Flow Remodeling in a Fusiform Distal Middle Cerebral Artery Aneurysm: A “Roundabout” Endovascular Treatment

Abstract

Fusiform aneurysms of the distal middle cerebral artery (MCA) are rare and present unique treatment challenges. We present a rare case of a fusiform aneurysm, located in the M4 segment of the MCA, successfully treated with a low-profile braided stent monotherapy. The aneurysm, situated in the posterior superior temporal gyrus, demonstrated early contrast stagnation and favorable long-term remodeling. Follow-up angiography at 4 months revealed approximately 50% reduction in aneurysmal filling. At 15 months, complete aneurysm occlusion (O'Kelly-Marotta—D, indicating complete filling suppression) was achieved, with preserved parent vessel patency and no ischemic complications. This case highlights the feasibility of stent monotherapy for fusiform aneurysms in distal, eloquent MCA territories and underscores the value of braided flow-modulating stents in complex cerebrovascular anatomy.

Keywords

middle cerebral artery aneurysm - fusiform aneurysm - flow remodeling

Case Presentation

A 53-year-old woman presented with a 6-month history of persistent, nonspecific headache. Neurological examination was normal and she was right-handed. Her medical history included hypertension, type 2 diabetes mellitus, and depression. Magnetic resonance imaging showed cortical vessel dilation in the left temporoparietal region (posterior superior temporal gyrus) ([Fig. 1]). Computed tomography angiography revealed a distal middle cerebral artery (MCA) aneurysm. Digital subtraction angiography (DSA) confirmed a fusiform, unruptured aneurysm (14.7 × 13.9 mm) in the left M4 segment (angular branch), measuring 23.8 mm in length. The aneurysm lacked neck, thrombus, or calcification. Parent vessel's diameter was 2.3 mm, and it was supplying an eloquent area.

Fig. 1 (A) Axial T2-weighted MRI demonstrating prominent dilation of cortical vessels in the left posterior superior temporal gyrus. (B–C) Axial and sagittal computed tomography angiography images demonstrating an aneurysm in the left distal MCA territory. (D–E) DSA in lateral and anteroposterior projections demonstrating a fusiform, unruptured aneurysm (size: 14.7 × 13.9 mm; length: 23.8 mm) in the angular branch of the M4 segment of the left MCA. No thrombus, calcification, or discrete neck was observed. The aneurysm was located in the angular branch of the left MCA within the posterior superior temporal gyrus, an eloquent cortical region and the parent artery measured approximately 2 mm in diameter. DSA, digital subtraction angiography; MCA, middle cerebral artery; MRI, magnetic resonance imaging.

Under general anesthesia, right femoral artery access was obtained. The patient received dual antiplatelet therapy with acetylsalicylic acid and ticagrelor. Systemic anticoagulation was maintained with intravenous heparin. Target activated coagulation time was 250 to 350 seconds. A 6F long sheath, and 5F distal access catheter were used. A Headway 17 microcatheter and Asahi Chikai X 010 microwire were navigated into the M4 segment. A 2.5 × 27 mm LVIS EVO stent was deployed across the fusiform segment ([Fig. 2]). Its flexibility, small cell size, and high metal coverage favored flow modulation. Postdeployment angiography showed contrast stagnation in the aneurysmal sac ([Video 1], available in the online version only). The procedure was uneventful. The patient awoke neurologically intact and was discharged on postoperative day 2 without complications.

Fig. 2 (A) Super selective catheterization of the parent artery using a Headway 17 microcatheter. (B) Roadmap view showing the microcatheter advanced distal to the aneurysm; the distal marker is clearly visualized beyond the fusiform segment. (C–D) Single-shot lateral and anteroposterior views after stent deployment. The radiopaque markers confirms full expansion and proper positioning at both proximal and distal ends of the stent. The stent bridges the fusiform aneurysm segment in the angular branch of the M4 segment of the left middle cerebral artery.

At 4-month follow-up, DSA showed approximately 50% reduction in aneurysmal filling with preserved parent artery patency ([Fig. 3]). At 15-month follow-up, angiography demonstrated complete aneurysm occlusion (O'Kelly-Marotta—D, indicating complete filling suppression) with approximately 25% luminal narrowing of the parent artery. There were no signs of ischemia on diffusion-weighted imaging or clinical examination. The patient was asymptomatic with modified Rankin Scale score of 0.

Fig. 3 (A) Preoperative DSA, anteroposterior view, demonstrating a large fusiform aneurysm in the angular branch of the left MCA M4 segment. Yellow arrow indicates the distal part of parent artery. (B) Follow-up DSA at 4 months showing significant flow stagnation and approximately 50% reduction in aneurysmal filling. (C) DSA at 15 months revealing complete aneurysm occlusion (OKM-D). The red bracket indicates the stented segment. The distal outflow of parent artery remains patent (yellow arrow), with approximately 25% luminal narrowing of the parent artery, consistent with neointimal hyperplasia and no signs of distal thrombosis. DSA, digital subtraction angiography; OKM-D, O'Kelly-Marotta—D; MCA, middle cerebral artery.

Discussion

In the literature, there are reported cases of fusiform aneurysms treated successfully with stents that possess flow-diverting properties. Comparable cases of fusiform MCA aneurysms treated with stent monotherapy have been reported using braided stents such as the Leo device.[1] In our case, the aneurysm was in the distal M4 segment of the MCA, where traditional flow diverters are typically unsuitable due to small vessel caliber and microcatheter compatibility. We therefore selected the LVIS EVO stent—a low-profile, braided device compatible with 0.0165- to 0.017-inch microcatheters, with approximately 28% metal coverage, which although not marketed as a dedicated flow diverter, provides a degree of flow-diverting effect.[2] Its flexibility, high radio-opacity, and conformability made it particularly suitable for this eloquent distal location, facilitating safe deployment and effective vessel remodeling.

Conclusion

In selected patients, low-profile braided stent monotherapy may offer a safe and effective solution for fusiform aneurysms in distal, eloquent MCA segments, achieving durable occlusion while preserving parent vessel patency.

Download Video

Video 1 Lateral view DSA immediately following stent deployment, demonstrating contrast stagnation within the fusiform aneurysm sac. The slowed opacification and delayed washout reflect early flow modulation achieved by the braided stent. DSA, digital subtraction angiography.

Conflict of Interest

None declared.

Ethical Approval Statement

Written informed consent was obtained from the patient for publication of this case report and accompanying images and video. The report does not include any identifiable personal information.

Authors' Contribution

M.B.E. contributed to conceptualization, investigation, writing—original draft, visualization. R.Ö. contributed to methodology, supervision, review, and editing.

• References

• 1 Pumar JM, Lete I, Pardo MI, Vázquez-Herrero F, Blanco M. LEO stent monotherapy for the endovascular reconstruction of fusiform aneurysms of the middle cerebral artery. AJNR Am J Neuroradiol 2008; 29 (09) 1775-1776
• 2 Foo M, Maingard J, Hall J. et al. Endovascular treatment of intracranial aneurysms using the novel low profile visualized intraluminal support EVO stent: multicenter early feasibility experience. Neurointervention 2021; 16 (02) 122-131

Publication History

Article published online:
19 December 2025