Fisher & Modified Fisher Grade (SAH)
Fisher (1980) + modified Fisher (Frontera 2006)Grades the CT blood burden after aneurysmal subarachnoid hemorrhage to estimate vasospasm risk. Both the original Fisher scale (1–4) and the modified Fisher scale of Frontera (0–4) are reported side by side because the two are frequently confused.
Also searched as: subarachnoid hemorrhage · ct · vasospasm · aneurysm · subarachnoid · bleed
Information
Incomplete input
- Please provide: Subarachnoid blood load (none / thin <1 mm / thick ≥1 mm or localized clot), intraventricular hemorrhage status, intracerebral (intraparenchymal) hemorrhage status.
How this tool works
The original Fisher scale (1980) relates the amount and distribution of subarachnoid blood on admission CT to the likelihood of symptomatic vasospasm: group 1 no blood; group 2 diffuse or thin (< 1 mm) blood; group 3 localized clot and/or thick (≥ 1 mm) blood; group 4 intracerebral or intraventricular hemorrhage with diffuse or no subarachnoid blood. The modified Fisher scale (Frontera 2006) reorders risk by combining SAH thickness with the presence of intraventricular hemorrhage: 0 no SAH/IVH; 1 thin SAH without IVH; 2 thin SAH with IVH; 3 thick SAH without IVH; 4 thick SAH with IVH. Because "Fisher 4" means entirely different things in the two systems, this calculator always states both grades explicitly.
References
- Fisher CM, et al. Neurosurgery 1980;6:1–9 (relation of CT blood to vasospasm)
- Frontera JA, et al. Neurosurgery 2006;59:21–7 (modified Fisher scale)
- Grading of aneurysmal SAH review incl. the Fisher group-4 pitfall (PMC)
Implemented from the cited published sources. Educational use only; confirm against current guidelines before clinical use.
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