Fisher Scale Calculator (Subarachnoid Hemorrhage)

Modified Fisher scale (0–4) for vasospasm risk after subarachnoid hemorrhage.

For educational and clinical reference. Not a substitute for medical judgment. See the medical disclaimer.
Score
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Interpretation
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References

  1. 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.
  2. Fisher CM, Kistler JP, Davis JM. Relation of cerebral vasospasm to subarachnoid hemorrhage visualized by CT scanning. Neurosurgery. 1980;6(1):1-9.

How to use

  1. Select the CT appearance that best describes the subarachnoid blood.
  2. The grade and vasospasm risk update instantly.
  3. Use the grade alongside clinical exam to guide vasospasm monitoring.

Frequently asked questions

What is the modified Fisher scale used for?

It grades aneurysmal subarachnoid hemorrhage on CT to predict the risk of symptomatic vasospasm and delayed cerebral ischemia.

Modified vs original Fisher scale?

The modified Fisher (Frontera 2006) is the current standard and adds the presence of IVH as a separate dimension, improving predictive performance.

When should the CT be obtained?

Within 24–72 hours of ictus, before significant blood breakdown alters the appearance.

Does Fisher grade dictate treatment?

Higher grades prompt closer monitoring (transcranial Doppler, neuro checks) and a low threshold for vasospasm prophylaxis with nimodipine and euvolemia.

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