Modified Fisher Scale (SAH vasospasm risk)
Modified Fisher grade (0-4) from cisternal SAH thickness and intraventricular hemorrhage, with the symptomatic-vasospasm risk band.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Cisternal subarachnoid blood
- Thick SAH (focal or diffuse)
- Intraventricular hemorrhage present
- Yes
Result: Modified Fisher grade 4 (thick SAH with IVH): symptomatic-vasospasm risk ~40%.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Grading
- grade 0 = no SAH or IVH; 1 = thin SAH, no IVH; 2 = thin SAH with IVH; 3 = thick SAH, no IVH; 4 = thick SAH with IVH.
- Vasospasm
- symptomatic-vasospasm incidence about 24% at grade 1, 33% at grades 2 and 3, and 40% at grade 4.
What you enter
- Cisternal subarachnoid blood
- Intraventricular hemorrhage present
How this is calculated
Frontera JA, Claassen J, Schmidt JM, et al. Prediction of symptomatic vasospasm after subarachnoid hemorrhage: the modified Fisher scale. Neurosurgery. 2006;59(1):21-27. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.