CC BY-NC-ND 4.0 · Asian J Neurosurg 2023; 18(01): 125-131
DOI: 10.1055/s-0043-1763528
Original Article

Morphological Factors affecting Coil-Only Embolization of Small Unruptured Aneurysms

Hiroshi Tenjin
1   Department of Neurosurgery, Kansai Medical University, Hirakata, Osaka, Japan
Osamu Saito
2   Department of Neurosurgery, Shizuoka Red Cross Hospital, Japan
Kuniaki Matsumoto
3   Department of Neurosurgery, Sano Memorial Hospital, Japan
Akio Asai
1   Department of Neurosurgery, Kansai Medical University, Hirakata, Osaka, Japan
› Author Affiliations


Objective When small unruptured aneurysms (SUA) are embolized by coils, manipulation of the microcatheter and coil is limited because of their small size. Previous studies suggested that the morphology of the artery and aneurysm is important. In the present study, we clarified the morphological factors affecting coil-only embolization of SUA.

Patients and Methods We retrospectively identified 17 patients who underwent embolization for unruptured aneurysm with a maximum diameter less than 5 mm. We investigated the following: (1) the relationships among dome/neck ratio (D/N), height/neck ratio (H/N), height/dome ratio (H/D), projection of aneurysm-parent artery, and adverse events, (2) immediate and late occlusion, and (3) number of coils.

Results (1) Adverse events developed in three cases in which the H/D was smaller than 1 (p < 0.02). There was a significant difference in the rate of adverse events by projection of the aneurysm-parent artery (p < 0.03), (2) Occlusion rate: Immediately after coil embolization, 71% (12/17) were neck remnant; however, 88% (15/17) of SUA became complete occlusion in the follow-up term, and (3) 1.5 ± 0.6 coils were used.

Conclusion To achieve successful coil-only embolization in SUAs, it is important to select aneurysms for which the projection of the parent artery is suitable for embolizing and the H/D ratio is larger than 1. In SUAs, occlusion develops naturally after coil embolization.

Ethical Approval

The research within our submission has been approved by ethics institutional review board of Shizuoka Red Cross Hospital (authorization number 2019-36).

Publication History

Article published online:
27 March 2023

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