neurologystaging system

WFNS SAH Scale

The World Federation of Neurosurgical Societies scale grades aneurysmal SAH severity using GCS and presence of major focal neurological deficit. It provides a more standardised and reproducible grading system compared to Hunt & Hess.

inputs

✓ when to use

Use alongside or instead of Hunt & Hess for SAH clinical grading. WFNS is preferred in research settings and increasingly in clinical practice due to its reliance on the objective GCS rather than subjective clinical descriptors.

✗ when not to use

Same limitations as any SAH grading system — does not capture radiographic severity (use Fisher/modified Fisher for that), aneurysm characteristics, or patient comorbidities. The focal deficit criterion can be difficult to assess in drowsy patients.

clinical pearls

  • WFNS Grade I = GCS 15 (no focal deficit). Grade II = GCS 13–14 without focal deficit. Grade III = GCS 13–14 WITH focal deficit. Grade IV = GCS 7–12. Grade V = GCS 3–6. The distinction between II and III is solely the presence of a major focal deficit.
  • WFNS is more reproducible than Hunt & Hess because it relies on GCS (standardised, quantitative) rather than subjective descriptors like 'drowsiness' or 'confusion'.
  • The critical clinical decision point is Grade III–IV: should intervention be offered? This depends on clinical trajectory, patient age, comorbidities, and aneurysm accessibility. Multidisciplinary neurovascular discussion is essential.
  • Always report both the WFNS grade AND the GCS components (E/V/M) for maximum information. A WFNS IV from E2V2M8 vs E3V3M6 implies different neurological states.
  • WFNS and Hunt & Hess do not always concordant. A patient with 'confusion and mild focal deficit' might be Hunt & Hess III but WFNS II (if GCS is 14 without major deficit). Be explicit about which system you are using.

related tools

hunt-hessAlternative clinical SAH gradinggcsGCS assessment underlying WFNS grade