In the present case, FD implantation effectively addressed these limitations by achieving complete aneurysm obliteration while permitting sustained antiplatelet therapy [20].

In our case, a patient with an IA and ipsilateral CI benefited from FD implantation during the chronic phase. This approach not only treated the aneurysm and prevented hemorrhagic stroke but also permitted the continuation of antiplatelet therapy for CI management. Although DAPT is routinely used to prevent thromboembolic events in CI, it carries an elevated risk of hemorrhagic transformation, particularly during the acute and subacute phases of stroke. In this case, the patient received DAPT to prevent thromboembolic complications; however, follow-up imaging and clinical evaluation revealed no evidence of hemorrhagic transformation at the infarction site, indicating minimal bleeding risk. The decision to proceed with FD implantation was guided by several key factors. First, the aneurysm’s anatomical features favored the use of an FD. The lesion measured 2.50×1.74×1.54 mm and had a wide neck, posing technical limitations for alternative treatments. Coil embolization is minimally invasive but presents a higher risk of coil protrusion into the parent artery in wide-necked aneurysms [17]; its 1-year obliteration rate (~60% for small ophthalmic aneurysms [17]) is inferior to that achieved with FD treatment (>80% at 3 years [18]). Surgical clipping, although effective, is invasive and involves increased risk among patients with recent infarction [17], making it less suitable in this context. Second, the patient’s need for long-term antiplatelet therapy – essential to prevent CI recurrence – aligned with the mechanism of FD treatment. Unlike coil embolization, which depends on mechanical occlusion and may be compromised by DAPT-related bleeding risk, FDs induce aneurysm occlusion through flow redirection and endothelialization, processes that are supported rather than hindered by sustained antiplatelet therapy [18,19]. This compatibility resolved the therapeutic conflict between aneurysm management and CI care, establishing FD implantation as a logical option for this dual-pathology condition. Third, FDs have demonstrated durable outcomes in the treatment of small, unruptured aneurysms. Previous reports indicate that FDs promote stable intra-aneurysmal thrombosis in small IAs (<3 mm), reducing the risk of recurrence – an important consideration in CI patients with vascular instability [7]. In our patient, whose IA was incidentally identified and asymptomatic, long-term durability was critical to prevent reintervention and preserve neurological function. Taken together, these factors – anatomical suitability, compatibility with antiplatelet therapy, and demonstrated long-term efficacy in small aneurysms – supported FD implantation as the optimal therapeutic choice, consistent with the rationale of chronic-phase stability and absence of hemorrhagic transformation.

Conclusions

This report describes a case of successful treatment of an IA with ipsilateral CI. The FD, an established endovascular device, represents an advanced therapeutic option for managing IAs. In this case, it facilitated simultaneous control of the aneurysm and CI, resulting in a favorable clinical outcome. However, further studies are required to confirm the generalizability of these findings.

Data Availability Statement

Videos supporting this study are openly available in Figshare at: https://doi.org/10.6084/m9.figshare.28748477.