What are the Fisher grades?

Grade 1: no blood. Grade 2: diffuse thin (<1mm) subarachnoid blood. Grade 3: thick (≥1mm) localized clot or blood layer. Grade 4: intracerebral or intraventricular blood with or without SAH. Modified Fisher scale adds intraventricular blood as an independent vasospasm predictor.

Which Fisher grade carries the highest vasospasm risk?

Modified Fisher grade 3 and 4 (thick cisternal blood with intraventricular hemorrhage) carry the highest vasospasm risk (~40%). Grade 3 alone (thick SAH without IVH) has ~33% vasospasm risk. All grades ≥2 warrant nimodipine prophylaxis.

Fisher Grade (SAH Blood Volume)

Classify subarachnoid hemorrhage blood volume on CT using the Fisher grade to predict vasospasm risk.

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Fisher Grade (SAH Blood Volume)

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Frequently Asked Questions

What are the Fisher grades?

Which Fisher grade carries the highest vasospasm risk?