WFNS grading system

Last revised by Arlene Campos on 23 Jan 2024

The WFNS subarachnoid hemorrhage grading system, proposed in 1988 by the World Federation of Neurosurgical Societies uses the Glasgow Coma Scale and the presence of focal neurological deficits to grade the clinical severity of subarachnoid hemorrhage 1.

In 2016 a modified grading system was proposed to address inter-rater variability in determining what signs and symptoms constitute a focal neurological deficit and was shown to have better outcome prediction (as measured by the modified Rankin Scale (mRS) 2,3.


Original WFNS grading scale (o-WFNS)

The scale groups various GCS brackets and assigns them to a WFNS grade. The presence or absence of a focal neurological deficit is used to distinguish between grades II and III and is this distinction that causes the greatest observed inter-rater variability 2,3.

  • grade I: GCS 15

  • grade II: GCS 13-14, without focal neurological deficit

  • grade III: GCS 13-14, with focal neurological deficit

  • grade IV: GCS 7-12

  • grade V: GCS 3-6

The scale reflects that the biggest determinant of mortality is conscious state, whilst the predictor of morbidity is the presence of hemiparesis or aphasia 4.

Modified WFNS grading scale (m-WFNS)

The proposed modified scale removes the incorporation of presence or absence of additional focal neurological deficit from the definition of grade II and III, and instead purely relies on the GCS 2,3.

  • grade I: GCS 15

  • grade II: GCS 14

  • grade III: GCS 13

  • grade IV: GCS 7-12

  • grade V: GCS 3-6

See also

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