Treatment of Small Intracranial Aneurysms Using the SMALLSS Scoring System: A Novel System for Decision Making

Friday, May 3, 2024

Presenting Author(s)

Michael Young, D.O.

Cerebrovascular Fellow, Neurosurgical Division
Beth Israel Deaconess Medical Center. Harvard Medical School. Boston, MA, United States.
Boston, Massachusetts, United States

Co-Author(s)

Mira Salih, M.D.

Clinical Research Fellow
Beth Israel Deaconess Medical Center - Harvard Medical School
Boston, Massachusetts, United States

Co-Author(s)

AA

Alexander Andreev, MD

Resident
Beth Israel Deaconess Medical Center, United States
Thomas B. Fodor, BSc

Research Trainee
Beth Israel Deaconess Medical Center
Christopher S. Ogilvy, MD

Endovascular and Operative Neurovascular Surgery
BIDMC Brain Aneurysm Institute, Neurosurgical Division, Beth Israel Deaconess Medical Center. Harvard Medical School. Boston, MA, United States.
Boston, Massachusetts, United States
SP

Samuel Pettersson, n/a

Research Fellow
Neurosurgical Division, Beth Israel Deaconess Medical Center. Harvard Medical School. Boston, MA, United States., United States
MS

Max Shutran, MD, n/a (he/him/his)

Endovascular and Operative Neurovascular Surgery
BIDMC Brain Aneurysm Institute, Neurosurgical Division, Beth Israel Deaconess Medical Center. Harvard Medical School. Boston, MA, United States.
Boston, Massachusetts, United States
PT

Philipp Taussky, MD

Endovascular and Operative Neurovascular Surgery
Neurosurgical Division, Beth Israel Deaconess Medical Center. Harvard Medical School. Boston, MA, United States., United States

Introduction: Treatment of unruptured intracranial aneurysms (UIA) less than 7mm is controversial. We created a scoring system to guide treatment decisions which incorporates factors known to increase rupture risk. We evaluate clinical outcomes and the efficacy of treating UIAs less than 7mm.

Methods: A review of prospectively maintained data for UIA patients treated between 2014- 2021 was performed. The system of evaluation of SMALLSS score including Size, (4-7 mm: 1 point , < 3.9 mm: 0 point ), Multiple aneurysms (yes: 1 , no: 0), Anatomic location (posterior: 1, anterior: 0), Lineage- family history of aneurysm (yes:1, no: 0), Lifetime risk (age < 65: 1 , age >65: 0), Smoking history (yes: 1, no: 0 ), Shape (irregular:1, smooth:0 ) were utilized to evaluate decision making and treatment outcomes.

Results: A total of 1152 cases with unruptured intracranial aneurysms were treated over the study interval, of which 771 aneurysms (66.9%) were under 7 mm (220, 28.5% < 3.9 mm; 551, 71.5% 4-7 mm). Of these cases with small lesions, 5 (0.65%) had SMALLSS scores of 6, 59 (7.65%) had scores of 5, 155 (21.53%) scores of 4, 266 (34.5%) score of 3, 208 (26.98%) score of 2 and 63 (8.17%) score of 1. Only 4 (0.52%) had a score of zero. During this same interval, an estimated 1126 patients with aneurysms < 7mm were evaluated and not offered treatment, with the majority having SMALLSS scores of 2 and under (841, 74.7%). Serious neurologic complications occurred in 18 out of 771 aneurysms (2.33%) of which 4 were hemorrhagic and 14 were ischemic. No increased risk of treatment was observed for patients with higher natural history risks of hemorrhage. The obliteration rate was 98% in microsurgery group, 89.7% in endovascular group.

Conclusion : The SMALLSS scoring system can be used to help guide treatment decision-making for patients with small UIA. The risk of treatment did not increase with projected increased risk of rupture and overall high obliteration rates were achieved with endovascular and surgical techniques.