Introduction: The International Study of Unruptured Intracranial Aneurysms (ISUIA) criteria and the PHASES score are widely used to weigh the risk of intervention for unruptured aneurysms. The present study was designed to investigate the characteristics of ruptured aneurysms at a tertiary referral center and to compare these to the data published in both the ISUIA and PHASES studies.
Methods: A large single-center SAH database was retrospectively reviewed and patients were stratified by ethnicity, size and aneurysm location, history of hypertension, history of SAH, age and smoking status.
Results: A total of 520 ruptured aneurysms were identified. 334 (64.2%) were in the anterior circulation. Size stratification showed: <7mm: 259 (77.5%), 7-12.9mm: 63 (18.9%), 13-24mm: 12 (3.6%), and =25mm: 0 (0%). Similar size distribution was seen in 186 (35.8%) posterior circulation/posterior communicating artery aneurysms: <7mm: 143 (76.9%), 7-12.9mm: 36 (19.4), 13-24mm: 7 (3.7%), =25mm: 0 (0%). Upon calculating PHASES scores, 7 patients were excluded due to insufficient data for score calculation. Of 513 patients, 99 (19.3%) had scores =2, 123 (23.9%) had a score of 4, and 125 (24%) had a score of 5, and only 6 (1.1%) had a score =12 (Table 1). Smoking was prevalent in approximately 20% of patients across most PHASES score groups.
Conclusions: Approximately 77% of ruptured aneurysms were < 7mm, regardless of location. More than half had PHASES scores < 4, with almost 90% having a score< 8. This score is reported as having a 5-year rupture risk of 3.2%, a similar percentage to the risk of 5-year mortality from surgical or endovascular intervention. Strict adherence to the ISUIA criteria and the PHASES score does not appear to prevent the majority of morbidity-mortality from ruptured intracranial aneurysms. Further studies are needed to re-evaluate these tools.
Patient Care: Understanding the limitations of ISUIA criteria and PHASES scores in determining aneurysmal rupture risk can improve decision making and patient counseling.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Discuss the aneurysm rupture risk reported by the ISUIA
2) Calculate the aneurysm rupture risk using the PHASES score
3) Evaluate the applicability of ISUIA criteria and PHASES scores to counsel patients on the aneurysmal rupture risk