Tiny (≤3 mm) Unruptured Intracranial Aneurysms: A 13-Year Contemporary Insight on Treatment Safety From a Multicenter Registry

BACKGROUND AND OBJECTIVES: Tiny or very small unruptured intracranial aneurysms (≤3 mm) carry a very low estimated rupture risk, yet many are electively treated. Although factors influencing procedural risks have the potential to guide treatment selection, they remain poorly characterized in this population. METHODS: A retrospective cohort study was conducted using prospectively collected data from the multicenter Stroke Thrombectomy and Aneurysm Registry, including patients treated for unruptured aneurysms between 2013 and 2025. Tiny aneurysms were defined as ≤3 mm. Primary outcomes were intraprocedural and postprocedural complications. Propensity score matching and multivariable logistic regression were performed. RESULTS: Among 5107 treated aneurysms, 783 (15.3%) were tiny. Patients with tiny aneurysms were younger, more often female, and had higher rates of vascular risk factors, prior subarachnoid hemorrhage, or family history of aneurysms (P < .05). Intraoperative complications (5.2% vs 5.1%, P = .91), postprocedural complications (8.4% vs 8.7%, P = .83), in-hospital mortality, and long-term outcomes were comparable with small (3-5 mm) aneurysms. On multivariable analysis, anterior communicating artery (odds ratio [OR] 4.92; 95% CI, 1.34-18.1; P = .016) and posterior communicating artery locations (OR 4.08; 95% CI, 1.40-11.9; P = .010), as well as stent-assisted coiling (OR 3.98; 95% CI, 1.33-11.9; P = .013) predicted intraoperative complications, while favorable preadmission functional status (modified Rankin Scale 0-1; OR 0.40; 95% CI, 0.21-0.76) predicted lower postprocedural complication risk. CONCLUSION: Treatment of tiny unruptured aneurysms remains common despite very low rupture risk. Procedural risks are low and comparable with slightly larger aneurysms. Treatment decisions should integrate both rupture risk and procedural safety, with anterior communicating artery or posterior communicating artery locations and unfavorable baseline functional status representing higher-risk features. When indicated, stent-assisted coiling was independently associated with higher intraoperative complication risk relative to clipping in this cohort.

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Journal
Neurosurgery
Published
2026-10-05
DOI
https://doi.org/10.1227/neu.0000000000004245
Primary Topic
Intracranial Aneurysms: Treatment and Complications
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article

Tiny (≤3 mm) Unruptured Intracranial Aneurysms: A 13-Year Contemporary Insight on Treatment Safety From a Multicenter Registry

James Castiglione, Antony A. Fuleihan, W. Christopher Fox, Stephanie N. Serva et al.
Neurosurgery
Intracranial Aneurysms: Treatment and Complications
article

Tiny (≤3 mm) Unruptured Intracranial Aneurysms: A 13-Year Contemporary Insight on Treatment Safety From a Multicenter Registry

James Castiglione, Antony A. Fuleihan, W. Christopher Fox, Stephanie N. Serva, Hidetoshi Matsukawa, Pedro Navía, Amir Shaban, Jonathan Andrew Grossberg, Stavropoula I. Tjoumakaris, Brian M. Howard, Ramesh Grandhi, Mohamad Ezzeldin, Justin Robert Mascitelli, Michael Anthony Rizzuto, Eyad Almallouhi, Robert H. Rosenwasser, Edgar Andres Samaniego, Isaac Josh Abecassis, Pascal M. Jabbour, Arbaz A. Momin, Victor Gabriel El-Hajj, Joseph W. Schaefer, Ryan Thomson Kellogg, Michael Reid Gooch, Julio Isidor, Shinichi Yoshimura, Alejandro M. Spiotta
article en

Abstract

BACKGROUND AND OBJECTIVES: Tiny or very small unruptured intracranial aneurysms (≤3 mm) carry a very low estimated rupture risk, yet many are electively treated. Although factors influencing procedural risks have the potential to guide treatment selection, they remain poorly characterized in this population. METHODS: A retrospective cohort study was conducted using prospectively collected data from the multicenter Stroke Thrombectomy and Aneurysm Registry, including patients treated for unruptured aneurysms between 2013 and 2025. Tiny aneurysms were defined as ≤3 mm. Primary outcomes were intraprocedural and postprocedural complications. Propensity score matching and multivariable logistic regression were performed. RESULTS: Among 5107 treated aneurysms, 783 (15.3%) were tiny. Patients with tiny aneurysms were younger, more often female, and had higher rates of vascular risk factors, prior subarachnoid hemorrhage, or family history of aneurysms (P < .05). Intraoperative complications (5.2% vs 5.1%, P = .91), postprocedural complications (8.4% vs 8.7%, P = .83), in-hospital mortality, and long-term outcomes were comparable with small (3-5 mm) aneurysms. On multivariable analysis, anterior communicating artery (odds ratio [OR] 4.92; 95% CI, 1.34-18.1; P = .016) and posterior communicating artery locations (OR 4.08; 95% CI, 1.40-11.9; P = .010), as well as stent-assisted coiling (OR 3.98; 95% CI, 1.33-11.9; P = .013) predicted intraoperative complications, while favorable preadmission functional status (modified Rankin Scale 0-1; OR 0.40; 95% CI, 0.21-0.76) predicted lower postprocedural complication risk. CONCLUSION: Treatment of tiny unruptured aneurysms remains common despite very low rupture risk. Procedural risks are low and comparable with slightly larger aneurysms. Treatment decisions should integrate both rupture risk and procedural safety, with anterior communicating artery or posterior communicating artery locations and unfavorable baseline functional status representing higher-risk features. When indicated, stent-assisted coiling was independently associated with higher intraoperative complication risk relative to clipping in this cohort.

Neurosurgery
University of Iowa (US), Mayo Clinic (US), Texas Medical Center (US), Hyogo Medical University (JP), Sanden (Japan) (JP), University of Louisville (US), Emory University (US), Medical University of South Carolina (US), The University of Texas at San Antonio Health Science Center (US), University of Utah (US), Thomas Jefferson University Hospital (US), Hospital Universitario La Paz (ES), Sarasota Memorial Hospital (US), Utah Department of Health (US), University of Virginia Medical Center (US), Lone Star College Kingwood (US), Mayo Clinic in Florida (US), University of Utah Health Care (US)
Openalex Percentile: Top 12%
Intracranial Aneurysms: Treatment and Complications
DOISourceOpenAlex
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