Use of overlapping Surpass Evolve Flow Diverters for the treatment of a ruptured P1 dissecting aneurysm in the context of bilateral carotid artery occlusion: A case report

Abstract

In the setting of internal carotid artery (ICA) occlusion, a dissecting aneurysm may develop and rupture in the P1 segment of the posterior cerebral artery. While endovascular treatment (EVT) represents a viable treatment option, optimal technique selection remains controversial. This report describes a rare case of a ruptured P1 dissecting aneurysm associated with bilateral ICA occlusion, which was successfully treated using overlapping Surpass Evolve Flow Diverters (SE FDs). A 61-year-old Han Chinese woman presented with subarachnoid hemorrhage (Hunt-Hess grade II). Digital subtraction angiography demonstrated bilateral ICA occlusion and a ruptured P1 dissecting aneurysm with a thickened P1 segment. After a loading dose of aspirin and ticagrelor, EVT was performed. After an unsuccessful attempt at coil embolization assisted by a SE FD, 2 overlapping SE FDs, measuring 4.5 mm × 17 mm and 4.5 mm × 15 mm, were deployed to cover the P1 dissecting aneurysm. Postoperatively, the patient demonstrated no new neurologic deficits. However, on postoperative day 11, she developed left upper limb weakness of Grade III muscle strength due to vasospasm. Management with intravenous hydration and nimodipine infusion resulted in marked improvement. Two-month follow-up computed tomography angiography confirmed occlusion of the P1 dissecting aneurysm. The patient’s left limb muscle strength recovered to Grade IV. At 6 months’ follow-up, she was almost normal. It is hypothesized that, in this case of bilateral ICA occlusion, hemodynamic stress may have contributed to the formation of the ruptured P1 dissecting aneurysm. Overlapping SE FD deployment proved to be a feasible treatment option.

Introduction

In the setting of extracranial or intracranial internal carotid artery (ICA) occlusion, the posterior circulation sustains elevated hemodynamic stress [1]. This predisposes to aneurysms along the posterior cerebral artery (PCA) distribution, including the basilar apex, proximal P1 segment, distal P2-P5 segments, and PCA branches [2]. Among these, P1 aneurysms are exceptionally rare and frequently exhibit dissection morphology [3]. Given ICA occlusion, the P1 segment serves as a critical collateral route to the anterior circulation, rendering P1 dissecting aneurysms particularly vulnerable to elevated hemodynamic stress. Intervention is often mandatory, especially for ruptured cases [4].

Currently, endovascular therapy (EVT) has emerged as the primary treatment for PCA aneurysms, including those involving the P1 segment. For P1 aneurysms, stent-assisted coiling is a viable option [4]. Given the dissecting nature commonly seen in P1 aneurysms, flow diverter (FD) deployment offers a theoretical advantage; however, reports of its use in this context remain exceptionally scarce [2]. Critically, no prior case of overlapping FD treatment for a ruptured P1 dissecting aneurysm has been documented. The present case is the first to describe a ruptured P1 dissecting aneurysm in the setting of bilateral ICA occlusion that was successfully treated with overlapping Surpass Evolve (SE) FDs.

Case presentation

Patient’s onset and diagnosis

A 61-year-old Chinese Han female presented with a sudden-onset severe headache lasting 2 hours. On examination, she was alert and oriented, with signs of meningeal irritation including nuchal rigidity, intact limb strength (Grade V), and absence of pathological reflexes. The Hunt–Hess score was Grade II. Computed tomography (CT) demonstrated subarachnoid hemorrhage (SAH) (Fig. 1A). CT angiography (CTA) identified a P1 dissecting aneurysm (Fig. 1B). She had no history of systemic hypertension, diabetes mellitus, or cerebrovascular disease. Following confirmation of eligibility for EVT based on preoperative laboratory and imaging findings, loading doses of aspirin (300 mg) and ticagrelor (180 mg) were administered orally 3 hours prior to the procedure as dual antiplatelet therapy (DAPT).

Fig. 1.

Diagnostic images of the case. (A) CT images demonstrate diffuse subarachnoid hemorrhage. (B) CT angiography identifies a dissecting aneurysm (arrow) of the left PCA P1 segment; the P1 segment is thickened. (C) DSA images in anteroposterior (left panel) and lateral (right panel) views depict occlusion of the right intracranial ICA (arrows). (D) DSA images in lateral (left panel) and anteroposterior (right panel) views show occlusion of the left extracranial ICA; branches of the ECA demonstrate collateral flow to the cavernous segment of the ICA (arrows). (E) DSA images of the bilateral VAs reveal compensatory blood flow from the posterior to the anterior circulation (arrows). (F) Three-dimensional DSA images delineate a thickened left PCA P1 segment with a finger-like dissecting aneurysm (arrows).

Abbreviations: BA, basilar artery; CT, computed tomography; DSA, digital subtraction angiography; ECA, external carotid artery; ICA, internal carotid artery; L, left; PCA, posterior cerebral artery, P1, first segment of the PCA; R, right; SCA, superior cerebellar artery; VA, vertebral artery.

Therapeutic process

EVT was performed under general anesthesia. Digital subtraction angiography (DSA) revealed occlusion of the right intracranial ICA and the left extracranial ICA (Figs. 1C and D). Collateral circulation was established via anastomosis between the left external carotid artery and the left cavernous ICA (Fig. 1D). The vertebral artery supplied compensatory blood flow to the anterior circulation (Fig. 1E). The left PCA P1 segment was hyperplastic with a ruptured dissecting aneurysm (Fig. 1F).

Transarterial access was established via the left vertebral artery using a 6F long sheath and a 6F distal access catheter. An XT-27 microcatheter (Stryker Neurovascular, Fremont, CA, USA) was advanced into the left P1 segment and posterior communicating artery (PcomA) under the guidance of a Synchro 14 microguidewire (Stryker Neurovascular, Fremont, CA, USA). Subsequently, an Echelon-10 microcatheter (Medtronic, Irvine, CA) was navigated to the ruptured dissection site, also guided by a Synchro 14 microguidewire. After partial deployment of a 4.5 mm × 20 mm SE FD across the dissection via the XT-27 microcatheter, attempted coil embolization through the Echelon-10 microcatheter was unsuccessful (Fig. 2A). Following 30 minutes of attempted coiling, thrombosis of the SE FD occurred within the PcomA. The Echelon-10 microcatheter, with retained coils, was then withdrawn. The SE FD was retracted into the XT-27 microcatheter, and the combined system (XT-27 with FD) was removed. Subsequently, the PcomA reopened and remained patent (Fig. 2B).

Fig. 2.

Therapeutic images of the case. (A) Left panel: DSA of the left VA reveals a dissecting aneurysm (arrow) of the left PCA P1 segment. Right panel: X-ray image demonstrates the coil (arrow) at the dissection base and partial deployment of the FD (arrow); the FD spans the P1 segment and the PcomA. (B) Left panel: DSA of the left VA depicts occlusion of the PcomA (arrow), indicating thrombosis within the partially deployed FD. Right panel: DSA documents restoration of PcomA patency after withdrawal of the FD. (C) X-ray images demonstrate the first FD deployed to cover the P1 dissecting aneurysm (left panel), followed by deployment of the second FD in overlap with the prior device (right panel). (D) Left panel: DSA confirms the P1 dissecting aneurysm remains visible (arrow). Right panel: DSA of the left VA demonstrates that the posterior circulation provides compensatory blood flow to the anterior circulation.

Abbreviations: DSA, digital subtraction angiography; FD, flow diverter; L, left; PCA, posterior cerebral artery; P1, first segment of the PCA; PcomA, posterior communicating artery; VA, vertebral artery.

Another XT-27 microcatheter was used to deploy a 4.5 mm × 17 mm SE FD to cover the dissection. Subsequently, a 4.5 mm × 15 mm SE FD was deployed in overlap with the prior device‌ (Fig. 2C). During FD deployment, tirofiban (4 ml by intravenous bolus) was administered. After completing the EVT, DSA confirmed patency of the P1 segment and the PcomA (Fig. 2D). Tirofiban infusion was planned to be continued at 4 ml/h the following day. Starting on the second day, DAPT was to be transitioned to aspirin 100 mg once daily and ticagrelor 60 mg twice daily, to be maintained for 6 months.

Postoperative and follow-up outcomes

Two hours after EVT, the patient regained consciousness and demonstrated no new neurologic deficits. On day 2, CT and CTA showed resolution of the SAH and a stable dissecting aneurysm (Fig. 3A). On day 11, the patient developed left upper limb weakness of Grade III muscle strength. CT was normal, and CTA confirmed a stable dissecting aneurysm (Fig. 3B), prompting suspicion of vasospasm. On day 12, magnetic resonance imaging revealed acute scattered patchy infarcts (Fig. 3C). The patient received intravenous fluids (2000 mL/24 h) and a continuous nimodipine infusion (4 mL/h) for 7 days, resulting in marked improvement of left upper limb weakness. On day 18, CT showed apparent infarction (Fig. 3D). At 1-month follow-up, CT and CTA demonstrated a stable dissecting aneurysm (Fig. 3E). At 2-month follow-up, CTA showed no evidence of the dissecting aneurysm and patency of the intracranial vessels (Fig. 3F). The patient’s limb weakness improved, with muscle strength graded as Grade IV. At 6-month follow-up, she was almost normal.

Fig. 3.

Postoperative and follow-up images of the case. (A) Left panel: Postoperative day 2 CTA reveals the visible dissecting aneurysm (arrow). Right panel: CT demonstrates resorption of the subarachnoid hemorrhage. (B) Left panel: Postoperative day 11 CT displays no apparent abnormality. Right panel: CTA depicts the visible dissecting aneurysm (arrow). (C) Postoperative day 12 magnetic resonance imaging illustrates multiple acute infarctions in the right cerebral hemisphere. (D) Postoperative day 18 CT images reveal multiple infarctions. (E) Left panel: Postoperative month 1 CTA documents the visible dissecting aneurysm (arrow). Right panel: CT reveals old infarction. (F) Postoperative month 2 CTA images demonstrate no evidence of the dissecting aneurysm.

Abbreviations: CT, computed tomography; CTA, CT angiography; P1, first segment of the posterior cerebral artery; R, right.

Discussion

When unilateral or bilateral ICA occlusion occurs, the PCA experiences increased hemodynamic stress [5]. This elevated pressure and flow volume can trigger the development of aneurysms at various sites along the PCA—ranging from the basilar artery quadrifurcation to P1, P2-P5 segments, and PCA branches (Figs. 4, Fig. 5, Fig. 6A–B). The pathogenesis of these aneurysms mirrors that of flow-related aneurysms associated with brain arteriovenous malformations (Fig. 6C) or moyamoya disease, where aberrant hemodynamic forces contribute to vascular remodeling and aneurysm formation [2,6,7].

Fig. 4.

Embolization of SCA and BA aneurysms in ICA occlusion. (A) Embolization of the SCA aneurysm. Panel 1: CTA reveals occlusion of the bilateral carotid arteries and a SCA aneurysm (arrow). Panel 2: CTA depicts a left SCA origin aneurysm (arrow). Panel 3: DSA images demonstrate occlusion of the right intracranial ICA (left), occlusion of the left extracranial ICA (middle), and a left SCA aneurysm (arrow) (right). Panel 4: DSA images show the SCA aneurysm before treatment (arrow) (left), the coiling (arrow) (middle), and patent posterior circulation vessels (right). (B) Embolization of the BA tip aneurysm. Panel 1: CTA reveals a BA tip aneurysm (arrow); the right middle cerebral artery is hypoplastic (frame); the right posterior cerebral artery provides collateral blood flow (circle) to the right middle cerebral artery territory. Panel 2: DSA images in anteroposterior (left) and lateral (middle) views depict occlusion of the right extracranial ICA (arrows). DSA (right) reveals that the left ICA provides collateral flow to the right territory (frame). Panel 3: DSA displays the BA tip aneurysm (arrow). Panel 4: X-ray image illustrates the WEB device (arrow) (left). DSA and reconstructive images (middle and right) confirm that the BA aneurysm is embolized.

Abbreviations: BA, basilar artery; CTA, computed tomography angiography; DSA, digital subtraction angiography; ICA, internal carotid artery; SCA, superior cerebellar artery; WEB, Woven EndoBridge.

Fig. 5.

Embolization of the PCA trunk aneurysm in ICA occlusion. (A) Embolization of the P1 aneurysm: Panels 1–2: CTA images reveal the occluded right extracranial ICA and a right P1 aneurysm (arrow in panel 2). Panel 3: DSA depicts the occluded right extracranial ICA. Panel 4: Three-dimensional DSA displays the P1 aneurysm (arrow). Panel 5: After stent-assisted coiling, six-month follow-up DSA demonstrates complete occlusion of the P1 aneurysm (arrow). Panels 6–7: Five-year follow-up CTA images show the P1 aneurysm with complete occlusion (panel 6) and the occluded right extracranial ICA (panel 7). (B) Embolization of the distal PCA trunk aneurysm: Panel 1: CT (left) demonstrates subarachnoid hemorrhage extending into the temporal horn of the lateral ventricle. CTA (right) reveals occlusion of the bilateral ICAs and a right distal PCA trunk aneurysm (arrow). Panel 2: DSA images illustrate bilateral ICA occlusion (left and middle) and a distal PCA aneurysm (arrow) (right). Panel 3: Unsubtracted DSA images (left and middle) show the FD assisting coiling. DSA (right) reveals collateral flow from the posterior to the anterior circulation (circle). Panel 4: Postoperative day 3 CT demonstrates infarction of the right cerebral hemisphere (circle).

Abbreviations: CT, computed tomography; CTA, CT angiography; DSA, digital subtraction angiography; FD, flow diverter; ICA, internal carotid artery; L, left; PCA, posterior cerebral artery; R, right; VA, vertebral artery.

Fig. 6.

Embolization of the aneurysm of the PCA branch in ICA occlusion. (A) Panel 1: CT (left) reveals subarachnoid hemorrhage extending into the temporal horn of the lateral ventricle. CT angiography (right) demonstrates occlusion of the right ICA. Panel 2: DSA (left) depicts occlusion of the right intracranial ICA (arrow). DSA (middle) illustrates collateral blood flow from the left anterior cerebral artery to the right MCA territory (frame). DSA of the VA (right) shows collateral flow to the anterior circulation (frame). Panel 3: DSA of the VA (left) displays an aneurysm (arrow) at the origin of a PCA branch. Onyx embolization is subsequently performed (right). Panel 4: Unsubtracted DSA (left) and DSA (right) images of the VA demonstrate complete occlusion of the aneurysm. Panel 5: CT reveals complete resorption of the hemorrhage. (B) Panel 1: CT images show subarachnoid hemorrhage (left) and intraventricular hemorrhage (right). Panel 2: DSA (left) depicts occlusion of the right intracranial ICA (arrow). DSA (middle) illustrates collateral blood flow from the left anterior cerebral artery to the right MCA territory (frame). DSA of the VA (right) reveals collateral flow to the anterior circulation (frame). Panel 3: DSA of the VA demonstrates an aneurysm (arrow) on a distal PCA branch. Panel 4: DSA (left) shows Onyx embolization (circle) for aneurysm occlusion. DSA (middle) reveals incomplete aneurysm occlusion (arrow). A roadmap image (right) depicts repeat Onyx embolization. Panel 5: Immediate postoperative DSA (left) and six-month follow-up DSA (right) demonstrate complete aneurysm occlusion. Panel 6: CT shows complete resorption of the hemorrhage. (C) Panel 1: CT reveals posterior callosal hemorrhage. Panel 2: DSA of the VA demonstrates an arteriovenous malformation supplied by the PCA (left). Three-dimensional DSA reveals a flow-related aneurysm (arrow) on a PCA branch (middle). Selective angiography confirms the aneurysm (arrow) (right). Panel 3: X-ray image illustrates complete occlusion of the aneurysm by Onyx embolization (left). DSA of the VA confirms persistent complete occlusion of the aneurysm, while the arteriovenous malformation remains intact.

Abbreviations: CT, computed tomography; DSA, digital subtraction angiography; ICA, internal carotid artery; L, left; PCA, posterior cerebral artery; R, right; SAH, subarachnoid hemorrhage; VA, vertebral artery.

The hemodynamic stress secondary to ICA occlusion predisposes PCA aneurysms to rupture, necessitating intervention—particularly in the setting of acute hemorrhage. Currently, EVT has emerged as the definitive management strategy for PCA aneurysms, offering superior efficacy in the posterior circulation compared with traditional surgical approaches [8,9]. PCA aneurysms are anatomically classified into 3 subgroups: proximal P1 aneurysms, distal P2–P5 aneurysms, and branch aneurysms. For aneurysms located in the distal P2–P5 segments or branches, therapeutic strategies include both reconstructive (vessel-preserving) and deconstructive (vessel-sacrificing) EVT techniques [2].

P1 aneurysms are exceptionally rare among all PCA aneurysms. When P1 aneurysms coexist with ICA occlusion, reconstructive endovascular therapy is mandatory. The P1 segment’s function as the primary posterior-to-anterior collateral conduit clearly contraindicates deconstructive approaches (Fig. 5, Fig. 6). Due to the absence of major branching vessels along the P1 segment, P1 aneurysms frequently demonstrate a dissecting morphology [10]. These lesions present unique challenges for conventional stent-assisted coiling, as microcatheter access is often precluded by anatomical constraints and conventional stents provide insufficient metal coverage. FD deployment is more effective than conventional stents for P1 dissections. In unruptured cases, standalone FD therapy may suffice, whereas adjunctive coiling may be considered for ruptured aneurysms to mitigate the risk of rebleeding [2,11].

In this case, FD-assisted coiling was initially planned using the following steps: 1) semi-deployment of a FD; 2) navigation of the microcatheter near the aneurysm neck; and 3) deployment of coils into the aneurysm using the FD as a backstop. This technique has demonstrated success in an anterior communicating aneurysm (Fig. 7A). However, it failed in this instance due to an inability to deploy coils. Furthermore, prolonged semi-deployment (30 minutes) of the FD precipitated in-stent thrombosis. This complication underscores the need for cautious application of semi-deployment, requiring intensive intraoperative angiographic monitoring (Fig. 7B). Following thrombus formation, the FD was withdrawn, necessitating consideration of alternative endovascular strategies for the P1 aneurysm.

Fig. 7.

EVT difficulty and double overlapping FD deployment for the ruptured aneurysms. (A) Coiling the AcomA aneurysm with LEO Baby stent assistance. Panel 1: DSA shows a small AcomA aneurysm (arrow) projecting upward. Panel 2: X-ray image (left) and roadmap image (right) show the LEO Baby stent was semi-deployed. The microcatheter (arrows) reached the aneurysm neck but could not enter the sac. Panel 3: X-ray image (left) and unsubtracted DSA (right) show the coil (arrows) was successfully pushed into the aneurysm with the stent acting as a backstop. (B) In-FD thrombosis.‌ ‌Panel 1:‌ DSA shows occlusion of the ICA due to in-FD thrombosis (left). X-ray image shows the semi-deployed FD (right). Panel 2: Following FD withdrawal, roadmap image shows ICA patency. ‌Panel 3:‌ X-ray shows the aneurysm coiled with Solitaire stent assistance (left). DSA shows the ICA patency (right). (C) Double overlapping FDs for a BBA.‌ Panel 1:‌ DSA shows a supraclinoid ICA BBA (arrow). Panel 2:‌ X-ray images show the first FD deployed to cover the BBA (left), the deployment of the second FD (middle), and the final configuration of the two overlapping FDs (right). Panel 3: DSA shows patency of the supraclinoid ICA and its branches, as well as an extracranial ICA aneurysm (arrow). (D) Double overlapping FDs for a VA dissection.‌ Panel 1:‌ CT (left) shows subarachnoid hemorrhage and hemorrhage in the fourth ventricle. CT angiography (right) shows a VA dissection (arrow). Panel 2:‌ The left image shows the double overlapping FDs with incomplete wall apposition (arrow). The right X-ray image shows improved wall apposition following mechanical massage using the microguidewire. Panel 3:‌ DSA shows patency of the VA and its branches.

Abbreviations: AcomA, anterior communicating artery; BBA, blister-like aneurysm; CT, computed tomography; DSA, digital subtraction angiography; EVT, endovascular treatment; FD, flow diverter; ICA, internal carotid artery; PICA, posterior inferior cerebellar artery; VA, vertebral artery.

Given that coiling was not feasible, FD deployment was the only option, necessitating a choice between a single FD or overlapping devices. A computational simulation study by Damiano et al. suggested that compacting a single FD may achieve greater aneurysmal flow reduction than using 2 overlapping FDs [12]. However, forceful manipulation to compact an FD in a clinical setting carries significant risks, such as vessel injury, perforation, or even rupture. Moreover, the device may collapse into the aneurysm itself. Furthermore, the compacted region may not precisely cover the aneurysm orifice, potentially resulting in inadequate neck coverage. In this case, maximal FD compaction via push-pull maneuvering was difficult due to pronounced tortuosity of the basilar artery and P1 segment, which compromised microcatheter support and thus precluded safe device manipulation (Fig. 1F).

Due to bilateral ICA occlusion resulting in high hemodynamic stress on the P1 segment, a stronger flow diversion effect may be necessary. To achieve enhanced flow diversion, the use of overlapping FDs can increase metal coverage and thereby provide a stronger flow-diverting effect [[13], [14], [15]]. In a hemodynamic study by Uchiyama et al. on overlapping FDs for cerebral aneurysms, intra-aneurysmal velocity decreased by 92% with overlapping FDs, compared to 31% with a single FD, relative to no-FD controls [16]. This strategy is supported clinically by the Pipeline Embolization Device trials for intracranial aneurysms [17,18]. Furthermore, overlapping FDs have been shown to be effective for blister-like aneurysms and ruptured, uncoilable cerebral aneurysms (Figs. 7C and D) [19,20].

Therefore, overlapping SE FDs were deployed in this case. When applying overlapping FDs‌, patency of small vessels/perforators and in-stent stenosis ‌were primary concerns‌. Dai et al.’s in vivo rabbit study demonstrated that small branch arteries ‌remain patent‌ when covered by multiple overlapping FDs. Although neointimal hyperplasia increased‌ in double- and triple-FD groups, parent artery stenosis measured ‌<15% at 6 months and 18% at 12 months‌, with no significant inflammatory response in any group [21]. Therefore, ‌the deployment of overlapping FDs for this P1 aneurysm was justified‌. In this case, occlusion of the dissecting aneurysm was progressive and was observed on the 2-month CTA follow-up. The aneurysm remained stable and did not rupture, and the P1 segment showed no apparent stenosis during this period. Therefore, overlapping SE FD deployment proved safe.

In this case, intraoperative ‌ischemic and hemorrhagic complications‌ warrant discussion. To mitigate ischemic risks, semi-deployment time of the FD must be minimized, and periprocedural DAPT is mandatory [22]. Accordingly, intravenous tirofiban was administered throughout the procedure and maintained postoperatively. Given the ‌high prevalence of clopidogrel non-responsiveness in East Asian cohorts, ‌a loading dose of aspirin with ticagrelor was initiated‌. Regarding hemorrhagic complications, high-support delivery systems carry inherent perforation risks, necessitating precise torque-controlled manipulation of microguidewires and microcatheters to prevent vessel injury (Fig. 8).

Fig. 8.

Vessel perforation by a microguidewire during FD deployment. Panel 1: DSA (left) shows an anterior choroidal artery aneurysm (arrow). Roadmap image (middle) shows the FD being delivered across the aneurysm. Post-deployment DSA (right) reveals no abnormality. Panel 2: Xper CT (left) demonstrates SAH (circle), indicating vessel rupture. Three-dimensional DSA (middle) shows a rupture point (arrow) on the MCA upper trunk. Selective angiography (right) identifies the rupture point (arrow) and active contrast extravasation (asterisk). Panel 3: X-ray image (left) shows an inflated balloon (arrow) in the MCA upper trunk to occlude the rupture site. After 1 hour of occlusion, bleeding persisted. The MCA upper trunk was subsequently coiled through the balloon catheter (middle). DSA (right) confirms occlusion of the MCA upper trunk (arrow). Panel 4: Immediate postoperative Xper CT (left) shows increased SAH (circle). Postoperative day 5 CT (middle) reveals resorption of the SAH and a left frontal lobe infarction (circle). Postoperative day 6 magnetic resonance imaging (right) demonstrates acute left frontal lobe infarction.

Abbreviations: CT, computed tomography; DSA, digital subtraction angiography; FD, flow diverter; L, left; MCA, middle cerebral artery; SAH, subarachnoid hemorrhage.

In addition, this reported case developed ischemic complications in non-EVT regions manifesting as multiple scattered, flaky infarctions. These findings strongly suggest delayed cerebral vasospasm as the primary etiology rather than acute branch occlusion, based on 2 key observations: 1) the frontal ischemic events occurring on post-SAH day 11, corresponding to the peak vasospasm period (typically days 7-14), and 2) characteristic radiographic patterns of multiple scattered infarctions typical of vasospasm [23]. Following conservative management, the patient achieved a favorable clinical outcome.

Conclusion

In cases of bilateral ICA occlusion, the resultant ‌elevated hemodynamic stress in the PCA‌ predisposes to ‌P1 dissecting aneurysms‌ with significant rupture risk. Given this hemodynamic burden, FD deployment constitutes a rational therapeutic strategy. When adjunctive coiling proves technically challenging, ‌augmented flow diversion becomes imperative‌. Overlapping SE FD deployment may be an effective option.

Data availability

No datasets were generated or analyzed during the current study.

Patient consent

Written informed consent was obtained from the patient and the patients involved for publication in this case report and any accompanying images.