Aneurysmal SAH on admission CT — grade 0 to 4 for delayed-ischaemia risk
Cisternal subarachnoid blood
No subarachnoid blood
Thin SAH (< 1 mm)
Thick SAH (≥ 1 mm, filling a cistern or fissure)
Intraventricular haemorrhage
No intraventricular haemorrhage
Intraventricular haemorrhage present
Select the SAH pattern and whether IVH is present
Evidence
Original publication
Frontera JA, Claassen J, Schmidt JM, et al. Prediction of symptomatic vasospasm after subarachnoid hemorrhage: the modified fisher scale. Revised the 1980 Fisher scale to account for both cisternal SAH thickness and intraventricular haemorrhage; the risk of symptomatic vasospasm rose progressively from grade 0 to grade 4.
Neurosurgery, 2006
Open source
Guideline
The modified Fisher grade is used at admission to stratify the risk of delayed cerebral ischaemia / symptomatic vasospasm and to guide monitoring intensity (e.g. transcranial Doppler, imaging). It complements clinical grading scales such as Hunt & Hess and WFNS. Reported vasospasm rates vary between cohorts; use local data where available.
Last reviewed: 2026-09
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