Calculators · Neurology · Classification

SAH grades: Hunt-Hess, WFNS and modified Fisher

Also called Hunt and Hess, WFNS grade, modified Fisher scale, subarachnoid haemorrhage grading

Grades aneurysmal subarachnoid haemorrhage three ways on one page: clinical (Hunt-Hess), GCS-based (WFNS) and CT blood load for vasospasm risk (modified Fisher).

Hunt-Hess: clinical picture
Modified Fisher: subarachnoid blood on CT

Fill 3 more fields to see the result.

Formula and scoring

WFNS: I = GCS 15 no motor deficit; II = 13–14 no deficit; III = 13–14 with deficit; IV = 7–12; V = 3–6. Modified Fisher: 0 no SAH/IVH; 1 thin SAH no IVH; 2 thin SAH + IVH; 3 thick SAH no IVH; 4 thick SAH + IVH.

Exam and ward pearls

  • Modified Fisher differs from the original Fisher scale by counting intraventricular blood; it predicted vasospasm better in 1355 patients.
  • Hunt-Hess: serious systemic disease or severe angiographic vasospasm moves the patient one grade worse.

When not to rely on it

  • "Thick" vs "thin" blood has no measured cut-off in the original modified Fisher paper; interrater reliability is limited.
  • Grade wording here is quoted from open-access secondary sources that cite the originals; the 1968 and 1988 primary papers were not available in full text.

Source

  1. Hunt WE, Hess RM. Surgical risk as related to time of intervention in the repair of intracranial aneurysms. J Neurosurg. 1968;28(1):14-20. doi:10.3171/jns.1968.28.1.0014 · PMID 5635959
  2. Report of World Federation of Neurological Surgeons Committee on a Universal Subarachnoid Hemorrhage Grading Scale. J Neurosurg. 1988;68(6):985-6. doi:10.3171/jns.1988.68.6.0985 · PMID 3131498
  3. Frontera JA, Claassen J, Schmidt JM, Wartenberg KE, Temes R, Connolly ES Jr, et al. Prediction of symptomatic vasospasm after subarachnoid hemorrhage: the modified Fisher scale. Neurosurgery. 2006;59(1):21-7. doi:10.1227/01.neu.0000243277.86222.6c · PMID 16823296
  4. Zhou Z, Yu J. CTA study of ruptured aneurysms of the posterior communicating artery. Stroke Res Treat. 2022;2022:5774735 (reproduces Hunt-Hess and modified Fisher definitions). doi:10.1155/2022/5774735 · PMID 36160068
  5. Guo L, Yang X, Yang B, Tang G, Li C. Prevalence, in-hospital mortality, and factors related to neurogenic pulmonary edema after spontaneous subarachnoid hemorrhage: a systematic review and meta-analysis. Neurosurg Rev. 2023;46(1):169 (reproduces the WFNS grades). doi:10.1007/s10143-023-02081-6 · PMID 37432487

Formula and cut-offs checked against these sources on 8 Nov 2026. Educational tool for clinicians; it does not replace clinical judgement.

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