Modified World Federation of Neurosurgical Societies subarachnoid hemorrhage grading system

A modified World Federation of Neurosurgical Societies scale (m-WFNS scale) for aneurysmal subarachnoid hemorrhage (SAH) recently has been proposed, in which patients with Glasgow Coma Scale (GCS) scores of 14 are assigned to grade II and those with GCS scores of 13 are assigned to grade III regardless of the presence of neurologic deficits. The study objective was to evaluate outcome predictability of the m-WFNS scale in a large cohort.

This was a multicenter prospective observational study conducted in Japan. A total of 1656 patients with SAH were registered during the 2.5-year study period, and the outcome predictability, using the Glasgow Outcome Scale (GOS) and modified Rankin Scale (mRS) scores at discharge and at 90 days after onset, was evaluated by comparing the m-WFNS with the original WFNS scale. We focused on whether significant differences in these scores were present between the neighboring grades.

In the m-WFNS scale, significant difference between any neighboring grades was observed both in the mean GOS and mRS scores at 90 days except between grades III/IV. However, differences were not significant between grades II/III and between grades III/IV in the original WFNS scale.

SAH-induced brain injury may be substantially severer in patients with GCS 13 than those with GCS 14, which may explain why grade III patients faired significantly worse than grade II patients by the modified WFNS scale. Although further validation is necessary, the m-WFNS scale has a potential of providing neurosurgeons with simpler and more reliable prognostication of patients with SAH.