WFNS Scale: World Federation of Neurosurgical Societies Subarachnoid Hemorrhage Scale

Hunt-Hess uses subjective descriptors (alert, drowsy, confused, stuporous, comatose) and presence of focal deficit. WFNS uses objective Glasgow Coma Scale (3-15) combined with focal deficit. For equivalent severity, WFNS is often lower grade than Hunt-Hess due to different thresholds (e.g., GCS 13-14 is Grade II WFNS but might be Grade II-III Hunt-Hess if drowsy/confused). Both predict outcome with similar accuracy (r=0.7-0.8 correlation). WFNS is more objective; Hunt-Hess is simpler. Most institutions use one system consistently; cite system used in publications.

With caution. GCS assessment in intubated patients is problematic: eye opening and verbal response are not evaluable (patient sedated and intubated); only motor response can be reliably scored. Some neurosurgeons use 'sedated GCS' or 'E1VtM3' notation (eye opening 1, verbal intubated, motor 3 example) acknowledging limitation. Better practice is to defer WFNS grade assessment until sedation clearance (24-48 hours post-extubation) when full GCS can be documented. Pre-intubation GCS (recorded by paramedics or ED) can be used if available, but acknowledge limitation.

WFNS assesses clinical severity (consciousness + neurological deficit); Fisher Scale assesses radiological severity (amount and distribution of subarachnoid blood on CT). The two are imperfectly correlated (r=0.5-0.7): small bleeds can produce severe deficits if in eloquent location; large bleeds can present with minimal deficits. Both WFNS and Fisher Scale independently predict outcome. Combined use (WFNS + Fisher) better predicts 30-day mortality and vasospasm risk than either alone. Report both when available.

Motor deficit includes: (1) Hemiparesis or hemiplegia (asymmetric strength 4/5 or lower on Motor Scale). (2) Aphasia or dysarthria (language/speech abnormality). (3) Pupil abnormality (anisocoria, blown pupil). (4) Ataxia or coordination abnormality. (5) Cranial nerve deficit (facial droop, eye deviation). Not included: drowsiness alone (part of GCS), headache, photophobia, nuchal rigidity (meningeal signs but not focal motor deficit). Absence of documented focal deficit means no motor deficit for WFNS grade determination, even if subtle weakness might be present.

WFNS grade typically refers to admission/initial assessment grade used for prognostic correlation. If patient improves clinically (e.g., GCS improves from 13 to 15), the improved GCS is documented but the original WFNS grade stands for outcome analysis. Some centers reassess WFNS at 48-72 hours or after intervention (vasospasm treatment, surgery) to document interval change, but the admission grade remains the prognostic predictor used in outcome studies. Always specify timing of grade assessment.