🧠 Modified Fisher Scale (SAH Vasospasm Risk)
Estimate cerebral vasospasm risk after SAH with the modified Fisher scale.
Clinical takeaway
Thick cisternal blood plus IVH carries the highest risk.
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When to use
Predict symptomatic vasospasm from the CT bleed pattern.
How it works
Grades 0–4 based on thickness of subarachnoid blood and presence of intraventricular haemorrhage. Higher grades carry higher vasospasm risk.
Key points
- Thick cisternal blood plus IVH carries the highest risk.
- Guides intensity of vasospasm surveillance.
- Complements clinical grading scales.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| CT appearance | 0 — No SAH or IVH |
|---|
→Modified Fisher0/4
- Approx. symptomatic vasospasm risk：~0%
| CT appearance | 4 — Thick SAH with IVH |
|---|
→Modified Fisher4/4
- Approx. symptomatic vasospasm risk：~40%
Frequently asked questions
- What is Modified Fisher Scale (SAH Vasospasm Risk)?
- Estimate cerebral vasospasm risk after SAH with the modified Fisher scale.
- How is Modified Fisher Scale (SAH Vasospasm Risk) calculated? What is the core formula?
- Grades 0–4 based on thickness of subarachnoid blood and presence of intraventricular haemorrhage. Higher grades carry higher vasospasm risk.
- When is Modified Fisher Scale (SAH Vasospasm Risk) used?
- Predict symptomatic vasospasm from the CT bleed pattern.
- What are the key clinical points for Modified Fisher Scale (SAH Vasospasm Risk)?
- Thick cisternal blood plus IVH carries the highest risk. Guides intensity of vasospasm surveillance. Complements clinical grading scales.
- What are the limits and cautions when using Modified Fisher Scale (SAH Vasospasm Risk)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is Modified Fisher Scale (SAH Vasospasm Risk) calculated in practice? Can you show a worked example?
- Inputs: CT appearance 0 — No SAH or IVH → Result: Modified Fisher 0 /4（Approx. symptomatic vasospasm risk: ~0%） Inputs: CT appearance 4 — Thick SAH with IVH → Result: Modified Fisher 4 /4（Approx. symptomatic vasospasm risk: ~40%）