Modified Fisher scale calculator

Modified Fisher Scale

Modified Fisher Scale — SAH Vasospasm Risk

CT Findings	Select Grade
Grade	1 Grade 0 — No SAH or IVH (0) Grade 1 — Thin SAH, no IVH (1) Grade 2 — Thin SAH with IVH (2) Grade 3 — Thick SAH, no IVH (3) Grade 4 — Thick SAH with IVH (4)
Modified Fisher Grade

Interpretation — Risk of Symptomatic Vasospasm
Grade	Vasospasm Risk	Description
0 | ~0% | No subarachnoid blood detected.
1 | ~24% | Focal or diffuse thin SAH, no intraventricular hemorrhage (IVH).
2 | ~33% | Focal or diffuse thin SAH with IVH.
3 | ~33% | Focal or diffuse thick SAH (>1mm), no IVH.
4 | ~40% | Focal or diffuse thick SAH with IVH. Highest vasospasm risk.

References
Fisher CM, Kistler JP, Davis JM. Relation of cerebral vasospasm to subarachnoid hemorrhage visualized by computerized tomographic scanning. Neurosurgery. 1980;6(1):1-9. PMID 7354892. 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. PMID 16823296.