A 45-year-old woman is found to have a 7 mm unruptured intracranial aneurysm at the middle cerebral artery bifurcation as an incidental finding on MRI done for headache. She is otherwise well with no prior haemorrhage. Which scoring system and which annual rupture risk estimate best guides the management decision?

• A WFNS grade; 7 mm aneurysms always require immediate surgical clipping
• B Hunt and Hess classification; prophylactic coiling is mandatory for all aneurysms >5 mm
• C GCS scoring; observation alone for all aneurysms <10 mm
• D PHASES score; aneurysm ≥7 mm at MCA bifurcation carries approximately 0.5% annual rupture risk ✓

Explanation

The PHASES score (Population, Hypertension, Age, Size, Earlier subarachnoid haemorrhage, Site) quantifies the 5-year rupture risk of unruptured intracranial aneurysms. For a 7–9.9 mm MCA aneurysm in a non-Finnish/Japanese population without hypertension or prior SAH, the annual rupture risk is approximately 0.5–0.7%. PHASES-based management involves individualised risk-benefit analysis, considering procedural risk of intervention versus rupture risk. The WFNS and Hunt-Hess scales grade severity of subarachnoid haemorrhage after rupture, not unruptured aneurysm management. Most guidelines recommend intervention (coiling or clipping) for 7–10 mm aneurysms at favourable locations given acceptable procedural risk.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.