Can Treatment Decision of Unruptured Intracranial Aneurysms Be Based on PHASES Score?

Background: The natural history of unruptured incidentally discovered intracranial aneurysms (UIA) remains unpredictable. Therefore, when asymptomatic, the management remains controversial. PHASES score was recently proposed to better estimate the 5-year risk of rupture of UIA. Methods: The aim of this study is to assess the usability of the PHASES score using our prospective and consecutive dataset (2006–2014). We compared scores calculated using the cohort of UIA followed-up (UIAFU), UIA initially treated (UIAIT) and patients diagnosed with subarachnoid hemorrhage (SAH). Score distributions were compared between cohorts and between cases with stable lesions and those with aneurysm growth or rupture. Results: Two-hundred ninety-one patients were followed up with a mean follow-up time of 3.2 years and 1,177.6 aneurysm years. Twenty-nine cases were observed with growing aneurysms and two unexpected aneurysm ruptures. PHASES score of patients with observed aneurysm growth or rupture showed a trend toward higher values (mean 3.9 ± 2.7 SD) than in patients with unruptured stable lesions (mean 3.0 ± 2.3 SD; p = 0.2). Comparing 269 SAH patients with 291 cases of UIAIT and with the 291 cases followed-up, we observed that SAH patients had a significantly higher PHASES score followed by initially treated and initially followed up patients (SAH: mean 5.6 ± 2.9 SD; UIAIT: mean 5.4 ± 3.14 SD; UIAFU: mean 3.0 ± 2.4 SD; p < 0.01). Conclusions: There is a clear shift toward the left of the PHASES score distribution in our prospective cohorts (UIAFU stable, UIAFU unstable, UIAIT, SAH aneurysms). The treatment threshold seems to be above a PHASES score of 3. The PHASES score can be used only for cases diagnosed with sporadic saccular bifurcation aneurysms. It cannot be used for patients with a familial history, PKD disease, or symptomatic aneurysms and does not take into account smoking among other important risk factors.