A 65-year-old man with a 7 mm unruptured intracranial aneurysm of the middle cerebral artery (MCA) bifurcation is evaluated for management. Per ISUIA (International Study of Unruptured Intracranial Aneurysms) and current guidelines, which factor most strongly predicts rupture risk?
- A Patient age >65 years
- B Aneurysm size, location (posterior circulation / posterior communicating), and morphology (irregular shape, daughter sac) ✓
- C Hypertension as a sole factor
- D Smoking history alone
Explanation
ISUIA data and subsequent meta-analyses identify aneurysm size >7 mm, posterior circulation location (basilar tip, posterior communicating artery), and irregular morphology (bilobular shape, daughter sac, aspect ratio >1.6) as the strongest independent predictors of rupture risk. The PHASES score incorporates these with population (Japanese/Finnish ancestry), hypertension, age, earlier SAH from another aneurysm, and size to estimate 5-year rupture risk. While hypertension and smoking are modifiable risk factors for aneurysm growth and rupture, they have lower discriminating power than size and morphology in individual aneurysms.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.